Efficient Cr(VI) remediation by electrospun composite porous nanofibers incorporating biomass with metal oxides and metal-organic framework.

To develop a highly efficient adsorbent to remediate and remove hexavalent chromium ions (Cr(VI)) from polluted water, cellulose acetate (CA) and chitosan (CS), along with metal oxides (titanium dioxide (TiO2) and ferroferric oxide (Fe3O4)), and a zirconium-based metal-organic framework (UiO-66) were used to fabricate the composite porous nanofiber membranes through electrospinning. The adsorption performance, influencing factors, adsorption kinetics and isotherms of composite nanofiber membranes were comprehensively investigated. The multi-layer membrane with interpenetrating nanofibers and surface functional groups enhanced the natural physical adsorption and provided potential chemical sites. The thermal stability was improved by introducing TiO2 and UiO-66. CA/CS/UiO-66 exhibited the highest adsorption capacity (118.81 mg g-1) and removal rate (60.76%), which were twice higher than those of the control. The correlation coefficients (R2) of all the composite nanofibers regressed by the Langmuir model were significantly higher than those by the Freundlich model. The pseudo-first-order kinetic curve of CA/CS composite nanofibers showed the highest R2 (0.973), demonstrating that the whole adsorption process involved a combination of strong physical adsorption and weak chemical adsorption by the amino groups of CS. However, the R2 values of the pseudo-second-order kinetic model increased after incorporating TiO2, Fe3O4, and UiO-66 into the CA/CS composite nanofiber membranes since an enhanced chemical reaction with Cr (VI) occured during the adsorption.

Design of hydrotalcite and biopolymers entrapped tunable cerium organic cubic hybrid material for superior fluoride adsorption.

The excess fluoride in drinking water is serious risk which leads to fluorosis. The adsorption method is facile route for defluoridation studies. Hybrid adsorbent possesses unique advantages like high surface area and high stability has been employed for water treatment. In the present work, hydrotalcite (HT) fabricated Ce-metal organic frameworks (MOFs) bridged with biopolymers (alginate and chitosan) namely HT-CeMOFs@Alg-CS cubic hybrid beads was developed and employed towards fluoride removal in batch mode. The fabricated HT-CeMOFs@Alg-CS beads were analyzed by DTA, FTIR, SEM, EDAX, TGA and XRD studies. Besides, FTIR and EDAX proved the affinity of HT-CeMOFs@Alg-CS cubic hybrid beads on fluoride was majorly attributed by electrostatic interaction, ion-exchange and complexation mechanism. To include detail insight into adsorption route; the kinetics, thermodynamic and isotherm studies were investigated for fluoride adsorption. The equilibrium data of HT-CeMOFs@Alg-CS cubic hybrid beads for fluoride adsorption was fitted with Langmuir isotherm model. Thermodynamic investigation results demonstrated that the fluoride adsorption was spontaneous with endothermic nature. The regeneration and field investigation results revealed that the developed HT-CeMOFs@Alg-CS cubic hybrid beads are reusable and more apt at field environment.

Evaluation of photocatalytic performances of PEG and PVP capped zinc sulfide nanoparticles towards organic environmental pollutant in presence of sunlight.

Advanced oxidation processes triggered by nanoscale materials are promising owing to the in-situ generation of reactive radicals that can degrade toxic organic pollutants. In the present study, zinc sulfide (ZnS) nanoparticles with polyethylene glycol-4000 (PEG-4000) and polyvinylpyrrolidone (PVP) cappings were prepared using the chemical precipitation method and characterized thoroughly. Optical and structural characteristics of the capped ZnS nanoparticles were investigated and compared with those of uncapped ZnS nanoparticles. Results showed that PVP and PEG capped ZnS nanoparticles exhibited smaller crystallite size of 1.42 and 1.5 nm, respectively, as compared to uncapped ZnS (1.93 nm). Consequently, band gap energies of capped ZnS nanoparticles were higher which enable them to work as solar photocatalyst. The photocatalytic performance of the PEG, PVP-capped, and uncapped ZnS nanoparticles were evaluated against methyl orange (MO) dye and showed 85%, 87%, and 80% dye removal efficiencies, respectively. Degradation rate constant derived using Langmuir-Hinshelwood model revealed faster degradation kinetics bycapped ZnS photocatalysts owing to broader light absorption range. A possible dye degradation mechanism based on the energy levels positions was proposed to explain the route of photocatalytic degradation of MO by ZnS materials. It was inferred that the generation of reactive oxygen species by photogenerated electron-hole pairs facilitate degradation of MO dye molecules under sunlight illumination. It is expected that this work will provide insights into the development of strategies employed to achieve enhanced photocatalysis by nanoscale materials through organic capping.

