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•Eco-friendly PVA/CMC hydrogels reinforced with GO and bentonite were prepared.•Introducing GO and bentonite promoted formation of porous structure of hydrogels.•Improving swelling, ...thermal stability and MB adsorption by introducing two fillers.•MB adsorption was well fitted by Langmuir isotherm and pseudo-second-order model.•The hydrogels displayed good pH sensitivity and reusability for MB adsorption.
Eco-friendly polyvinyl alcohol/carboxymethyl cellulose (isolated from pineapple peel) hydrogels reinforced with graphene oxide and bentonite were prepared as efficient adsorbents for methylene blue (MB). The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). Introducing graphene oxide and bentonite into the hydrogels evidently enhanced the thermal stability, swelling ability and MB adsorption capacity. The effects of initial concentration of MB, pH, contact time and temperature on MB adsorption capacity of the prepared hydrogels were investigated. Adsorption kinetics and equilibrium adsorption isotherm fitted pseudo-second-order kinetic model and Langmuir isotherm model well, respectively. After introducing graphene oxide and bentonite into the hydrogels, the maximum adsorption capacity calculated from the Langmuir isotherm model reached 172.14 mg/g at 30 °C, obviously higher than the hydrogels prepared without these additions (83.33 mg/g). Furthermore, all the prepared hydrogels also displayed good reusability for the efficient removal of MB. Consequently, the prepared hydrogels could be served as eco-friendly, stable, efficient and reusable adsorbents for anionic dyes in wastewater treatment.
This research aims to develop low cost, sustainable, environmentally friendly, and high performance water-based drilling fluids (WDFs) using bentonite (BT), polyanionic cellulose (PAC), and cellulose ...nanocrystals (CNCs). The effect of concentration of BT, PAC, and CNCs on the rheological and filtration properties of PAC/CNC/BT-WDFs was investigated. Eight empirical rheological models were applied to fit quantitatively the fluid properties. Results showed that the presence of PAC, CNCs, and BT improved the rheological and filtration properties of the WDFs. Among the eight empirical rheological models, the Sisko model performed the best in simulating the rheological behavior of the fluids. At the same concentration level of PAC and CNCs, CNCs had more impact on the rheological properties, whereas PAC had more influence on the filtration property. The incorporation of PAC resulted in very low permeable filter cakes, leading to the excellent filtration property. The combined use of PAC and CNCs yielded better rheological and filtration properties.
Geopolymers are a class of synthesized amorphous aluminosilicate materials that can be used as an adsorbent for the removal of heavy metals. In this paper, the bentonite clay was employed to ...synthesize geopolymer that can remove heavy metals such as Cu(II), Pb(II), Ni(II), Cd(II), and Hg(II) from industrial wastewaters. The Fe3O4 nanoparticles were applied to modify the geopolymer and the use of a geopolymer/Fe3O4 nanocomposite as an efficient and magnetic adsorbent for heavy metals removal from aqueous solution was investigated in this work, for the first time. The influence of different contact time and initial concentrations of metal ions on sorption was examined and the best result was achieved in 2 min contact time in the presence of 0.05 g nanocomposite. The prepared geopolymer and nanocomposite samples were characterized by Fourier transform infrared spectroscopy spectra, field-emission scanning electron micrograph images, thermogravimetric analysis, energy dispersive X-ray analysis, X-ray diffraction pattern and Brunauer-Emmett-Teller analysis. The prepared magnetic geopolymer base on bentonite clay showed 99%, 99%, 92%, 96% and 92% removal efficiency for the sorption of copper, lead, nickel, cadmium, and mercury ions from industrial wastewaters. The present work includes diverse advantageous such as environmentally-friendly protocol, magnetic separation, inexpensive raw materials, easy and simple conditions and high yields as same as short adsorption times.
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•Synthesis of geopolymer based on bentonite for removing of various heavy metals.•Using the geopolymer/Fe3O4 nanocomposite as an adsorbent for heavy metals.•Characterizing the nanocomposite by FT-IR, FE-SEM, TGA, BET, EDX and XRD.•Excellent adsorption of copper, lead, nickel, cadmium and mercury ions.•Advantages: easy separation of adsorbent, natural materials and short contact time.
Previously, our group developed a vinylimidazolium-based ionic liquid (IL) as an excellent shale hydration inhibitor for water-based drilling fluids (WBDFs). Herein, several ILs with different ...alkyl-chain lengths on the vinylimidazolium group were successfully synthesized by adjusting the cation composition to study their influence on inhibition performance. The results indicated that the IL with an ethyl group (C2) showed the strongest inhibitory effects for bentonite swelling, shale-cutting dispersion and rheological properties of bentonite suspension. Furthermore, the IL inhibition performance decreased with increasing alkyl-chain length. Accordingly, we concluded that as alkyl-chain length increased, the IL molecular volume increased, while the IL hydrophilicity and solubility decreased; minimizing the interlayer space and decreasing the water activity became more difficult, thus decreasing their inhibiting performance. Simultaneously, the reduction in inhibition performance has little relationship with the ability to suppress the double electron layers. All these findings can serve as a basis for designing ILs for high-performance shale hydration inhibition in WBDFs.
