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Adsorptive removal of lead (Pb 2+ ) ion from water using cellulose acetate/polycaprolactone reinforced nanostructured membrane

DOI:10.1088/1755-1315/191/1/012139
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Abstract and Figures

Nanostructured membranes of cellulose acetate (CA) with various polycaprolactone (PCL) loadings (0%, 10%, 20% and 30%) were produced via electrospinning process for the removal of Pb²⁺ ion from wastewater. Optimized electrospinning parameters were utilized: voltage supply (30 kV), temperature (25 °C), tip to collector distance (18 cm) and needle size (25 G). Certain characterization techniques were used to investigate the effect of PCL addition on CA nanostructured membranes. The surface morphology was examined through Scanning Electron Microscopy (SEM), and chemical composition and molecular structure were determined using Scanning Electron Microscope - Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Fourier Transform Infrared Spectroscopy (FTIR), respectively. Results showed that the incorporation of PCL in CA produced finer fiber diameter which gave the membrane a larger surface area; thus, increasing the adsorption sites. Based on the results, adsorption capacity was improved from 43.96 mg Pb²⁺/g of pure CA membrane to 70.50 mg Pb²⁺/g of CA/PCL doped membrane. Moreover, the results of this experiment best fitted the pseudo second-order kinetics, and the Freundlich isotherm which appropriately describe the adsorption process. CA membranes are widely used in several separation processes, and the results showed, its capability can be further enhanced by the incorporation of PCL to produce nanostructured membranes.
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IOP Conference Series: Earth and Environmental Science
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Adsorptive removal of lead (Pb2+) ion from water using cellulose
acetate/polycaprolactone reinforced nanostructured membrane
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The 4th International Conference on Water Resource and Environment (WRE 2018)
IOP Conf. Series: Earth and Environmental Science 191 (2018) 012139 IOP Publishing
doi:10.1088/1755-1315/191/1/012139
1
Adsorptive removal of lead (Pb2+) ion from water using
cellulose acetate/polycaprolactone reinforced nanostructured
membrane
R R Aquino1,3, M S Tolentino1,3, R M P D Elacion1, R Ladrillono1, T R C
Laurenciana1 and B A Basilia1,2
1School of Chemical, Biological, and Materials Engineering and Sciences, Mapúa
University, 658 Muralla St., Intramuros, Manila 1002, Philippines
2Industrial Technology Development Institute, Department of Science and Technology,
Bicutan, Taguig City, Metro Manila 1631, Philippines
E-mail: rraquino@mapua.edu.ph/marvstolentino@yahoo.com
Abstract. Nanostructured membranes of cellulose acetate (CA) with various polycaprolactone
(PCL) loadings (0%, 10%, 20% and 30%) were produced via electrospinning process for the
removal of Pb2+ ion from wastewater. Optimized electrospinning parameters were utilized:
voltage supply (30 kV), temperature (25 °C), tip to collector distance (18 cm) and needle size
(25 G). Certain characterization techniques were used to investigate the effect of PCL addition
on CA nanostructured membranes. The surface morphology was examined through Scanning
Electron Microscopy (SEM), and chemical composition and molecular structure were
determined using Scanning Electron Microscope – Energy Dispersive X-ray Spectroscopy
(SEM-EDX) and Fourier Transform Infrared Spectroscopy (FTIR), respectively. Results
showed that the incorporation of PCL in CA produced finer fiber diameter which gave the
membrane a larger surface area; thus, increasing the adsorption sites. Based on the results,
adsorption capacity was improved from 43.96 mg Pb2+/g of pure CA membrane to 70.50 mg
Pb2+/g of CA/PCL doped membrane. Moreover, the results of this experiment best fitted the
pseudo second-order kinetics, and the Freundlich isotherm which appropriately describe the
adsorption process. CA membranes are widely used in several separation processes, and the
results showed, its capability can be further enhanced by the incorporation of PCL to produce
nanostructured membranes.
1. Introduction
The presence of heavy metals in different water sources can pose a great threat to various living
organisms, specifically to humans. With this as a problem, many researches in the past years focused
on the removal of certain heavy metals in water [1]. Several processes are being conducted to treat
wastewater to remove heavy metals, and protect further water resources [2]. Emerging treatment
techniques such as adsorption using different adsorbent media, namely, modified natural materials [3],
industrial by-products [4], agricultural wastes [5], biological wastes (bio-sorption) [6], and modified
biopolymers and hydrogels [7], are commonly used in the removal of heavy metals from water.
Furthermore, other techniques include membrane filtration using different membrane blends [8],
electrodialysis [9] and photocatalysis [10].
The 4th International Conference on Water Resource and Environment (WRE 2018)
IOP Conf. Series: Earth and Environmental Science 191 (2018) 012139 IOP Publishing
doi:10.1088/1755-1315/191/1/012139
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Among the known water treatment techniques, adsorption process is widely used because of its
versatile applications other than heavy metal adsorption. Its applications also include adsorptive
removal of nitrogen contamination [11] and organic pollutants [12]. In addition to adsorption is
membrane technology, which is also known for its significant contribution in the field of water
treatment processes [13]. Furthermore, distinct advantages in applying membrane processes compared
to other water treatment processes include low energy consumption, membrane separations with mild
operating conditions, possible optimization of different membrane properties to satisfy various
requirements, minimal footprint, and most importantly, the feasibility to combine membrane processes
with other processes [14]. Several ways can be utilized in producing membranes, but a prominent
method is the electrospinning process, wherein nanofibers can be produced exhibiting special
properties such as large surface area to mass ratio, low density, high pore volume and tight pore size
make them suitable for a wide range of applications [15]. With the flexible uses of adsorption together
with the unique properties of electrospun membranes, an innovative technique for water treatment
applications [16], specifically the removal of heavy metals from wastewater [17], can be achieved.
