P. C. Srivastava

Bio: P. C. Srivastava is an academic researcher from Banaras Hindu University. The author has contributed to research in topics: Magnetization & Ferromagnetism. The author has an hindex of 12, co-authored 35 publications receiving 305 citations.

Biomass of mucor heimalis for the biosorption of cadmium from aqueous solutions: equilibrium and kinetic studies

Abstract: The present study deals with the utilization of a cellulosic material, i.e. fungal biomass of Mucor heimalis, for the removal of cadmium from aqueous solution in a batch system. Effects of various parameters such as pH, biomass dosage, contact time, and initial metal concentrations were investigated. The sorption of cadmium followed pseudo-second-order rate kinetics (R2=0.998). Intraparticle diffusion was found not to be the sole rate-controlling step. Thermodynamic studies revealed that the sorption of cadmium was feasible, spontaneous, and exothermic. Various isotherm models viz. Langmuir, Freundlich, Redlich–Peterson, Dubinin-Radushkevich, and Temkin isotherms were applied. The Langmuir and Redlich–Peterson models were found to be in good agreement with experimental data with high R2, low RMSE, and low χ2 values. The Redlich–Peterson isotherm constant g was found to be unity, which implies a good fit to the Langmuir model. The maximum sorption capacity calculated from the Langmuir isotherm was 85.47 mg/g at optimum conditions of pH 6.0, contact time of 35 min, biomass dosage of 1g/L, and temperature of 25 oC.

Effluents from Paper and Pulp Industries and their impact on soil properties and chemical composition of plants in Uttarakhand, India

Abstract: Industrial effluents of Paper and Pulp industries Mill were characterized and their impact on soil properties and chemical composition of crop plants was studied in Uttarakhand State of India. The effluent characteristics particularly, total suspended and total dissolved solids, biological oxygen demand, chemical oxygen demand and the content of Na were higher than the prescribed limits. In general, a considerable decrease in the concentration of total suspended and dissolved solids, bicarbonate, chloride, ammoniacal, calcium, sodium, potassium, copper, manganese and cobalt occurred during the flow of effluents downstream. The lateral seepage of paper and pulp industrial effluent to agricultural lands increased the soil pH and electrical conductivity (EC). At shorter distances from point source, the lateral seepage of effluent increased exchangeable K, Na and extractable S, Zn, Fe, Mn, Pb and Ni in soil. The contents of P, K, micronutrients, Pb and Ni in wheat plants increased due to seepage of effluent to the nearby agricultural fields close to the point source.

Fe doping in ZnS for realizing nanocrystalline-diluted magnetic semiconductor phase

Abstract: Zn1−x Fe x S (x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.12, and 0.15) samples have been synthesized by the chemical co-precipitation method, using ZnCl2 and Na2S as starting materials, FeCl3 as a dopant and Ethylenediaminetetraacetic acid (EDTA) as capping agent. Investigations of the structural, optical, and magnetic properties of the prepared samples have been carried out. The results of X-ray diffraction (XRD), selected area electron diffraction of TEM images, Fourier transform infrared spectroscopy have shown that Fe ions are incorporated into the lattice of ZnS crystallites as substitutional impurity at Zn sites in the structure without disturbing the original ZnS wurtzite structure. The average crystallite size from the XRD data and transmission electron microscopy has been found to be in the range of 4–10 nm. Magnetization behavior (i.e., M–H Characteristics) shows the evolution of ferromagnetic behavior with Fe incorporation. It has been found that there is an optimum iron ion concentration for observing the maximum magnetization. The optimum iron ion concentration has been found to be, x = 0.08 in the synthesized samples of Zn1−x Fe x S. The observed magnetization behavior has been understood as ferromagnetic behavior of Fe ions. The decrease of ferromagnetism for the higher Fe ion concentration has been discussed as a result of Fe–Fe interaction in close proximity to result antiferromagnetism for decreasing the magnetization.

Proton Conductivity: Materials and Applications

Abstract: In this review the phenomenon of proton conductivity in materials and the elements of proton conduction mechanismsproton transfer, structural reorganization and diffusional motion of extended moietiesare discussed with special emphasis on proton chemistry. This is characterized by a strong proton localization within the valence electron density of electronegative species (e.g., oxygen, nitrogen) and self-localization effects due to solvent interactions which allows for significant proton diffusivities only when assisted by the dynamics of the proton environment in Grotthuss and vehicle type mechanisms. In systems with high proton density, proton/proton interactions lead to proton ordering below first-order phase transition rather than to coherent proton transfers along extended hydrogen-bond chains as is frequently suggested in textbooks of physical chemistry. There is no indication for significant proton tunneling in fast proton conduction phenomena for which almost barrierless proton transfer is suggest...

Application of Biosorption for Removal of Heavy Metals from Wastewater

Abstract: Fresh water accounts for 3% of water resources on the Earth. Human and industrial activities produce and discharge wastes containing heavy metals into the water resources making them unavailable and threatening human health and the ecosystem. Conventional methods for the removal of metal ions such as chemical precipitation and membrane filtration are extremely expensive when treating large amounts of water, inefficient at low concentrations of metal (incomplete metal removal) and generate large quantities of sludge and other toxic products that require careful disposal. Biosorption and bioaccumulation are ecofriendly alternatives. These alternative methods have advantages over conventional methods. Abundant natural materials like microbial biomass, agro-wastes, and industrial byproducts have been suggested as potential biosorbents for heavy metal removal due to the presence of metal-binding functional groups. Biosorption is influenced by various process parameters such as pH, temperature, initial concentration of the metal ions, biosorbent dose, and speed of agitation. Also, the biomass can be modified by physical and chemical treatment before use. The process can be made economical by regenerating and reusing the biosorbent after removing the heavy metals. Various bioreactors can be used in biosorption for the removal of metal ions from large volumes of water or effluents. The recent developments and the future scope for biosorption as a wastewater treatment option are discussed.