Environmental Remediation Potential of Ferrous Sulfate Waste as an Eco-Friendly Coagulant for the Removal of NH3-N and COD from the Rubber Processing Effluent.

The present study was conducted to determine the potential of utilizing the FeSO4·7H2O waste from the titanium manufacturing industry as an effective coagulant for treating industrial effluent. In this study, the secondary rubber processing effluent (SRPE) was treated using ferrous sulfate (FeSO4·7H2O) waste from the titanium oxide manufacturing industry. The FeSO4·7H2O waste coagulation efficiency was evaluated on the elimination of ammoniacal nitrogen (NH3-N) and chemical oxygen demand (COD) from SRPE. The central composite design (CCD) of experiments was employed to design the coagulation experiments with varying coagulation time, coagulant doses, and temperature. The coagulation experiments were optimized on the optimal elimination of NH3-N and COD using response surface methodology (RSM). Results showed that coagulant doses and temperature significantly influenced NH3-N and COD elimination from SRPE. The highest NH3-N and COD removal obtained were 98.19% and 93.86%, respectively, at the optimized coagulation experimental conditions of coagulation time 70 min, coagulant doses 900 mg/L, and temperature 62 °C. The residual NH3-N and COD in treated SPRE were found below the specified industrial effluent discharge limits set by DoE, Malaysia. Additionally, the sludge generated after coagulation of SRPE contains essential plant nutrients. The present study's finding showed that FeSO4·7H2O waste generated as an industrial byproduct in a titanium oxide manufacturing industry could be utilized as an eco-friendly coagulant in treating industrial effluent.

Adsorptional-photocatalytic removal of fast sulphon black dye by using chitin-cl-poly(itaconic acid-co-acrylamide)/zirconium tungstate nanocomposite hydrogel.

In the present work, the removal of fast sulphon black (FSB) dye from water was executed by using chitin-cl-poly(itaconic acid-co-acrylamide)/zirconium tungstate nanocomposite hydrogel (Ch-cl-poly(IA-co-AAm)-ZrW NCH). The Ch-cl-poly(IA-co-AAm)-ZrW NCH was fabricated proficiently by microwave-induced sol-gel/copolymrization method. The zirconium tungstate (ZrW) photocatalyst was prepared by co-precipitation method using sodium tungstate and zirconium oxychloride in ratio (2:1). The polymeric hydrogel part has been used to support the ZrW, and it acted as an adsorbent for adsorptive removal of FSB dye. The band gap for nanocomposite hydrogel was found about 4.18 eV by using Tauc equation. The Ch-cl-poly(IA-co-AAm)-ZrW NCH was characterized by various techniques as FTIR (Fourier-transform infrared spectroscopy), X-ray diffraction (XRD), transmittance electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). The adsorptional-photocatalytic remediation experiment of FSB dye was optimized for reaction parameters as FSB dye and Ch-cl-poly(IA-co-AAm)-ZrW NCH concentration, and pH. The maximum percentage removal for FSB dye was observed at 92.66% in 120 min under adsorptional-photocatalysis condition.

Fabrication of starch-salicylaldehyde based polymer nanocomposite (PNC) for the removal of pollutants from contaminated water.

