Article

Multiwall carbon nanotube reinforced teflon fibrils for oil spill clean up and its effective recycling as textile dye sorbent

Authors:
  • CSIR-Central Electrochemical Research Institute, Karaikudi, Tamil Nadu
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Abstract

Surface functionalized multiwall carbon nanotube (MWCNT) reinforced teflon fibrils (MWCNT@Teflon) were successfully tested as an - oil - absorbent that can be used as a potential oil recovery material at the time of oil spill accidents in water. We found that oleic acid functionalization of MWCNTs was important for their adhesion onto teflon fibrils and at the same time prevented the MWCNT leaching into oil/water interface. The fibrils had displayed superior mechanical and thermal stability and provided a new insight to oil spill clean-up applications with easy recovery of absorbed oil by simple squeezing. Recycling of exhausted MWCNT@Teflon fibrils after oil recovery applications was conducted by pyrolysis under inert atmosphere in presence of magnetic clay. The magnetic clay absorbed the pyrolysis products, resulting in a heterostructured magnetic clay carbon composite (MCC) which was found super paramagnetic and chemically stable in all pH. The MCC was found capable of adsorbing textile dye from water ultra-fast with in a maximum contact time of 2 min and magnetically separable after adsorption experiments.

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... Adsorption equilibria explain the physicochemical processes involved in sorption and kinetic measures [32,59,60]. It also explains the degree of the transport mechanism of wastewater pollutants into the adsorbent which is comprised of the external mass transfer of the sorbate from the bulk solution to the surface of the sorbent, the internal diffusion of the sorbate to the adsorption site, and the overall adsorption process [33,61]. The kinetic models are relatively efficient when determining the rate at which the adsorbent efficiently removes the adsorbate such as kerosene. ...
... The interactions between the sorbents and adsorbents are e retical approaches such as equilibrium isotherms and adsorpti equilibria explain the physicochemical processes involved i measures [32,59,60]. It also explains the degree of the transport m pollutants into the adsorbent which is comprised of the external m ate from the bulk solution to the surface of the sorbent, the interna to the adsorption site, and the overall adsorption process [33,61] relatively efficient when determining the rate at which the adsor the adsorbate such as kerosene. Figure 10 shows the changes in kerosene amount adsorbed ( tion of time. ...
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A new polyacrylamide-bentonite composite with amine functionality (Am-PAA-B) was prepared by direct polymerization in the presence of N,N'-methylenebisacrylamide as a crosslinking agent and potassium peroxydisulphate as an initiator followed by reaction with ethylenediammine. The Am-PAA-B was modified by immobilizing humic acid and tested as an adsorbent to remove basic dyes (Malachite Green, Methylene Blue and Crystal Violet) from aqueous solutions. XRD, conductometric and potentiometric titrations were used to characterize the adsorbent. The adsorbent behaved like a cation exchanger and more than 99.0% removal of dyes was observed at the pH range 5.0 to 8.0. The adsorption kinetic data were interpreted by pseudo-second-order rate equation and the film diffusion was the rate-limiting step. The equilibrium data were fitted well with the Freundlich isotherm model. Desorption of dyes was achieved by treatment with 0.1 M HNO3 and four adsorption desorption cycles were performed without significant decrease in adsorption capacity.
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The rapidly growing applications of nanomagnets require acid/base stable, oxidation-resistant shells with chemically controlled surface structure. An ideal core should be metallic and highly magnetic. We demonstrate the production of iron-based nanoparticles, ranging from iron oxide to iron and iron carbide, by systematically modifying the degree of reduction during flame spray synthesis under a controlled atmosphere. At a laboratory scale, continuous production yields iron-based particles of 20−50 nm at a production rate of >10 g h−1. Carbon-encapsulated iron carbide (C/Fe3C) combines exceptionally high saturation magnetization (140 emu g−1), air stability (up to 200 °C), and resistance against acidic dissolution (1 week in 24% HCl). The top graphene-like carbon layer could be covalently functionalized with various linkers, thus allowing us to chemically design the particle surface. Activity was demonstrated by reacting 2-phenyl ethyl amine functionalized nanomagnets with carboxylic acid chlorides as a model reaction. The present nanomagnets consist of biologically well-accepted constituents. They combine the required chemical reliability, improved magnetization if compared to magnetite with the potential for technical scale manufacturing, and therefore open stable nanomagnets to a broad range of fascinating separation problems (extraction/water treatment) and biomedical research.
