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Chitosan- and Carboxymethyl cellulose-based hydrogel materials are synthesized by incorporating Bentonite and characterized with different characterization techniques like FTIR, FESEM, EDX and XRD. The most optimized conditions for getting maximum percentage swelling were 50 °C temperature, 25 ml of solvent, pH (9), 20 h of reaction time and 1:1 ra...
Citations
... It is observed from Fig. 6f that MG dye removal % and q e gradually decreased from 94 to 86 and from 3778 to 3422 mg/g with increasing temperatures from 20 to 60 °C implying that the adsorption of MG dye molecules onto Pcn-g-P(Am-co-SA) hydrogel is less favorable at high temperatures and exothermic in nature. This is probably because of increase in the mobility of dye molecules with increasing the temperature of dye solution causing escaping of dye molecules from solid phase and weakening electrostatic interactions between MG dye and Pcn-g-P(Am-co-SA) hydrogel leading to decrease in both MG dye removal % and q e [6,17,84]. ...
Grafting of copolymer of sodium acrylate (SA) and acrylamide (Am) onto pectin (Pcn) was successfully performed in order to synthesis Pcn-g-P(Am-co-SA) hydrogel using combined microwave-assisted method and potassium persulfate (KPS) as a free radical initiator. The prepared hydrogel was characterized by FTIR, SEM and TGA. This hydrogel was used to remove malachite green (MG) dye from aqueous solutions. The swelling ratio of the best grade of hydrogel was 214 g/g at pH (7). Factors affecting MG dye adsorption on hydrogel (grafting percentages, pH, contact time, hydrogel dosage, dye initial concentration and temperature) were studied, and the reusability study was also investigated which, in turn, showed the high adsorption capacity of hydrogel for MG dye. The adsorption data were fitted well with Langmuir adsorption isotherm model proposing the formation of monolayer of MG dye molecules on the hydrogel’s surface with maximum adsorption capacity (5000 mg/g). Moreover, the thermodynamic studies indicated the spontaneity and exothermic nature of adsorption of MG dye on hydrogel. From the reusability study, it was found that the prepared hydrogel still retains good adsorption properties after eleven successive cycles. Therefore, Pcn-g-P(Am-co-SA) hydrogel was considered as a highly potential adsorbent for MG dye removal from aqueous solutions.
... Thermodynamic characteristics of MB dye uptake onto CHI-PHA/ANPs were determined by calculating the change in Gibbs free energy (ΔG°), enthalpy (∆H°), and entropy (∆S°) using formulae (6)(7)(8)(9) at various temperatures (298.15, 308.15, 318.15, and 328.15 K) [60]. ...
The application of polymer-based nanocomposites for the removal of organic dyes from water bodies presents a relevant approach. In the present study, a chitosan/alumina nanoparticles were chemically modified with carboxylic groups using phthalic anhydride to develop an effective adsorbent of chitosan-phthalic anhydride/alumina nanoparticles for methylene blue dye adsorption. The physicochemical characteristics of the developed adsorbent (carboxylated chitosan-phthalic anhydride/alumina nanoparticles, CHI-PHA/ANPs) have been thoroughly examined using various methods such as pHpzc, CHN–O, XRD, FTIR, BET, and FESEM–EDX. The study thoroughly investigated the modeling of adsorption using response surface methodology. It carefully examined the various factors that influence adsorption, such as the dose of CHI-PHA/ANPs (0.02–0.08 g), the duration of time (10–140 min), and the pH level (4–10). The Freundlich isotherm exhibits the equilibrium behavior of MB by CHI-PHA/ANPs. The kinetics results of MB adsorption by CHI-PHA/ANPs were accurately explained using a pseudo-second-order model. The adsorption process was shown to be endothermic by the positive value of enthalpy (∆H°, 5.002 kJ/mol), spontaneous by the negative values of Gibbs free energy (ΔG°, 4.706–5.683 kJ/mol), and more random at the adsorbate/adsorbent contact by the positive value of entropy (∆S°, 0.032 kJ/molK). The Langmuir’s maximum adsorption capacity of CHI-PHA/ANPs is 207.7 mg/g. The efficient adsorption of MB on the CHI-PHA/ANPs can be attributed to various interactions (electrostatic forces, π–π, n–π, and H-bond interactions). This study highlights the significant potential of CHI-PHA/ANPs as a promising adsorbent for effectively removing cationic dyes from wastewater.
... This is due to their ability to remove a wide range of pollutants and simpler ways to synthesize them [19][20][21][22]. CH is a cationic polymer, and its biosorbents can be held together either by physical interactions like hydrogen bonding, electrostatic interactions, Vander Waal's forces, or by chemical crosslinking by covalent bonds [12,[23][24][25][26][27]. Nevertheless, for the practical application of CH, there is a need to develop methods for enhancing the adsorption capacity of CH. ...