In the present study, we have fabricated magnetic nanocomposite based on the starch and salicylaldehyde resin embedded with magnetic Fe3O4 nanoparticles (SS@Fe3O4). The fabricated nanocomposite was characterized using various analytical methods including XRD, SEM, FTIR, TGA, TEM, BET and XPS. As-fabricated nanocomposite was used for the adsorption of Pb(II) and Cd(II) from aqueous solution. The adsorption results revealed that the maximum adsorption capacity was found to be 265.4 and 247.2 mg/g for Pb(II) and Cd(II) respectively at pH 6 and room temperature. The adsorption kinetic results support that the adsorption of both the toxic metals was carried out via second order reaction and the rate constants were found to be 6.31 × 10-5 and 7.18 × 10-5 g·mg-1·min-1 for Pb(II) and Cd(II) respectively. The adsorption isotherm displays the Langmuir adsorption isotherm and supports the monolayer and mainly chemisorption with poor physisorption. Additionally, the thermodynamic parameters were evaluated and the adsorption came true in exothermically and spontaneously with both Pb(II) and Cd(II). As-fabricated starch based magnetic nanocomposite displays excellent adsorption as well as outstanding reusability. Therefore, these outcomes support that the SS@Fe3O4 nanocomposite can be used as a promising adsorbent for industrial application.

Atrazine removal using chitin-cl-poly(acrylamide-co-itaconic acid) nanohydrogel: Isotherms and pH responsive nature.

Removal of commonly used pesticide, atrazine was examined by employing chitin based nanohydrogel. Chitin-cl-poly (acrylamide-co-itaconic acid) nanohydrogel was synthesized by microwave method. Dissolution of chitin was done by freezing thawing method in NaOH/urea solution. The morphology and functional characteristics were confirmed by FTIR, XRD, SEM, TGA, TEM, and EDX techniques. Maximum swelling capacity, isotherm study, kinetics, adsorption and desorption of atrazine pesticide were evaluated in this study. Maximum adsorption capacity of designed nanohydrogel was found to be 204.08 mg/g. Langmuir and pseudo- second order models were determined to be applicable for explaining the undertaken adsorption process. Neutral pH was found to be favorable for maximum adsorption. In addition, results have specified the pH responsive nature of nanohydrogel for controlled release of atrazine.

Chitosan polymer complex derived nanocomposite (AgNPs/NSC) for electrochemical non-enzymatic glucose sensor.

N/S-doped carbon supported AgNPs has been synthesized at low-cost, and scalable method using silver complex of chitosan based polymer. The fabricated nanocomposites exhibited excellent electrocatalytic performance as a glucose sensor. Remarkably, the fabricated glucose sensor is exhibited an ultrahigh sensitivity of 35.22 mAmM-1 cm-2 with a very low detection limit (0.046 mM) and long-term durability (30 days). Under optimized conditions, a wide linear response was obtained from 5 µM to 3 mM with an excellent linear response (R2 = 0.9940) was also obtained by AgNPs/NSC modified electrode. The presence of the heteroatom and AgNPs into the carbon matrix greatly enhances the selectivity for glucose over potential interferences in aqueous solution, with interfering agents. Overall, the present methodology demonstrates an efficient, robust, and aqueous-media-tolerable nanocomposite material as an electrochemical sensor and a potential alternative tool for the detection of glucose.

Ultra-fast spill oil recovery using a mesoporous lignin based nanocomposite prepared from date palm pits (Phoenix dactylifera L.).