Cellulose acetate (CA) is mostly used as membrane in several separation and water treatment
processes because of its desirable properties, mainly low cost/benefit ratio [18]. Its competence in
sequestering heavy metals in water had been proven because of the presence of different functional
groups such as –COOH, –SO3H and –NH2 groups, which are naturally grafted on CA. Hence, heavy
metals ions can attach and form bonds on the surface of CA through complexation mechanisms [19].
Studies had been made wherein reinforcement of synthetic polymers with CA were done to improve
its adsorption capability. In the study conducted by Tian and co-workers [20], electrospun CA was
surface-modified using poly (methacrylic acid) (PMAA). The results of their study showed an
increased adsorption capacity for Cd2+, Cu2+ and Hg2+ upon modification of CA. For instance, it was
found that there is the shifting of adsorption peak for –COO– from 1734 cm-1 to 1730 cm-1. This
signifies the decrease in the electronegativity of –COO– which is the main reason in the attraction of
electropositive heavy metal ions.
Other than water treatment, electrospun membranes are also significant in the biomedical field,
usually used as wound dressing [21]. One of the promising materials being used to fabricate
biocompatible membranes is the polycaprolactone (PCL), mainly because of its outstanding structure,
and excellent mechanical and physical properties [22].
In this study, it was aimed to fabricate a novel electrospun CA nanostructured membrane
impregnated with PCL to remove toxic Pb2+ from wastewater by means of membrane adsorption. The
material that produced underwent a series of characterizations using Scanning Electron Microscopy
(SEM) and Fourier Transform Infrared Spectroscopy (FTIR) to investigate its acquired properties. The
ability of the nanostructured membrane in removing Pb2+ metal ions from wastewater was investigated.
The adsorption kinetics, equilibrium, and adsorption isotherm were also studied.
2. Experimental
CA (65,000 g/mol) and commercial grade PCL (60,000 g/mol) utilized in this study were
provided by Chemline Enterprises. Acetone and dichloromethane (DCM) were used as solvents
for CA and PCL, respectively. Pure CA and CA/PCL blends of different PCL loading (0%, 10%,
20%, and 30%) were electrospun and the following parameters were applied: room temperature
(25 °C), 30 kV applied voltage and the distance from the tip to the collector was fixed at 18 cm.
The nanostructured membranes produced were characterized using the following techniques:
Fourier Transform Infrared Spectroscopy (FTIR) to confirm the presence of organic molecules
and provides a direct evidence of PCL and CA attachment, Scanning Electron Microscope (SEM)
for the morphological investigation of the material, SEM–Energy Dispersive X-ray Spectroscopy
(SEM-EDX) – with SEM in combination to determine the elemental composition of the sample.
Afterwards, the adsorption analysis was performed making use of the best CA/PCL blend
membrane and pure CA membrane as adsorbent at various amounts (0.05 g to 0.15 g at 0.025 g
interval) in a 250 mL flask having 200 mL Pb2+ solution with 100 ppm concentration. From these
The 4th International Conference on Water Resource and Environment (WRE 2018)
IOP Conf. Series: Earth and Environmental Science 191 (2018) 012139 IOP Publishing
doi:10.1088/1755-1315/191/1/012139
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fiber dosages and volume, the liquor to sorbent ratio ranges from 500:1 to 2000:1. The set up was
then placed in a water bath shaker for24 hours. Then every 8 hours, a 50 mL aliquot was collected
and digested. Analysis of each solution was conducted using Absorption Spectrophotometer
analyzer (AAS) to determine the following:the effect of contact time and Pb2+ initial concentration
on the adsorption capacity, adsorption kinetics (the best fit between pseudo first-order and pseudo
second-order kinetic model), and adsorption isotherm (Langmuir and Freundlich isotherm model).
3. Results and discussion
3.1. Effect of PCL on fiber structure
Figure 1 shows the SEM micrograph of pure CA membrane having uniform and straight fiber
morphology. The incorporation of PCL to CA reduced the fiber diameter of the membrane produced
which can be observed from the morphologies of the CA/PCL blends and their corresponding average
fiber diameters. Since PCL has a better conductivity compared to CA, and has good adhesion to a
broad spectrum of substrates [23], it provides better stretching of the solution which produced finer
fiber diameter [24]. Based from the obtained micrographs, CA with 10% PCL produced the
nanostructured fiber with the minimum average fiber diameter (570 ± 188 nm).
Figure 1. SEM micrographs of electrospun pure CA and CA/PCL blends at low (first row) and high
(second row) magnifications, with their corresponding average fiber diameters.
3.2. Molecular structure of the fibers
The FTIR results of the electrospun membranes were presented in figure 2.a. For pure PCL, at around
2900 cm-1 and 1700 cm-1, the spectrum indicates the presence of carbon-hydrogen (C-H) stretching
and carbonyl (C=O) stretching of carboxylic acid, respectively. For pure CA, the carbonyl (C=O)
group stretching is found at 1748.26 cm-1. The three changes or shifting of peaks for pure CA as
shown in figure 2.a shows the effect of adding PCL in the solution. The continuous increase in peaks
upon PCL additionimplies the successful bonding of the CA with the PCL in the membrane.