Article
This study concerns with the development of a new adsorbent, iron(III) complex of an amino-functionalized polyacrylamide-grafted coconut coir pith (CP), a lignocellulosic residue, for Cr(VI) in water and industry effluents. The adsorbent (AM-Fe-PGCP) was characterized by FTIR, EDS, Mössbauer, surface area analyzer, TG/DTG, and potentiometric titration. The effects of contact time, initial sorbate concentration, pH, dose of adsorbent, and temperature on Cr(VI) adsorption were studied to optimize the conditions for maximum adsorption. The kinetics of sorption was investigated using pseudo-first-order and pseudo-second-order rate equations with the later giving a better fit to the experimental data. The mechanism of sorption was found to be film diffusion controlled. The Langmuir isotherm model yields a much better fit than the Freundlich and Dubinin–Radushkevich models with maximum adsorption capacity of 142.76 mg/g at 30°C. Simulated industry wastewater sample was treated with AM-Fe-PGCP to demonstrate its efficiency in removing Cr(VI) from wastewater. The alkali treatment (0.1M NaOH) and re-introduction of Fe3+ lead to a reactivation of the spent adsorbent and can be reused through many cycles of water treatment and regeneration without any loss in the adsorption capacity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Article
In this work, chemical vapour deposition (CVD) synthesis of carbon nanotubes (CNT) and nanofibers on the surface of expanded vermiculite (EV) was used to produce a highly hydrophobic floatable absorvent to remove oil spilled on water. XRD, SEM, TG and Raman spectroscopy showed that the carbon nanotubes and nanofibers grow on FeMo catalyst impregnated on the EV surface to form a “sponge structure”. As a result of these carbonaceous nanosponges the absorption of different oils remarkably increased ca. 600% with a concomitant strong decrease of the undesirable water absorption.
Article
To improve the oleophilic/hydrophobic properties of polyurethane (PU) foams for oil spill cleanup, PU samples were modified by grafting with oleophilic monomer Lauryl methacrylate (LMA) in solvent and/or coating with LMA microspheres through heating and curing. Modified PU cubes were characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR). The water sorption of modified PU cubes was decreased by 24-50%, while the diesel or kerosene sorption of modified PU cubes was increased by 18-27%. In water-oil system, compared with blank PU cubes, the sorption capacity of PU cubes grafted with LMA was increased by 44% for diesel and 100% for kerosene. The sorption capacity of PU cubes coated with LMA microspheres was increased by 20% for diesel and 7% for kerosene. The solvent sorption of modified PU cubes could reach 50-69 g/g. The modified PU cubes can be effectively used in oil/solvent spill cleanup.
Article
The present study aims at utilising an inorganic industrial by-product, high calcium fly ash (HCFA), in an environmental field: oil spill clean up. Properties, such as fine particle size, floating ability, hydrophobic character and porosity, make this material attractive for such a use. In order to investigate the oil sorption behaviour of HCFA an oil spill has been simulated, by using artificial ocean water and three types of oil (heating oil (HO), light cycle oil (LCO) and Iranian light crude oil (ILCO)). Two HCFA samples, a Ca-rich one (AD) and a Si-rich one (M), have been examined, so as to investigate the role of HCFA composition in its behaviour. The addition of HCFA to an oil spill results in the formation of a semi-solid oil–HCFA phase, allowing the quite total removal of oil from the water surface. HCFA’s oil sorption capacity in dry environment after 24 h is 0.7–0.9 g oil/g HCFA for AD and 0.5–0.6 g oil/g HCFA for M. HCFA’s behaviour, when added to an oil spill, necessitates the amelioration of its floating ability and affinity for oil and to this direction its hydrothermal treatment in an aqueous solution of sodium oleate (SO) under several conditions (time, temperature, HCFA:SO mass ratio, SO solution concentration, solution:HCFA ratio) has been applied. The treatment of the calcareous HCFA (AD) at 25 °C at a mass ratio HCFA:SO = 1:0.004 results in the formation of a cohesive semi-solid oil–HCFA phase, allowing the total removal of oil from the water surface, while the siliceous HCFA (M) requires a greater amount of SO (HCFA:SO = 1:0.5). The oil sorption behaviour of both HCFA and SO-modified HCFA seems to be related to the initial CaO content. During the treatment with SO, CaO is converted to calcite and calcium oleate, which contributes to the improvement of HCFA’s floating ability, due to its greater affinity for oil.