Oil spills present the enormous harm to the environment, and its potential remediation for environmental protection is import worldwide. Herein, we report an effective strategy inspired by the lignin based bio-waste date palm pits powder (Phoenix dactylifera L.), which was modified with magnetic Fe3O4 nanocrystals and used as a porous, hierarchical graphite carbon oil/solvent sorption magnetic materials. The fabricated nanocomposite (Fe3O4@MPC) was characterized using several analytical techniques. The results revealed that Fe3O4 nanoparticles with a 22 nm in average size were embedded into the graphite carbon matrix. The rate of sorption, sorption capacity, oil retention, water uptake, adsorption isotherm model, and kinetic behavior were evaluate and >85% of both oils were adsorbed, onto Fe3O4@MPC surface in the first 30 min followed by equilibrium in both type of aqueous solution. The batch equilibrium data supported the Langmuir isotherm model with the adsorption capacity about to 23.01 mg/g. The kinetics data was well fitted with pseudo-second-order kinetic model. After saturation, the Fe3O4@MPC was recycled using ethanol and reused for further cycle. The fabricated nanocomposite exhibited a significant dual oleophilic and hydrophobic nature that can be applicable for oil removal from oil-contaminated wastewaters. Meanwhile, the magnetic properties allowed Fe3O4@MPC to be separated conveniently and effectively from the solution and used as oil absorbent without touching the oil.

N/S doped highly porous magnetic carbon aerogel derived from sugarcane bagasse cellulose for the removal of bisphenol­A.

In this study, highly porous N/S doped magnetic carbon aerogel (N/S-MCA) was successfully fabricated using sugarcane bagasse based cellulose and used for the removal of bisphenol­A (BPA) from aqueous solution. The fabricated N/S-MCA nanocomposite derived from cellulose was characterized by various analytical techniques and supports the formation of the N/S-MCA in good yield and high purity. The batch adsorption studies were used for the adsorption of BPA onto N/S-MCA. The maximum removal of the BPA (98-99%) by the N/S-MCA was noted at pH 7, temperature 343 K, and initial BPA concentration of 100 ppm. The adsorption process followed pseudo-second-order reaction kinetics, as well as Langmuir isotherms. The thermodynamic parameters of the adsorption (the Gibbs free energy, entropy, and enthalpy) supported the spontaneity of the adsorption process. The results revealed that the mechanism on the synergistic adsorption between N/S doped magnetic carbon aerogel and BPA will therefore be an important guideline to design a carbon based adsorbent for high-efficient adsorption of environmental pollutants.

Revolution from monometallic to trimetallic nanoparticle composites, various synthesis methods and their applications: A review.

Trimetallic nanoparticles are mainly formed by the combination of three different metals. The trimetallic catalysts were considerably more professional than bimetallic one. The trimetallic and bimetallic nanoparticles are of enormous attention than that of monometallic in both technological and scientific view as in these nanoparticles the catalytic properties can be tailored better than that of in the single monometallic catalyst. The trimetallic nanoparticles have been synthesized by different methods such as microwave, selective catalytic reduction, micro-emulsion, co-precipitation and hydrothermal etc. The surfaces area of trimetallic nanoparticles is comparatively unstable and thus gets simply precipitated away from their solution and ultimately resulted in their reduced catalytic activity. By using stabilizers like block copolymers, organic ligands, surfactants and dendrimers the trimetallic nanoparticles can be stabilized. The nanocomposites of trimetallics have been synthesized with inorganic and organic compounds such as: carbon, graphene, gelatin, cellulose, starch, chitosan, alginate, collagen and Al2O3 etc. Trimetallic nanoparticles are used as a catalyst due to their outstanding electrochemical catalytic activity in comparison with the monometallic or bimetallic nanoparticles.

Preparation of a novel chitosan-g-poly(acrylamide)/Zn nanocomposite hydrogel and its applications for controlled drug delivery of ofloxacin.

Chitosan-g-poly(acrylamide)/Zn (CPA-Zn) nanocomposite was synthesized using simple method in the presence of microwave radiations. CPA-Zn nanocomposite was characterized by various analytical techniques. CPA-Zn nanocomposite was used for controlled drug delivery of ofloxacin. The maximum drug release was 75% which was observed in acidic medium. The cumulative drug release and drug released kinetics of CPA-Zn was investigated. It was noticed that the drug release behavior depended upon the pH of medium as well as on the the nature of matrix. CPA-Zn nanocomposites were also studied for their antibacterial activity against E. coli bacteria.