3.3. Adsorption analysis
As observed from the SEM micrographs (figure 1), the CA/PCL (10%) blend produced, has the finest
fiber diameter among the different blends. Finer fiber diameter would mean larger surface area which
would, in turn, mean larger adsorption area. Hence, the said blend and pure CA were used in the
adsorption experiment to compare the adsorption capacity as well as the kinetics of both fibers.
The 4th International Conference on Water Resource and Environment (WRE 2018)
IOP Conf. Series: Earth and Environmental Science 191 (2018) 012139 IOP Publishing
doi:10.1088/1755-1315/191/1/012139
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Furthermore, based on the results of the SEM-EDX as seen on figure 2.b and 2.c, traces of Pb2+ were
detected after the adsorption process which proved the effectivity of the membrane produced.
Figure 2. a.) FTIR spectra of the different membrane blends, and SEM-EDX results for
CA/PCL (10%) blend b.) before and c.) after Pb2+ adsorption.
3.3.1. Effect of adsorbent dosage. For pure CA, based on the graph on figure 3.a, there is a noticeable
increase in the Pb2+ uptake when the CA fiber dosage was increased from 0.05 g to 0.075 g. As for the
CA/PCL (figure 3.b), similar characteristics and behavior could be observed. In this case, the optimum
adsorption dosage was determined to be 0.075 g. For both membranes, decrease in the adsorption
capacity can be observed when the fiber dosage exceeds 0.075 g. The decrease in adsorption capacity
could mean two things. First, adsorption equilibrium may not have been attained as the fiber dosage
was increased. Second, it is also possible that all Pb2+ ions from the solution adhered to the adsorbent
while there were still available sites for adsorption [23]. Thus, the results show that 100 ppm of Pb2+
was enough to saturate 0.075 g of pure CA, and CA/PCL blend.
Figure 3. Adsorption capacity of a.) pure CA and b.) CA/PCL (10%) fibers for Pb2+
as a function of adsorbent dosage at different time intervals.
3.4. Kinetics study
3.4.1. Effect of contact time. As can be seen on figure 4.a, equilibrium state was reached after 6 hours
for pure CA. Increasing trend for the adsorption capacity with time was observed up to 6 hours but at
time values greater than 6 hours, the adsorption capacity remained constant. This is most possibly due
to the large amount of active sites in the adsorbent [25] initially available, before the fiber started to
become saturated. In addition, initially there exist a high concentration gradient which aids the fast
The 4th International Conference on Water Resource and Environment (WRE 2018)
IOP Conf. Series: Earth and Environmental Science 191 (2018) 012139 IOP Publishing
doi:10.1088/1755-1315/191/1/012139
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diffusion of Pb2+ onto the surface of the adsorbent. Conversely,for CA/PCL blend, equilibrium was not
attained. Based figure 4.a, even at 10 hours, the adsorption capacity sill tends to increase. In this case,
due to the interaction of CA and PCL, and also because of finer fiber diameters produced, higher
amount of active sites became available for the adsorption of Pb2+ on the membrane.
3.4.2. Adsorption kinetics. Based on the results of the experimental data fitting (figure 4.b and 4.c),
pseudo second-order was found to be the model that best fitted the adsorption of Pb2+ onto fibers with
R2 value of 0.9174 for pure CA and 0.9934 for CA/PCL (10%) blend, compared to that of the pseudo
first-order model with R2 value of 0.2502 and 0.1598 for pure CA and CA/PCL (10%), respectively.
This means that the Pb2+ ion first dissociate from its parent molecule and form a chemical bond, likely
dipolar covalent, with the potential functional group of the fibers thereafter. These potential binding
sites are the amines, hydroxyls and carbonyls from CA and PCL. Also, the pseudo second-order
kinetics reveals that for both pure CA and CA/PCL (10%) membranes, the chemisorption is the
rate-limiting step for the adsorption of Pb2+, wherein the Pb2+ ions affix to the membrane with a
covalent bond among the sorbent and sorbates. Here, sites may be searched to which maximizes
the coordination number with the surface [26].
Figure 4. a.) Effect of contact time on the adsorption capacity of the fibers for Pb2+,
b.) pseudo first-order and c.) pseudo second-order model plots for the adsorbents.
3.5. Equilibrium study
Based from the gathered results (figure 5), the adsorption capacity is linearly increasing with initial
concentration of Pb2+ for both fibers at a fixed adsorbent dosage. This is due to the increase in the
driving force of the concentration gradient which accelerates the diffusion of Pb2+from the solution to
the adsorbent surface. For pure CA adsorbent, an increase in the adsorption capacity was observed
from 3-6 hours of immersion and decreases at 9 hours of immersion due to reversibility in the
adsorption process. On the other hand, it was observed that the adsorption capacity of PCL is steady
and decreases slightly which suggests that PCL dope fibers were more stable adsorbent for metal
specie at longer times. In addition, it can be seen that PCL doped fibers have higher adsorption
capacities compared to pure CA for all varied initial concentration of Pb2+ solution.
Figure 5. Effect of initial Pb2+ concentration on the adsorption capacity of a.) pure CA and
b.) CA/PCL (10%) fibers at different time intervals.
The 4th International Conference on Water Resource and Environment (WRE 2018)
IOP Conf. Series: Earth and Environmental Science 191 (2018) 012139 IOP Publishing
doi:10.1088/1755-1315/191/1/012139
6
3.6. Adsorption isotherm
Based on the results in figure 6, the regression coefficient R2 of linear Freundlich isotherm for pure
CA and CA/PCL were found to be 0.9957 and 0.994, respectively. The experimental data best-fitted
the Freundlich isotherm model because it has the best R2 compared to Langmuir isotherm model. This
explains that the adsorption process occurred on a heterogenous (multiple layer) surface with uniform
energy [25]. Also, physisorption and chemisorption occur at low coverages.