Article
A new method is developed to chemically functionalize multi-walled carbon nanotubes (MWCNTs) based on silanization reaction for use as the reinforcement for polymer matrix composites. To oxidize and create active moieties on the MWCNTs, the samples were exposed to UV light within the ozone chamber, followed by silanization using 3-glycidoxypropyltrimethoxy silane after the oxidized MWCNTs were reduced by lithium aluminum hydride. FT-IR, TEM and XPS were employed to characterize the changes in carbon nanotubes surface morphology, chemistry and physical conditions at different processing stages. The results indicate improved dispersion and attachment of silane molecules on the surface of the MWCNTs.
Article
We present a sugar-templated polydimethylsiloxane (PDMS) sponge for the selective absorption of oil from water. The process for fabricating the PDMS sponge does not require any intricate synthesis processes or equipment and it is not environmentally hazardous, thus promoting potential in environmental applications. The proposed PDMS sponge can be elastically deformed into any shape, and it can be compressed repeatedly in air or liquids without collapsing. Therefore, absorbed oils and organic solvents can be readily removed and reused by simply squeezing the PDMS sponge, enabling excellent recyclability. Furthermore, through appropriately combining various sugar particles, the absorption capacity of the PDMS sponge is favorably optimized.
Article
Mutual radiation grafting technique was employed to graft polyacrylic acid (PAA) onto Polytetrafluoroethylene (Teflon) scrap using high energy gamma radiation. Polyacrylic acid-g-Teflon (PAA-g-Teflon) adsorbent was characterized by grafting extent measurement, FTIR spectroscopy, SEM and wet ability & surface energy analysis. The PAA-g-Teflon adsorbent was studied for dye adsorption from aqueous solution of basic dyes, namely, Basic red 29 (BR29) and Basic yellow 11 (BY11). The equilibrium adsorption data were analyzed by Langmuir and Freundlich adsorption isotherm models, whereas, adsorption kinetics was analyzed using pseudo-first order, pseudo-second order and intra-particle diffusion kinetic models. Equilibrium adsorption of BR29 was better explained by Langmuir adsorption model, while that of BY11 by Freundlich adsorption model. The adsorption capacity for BY11 was more than for BR29. Separation factor (R(L)) was found to be in the range 0 < R(L) < 1, indicating favorable adsorption of dyes. Higher coefficient of determination (r(2) > 0.99) and better agreement between the q(e,cal) and q(e,exp) values suggested that pseudo-second order kinetic model better represents the kinetic adsorption data. The non-linearity obtained for intra-particle diffusion plot indicated, more than one process is involved in the adsorption of basic dyes. The desorption studies showed that ~95% of the adsorbed dye could be eluted in suitable eluent.
Article
Carbon nanotube sponges are synthesized by chemical vapor deposition, in which nanotubes are self-assembled into a three-dimensionally interconnected framework. The sponges are very light, highly porous, hydrophobic in pristine form, and can be elastically and reversibly deformed into any shape. The sponges can float on water surfaces and absorb large-area spreading oil films (see images), suggesting promising environmental applications.
