Biosorption of zinc from aqueous solution using leaves of Corchorus olitorius as a low-cost biosorbent.

Zinc (Zn) is one of the hazardous metal pollutants commonly found in industrial effluents and poses severe environmental and human health impacts. The present study chosen the leaves of Corchorus olitorius as a potential biosorbent among four different types of leaves employed for removing Zn from aqueous solution. The process parameters-contact time, pH, biosorbent dose, and initial Zn concentration were optimized for maximum removal of Zn using standard protocols. The Fourier-transform infrared spectroscopy study was performed to identify the functional groups involved in Zn biosorption mechanism. The biosorption equilibrium was achieved at 120 min of contact time. The biosorption of Zn was highest at pH 6 and biosorbent dose of 2 g/L. The sorption equilibrium data were well fitted with the Freundlich isotherm model (R2  = 0.995). Highest adsorption capacity of C. olitorius leaves was 11.63 mg/g. It is concluded that the leaves of C. olitorius could be used as a potentially low-cost novel biosorbent to remove Zn from contaminated water. PRACTITIONER POINTS: Optimum Zn sorption process parameters of Corchorus olitorius leaf biosorbent were determined. Zn sorption kinetic data of C. olitorius leaf were well fitted by Freundlich isotherm model. C. olitorius leaf biosorbent showed excellent Zn sorption capacity (11.63 mg/g) from water. Leaves of C. olitorius could be used as a potentially low-cost novel biosorbent.

A study to investigate fluoride contamination and fluoride exposure dose assessment in lateritic zones of West Bengal, India.

To assess the status of severity of fluoride contamination in lateritic Bankura and Purulia districts of West Bengal, concentrations of fluoride in different water sources and agricultural field soils were investigated. The fluoride content (mg/l) was observed to differ with aquifer depths: 0.19-0.47 in dug wells, 0.01-0.17 in shallow tube wells, and 0.07-1.6 in deep tube wells. Fluoride within the World Health Organization (WHO) prescribed range (1.0-1.5 mg/l) was estimated only in ~17% of the total collected water samples while ~67% showed <0.7 mg/l fluoride and thus may impede in the production and maintenance of healthy teeth and bones of the residents, especially children. Fluoride in water was found to be significantly correlated (r = 0.63) with pH. The exposure dose of fluoride (mg/kg/day) from drinking water in infants, children, and adults was estimated in the ranges 0.02-0.53, 0.01-0.24, and 0.01-0.14, respectively against the standard value of 0.05. A clear risk of dental fluorosis is apparent in infants and children of the study area. The fluoride in soil (55-399 mg/kg) was detected to be significantly correlated with the fluoride content in deep tube wells and soil pH (r = 0.56 and 0.71, respectively). The relationships of soil fluoride with total hardness and that with phosphate were not significant. There is a high possibility of bioaccumulation of fluoride from contaminated soil and water of the study area to cultivated crops. This will enhance the quantity of fluoride intake into human food chain in addition to drinking water pathway.