Ayyaz Ahmad

An efficient catalytic degradation of trichloroethene in a percarbonate system catalyzed by ultra-fine heterogeneous zeolite supported zero valent iron-nickel bimetallic composite

Zeolite supported nano iron-nickel bimetallic composite (Z-nZVI-Ni) was prepared using a liquid-phase reduction process. The corresponding surface morphologies and physico-chemical properties of the Z-nZVI-Ni composite were determined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Energy dispersive X-ray spectra (EDS), Brunauer Emmett Teller (BET) adsorption, wide angle X-ray diffractometry (WA-XRD), and Fourier transform infrared spectroscopy (FTIR). The results indicated high dispersion of iron and nickel nano particles on the zeolite sheet with an enhanced surface area. Complete destruction of trichloroethene (TCE) and efficient removal of total organic carbon (TOC) were observed by using Z-nZVI-Ni as a heterogeneous catalyst for a Fenton-like oxidation process employing sodium percarbonate (SPC) as an oxidant. The electron spin resonance (ESR) of Z-nZVI-Ni verified the generation and intensity of hydroxyl radicals (OH•). The quantification of OH• elucidated by using p-chlorobenzoic acid, a probe indicator, confirmed the higher intensity of OH•. The transformation products were identified using GC-MS. The slow iron and nickel leaching offered higher stability and better catalytic activity of Z-nZVI-Ni, demonstrating its prospective long term applications in groundwater for TCE degradation.

Antibacterial activity of graphene supported FeAg bimetallic nanocomposites.

We report the simple one pot synthesis of iron-silver (FeAg) bimetallic nanoparticles with different compositions on graphene support. The nanoparticles are well dispersed on the graphene sheet as revealed by the TEM, XRD, and Raman spectra. The antibacterial activity of graphene-FeAg nanocomposite (NC) towards Bacillus subtilis, Escherichia coli, and Staphylococcus aureus was investigated by colony counting method. Graphene-FeAg NC demonstrates excellent antibacterial activity as compared to FeAg bimetallic without graphene. To understand the antibacterial mechanism of the NC, oxidative stress caused by reactive oxygen species (ROS) and the glutathione (GSH) oxidation were investigated in the system. It has been observed that ROS production and GSH oxidation are concentration dependent while the increase in silver content up to 50% generally enhances the ROS production while ROS decreases on further increase in silver content. Graphene loaded FeAg NC demonstrates higher GSH oxidation capacity than bare FeAg bimetallic nanocomposite. The mechanism study suggests that the antibacterial activity is probably due to membrane and oxidative stress produced by the nanocomposites. The possible antibacterial pathway mainly includes the non-ROS oxidative stress (GSH oxidation) while ROS play minor role.

Synthesis of Ag2O nano-catalyst in the spherical polyelectrolyte brushes and its application in visible photo driven degradation of dye

Abstract Ag2O nanoparticles (NPs) were synthesized using colloidal solution of spherical polyelectrolyte brushes (SPB) as nano-reactors. In this work, the average diameter of Ag2O NPs was around 10 nm as determined by transmission electron microscopy (TEM). The composite NPs of Ag2O immobilized in SPB (Ag2O-SPB) showed significant absorption in the visible light region as confirmed by UV-Vis diffuse reflectance spectra (DRS), and their photoluminescence (PL) exhibited emission peak in the visible range. Ag2O-SPB has shown outstanding photocatalytic activity during degradation of methyl blue (MB) in the visible light. This work will open up a new way to prepare ideal Ag2O nano-catalyst for the remediation of wastewater using visible light.

Production, Purification and Partial Characterization of Organo-Solvent Tolerant Protease from Newly Isolated Bacillus sp. BBXS-2

Proteolytic enzymes are applied in various industries such as detergent, leather, food, textile, cosmetics, pharmaceutical, and synthetic biotechnology. To meet commercial needs, microbial strains of high value in terms of cost-effective production have been focused. In this study, thermophilic strain, Bacillus sp. BBXS-2 was activated on simple growth medium and then transferred to Luria Bertani (LB) medium. Maximum protease concentration of 6723 U/mL under optimized fermentation conditions (molasses, corn steep liquor, pH 9.0, and 45°C). The results showed, there was no difference observed in bacterial growth and protease titer while replacing yeast extract with corn steep liquor so, in this way, about 90% cost of nitrogen source can be saved. The extracellular enzyme was purified to homogeneity from cell-free supernatant by ammonium sulphate precipitation followed by dialysis and ion exchange chromatography, recovery yield reduced from 100 to 22% and purification fold increased from 1 to 9.82. The enzyme was active in broad pH and temperature range 8-12 pH and 30-60°C, with maximum activity at pH 10.0 and 60°C, respectively. Protease retained more than 90% activity after incubation at 40°C for 2 weeks in the presence of (40% v/v) organic solvents including ethanol, methanol, and isopropanol. Overall, research suggests that this strain is a more promising candidate and possess practical ability to use in industries.