Mu. Naushad

Effect of ionic liquid on activity, stability, and structure of enzymes: A review

Ionic liquids have shown their potential as a solvent media for many enzymatic reactions as well as protein preservation, because of their unusual characteristics. It is also observed that change in cation or anion alters the physiochemical properties of the ionic liquids, which in turn influence the enzymatic reactions by altering the structure, activity, enatioselectivity, and stability of the enzymes. Thus, it is utmost need of the researchers to have full understanding of these influences created by ionic liquids before choosing or developing an ionic liquid to serve as solvent media for enzymatic reaction or protein preservation. So, in the present review, we try to shed light on effects of ionic liquids chemistry on structure, stability, and activity of enzymes, which will be helpful for the researchers in various biocatalytic applications.

Fabrication and characterization of chitosan-crosslinked-poly(alginic acid) nanohydrogel for adsorptive removal of Cr(VI) metal ion from aqueous medium.

In this study, chitosan-crosslinked-poly (alginic acid) nanohydrogel (CN-cl-PL(AA)NHG) was synthesized by co-polymerization method. It was used an effective adsorbent for the exclusion of Cr(VI) metal ion from aqueous medium. The synthesized nanohydrogel was characterized by FTIR, SEM and TEM. The TEM images clearly indicated the appearance of smooth surface with average size of particles ranging from 30 to 80nm. The effect of different adsorption parameters like agitation time, temperature, initial metal ion concentration and adsorbent dosage was studied and optimized. The results demonstrated that the prepared chitosan-crosslinked-poly (alginic acid) nanohydrogel had high adsorption tendency for the removal of Cr(VI) from the aqueous solution. The pseudo-second-order equation represented the better adsorption kinetics for the adsorption process. The thermodynamic studies showed the adsorption of Cr(VI) onto CN-cl-PL(AA)NHG was spontaneous and chemical in nature.

Magnetically recoverable ZrO2/Fe3O4/chitosan nanomaterials for enhanced sunlight driven photoreduction of carcinogenic Cr(VI) and dechlorination & mineralization of 4-chlorophenol from simulated waste water

In this laboratory-scale experiment we report the treatment of carcinogenic Cr(VI) and 4-chlorophenol by ferromagnetic ZrO2/Fe3O4 nano-heterojunctions supported on chitosan. A combination of different semiconductors with different photo-activities has proven to be a tested and effective technique for harnessing solar light in waste water treatment. The prepared heterojunction and its composite with chitosan has been characterized by X-Ray Diffraction (XRD), Fourier Transform Infra Red spectroscopy (FTIR), High Resolution Transmission Electron Microscopy (HRTEM), Small Area Electron Diffraction (SAED), Vibrating Sample Magnetometry (VSM), Energy Dispersive X-ray analysis (EDX), UV-visible spectrophotometry and Brunauer–Emmet–Teller surface area analysis (BET). Treatment of chlorophenols is challenging because of their hydrophobicity and stability. In our study we have reported excellent results for the dechlorination of 4-chlorophenol and the results were analyzed in terms of Liquid Chromatography-Mass Spectrometry (LC-MS), Chemical Oxygen Demand analysis (COD) and emission. 88.6% of 4-CP degradation was achieved in the presence of ZrO2/Fe3O4/chitosan in 3 h under sunlight and a reduction of 90.2% for Cr(VI) was obtained. The heterojunction formation leads to charge separation and decreased recombination of charge carriers. The synergistic effects of charge separation in the heterojunction, alcohols, peroxide, magnetism and adsorption with essential explanation of mechanisms make this study important and promising.

Modification of Hibiscus cannabinus fiber by graft copolymerization: application for dye removal

AbstractHibiscus cannabinus fiber was modified by graft copolymerization with vinyl monomer acrylic acid (AAc) and binary mixture of AAc and acrylamide (AAm). The different reaction parameters were optimized to get maximum grafting yield. The optimized percent grafting for AAc and binary mixture (AAc + AAm) was found to be 93.6 and 74.6%, respectively, at the molar concentration of 0.35 M for AAc and 0.4 M for AAm. The raw AAc grafted H. cannabinus fiber (Hcf-g-polyAAc) and AAc + AAm grafted H. cannabinus fiber (Hcf-g-polyAAc + AAm) were characterized by FTIR and scanning electron microscopy. The modified H. cannabinus fibers were used as potential candidate for the removal of dye from aqueous system.

