Muhammad Abdur Rehman

Green biocides, a promising technology: current and future applications to industry and industrial processes

The study of biofilms has skyrocketed in recent years due to increased awareness of the pervasiveness and impact of biofilms. It costs the USA literally billions of dollars every year in energy losses, equipment damage, product contamination and medical infections. But biofilms also offer huge potential for cleaning up hazardous waste sites, filtering municipal and industrial water and wastewater, and forming biobarriers to protect soil and groundwater from contamination. The complexity of biofilm activity and behavior requires research contributions from many disciplines such as biochemistry, engineering, mathematics and microbiology. The aim of this review is to provide a comprehensive analysis of emerging novel antimicrobial techniques, including those using myriad organic and inorganic products as well as genetic engineering techniques, the use of coordination complex molecules, composite materials and antimicrobial peptides and the use of lasers as such or their modified use in combination treatments. This review also addresses advanced and recent modifications, including methodological changes, and biocide efficacy enhancing strategies. This review will provide future planners of biofilm control technologies with a broad understanding and perspective on the use of biocides in the field of green developments for a sustainable future.

Removal of Cd(II) onto Raphanus sativus peels biomass: equilibrium, kinetics, and thermodynamics

Abstract Raphanus sativus peels (RSP) biomass for the adsorptive removal of Cadmium (II) has been studied. The effect of different experimental parameter like pH, temperature, contact time, and initial concentration has been reported. The equilibrium adsorption data were subjected to different adsorption isotherms (Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Flory-Huggins isotherm, and Brunauer, Emmet and Teller isotherms), for kinetic studies pseudo-first-order, pseudo-second-order, Banghams’s model, and intraparticle diffusion kinetic models were applied. The experimental results indicated that the adsorption of Cd(II) followed monolayer adsorption model and pseudo-second-order kinetics. The change in thermodynamic parameters like free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) was also evaluated. It was found that the RSP exhibits good adsorption capacity for Cadmium (II) from aqueous solution.

Fluoride adsorption by doped and un-doped magnetic ferrites CuCexFe2-xO4: Preparation, characterization, optimization and modeling for effectual remediation technologies

A series of doped and un-doped magnetic adsorbents CuCexFe2-xO4 (x=0.0-0.5) for fluoride were prepared with the micro-emulsion method. Fluoride adsorption was optimized for solution pH, temperature, contact time, and initial concentration and was monitored via normal phase ion chromatography (IC). The effect of concomitant anions was also explored to perform and simulate competitive fluoride adsorption in real water samples. Optimal adsorption was discovered by a simple quadratic model based on central composite design (CCD) and the response surface method (RSM). The adsorption, electrochemical and magnetic properties were compared between doped and un-doped ferrites. Doped ferrites (x=0.1-0.5) were found to be superior to un-doped ferrites (x=0) regarding the active sites, functional groups and fluoride adsorption. The characterization, optimization and application results of the doped ferrites indicated enhanced fluoride adsorption and easy separation with a simple magnet.

Electrochemical investigation on the corrosion inhibition of mild steel by Quinazoline Schiff base compounds in hydrochloric acid solution

The inhibitory effect of two Schiff bases 3-(5-methoxy-2-hydroxybenzylideneamino)-2-(-5-methoxy-2-hydroxyphenyl)-2,3-dihydroquinazoline-4(1H)-one (MMDQ), and 3-(5-nitro-2-hydroxybenzylideneamino)-2(5-nitro-2-hydroxyphenyl)-2,3-dihydroquinazoline-4(1H)-one (NNDQ) on the corrosion of mild steel in 1M hydrochloric acid were studied using mass loss, potentiodynamic polarization technique and electrochemical impedance spectroscopy measurements at ambient temperature. The investigation results indicate that the Schiff Bases compounds with an average efficiency of 92% at 1.0mM of additive concentration have fairly effective inhibiting properties for mild steel in hydrochloric acid, and acts as mixed type inhibitor character. The inhibition efficiencies measured by all measurements show that the inhibition efficiencies increase with increase in inhibitor concentration. This reveals that the inhibitive mechanism of inhibitors were primarily due to adsorption on mild steel surface, and follow Langmuir adsorption isotherm. The temperature effect on the inhibition process in 1MHCl with the addition of investigated Schiff bases was studied at a temperature range of 30-60°C, and the activation parameters (Ea, ΔH and ΔS) were calculated to elaborate the corrosion mechanism. The differences in efficiency for two investigated inhibitors are associated with their chemical structures.

Intercationic effect on biosorbent efficacy.

The efficacy of the biosorbent coconut hust (Cocos nucifera) was tested for the removal of lead, copper, zinc, and nickel metal ions using batch experiments in multimetal solution system under controlled experimental conditions. It is found that metal sorption increases when the equilibrium metal concentration rises. At highest experimental solution concentration (150mg/L), the removal of metal ions was 92.52% for lead, 79.55% for copper, 63.23% for zinc, and 68.10% for nickel, while at lowest experimental solution concentration (25mg/L), the removal of metal ions was 94.80% for lead, 86.81% for copper, 84.63% for zinc, and 82.36% for nickel. Biosorption equilibrium isotherms were plotted for metal uptake capacity (q) against residual metal concentrations (Cf) in solution. The q vs. Cf sorption isotherm relationship was mathematically expressed by Langmuir and Freundlich models. The values of separation factor were between zero and one indicating favorable sorption for four tested metals on the biosorbent. The surface coverage values were approaching unity with increasing solution concentration, indicating effectiveness of the biosorbent.