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A novel amidoxime functionalized adsorbent, poly(amidoxime)-grafted-chitosan/bentonite composite P(AO)-g-CTS/BT was prepared by in situ intercalative polymerization of acrylonitrile ...(AN) and 3-hexenedinitrile (3-HDN) onto chitosan/bentonite composite using ethylene glycol dimethacrylate (EGDMA) as cross linking agent and potassium peroxy disulphate (K2S2O8) as free radical initiator. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), BET surface area analyser and X-ray photoelectron spectroscopy (XPS). Nitrile groups from two monomers converted to amidoxime groups and therefore, increases the adsorption efficiency of uranium(VI) U(VI) from seawater. The optimum pH for U(VI) adsorption was found to be 8.0. The adsorbent dosage of 2.0 g/L was sufficient for the complete removal of U(VI) from seawater. The kinetic data fitted well with pseudo-second-order kinetic model which assumes the presence of chemisorption. The equilibrium attained within 60 min and well agreement of equilibrium data with Langmuir adsorption model confirms monolayer coverage of U(VI) onto P(AO)-g-CTS/BT. The maximum adsorption capacity was found to be 49.09 mg/g. Spent adsorbent was effectively regenerated using 0.1 N HCl. Six cycles of adsorption-desorption experiments were conducted to study the practical applicability and repeated use of the adsorbent. The feasibility of the adsorbent was also tested using natural seawater. The results show that P(AO)-g-CTS/BT is a promising adsorbent for the removal of U(VI) from seawater.
This study investigated phosphate ions removal from aqueous solutions by using modified bentonite with magnesium hydroxide in batch system. Raw bentonite (RB) and Mg-modified bentonite (MB) were ...characterized by Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FT-IR). Adsorption experiments were conducted on the adsorption of phosphate onto RB and MB in batch experiments. Phosphate ion removal by MB was pH dependent, and the optimum adsorption was observed at pH7. The adsorption process was relatively fast and equilibrium conditions were established within 120min at 45°C. The results were analyzed according to the Langmuir and Freundlich isotherm equations. The adsorption data is well interpreted by the Langmuir isotherm. Phosphate solution at a concentration of 25mg/L was adsorbed by MB, and the final adsorption efficiency was >54%. The results showed that phosphate adsorption density of MB was high with the maximum adsorption density of 14.33mg/m2, which suggested that MB was an excellent adsorbent for effective phosphate removal from water. Thermodynamically negative ΔG°, positive ΔH°, and positive ΔS° demonstrated the high affinity, and endothermic adsorption process between MB and phosphate from aqueous solutions.
The chemical contamination of water from an extensive variety of toxic derivatives, specifically heavy metals, aromatic molecules and dyes, is a genuine ecological issue attributable to their ...potential human lethality. In this way, there is an earnest need to create advances that can remove harmful toxins found in wastewaters. Among all the reported treatment techniques, adsorption is one of the more prevalent systems for the removal of contaminations from the water. Adsorption is a standout among the most simple and effective strategy for treating industrial effluents, and a valuable device for ensuring nature. The increasing number of publications on adsorption of toxic compounds by modified bentonites demonstrates that there is a recent increasing interest in the synthesis of new low-cost adsorbents used in water treatment. The present review demonstrates the late advancements of nanotechnology in the synthesis of nanoadsorbents containing bentonite and its composites. The primary target of this review is to depict the adaptable way of bentonite and its composite and their capacity to absorb variety of inorganic contaminants, which are available in the water. It is evident from the review that modified bentonite composites (low-cost adsorbents) have demonstrated high removal capabilities for certain inorganic contaminants from water.
•Polymer–bentonite composites as emerging adsorbents for water treatment.•Bentonite/modified bentonite composites show excellent adsorption performance.•Composites are eco-friendly adsorbents for treating the wastewaters.•Remove inorganic pollutants from wastewater.•Tremendous cost advantage.