Synthesis and characterization of Fe3O4@TSC nanocomposite: highly efficient removal of toxic metal ions from aqueous medium

In the present study, trisodium citrate (TSC) modified magnetite (Fe3O4) nanocomposite was synthesized and characterized using various analytical techniques. The transmission electron microscope images show that the Fe3O4@TSC nanoparticles are well dispersed due to the presence of the TSC coating on Fe3O4, and the particles sizes are in the range of 5–10 nm. The SBET and the total pore volume of Fe3O4@TSC are 245.42 m2 g−1 and 0.368 cm3 g−1, respectively. The saturation magnetization values of Fe3O4 and Fe3O4@TSC are 78.4 and 55.4 emu g−1, respectively. The Fe3O4@TSC is a magnetic adsorbent and was used for the removal of Cr3+ and Co2+ metal ions from aqueous medium. The adsorption of both metal ions onto Fe3O4@TSC is rapid and efficient. The adsorption process is performed at diverse temperatures and the outcomes are investigated kinetically. The results show that adsorption was exothermic and followed the pseudo-second-order kinetic model. Isotherm modelling reveals that the Langmuir equation described the adsorption of both metal ions. Moreover, the loaded Fe3O4@TSC could be recovered easily from aqueous solution by magnetic separation and regenerated by simply washing with 0.1 M HCl solution. Consequently, Fe3O4@TSC nanocomposite could be utilized as an efficient and recyclable adsorbent for the removal of toxic metal ions from aqueous solution.

Kinetics, isotherm and thermodynamic investigations for the adsorption of Co(II) ion onto crystal violet modified amberlite IR-120 resin

The adsorption characteristics of crystal violet (CY)-modified amberlite IRA-120 resin for the removal of Co(II) ion from aqueous medium at different experimental conditions were established by means of batch method. The adsorption uptake was increased with the increase in contact time and temperature. The adsorption process was controlled by pseudo-first-order kinetic model. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models. The Freundlich adsorption model fitted the experimental data reasonably well compared to the Langmuir model. A well-known thermodynamic equation was used to assess the ΔG0 (standard free energy change), ∆H0 (enthalpy change), and ∆S0 (entropy change). The thermodynamic data was indicative of the spontaneous nature of the endothermic sorption process of Co(II) ion onto CY-modified amberlite IRA-120 resin.

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.

Ion-exchange kinetic studies for Cd(II), Co(II), Cu(II), and Pb(II) metal ions over a composite cation exchanger

AbstractExplicit Nernst–Planck approximation is used to study the kinetics of H(I)-metal ion-exchange processes for ions having different effective diffusion coefficients, that is, for non-isotopic exchange process. Kinetic studies of four heavy metal ions (Cd2+, Co2+, Cu2+, and Pb2+) of environmental importance on the surface of acetonitrile stannic(IV) selenite composite cation exchanger were carried out successfully. On the basis of kinetic studies, various physical parameters, that is, fractional attainment of equilibrium U(τ), self-diffusion coefficients (Do), energy of activation (Ea), and entropy of activation (ΔS*) are estimated to evaluate the mechanism of ion exchange on the surface of composite ion-exchange material. The activation entropy and energy revealed that the greater degree and minimum energy was achieved during forward ion-exchange process. The results revealed that the kinetic studies are very important for the economic and industrial applications of ion-exchange materials.

Novel guar gum/Al2O3 nanocomposite as an effective photocatalyst for the degradation of malachite green dye.

Guar gum/Al2O3 (GG/AO) nanocomposite was prepared using simple and cost effective sol-gel method. This nanocomposite was characterized by several analytical techniques viz. scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal analysis (TGA/DTA), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-vis). The FTIR analysis confirmed that GG/AO composite material was formed. TEM images inferred the particle size in the range between 20 and 45nm. GG/AO nanocomposite exhibited good photocatalytic performance for malachite green (MG) dye (dye initial concentration 1.5×10(-5)M) degradation from aqueous phase. The adsorption followed by photocatalysis and coupled adsorption/photocatalysis reaction achieved about 80% and 90% degradation of MG dye under solar irradiation. Antibacterial test showed the excellent activity of GG/AO nanocomposite against Staphylococcus aureus.

ZnSe-WO3 nano-hetero-assembly stacked on Gum ghatti for photo-degradative removal of Bisphenol A: Symbiose of adsorption and photocatalysis

In this research work we report Gum-ghatti supported ZnSe-WO3 nano-hetero-assembly for solar powered degradation of endocrine disruptor Bisphenol S (BPA). The photocatalyst was characterized by Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM), Small area electron diffraction (SAED), X-Ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), Photoluminescence (PL), Energy dispersive X-ray (EDX), UV-vis spectrophotometry and Brauner Emmet Teller surface area analyzer (BET). We achieve a Z-scheme photocatalyst (ZnSe-WO3) with a higher charge flow and visible absorption. Gum ghatti acts as a superadsorbent and a sink for charge carriers. The removal of BPA has been studied under three experimental protocols where 99.5% removal was achieved by symbiose of photocatalysis-adsorption-ozonation in just 45min hetero-assembly has a high surface area, stability and reduced carrier recombination. The results have been analyzed by scavenger effect, mass spectrometry, kinetics and total organic carbon (TOC) analysis. 49.4% of TOC was removed and COD was reduced to 16.7% after 2h in symbiotic condition. From the band edges and scavenger effect it was inferred that superoxide radical anions are major attacking species. The work paves way for designing of novel photocatalysts with increasing biogenic quotient and higher efficiency.