Palas Roy

Eggshell Powder as an Adsorbent for Removal of Fluoride from Aqueous Solution: Equilibrium, Kinetic and Thermodynamic Studies

A new medium, eggshell powder has been developed for fluoride removal from aqueous solution. Fluoride adsorption was studied in a batch system where adsorption was found to be pH dependent with maximum removal efficiency at 6.0. The experimental data was more satisfactorily fitted with Langmuir isotherm model. The kinetics and the factor controlling adsorption process fully accepted by pseudo-second-order model were also discussed. Ea was found to be 45.98 kJmol-1 by using Arrhenius equation, indicating chemisorption nature of fluoride onto eggshell powder. Thermodynamic study showed spontaneous nature and feasibility of the adsorption process with negative enthalpy (∆H0) value also supported the exothermic nature. Batch experiments were performed to study the applicability of the adsorbent by using fluoride contaminated water collected from affected areas. These results indicate that eggshell powder can be used as an effective, low-cost adsorbent to remove fluoride from aqueous solution as well as groundwater.

ARSENIC CONTAMINATION IN GROUNDWATER: A STATISTICAL MODELING

Mathematical modeling of water quality in rivers is an important tool for the planning and management of water resources. Nevertheless, the available models frequently show structural and functional limitations. With the objective of reducing these drawbacks, a new model has been developed to simulate water quality in rivers under unsteady conditions; this model runs on the Vensim PLE ® software and can also be operated for steady-state conditions. The following eighteen water quality variables can be simulated: DO, BODc, organic nitrogen (No), ammonia nitrogen (Na), nitrite (Ni), nitrate (Nn), organic and inorganic phosphorus (Fo and Fi, respectively), inorganic solids (Si), phytoplankton (F), zooplankton (Z), bottom algae (A), detritus (D), total coliforms (TC), alkalinity (Al.), total inorganic carbon (TIC), pH, and temperature (T). Methane as well as nitrogen and phosphorus compounds that are present in the aerobic and anaerobic layers of the sediment can also be simulated. Several scenarios were generated for computational simulations produced using the new model by using the QUAL2K program, and, when possible, analytical solutions. The results obtained using the new model strongly supported the results from the QUAL family and analytical solutions.

Correlation between arsenic intoxication and cognitive ability of primary school children of West Bengal

Arsenic contamination of the groundwater in West Bengal is a serious problem. Chronic exposition to arsenic contaminated water can cause serious diseases like dermal pigments, skin, lung cancer and neurotoxicant that affects the peripheral nervous system[1,2]. The World Health Organization lowered the drinking guideline from 50 ppb to 10 ppb in 1993 to encourage public organizations to comfort this mass contamination. School children are very much susceptible to arsenic exposure. Approximately 90% of children below 11 years of age in affected from Bangladesh and West Bengal, India showed significant level of arsenic in hair and nail[3]. In this study, the primary objective was to find out the relationship between arsenic toxicity (through potable water and vegetables) and cognitive level of primary school children. A standardized questionnaire (Raven’s Standard Progressive Matrices) was used to assess the cognitive function in the form of mental performance of school children in an arsenic contaminated area (Kalyanpur, Purbasthali) and a uncontaminated area (Biswarambha, Purbasthali). The two villages were similar to each other apart from arsenic contamination in the drinking water. Moreover, demographically two studied villages were similar to each other i.e., school children were coming from similar set of family= background (economics, land ownership, crops production and number of family member per household). The testing was administered individually to each respondent (both boys and girls of grade III and IV students) in accordance with the guidelines and procedures of the Raven’s progressive matrices manual. Along with the questionnaire, the anthropometric studies were also done for BMI and other related parameter to check whether there exist any differences between arsenic contaminated and uncontaminated areas. The results also revealed that mean scores of Kalyanpur area were significantly (P<0.05) lower than uncontaminated area (Biswarambha, Purbasthali). The mean BMI of two studied population were significantly (P<0.05) different from each other. From the present outcomes, it is highlighted that exposure to arsenic significantly affected on both cognitive function and BMI. To the best of our survey, this is the first reported study from West Bengal, India of interference of arsenic on cognitive function of school children.