Figure 6. Adsorption isotherm fitting; a.) Langmuir isotherm and b.) Freundlich isotherm.
4. Conclusion
Electrospun CA/PCL nanostructured membranes for the adsorption of Pb2+ were successfully
produced. The SEM results showed that CA/PCL (10%) exhibited the smallest average fiber
diameter, which means larger adsorption surface area. Interaction between CA and PCL was
supported by the results of FTIR analysis. For the adsorption experiment, based from the gathered
results, it was observed that the incorporation of 10% PCL improved the adsorption capacity of
pure CA from 43.96 mg Pb2+/g membrane of pure CA to 70.50 mg Pb2+/g of PCL doped fibrous
membrane, after 6 hours in which the saturation of pure CA had occurred. The adsorption data of
the study were best fitted in the pseudo-second order model and Freundlich isotherm model.In
general, it had been observed that the incorporation of PCL can improve the adsorption capacity
of pure CA, which shows that the CA/PCL (10%) blend is a more suitable adsorbent for heavy
metals at longer time intervals and can be a promising material for wastewater treatment.
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Full-text available
  • Jul 2023
To achieve high throughput, low-pressure drops, and high adsorption capacity of Cr(VI) and Pb(II) in industrial wastewater treatment, cellulose membranes containing cationic and anionic groups were fabricated, respectively. In this process, cost-effective cotton fabrics were oxidized using sodium periodate, followed by quaternary ammonium or sulfonation modifications. The chemical composition, surface morphology, and thermal and mechanical properties of the cellulose membranes were investigated by ATR-FTIR, solid-state NMR, SEM, TGA, and tensile experiments. Quaternary ammonium, aldehyde, and sulfonate groups were distributed on the cationic/anionic cellulose fibers as adsorption sites, which issue remarkable adsorption capability to the cellulose membranes. The highly toxic Cr(VI) and Pb(II) ions were used to challenge the adsorption capacity of the cationic and anionic cellulose membranes, respectively. The maximum adsorption capacities of Cr(VI) and Pb(II) ions were 61.7 and 63.7 mg/g, respectively, suggested by Langmuir isotherms, kinetics, and thermodynamics in the static experiments. The dynamic adsorption capability of cationic cellulose membranes against Cr(VI) ions was determined and compared with that of commercially available anionic-exchange membranes. Spiral wound filtration cartridges were fabricated by cationic and anionic cellulose membranes, respectively, and were used to adsorb Cr(VI) and Pb(II) from lab-made wastewater, respectively. The cationic cellulose cartridge can purify 4.4 L of wastewater containing 1.0 mg/L of Cr(VI) ions with a 100% removal ratio, while the pressure drop was retained at 246 Pa. Similarly, the anionic cellulose cartridge exhibited even more impressive adsorption capability; the removal ratio against Pb(II) was 99% when 8.6 L of 1.0 mg/L of Pb(II) ions containing wastewater was treated, and the pressure drop was retained at 234 Pa. A composite cartridge fabricated by the integration of cationic and anionic cellulose membranes was successfully employed to purify the wastewater containing Cr(VI) and Pb(II) simultaneously. The possible adsorption mechanism was proposed, and the recycling ability of the cellulose membranes was also discussed.
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... Table S3: Comparison of maximum Pb 2+ ions adsorption capacity of other reported adsorbents. References [73][74][75][76][77][78][79][80][81][82] are cited in the supplementary materials. Data Availability Statement: All data generated or analyzed during this study are included in the published article. ...
Adsorption of Pb2+ Ions from Aqueous Solution onto Porous Kappa-Carrageenan/Cellulose Hydrogels: Isotherm and Kinetics Study
Article
Full-text available
  • Jun 2023
Heavy metal ion pollution poses severe health risks. In this study, a kappa-carrageenan/cellulose (κ-CG/CL) hydrogel was prepared using a facile one-step method to remove Pb2+ ions from aqueous solutions. The functional groups and crystallinity nature of κ-CG/CL hydrogel have been identified via Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). In contrast, the porous morphology and size distribution on the surface of κ-CG/CL hydrogel with a pore size of 1–10 μm were identified using scanning electron microscope (SEM) and Brunauer–Emmett–Teller (BET) surface area analysis. The as-prepared κ-CG/CL hydrogel effectively removed Pb2+ ions, primary environmental pollutants. The effects of pH and contact time on Pb2+ adsorption were studied along with the adsorption isotherms and kinetics of Pb2+ adsorption onto the hydrogels from aqueous solutions. Notably, the aqueous solutions were effectively treated with the prepared κ-CG/CL hydrogels to remove Pb2+ ions. The adsorption results fit well with pseudo-first- and second-order kinetic, Elovich, intra-particle diffusion, and Langmuir and Freundlich isotherm models. Based on the fitting results, the maximum adsorption capacity was obtained with the Freundlich isotherm model of κ-CG/CL hydrogel found to be 486 ± 28.5 mg/g (79%). Reusability studies revealed that the κ-CG/CL hydrogel could remove Pb2+ ions with more than 79% removal efficiency after eight adsorption–desorption cycles. In addition, its mechanism for efficiently adsorbing and removal of Pb2+ ions was analyzed. These findings imply that the κ-CG/CL hydrogel has substantial potential for application in removing and recycling heavy metal ions from aqueous solutions.