This study is aimed at developing a highly effective adsorbent by physically crosslinking chitosan (CH), kappa-carrageenan (KCG), and β-cyclodextrin (β-CD) for removing acid fuchsin (AF) dye from water. Various analytical techniques, such as PXRD, FTIR, FE-SEM, and EDS, were utilized to analyze the interactions and morphology of the crosslinked biosorbents. The adsorption performance of CH/KCG and CH/β-CD/KCG biosorbents was assessed under diverse reaction conditions. The adsorption capacity increased with agitation time, reaching equilibrium at 240 min for CH/β-CD/KCG and 300 min for CH/KCG. CH/β-CD/KCG demonstrated the highest adsorption capacity among the two adsorbents studied. The maximum adsorption efficiencies were found to be 9.979 mg/g for CH/KCG and 10.98 mg/g for CH/β-CD/KCG biosorbents under neutral pH and at 30 °C (optimum temperature). Comparing CH/KCG with CH/β-CD/KCG, a notable increase of approximately 13.6% in AF adsorption was observed. Kinetics revealed a pseudo-second-order mechanism, and isotherm models suggested monolayer adsorption following Langmuir isotherm. Thermodynamic analysis indicated a low temperature, spontaneous, and exothermic adsorption process. The activation energy values were calculated as 47.515 and 18.269 kJ/mol for CH/β-CD/KCG and CH/KCG, respectively, indicating physical interactions as the driving force for adsorption. Acid fuchsin adsorption was primarily attributed to physical interactions and hydrogen bonding, facilitated by polymer and inclusion formation mediated by β-CD through host–guest interactions. Furthermore, the biosorbents showed remarkable reusability after three cycles of adsorption and desorption, indicating their promising potential as natural biosorbents for the removal of cationic dyes.
Graphical Abstract
... Malachite green (MG) is a green crystalline powder that serves as both an organic and a cationic dye with a metallic luster [13]. Its widespread applications encompass coloring and dyeing wool, cotton, silk, paper, and hair within the textile and dyeing industries [13,14]. ...
... Malachite green (MG) is a green crystalline powder that serves as both an organic and a cationic dye with a metallic luster [13]. Its widespread applications encompass coloring and dyeing wool, cotton, silk, paper, and hair within the textile and dyeing industries [13,14]. Furthermore, it is used as a disinfectant in aquaculture and as a colorant in various industries, along with applications in food additives, medicinal disinfectants, food colorants, and anthelmintics [15][16][17]. ...
... As the dose of the adsorbent increased, particle accumulation took place and affected the total surface area. At high adsorbent dosages, the saturation of the adsorbent active sites led to a reduction in adsorption capacity [13]. Hence, Fig. 10(a) illustrates the significant decline in adsorption capacity that occurred above dose concentrations of 0.08 g, indicating inadequate utilization of the active sites. ...
In this work, we synthesized a novel hydrogel based on poly(acrylamide) grafted Guar/locust bean gums, i.e. (GG/LBG-g-poly(AAm)) through free radical polymerization, aiming for the removal of malachite green (MG) dye from aqueous solutions. Response surface methodology and a full factorial rotatable central composite design were used to optimize various reaction parameters, enhancing the percentage swelling of the synthesized hydrogel. This optimization resulted in a notable increase in swelling capacity, reaching 1050%. The incorporation of acrylamide chains onto the guar/locust bean gum-based hybrid backbone, as well as crosslinking between different polymeric chains, was confirmed through various characterization techniques, including FTIR, TGA, XRD, FE-SEM, wettability studies, and zeta potential analysis. We evaluated the synthesized hydrogel adsorption performance for MG under specific conditions: pH (7.0), contact time (300 min), adsorbent dose (0.08 g), and dye concentration (50 mg/L). Under ambient conditions, GG/LBG-g-poly(AAm) demonstrated a maximum adsorption capacity of 52.96 mg g−1, achieving a removal efficiency of 98%. The Freundlich model best described the adsorption data and followed pseudo-second-order kinetics, indicating a consistent agreement. Furthermore, the Dubinin-Radeshkovich isotherm and Elovich model perfectly depicted the chemisorption nature of the adsorption process. The synthesized GG/LBG-g-poly(AAm) demonstrates significant potential for effectively removing toxic dyes from wastewater.
... In the distinction between chemisorption and physisorption, ΔG° and ΔH° values are typically considered as defining parameters. It is observed that chemisorption is characterized by ΔG° values ranging from −400 to −80 kJ mol −1 and ΔH° values between 2.1 to 20.9 kJ mol −1 , while physisorption exhibits ΔG° values from −20 to 0 kJ mol −1 and ΔH° values from 80 to 200 kJ mol −1 [67][68][69]. In this study, ΔG° values ranged between −7.5 and −1.67 kJ mol −1 , indicative of MG adsorption's spontaneous and favorable nature onto JPLP. ...
This study investigates Java Plum Leaves Powder (JPLP) as a cost-effective biosorbent for malachite green (MG) removal from water, achieving up to 95% efficiency under optimal conditions: pH 7, 75 min contact time, 30 mg L⁻¹ initial dye concentration, and 2.5 g L⁻¹ biosorbent dose. SEM and FTIR analyses revealed the biosorbent's detailed morphology and chemistry, highlighting functional groups key to MG adsorption. The Freundlich isotherm model fitting suggests a preference for heterogeneous adsorption sites, supported by kinetic data aligning with a pseudo-second-order model. JPLP demonstrated a high adsorption capacity (140 mg g⁻¹), effective in river and tap water, marking it as a sustainable, affordable solution for dye pollution. This research offers significant insights into dye removal and environmental remediation, establishing JPLP as a viable, eco-friendly alternative for aqueous dye pollution mitigation and a practical option for water purification.
