Preparation of activated carbon from dried pods of Prosopis cineraria with zinc chloride activation for the removal of phenol

Utilization of agrowaste materials for the production of activated carbon, as an excellent adsorbent with large surface area, is well established industrially, for dephenolation of wastewater. In the present work, dried pods of Prosopis cineraria—a novel and low-cost agrowaste material—were used to prepare activated carbons by zinc chloride activation. Batch adsorption experiments were carried out to study the effects of various physicochemical parameters such as initial phenol concentration, adsorbent dose, initial solution pH, and temperature. Pseudo-first-order second-order and diffusion kinetic models were used to identify the possible mechanisms of such adsorption process. The Langmuir and Freundlich equations were used to analyze the adsorption equilibrium. Maximum removal efficiency of 86 % was obtained with 25 mg?L^?1 of initial phenol concentration. The favorable pH for maximum phenol adsorption was 4.0. Freundlich equation represented the adsorption equilibrium data more ideally than the Langmuir. The maximum adsorption capacity obtained was 78.32 mg?g^?1 at a temperature of 30 °C and 25 mg?L^?1 initial phenol concentration. The adsorption was spontaneous and endothermic. The pseudo-second-order model, an indication of chemisorption mechanism, fitted the experimental data better than the pseudo-first-order Lagergren model. Regeneration of spent activated carbon was carried out using Pseudomonas putida MTCC 2252 as the phenol-degrading microorganism. Maximum regeneration up to 57.5 % was recorded, when loaded phenol concentration was 25 mg?L^?1. The data obtained in this study would be useful in designing and fabricating an efficient treatment plant for phenol-rich effluents.     

Removal of hydrocarbon from refinery tank bottom sludge employing microbial culture

Accumulation of oily sludge is becoming a serious environmental threat, and there has not been much work reported for the removal of hydrocarbon from refinery tank bottom sludge. Effort has been made in this study to investigate the removal of hydrocarbon from refinery sludge by isolated biosurfactant-producing Pseudomonas aeruginosa RS29 strain and explore the biosurfactant for its composition and stability. Laboratory investigation was carried out with this strain to observe its efficacy of removing hydrocarbon from refinery sludge employing whole bacterial culture and culture supernatant to various concentrations of sand–sludge mixture. Removal of hydrocarbon was recorded after 20 days. Analysis of the produced biosurfactant was carried out to get the idea about its stability and composition. The strain could remove up to 85?±?3 and 55?±?4.5 % of hydrocarbon from refinery sludge when whole bacterial culture and culture supernatant were used, respectively. Maximum surface tension reduction (26.3 mN m^?1) was achieved with the strain in just 24 h of time. Emulsification index (E24) was recorded as 100 and 80 % with crude oil and n-hexadecane, respectively. The biosurfactant was confirmed as rhamnolipid containing C₈ and C₁₀ fatty acid components and having more mono-rhamnolipid congeners than the di-rhamnolipid ones. The biosurfactant was stable up to 121 °C, pH 2–10, and up to a salinity value of 2–10 % w/v. To our knowledge, this is the first report showing the potentiality of a native strain from the northeast region of India for the efficient removal of hydrocarbon from refinery sludge.     

Bioavailable DDT residues in sediments: laboratory assessment of ageing effects using semi-permeable membrane devices

We describe the reduction in bioavailability of DDT in contaminated soil after it was incubated as sediment for 365 d. Bioavailability was assessed using semi-permeable membranes. Contaminated soils from three cattle dip sites, one spiked paired uncontaminated site, and one spiked OECD standard soil were studied. Sandy soil with residues of 1880 mg/kg summation operator DDT incurred since 1962, initially had 4.6% of summation operator DDT available, reducing to 0.6% following 365 d. Clay soil (1108 mg summation operator DDT/kg) had 4.1% initially available, reducing to 0.3% after 365 d. Freshly spiked soils had a greater amount of DDT initially available (10.9%), but this reduced to 1.5% by the end of the incubation. Of the DDT congeners, both o,p'-DDD and p,p'-DDD were most bioavailable in the soils, but also had the most significant decrease following incubation.     

Preconcentration technique for the determination of trace elements in natural water samples by ICP-AES

A procedure was developed for the determination of Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) after preconcentration on a morpholine dithiocarbamate (mor-DTC) supported by bagasse (Saccharam aphisinaram). The sorbed elements were subsequently eluted with 4,M HNO₃ and the acid eluates were analysed by ICP–AES. The influence of various parameters such as pH, flow rate of sample, eluent concentration, volume of the sample and volume of eluent were investigated to enhance the sensitivity of the present method. A 20,mL disposable syringe served as preconcentration column. Under the optimal conditions Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in aqueous sample was concentrated about 100-fold. The sorption recoveries of elements were higher than 99.6%. The method is also applied for the analysis of natural and spiked water samples.     

A Novel Biodegradable Green Poly(l-Aspartic Acid-Citric Acid) Copolymer for Antimicrobial Applications

Poly (l-aspartic acid-citric acid) green copolymers were developed using thermal polymerization of aspartic acid (ASP) and citric acid (CA) followed by direct bulk melt condensation technique. Antibacterial properties of copolymer of aspartic acid based were investigated as a function of citric acid content. This study is focused on the microorganism inhibition performance of aspartic acid based copolymers. Results showed that inhibition properties increase with increasing citric acid content. Characterization of obtained copolymers was carried out with the help of infrared absorption spectra (FTIR), x-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). The antibacterial activity of copolymers against bacteria like E-coli, Bacillus and pseudomonas was investigated. The copolymers showed excellent antimicrobial activities against three types of microorganisms. Overall studies indicated that the above copolymers possess a broad wound dressing activity against above three types of bacteria and may be useful as antibacterial agents.     

Changes in hematological profile of male albino rats after acephate administration

The present study was designed to evaluate the possible adverse effects of acephate, an organophosphate insecticide, on hematological parameters in male albino rats. Acephate was administered orally to rats at either 25, 50, or 75 mg/kg bwt/day for 30 days. Data showed a significant decrease in total erythrocyte count, hemoglobin concentration, and hematocrit value; however, an increase in total leukocyte count was noted. The levels of blood sugar and blood urea were significantly elevated when administered by acephate. There were no significant changes in mean corpuscular hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin concentration for all doses. Thus, obtained results collectively revealed that acephate administration produced significant alterations in hematological parameters in dose-dependent manner.     

A review on current techniques used in India for rice mill wastewater treatment and emerging techniques with valuable by-products

Environmental Science and Pollution Research - Parboiling rice mills produce a large amount of wastewater. The effluent from the rice mill contains high concentration of organic and inorganic...