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... The maximum Pb 2+ adsorption capacity (qmax) of gCs1, gCs2, and gCs3 is 74, 93.5, and 95.5 mg/g, respectively, which are higher than the adsorption capacity of other adsorbents stated in the literature (Table S4). For example, qmax was 6.34 mg/g for Non-living Chlorella Vulgaris Alga/Date pit activated carbon composite (Dakroury et al., 2022), 39 mg/g for cellulose-MT-CBM bio-sorbents (Mwandira et al., 2020), and 80.9 mg/g for Natural clinoptilolite (Aquino et al., 2018). In addition, the maximum BR46 adsorption capacity (qmax) of gCs2, gCs3, NC5, and NC6 is 50.2, 78.8, 43.3, and 56.8 mg/g, respectively, which are higher than the adsorption capacity of other adsorbents stated in the literature (Table S4). ...
Preparation and performance of bionanocomposites based on grafted chitosan, GO and TiO2-NPs for removal of lead ions and basic-red 46
Article
Wastewater rich in heavy metals and organic compounds represents one of the essential environmental pollutants. Therefore, a practical approach is to fabricate eco-friendly polymer-based systems with a high ability to absorb pollutants. Herein, bionanocomposites consisting of chitosan (Cs) grafted by various monomers, such as acrylamide (Am), acrylic acid (AA), and 4-styrene sulfonic acid (SSA), and hybrid nanoparticles of graphene oxide/titanium dioxide nanoparticles (GO@TiO2-NPs) were fabricated. The prepared nanomaterials and bionanocomposites characterized via various tools. The data illustrated that the prepared GO had a thickness of 10 nm and TiO2-NPs had a diameter of 25 nm. In addition, the grafted chitosan (gCs) using Am and SSA had the largest surface area (gCs2; 22.89 nm) and its bionanocomposite (NC5; 104.79 nm). In addition, the sorption ability of the 0.15 g of prepared bionanocomposites to the (100 mg/L) of lead ions (Pb2+) and (25 mg/L) of basic-red 46 (BR46) under various conditions has been studied. The results showed that gCs3 and NC5 had the highest adsorption of Pb2+ (79.54 %) and BR46 (79.98 %), respectively. The kinetic study results of the sorbents obeyed the Pseudo second-order model. In contrast, the isothermal study followed the Freundlich adsorption model for Pb2+ and the Langmuir adsorption model for BR46.
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Functionalised electrospun membranes (TETA-PVC) for the removal of lead( ii ) from water
Article
Full-text available
  • Aug 2022
Driven by the need for delivering sustainable water purification solutions for the removal of heavy metals from water, electrospun PVC membranes were functionalised with triethylenetetramine (TETA) and were used to remove lead(ii) ions selectively from water. The membranes were characterised and their adsorption behavior towards the removal of lead from water was investigated. The incorporation of TETA on the membrane's surface significantly improved the removal efficiency of lead(ii) up to 99.8% in 30 minutes and under ambient conditions, with the lowest concentration of 50 ppm. The adsorption mechanism was investigated and kinetic data showed a better correlation with the pseudo-second-order model. Similarly, the equilibrium data best fitted with the Langmuir adsorption isotherm model with a relatively high maximum adsorption capacity of 1250 mg g-1 for lead(ii) ions, larger than recently reported adsorption capacities for similar membranes. The functionalised membrane also showed high selectivity to lead(ii) in a mixed solution containing lead(ii), mercury(ii), cadmium(ii), arsenic(iii), copper(ii), and zinc(ii). The functionalised membrane was regenerated, where desorption of lead(ii) was achieved, under mildly acidic conditions. The removal efficiency of the regenerated membrane after six cycles of adsorption/desorption was maintained at a high level of 98%. The proposed design offers a simple yet effective, sustainable, and environmentally friendly solution for water treatment.
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EDTA-Functionalized Magnetic Graphene Oxide/Polyacrylamide Grafted Carboxymethyl Cellulose Hydrogel for Removal of Pb+2 from Aqueous Solution
Article
Full-text available
  • May 2022
A promising sorbent was prepared by a combination of different eco-friendly functional groups such as ethylenediaminetetraacetic acid with 3-aminopropyltriethoxysilane (EDTA/Si) and polyacrylamide grafted carboxymethyl cellulose (AmCMC) with magnetic graphene oxide (mGO) and N,N-Methylene bis-acrylamide as a crosslinker for efficient removal of lead ions (Pb²⁺) from aqueous solutions. The prepared sorbent was characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), the scanning electron microscope (SEM), Vibrating sample magnetometer (VSM), and Zeta-potential measurements. The oxidation of graphite was confirmed by XRD and transmission electron microscope (TEM). The adsorption conditions such as contact time, pH, sorbent dosage, and initial Pb²⁺ concentrations were investigated to optimize the adsorption efficiency of the prepared sorbent. EDTA/Si/mGO/AmCMC was found to be an ideal sorbent for Pb²⁺ removal with a higher adsorption capacity due to the successive link of chelating groups onto AmCMC. From the data, at pH = 5.3 after 120 min, EDTA/Si/mGO/AmCMC has high removal efficiency of Pb²⁺ (92%) compared with AmCMC (46%). For deep information, Kinetic and isotherm models were applied for the adsorption process. From the data, the harmony of data fitting with the pseudo-second-order kinetic model and the Langmuir isotherm model. According to the Langmuir adsorption isotherms, the maximum adsorption capacity of 0.15 g EDTA/Si/mGO/AmCMC at pH = 5.3 after 120 min is 86 mg/g. Graphic Abstract