Graphical Abstract
... The amount of MG adsorbed onto per gram of MBC was increased with increased solution pH. Because at higher pH the surface of MBC becomes more negative charge due to the release of H + in the basic medium and positive MG ions have a stronger attraction with the negative surface [43]. The adsorption capacity increases from 429.142 ± 2.074 mg/g to 1288.543 ± 1.597 mg/g with an increasing pH of 2.0-10.0.. ...
Adsorption of malachite green (MG) onto sodium dodecyl sulfate (SDS) modified bentonite clay (MBC) was investigated. MBC was synthesized and characterized by X-ray diffraction (XRD), thermos-gravimetric analysis (TGA), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelec-tron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) Sorptometer. According to XRD analysis, the interlayer distance d-spacing increases from 1.2496 nm to 1.4000 nm after modification of bentonite clay (BC). TGA analysis suggests that the residual mass at 1198.4 • C is 92.74% which indicates that the MBC adsorbent is thermodynamically stable. BET analysis confirms that surface area decreases from 22.87 m 2 /g to 20.13 m 2 /g after modification. TEM, EDS and XPS analysis confirm the adsorption of MG onto MBC. The efficiency of this adsorbent for the uptake of MG was investigated using batch adsorption technique at various contact times, pHs, dye concentration, temperature, particle size, concentration of competitive ion and adsorbent dosage. Adsorption capacity rises as contact time, starting dye concentration and temperature increase, while decreasing when the particle size and competing ion concentration increase. The adsorption process follows the pseudo second order kinetics model over the pseudo first order kinetics model and the Elovich kinetics model. Compared to the Freundlich, Temkin and Dubinin-Radushkevich isotherm models, the Langmuir isotherm model provides greater insight into the adsorption process. The maximum adsorption capacity, q m was 1988.387 mg/g at optimum conditions (45 • C, pH 10, contact time 180 min, adsorbent dosage 200 mg/L) which was calculated from the Langmuir isotherm model. Negative values of free energy change, ΔG (− 2.8464 kJ/mol at 30 • C) indicated spontaneity of the adsorption of MG onto MBC and The process is endothermic, as suggested by positive values of the heat of adsorption, ΔH (5.6514 kJ/mol). The value of activation energy (E a = 9.7956 KJ/mol) and the estimated average free energy of adsorption (E < 8) supported that the adsorption process is physisorption.
... Adsorption capacity and percentage removal Reference (Gum rosin alcohol-psyllium)cross-linked-poly(acrylic acid) hydrogel 17.4 mg/g (Langmuir maximum adsorption capacity) and 98.19 % (500 mg/100 mL dose) [81] Cobalt and copper nanoparticle containing poly (acrylic acidco-acrylamide) hydrogel 73-220 mg/g (dye concentration 50-250 mg/L) [82] Poly (acryl-amide-maleic acid) hydrogel Less than 20 mg/g [83] Hydroxyl-ethyl-starch hydrogel 89.3 mg/g (Langmuir adsorption isotherm) [84] Chitosan/CMC/Bentonite-based hydrogel 96.09 % [85] PHG (present work) *98.65 % *49.45 mg/g to 715.07 mg/g mg/ g (dye concentration 10-160 mg/ L) *According to Langmuir maximum adsorption capacity Q max = 658.1 mg/g (Present work) ...
The contamination of water by organic dye compounds are worldwide environmental problem due to their highly toxic nature. To address this environmental issue, a simple technique with highly efficient dye removal was developed to prepare pH‐ sensitive dual‐crosslinked anionic and amphoteric interpenetrating network (IPN) hydrogels based on Na‐carboxymethyl cellulose (Na‐CMC) using jute stick‐based cellulose. Crosslinked Na‐CMC and crosslinked κ‐carrageenan (KC) were interlaced by H‐bonding in anionic IPN hydrogel (An‐gel), but crosslinked Na‐CMC and crosslinked Chitosan (CS) were interlaced by electrostatic interaction in amphoteric IPN hydrogel (Am‐gel). In various operating conditions (pH, temperature, etc.) An‐gel displayed a higher number of swelling ratios of about 2560% at pH 7.2 and Am‐gel of about 1874% at pH 5.5. Based on the point of zero charge, An‐gel achieved the maximum removal efficiency of 81.62 % for methylene blue (MB) at pH 7.2, whereas Am‐gel achieved 85.38% removal efficiency for eosin yellow (EY) at pH 5.5. The adsorption kinetics of IPN hydrogels followed a pseudo‐second order model and best fitted by Langmuir isotherm model. The removal efficiency of MB and EY decreased slightly with increasing temperature. The values of ΔH°, ΔG°, and ΔS° indicated an exothermic, spontaneous, and disordered adsorption process.