Nickel being a toxic heavy metal is considered as a hazardous pollutant in the soil environment. The cultivation of edible vegetables on Ni contaminated soil can deteriorate plant quality which ...causes critical health issues to humans and animals. Therefore, the remediation for such Ni polluted soils has currently become a great challenge for the researchers. Contrastingly, lowering bioavailability of Ni in those soils based on applying appropriate immobilizing amendments demonstrating a target to relieve virulence to plants can remarkably diminish the environmental hazard. In this experiment, biochar (BR) along diverse clays like bentonite (BE), cationic-zeolite (C-ZE), chitosan (CN) and attapulgite (AP) as individual doses at 2% each in a soil synthetically spiked with Ni (at 50 ppm) magnificently immobilize Ni and curtailed its bioavailability to lettuce (Lactuca sativa L.). In addition, the related influences of planned treatments on translocation of Ni to shoots and leaves, antioxidant preventive system over oxidative injury, biochemistry and nutritional ability of lettuce were monitored. Results suggested that the CN2% treatment performed excellently in terms of reducing Ni concentrations in leaves and roots of lettuce plants along bioavailable Ni in the soil after plant harvest. Surprisingly, the BR2% treatment efficiently promoted enzymatic activities in the soil and developed moisture content, photosynthesis, biomass, biochemistry, and nutrition (both micronutrients and macronutrients) and antioxidant preventive system while diminished Ni oxidative injury in lettuce plants over rest of the treatments. Finally, our results confirmed that individually applying CN at 2% in a Ni contaminated soil could significantly control Ni bioavailability, whereas, application of BR at 2% could remarkably develop aforementioned parameters in lettuce plants.
•The CN2% treatment showed the highest Ni reduction in lettuce parts and DTPA extract.•The activities of soil enzymes were the highest at BR2% treatment followed by CN2%.•The BR2% and CN2% treatments showed the least oxidative stress to plants.•The highest boost in the plant antioxidant defense machinery was at BR2%.•The highest nutritional quality of lettuce was at BR2% treatment followed by CN2%.
•Smart packaging Chitosan/PVA film was prepared using anthocyanin as pH indicator.•The presence of bentonite decreased the water vapor permeability of the films.•Addition of black carrot anthocyanins ...caused to increasing the tensile strength.•Addition of bentonite and anthocyanins improved antibacterial effect of the films.
This study investigated the potential of chitosan/PVA films containing black carrot anthocyanins as a natural pH indicator and bentonite as a nano-filler, for intelligent packaging applications. Two series of chitosan/PVA (CP) films, with different concentrations of bentonite (CPB3%, CPB5%) and with a constant concentration of anthocyanin (CPA, CPAB3%, CPAB5%) were prepared by solution casting method. The colorimetric parameter b* showed an increase from 1.0 ± 0.2 for CP films to 2.7 ± 0.2 and 8.8 ± 1.1 for CPB3% and CPB5% films, respectively which indicates that addition of bentonite increases the intensity of yellow color in the nanocomposite films. The presence of anthocyanins caused to shifting of a* values from negative to positive values which indicated the color change of films from greenness to redness. Addition of bentonite reduced the tensile strength from 100.6 for CP film to 86.5 and 67.2 for CPB3% and CPB5% films which was related to the solution intercalation method used for preparation of nanocomposite films. In contrast, addition of anthocyanins increased the tensile strength for CPA, CPAB3% and CPAB5% due to the hydrogen bonding interactions between its OH groups and PVA and chitosan chains. Water vapor permeability (WVP) of the films was decreased from 1.140 (mg.mm/m2.kPa.h) for CP film to 0.5620 and 0.3515 for CPB3% and CPB5% films, respectively. In contrast, anthocyanins caused to increase WVP of the samples compared to the anthocyanin free films. Thermo-gravimetric analysis showed that the films containing bentonite and anthocyanins have a better thermal stability. Finally, CPAB5% showed the highest bacterial growth inhibition against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, respectively 75.20%, 69.95% and 44.38%.
Shale hydration and swelling are disadvantageous for well drilling, especially when using water-based drilling fluids. In this work, the ionic liquid 1-vinyl-3-ethylimidazolium bromide (VeiBr) ...monomer and its corresponding homopolymers (PV) were innovatively used as shale hydration inhibitors. Both composites of sodium bentonite (Na-BT) with VeiBr and PV (hereafter denoted as Na-BT/VeiBr and Na-BT/PV composites) exhibited excellent temperature stability up to 300 °C, showing potential application in high-temperature well drilling. The inhibiting performance was evaluated by measuring the linear swelling height, rheological property of Na-BT aqueous solutions, and recovery percentage of shale cuttings after hot rolling. Results indicated that VeiBr monomer and PV polymer displayed better inhibition performance than inorganic KCl and organic quaternary amine 2,3-epoxypropyltrimethylammonium chloride in all tests. In addition, PV was even better than VeiBr. The underlying mechanism was analyzed by measuring the interlayer distance through X-ray diffraction, observing the aggregation through scanning electron microscopy, and determining the ζ potential and particle size distribution. The monomer exerted its effect mainly by decreasing the interlayer spacing, whereas the polymer increased the viscosity, encapsulated Na-BT particles, prevented the exfoliation of Na-BT, and decreased the interlayer spacing depending upon the molecular weight. This study can serve as a basis for using ionic liquids in the design of permanent shale inhibitors for drilling fluids.