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Development of fast and high-efficiency sponge-gourd fibers (Luffa cylindrica)/hydroxyapatite composites for removal of lead and methylene blue
Article
Full-text available
  • Jun 2021
Oxidized-fibers, cellulose, and oxidized-nanocellulose were isolated from sponge-gourd fibers (Luffa cylindrica) and used as natural, non-toxic, and low-cost adsorbents. The effect of three luffa forms with or without hydroxyapatite (HAp) on the removal efficiency of lead ions (Pb²⁺) and methylene blue (MB) was investigated. HAp was successfully synthesized on the surface of Luffa with an average length of 40-56 nm and a width of 14-19 nm. Prepared materials showed differences in morphology (shape and size), chemical structure, and crystalline properties. The effect of sorbent type, contact time, and initial MB and Pb²⁺ concentrations were studied. The results showed that luffa/HAp composites were more effective in removal of Pb²⁺ ions than MB compared to Luffa without HAp, and vice versa. Kinetic and adsorption studies of MB and Pb²⁺ ions were well fitted with the pseudo-second-order and Langmuir models. The maximum adsorption capacity of Pb²⁺ was 625 mg/g, 714 mg/g, and 714.5 mg/g for oxidized-fibers/HAp, oxidized-nanocellulose/HAp, and cellulose/HAp, respectively, at dose 4 g/L, pH 5.3, 25 °C. While the maximum adsorption capacity of MB was 25.2 mg/g, 30.8 mg/g, and 36.2 mg/g for oxidized-fibers/HAp, oxidized-fibers, and cellulose, respectively, at dose 4 g/L, pH 7.3, 25 °C. Also, more than 95% of lead (500 mg/L) and 85% of MB (25 mg/L) were removed within the first 5 min. Separately, cellulose sample was the most effective in removing MB while cellulose/HAp for removal of Pb²⁺. However, oxidized-fibers/HAp composite was the easiest to prepare and the most effective in removing both MB and Pb²⁺.
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Preparation and characterization of multifunctional sponge-gourd fibers (Luffa cylindrica)/ hydroxyapatite composites for removal of lead and methylene blue
Preprint
Full-text available
  • Feb 2021
Cellulose, oxidized-fibers, and oxidized-nanocellulose were isolated from sponge-gourd fibers ( Luffa cylindrica ). Isolated materials showed different morphology (shape and size), chemical, crystalline properties, and removal efficiency against methylene blue (MB) and lead ions (Pb ²⁺ ). The cellulosic materials showed high efficiency in removing MB more than Pb ²⁺ . So, different luffa forms/hydroxyapatite (HAp) composites were prepared and used as adsorbents for removal of both MB and Pb ²⁺ from aqueous solutions. The effect of sorbent type, contact time, and initial MB and Pb ²⁺ concentrations were studied. HAp was successfully synthesized on the surface of luffa with an average length of 40–56 nm and width of 14–19 nm. Kinetic and adsorption studies of MB and Pb ²⁺ ions were well fitted with the pseudo-second-order model and Langmuir model. The maximum adsorption capacity of MB was 25.2 mg/g, 30.8 mg/g, and 36.2 mg/g for oxidized-fibers/HAp, oxidized-fibers, and cellulose, respectively, and for Pb ²⁺ was 625 mg/g, 714 mg/g, and 714.5 mg/g for oxidized-fibers/HAp, oxidized-nanocellulose/HAp, and cellulose/HAp, respectively. Also, more than 85% of MB (25 mg/L) and 95% of lead (500 mg/L) were removed within the first 5 min. Oxidize-fibers/HAp composite showed effective adsorption with both MB and Pb ²⁺ in a very short time.
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Adsorption of Lead Ion from Wastewater Using Non-Crystal Hydrated Calcium Silicate Gel
Article
Full-text available
  • Feb 2021
In order to obtain low-cost and excellent adsorption materials, this paper used calcium acetate and water glass as raw materials to synthesis hydrated calcium silicate gel by precipitation method. The performance and structure of hydrated calcium silicate gel were systematically studied by X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, specific surface area analyzer and scanning electron microscope. Studies have shown that, non-crystal hydrated calcium silicate gel (CSH) were successfully prepared, and the removal rate of lead ion using CSH reached more than 90%. The adsorption process is consistent with the pseudo-second-order kinetic model and Langmuir adsorption isotherm model, and the limit adsorption capacity reaches 263.17 mg·g−1. The acid treatment experiment proved that the adsorption capacity of lead ion using CSH was satisfactory, and the adsorption rate remained at >60% after 5 cycles. The research may provide a low-cost, high-efficiency and high stability adsorbent.