Article
The fabrication and attractive performance of carbon nanotube (CNT)/Teflon composite electrodes, based on the dispersion of CNT within a Teflon binder, are described. The resulting CNT/Teflon material brings new capabilities for electrochemical devices by combining the advantages of CNT and "bulk" composite electrodes. The electrocatalytic properties of CNT are not impaired by their association with the Teflon binder. The marked electrocatalytic activity toward hydrogen peroxide and NADH permits effective low-potential amperometric biosensing of glucose and ethanol, respectively, in connection with the incorporation of glucose oxidase and alcohol dehydrogenase/NAD(+) within the three-dimensional CNT/Teflon matrix. The accelerated electron transfer is coupled with minimization of surface fouling and surface renewability. These advantages of CNT-based composite devices are illustrated from comparison to their graphite/Teflon counterparts. The influence of the CNT loading upon the amperometric and voltammetric data, as well as the electrode resistance, is examined. SEM images offer insights into the nature of the CNT/Teflon surface. The preparation of CNT/Teflon composites overcomes a major obstacle for creating CNT-based biosensing devices and expands the scope of CNT-based electrochemical devices.
Article
The main objective of this study was to examine the removal of oil from water by expanded and hydrophobized vermiculite. A pH of 9 showed a higher removal efficiency of oil by vermiculite. Oil removal efficiencies at pH 9 were found to be 79%, 93%, 90%, 57% for standard mineral oil (SMO), Canola oil (CO), Kutwell oil (KUT45), refinery effluent (RE), respectively, in the case of expanded vermiculite, and 56%, 58%, 47%, 43% for SMO, CO, KUT45 and RE, respectively, for hydrophobized vermiculite. Kinetic data satisfied both the Lagergren and Ho models. Equilibrium studies showed that the Langmuir isotherm was the best-fit isotherm for oil removal by both expanded and hydrophobized vermiculite. The data showed a higher adsorptive capacity by the expanded vermiculite compared to the hydrophobized vermiculite. Desorption studies showed that the expanded vermiculite did not desorb oil to the same extent compared to hydrophobized vermiculite. The Freundlich isotherm was the best-fit model for desorption. Expanded vermiculite showed better retention than hydrophobic vermiculite. The results showed that the expanded vermiculite had a greater affinity for oil than hydrophobized vermiculite.
Article
The effect of operating conditions on the performance of a sawdust bed filter used for the treatment of an oil-in-water emulsion was investigated. A metalworking fluid (3 vol.% oil) was used as oil-in-water emulsion and sawdust as filter medium and sorbent. Because of the high stability of the emulsion, small amounts of inorganic salt (calcium sulphate) were mixed with the sorbent, acting as coagulant to achieve the emulsion breakdown. The influence of flow rate, bed height, temperature and the amount of coagulant salt added was studied. Experimental results show that several processes are involved in oil removal from oil-in-water emulsions, i.e. coagulation, coalescence, adsorption or straining. More than 99% of oil content in the influent stream was removed. Experimental results show that low-cost sorbents like sawdust are feasible to be used in the treatment of oil-in-water emulsions if small amounts of coagulant salts are added to the filter media.
Article
A method is presented for the preparation of a biocompatible ferrofluid containing dye-functionalized magnetite nanoparticles that can serve as fluorescent markers. This method entails the surface functionalization of magnetite nanoparticles using citric acid to produce a stable aqueous dispersion and the subsequent binding of fluorescent dyes to the surface of the particles. Several ferrofluid samples were prepared and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), BET surface area analysis, transmission electron microscopy (TEM), and SQUID magnetometry. In addition, confocal fluorescence microscopy was used to study the response of the fluorescent nanoparticles to an applied magnetic field and their uptake by cells in vitro. Results are presented on the distribution of particle sizes, the fluorescent and magnetic properties of the nanoparticles, and the nature of their surface bonds. Biocompatible ferrofluids with fluorescent nanoparticles enable optical tracking of basic processes at the cellular level combined with magnetophoretic manipulation and should be of substantial value to researchers engaged in both fundamental and applied biomedical research.