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Adsorption of Polyelectrolyte onto Nanosilica Synthesized from Rice Husk: Characteristics, Mechanisms, and Application for Antibiotic Removal
Article
Full-text available
  • Feb 2018
Adsorption of the polyelectrolyte polydiallyldimethylammonium chloride (PDADMAC) onto nanosilica (SiO2) fabricated from rice husk was studied in this work. Nanosilica was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Adsorption of PDADMAC onto SiO2 increased with increasing pH because the negative charge of SiO2 is higher at high pH. Adsorption isotherms of PDADMAC onto silica at different KCl concentrations were fitted well by a two-step adsorption model. Adsorption mechanisms of PDADMAC onto SiO2 are discussed on the basis of surface charge change, evaluation by ζ potential, surface modification by FTIR measurements, and the adsorption isotherm. The application of PDADMAC adsorption onto SiO2 to remove amoxicillin antibiotic (AMX) was also studied. Experimental conditions such as contact time, pH, and adsorbent dosage for removal of AMX using SiO2 modified with PDADMAC were systematically optimized and found to be 180 min, pH 10, and 10 mg/mL, respectively. The removal efficiency of AMX using PDADMAC-modified SiO2 increased significantly from 19.1% to 92.3% under optimum adsorptive conditions. We indicate that PDADMAC-modified SiO2 rice husk is a novel adsorbent for removal of antibiotics from aqueous solution
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Removal of heavy metals from wastewater using modified agricultural adsorbents
Article
Full-text available
  • Oct 2017
Agricultural waste has been investigated as an efficient adsorbent for heavy metal removal because of their low cost. The functional groups present in agricultural wastes such as carbonyl, phenolic, acetamido, alcoholic, amido, amino and sulphydryl group etc. have an affinity for heavy metal ions to form metal complexes or chelates. The removal of heavy metal ions from wastewater using agricultural waste is based upon metal biosorption. The mechanism of biosorption includes chemisorption, complexation, adsorption on the surface, diffusion through pores and ion exchange etc. These heavy metal ions cause life-threatening problems for the humans and aquatic ecosystem. Certain modifications in these adsorbents enhance the adsorption capacity of these adsorbents. Some chemicals such as mineral and organic acids, bases, oxidising agent are used for modification of adsorbents. The purpose of this article is to compare removal efficiency of different adsorbents.
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Adsorptive removal of ammonium ion from aqueous solution using surfactant-modified alumina
Article
Full-text available
  • Jun 2017
Environmental context. Ammonium ion, an inorganic pollutant in agricultural land, can induce eutrophication, impacting on water quality. We investigate the adsorption of ammonium ion on surfactant-modified alumina and demonstrate highly efficient removal of ammonium ions by the alumina from two agricultural water samples. Adsorption mechanisms are also proposed based on adsorption isotherms, surface modification and the change in surface charge.. The adsorptive removal of ammonium ions (NH4+) from aqueous solution using surfactant-modified alumina (SMA) was investigated. The optimum NH4+ adsorption removal conditions on SMA were systematically studied and found to be pH 4, contact time 180 min, adsorbent dosage 30 mg mL–1 and ionic strength 1 mM NaCl. The equilibrium concentration of NH4+ was measured by capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) and spectrophotometry. Surface modification of α-Al2O3 with the anionic surfactant sodium dodecyl sul
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Adsorptive Removal of Copper by Using Surfactant Modified Laterite Soil
Article
Full-text available
  • Mar 2017
Removal of Copper ion (Cu2+) by using surfactant modified laterite (SML) was investigated in the present study. Characterizations of laterite were examined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively couple plasma mass spectrometry (ICP-MS) and total carbon analysis. The optimum conditions for removal of Cu2+ by adsorption using SML were systematically studied and found as pH 6, contact time 90 min, adsorbent dosage 5 mg/ml and ionic strength 10 mM NaCl. The equilibrium concentration of copper ions was measured by flame atomic absorption spectrometry (F-AAS). Surface modification of laterite by anionic surfactant, sodium dodecyl sulfate (SDS) induced a significant increase of the removal efficiency of Cu2+. The surface modifications of laterite by pre-adsorption of SDS and sequential adsorption of Cu2+ were also evaluated by XRD and FT-IR. The adsorption of Cu2+ onto SML increases with increasing NaCl concentration from 1 to 10 mM at but at high salt concentration, this trend is reversal because desorption of SDS from laterite surface was enhanced by increasing salt concentration. Experimental results of Cu2+/SML adsorption isotherms at different ionic strengths can be represented well by a two-step adsorption model. Based on adsorption isotherms, surface charge effects and surface modification, we suggest that the adsorption mechanism of Cu2+ onto SML was induced by electrostatic attraction between Cu2+ and the negatively charged SML surface as well as non-electrostatic interactions between Cu2+ and organic substances in the laterite.
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Adsorption of Methylene Blue (MB) Dye in Wastewater by Electrospun Polysulfone (PSF)/Organo-Montmorillonite (O-MMT) Nanostructured Membrane
Article
  • Mar 2018
In this study, organo-montmorillonite was utilized as an additive for the fabrication of the nanostructured membrane via electrospinning process.The purpose of this study is to investigate the performance of 95% PSF and 5% O-MMT blend in terms of its adsorption capacity towards MB dye in wastewater and comparing it to pure PSF membranes. Pure PSF and 5% O-MMT blend were immersed in the simulated wastewater at different time intervals (1, 5, 12, 24 and 48 hours), and the change in MB dye concentration was observed by UV-Vis absorbance reading. To determine the mechanism of adsorption, the data obtained were subjected to pseudo-first order and pseudo-second order kinetic models, and were fitted to Langmuir, Freundlich and Temkin adsorption isotherms to determine the adsorption equilibrium data. The results show that the adsorption efficiency was improved by 5.32%.
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Fabrication and Characterization of Electrospun Polysulfone (PSF)/Organo-Montmorillonite (O-MMT) Nanostructured Membranes
Article
  • Mar 2018
Polymeric membranes infused with clays have attracted researchers for it poses a great potential in water treatment applications. In this study, polysulfone (PSF) has been infused with organo-montmorillonite (O-MMT) clay to fabricate membranes through electrospinning and were subjected into different characterizations to find out the effect of adding the clay to the polymer.Four sampleswith different amounts of O-MMT have been fabricated (Pure PSF, 1% O-MMT, 3% O-MMT and 5% O-MMT). The fiber morphology, fiber diameter,surface chemical composition, hydrophobicity, and mechanical properties of these samples were studied. Preliminary investigationhas revealed that shallow pores and smaller fiber diameter were formed with increasing O-MMT concentration. Molecular interaction between the PSF and O-MMT was also revealed through the FT-IR analysis. With regards to contact angle, there are no significant differences between the measurements for each PSF/O-MMT blend. Improvements in the mechanical properties of the samples were also observed as the O-MMT concentration increases.
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Heavy metal removal from aqueous solutions by calcium silicate powder from waste coal fly-ash
Article
The removal of Ni (II), Cu (II), Zn (II), and Co (II) ions from simulated aqueous solutions using calcium silicate powder (CSP), a new by-product derived from the production of alumina from coal ash, has been studied. CSP showed high efficiency for the removal of these metal ions. The maximum adsorptions were 420.17, 680.93, 251.89, and 235.29 mg/g for Ni (II), Cu (II), Zn (II), and Co (II), respectively. Total (100%) removal of Ni (II) was obtained when the initial concentration was 100 mg/L, indicating that CSP was highly effective even at an extremely low concentration. Adsorption isotherms and kinetics have been studied using different models. It has been found that the adsorption isotherms can best be described on the basis of the Langmuir model, with the kinetics of adsorption following a pseudo-second-order reaction process. The calcium ion concentration was examined before and after adsorption to investigate the mechanism of removal of the heavy metal ions. It was found that the removal of heavy metal ions is mainly achieved through ion-exchange, combined with some adsorption.
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Electrospun AOPAN/RC blend nanofiber membrane for efficient removal of heavy metal ions from water
Article
In this study, an innovative nano-material was prepared, which was ultilized to removal of heavy metal ions from wastewater. Polyacrylonitrile/cellulose acetate (PAN/CA) composite nanofibrous membranes were generated by the electronspinning technique first, and then amidoxime ployarcylonitrile/regenerate cellulose (AOPAN/RC) composite nanofibrous membranes were prepared by combining hydrolysis and amidoximation modification. The modification of composite nanofibers (AOPAN/RC) were consequently used in heavy metal ions adsorption. The characterizations of various different nanofibers were analyzed using scanning electron microscopy, Fourier transform infrared spectroscopy, surface area and pore size distribution analyzer and energy dispersive X-ray spectroscopy. Meantime, the adsorption equilibrium studies were studied. In addition, the saturation adsorption amount of nanofibrous membranes (at 25°C) for Fe(III), Cu(II) and Cd(II) of 7.47, 4.26 and 1.13mmolg(-1), respectively. The effects of pH value of solution, adsorption time and ions concentration on adsorption capacity were also investigated. Furthermore, the composite nanofibrous membranes after five times consecutive adsorption and desorption tests, the desorption rate of the Fe(III), Cu(II) and Cd(II) mental ions maintained more than 80% of their first desorption rate, AOPAN/RC composite nanofibrous reflected excellent resuability.
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Progress in electrospun polymeric nanofibrous membranes for water treatment: Fabrication, modification and applications
Article
Research on membrane technologies has grown exponentially to treat wastewater, recycle polluted water and provide more freshwater. Electrospun nanofibrous membranes (ENMs) exhibit great potential to be applied in membrane processes due to their distinctive features such as high porosity of up to 90% and large specific surface area. Compared with other nanofiber fabrication techniques, electrospinning is capable of developing unique architectures of nanofibrous scaffolds by designing special assemblies, and it is facile in functionalizing nanofibers by incorporating multi-functional materials. This review summarizes the state-of-the-art progress on fabrication and modification of electrospun polymeric membranes with a particular emphasis on their advances, challenges and future improvement in water treatment applications. First, we briefly describe the complex process governing electrospinning, illustrate the effects of intrinsic properties of polymer solutions, operational parameters and surrounding environment conditions on the formation of nanofibers and resultant nanofibrous membranes, and summarize various designs of electrospinning apparatus. That is followed by reviewing the methods to prepare multifunctional composite ENMs, assorted into three categories, including modification in nanofibers, loading target molecules onto nanofibers surface, and implementing selective layers on the ENM surface. Comprehensive discussion about past achievements and current challenges regarding utilization of composite ENMs in water treatment are then provided. Finally, conclusions and perspective are stated according to reviewed progress to date.
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Novel electrodialysis cation exchange membrane prepared by 2-acrylamido-2-methylpropane sulfonic acid; heavy metal ions removal
Article
  • May 2017
In the present work a novel heterogeneous cation exchange membrane (CEM) composed of poly vinyl chloride (PVC) and 2-acrylamido-2-methylpropane sulfonic acid based hydrogel (AMAH) was prepared. The membranes were fabricated with different fractions of AMAH to optimize the performance in desalination. The hydrogel was characterized by FT-IR to prove the successful synthesis. The membrane properties such as permselectivity, ionic permeability, flux, water content, electrical resistance, morphology, contact angle and dimensional stability were evaluated. Modified membranes showed acceptable dimensional stabilities, more hydrophilic surface, higher water content and porosity. SEM images revealed the formation of a more porous membrane structure. Membrane permselectivity and transport number showed a relatively constant then decreasing trend in Na⁺ and Ba²⁺ solutions. The experimental results showed that the incorporation of AMAH into the PVC matrix obviously improved ionic permeability and flux of Na (∼9%) and Ba (∼23%). Membrane electrical resistance was declined about 36% by adding AMAH in the membrane structure. Membranes’ performance in potassium and heavy metal ions removal showed a remarkable separation capacity of K⁺ (99.9%), Pb²⁺ (99.9%) and Ni²⁺ (96.9%). Membranes showed desirable potential for scaling removal.
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