Madhurima Pandey

Biosorptive removal of arsenic from drinking water

A biomass derived from the plant Momordica charantia has been found to be very efficient in arsenic(III) adsorption. An attempt was made to use this biomass for arsenic(III) removal under different conditions. The parameters optimized were contact time (5-150 min), pH (2-11), concentration of adsorbent (1-50 g/l), concentration of adsorbate (0.1-100mg/l), etc. It was observed that the pH had a strong effect on biosorption capacity. The optimum pH obtained for arsenic adsorption was 9. The influence of common ions such as Ca(2+), Mg(2+), Cd(2+), Se(4+), Cl(-), SO(4)(2-), and HCO(3)(-), at concentrations varying from 5 to 1000 mg/l was investigated. To establish the most appropriate correlation for the equilibrium curves, isotherm studies were performed for As(III) ion using Freundlich and Langmuir adsorption isotherms. The pattern of adsorption fitted well with both models. The biomass of M. charantia was found to be effective for the removal of As(III) with 88% sorption efficiency at a concentration of 0.5mg/l of As(III) solution, and thus uptake capacity is 0.88 mg As(III)/gm of biomass. It appears that this biomass should be used as a palliative food item. Further it also appears that the dietary habits may play a role in the toxic effects of ingested arsenic.

Arsenic contamination in central-east India: new lessons for environmental health

This paper reports high levels and variability in the arsenic (As) levels at locations identified as one of the highest As-contaminated locations in the world. The high levels and variability in As levels were established by a strict monitoring protocol and the minimum possible time lag between the sampling and analysis. Special sampling arrangements were created at the central-east Indian location to monitor regularly the various water quality parameters at four specific locations. Out of the four monitored locations the locations 1–3 were found contaminated on more than 90% and the public water supply source (location 4) was found contaminated on more than 38% sampling episodes as per Indian standards. If the WHO standards for As (max. 0.01 mg/L) are considered then all the inhabitants were supplied with unacceptable drinking water on ∼93% of the sampled days during the sampling period. The paper identifies many complexities in the management of As-contamination and the perils of low level contamination in the As-endemic areas.

Arsenic contamination and its causative factors in parts of Chhattisgarh, Central East India

This paper reports the present status of ground water arsenic contamination in the parts of Ambagarh Chowki block in District Rajnandgaon, of Chhattisgarh State. This location is the first arsenic contaminated location reported outside Bengal Delta Plain. The analysis of arsenic contamination measured during year 2008 to 2009 is compared with previously reported synoptic sampling results. This study was necessitated to know and account for the extent of arsenic spread in the groundwater of the area. In the area survey, many new arsenic contaminated locations have been identified in these areas, which were not reported earlier. The water samples were collected from 46 sites of Rajnandgaon District and 78% of the studied locations are contaminated by the presence of arsenic in the range of 2–4,570 µg/L. It was observed that the arsenic levels are fluctuating and appear to be geogenic. Overall the results indicate an urgent need for scientific management of arsenic contamination issues.

Efficient biosorptive removal of chromium(VI)

This paper reports the high biosorptive properties of an indigenous plant for Cr(VI) biosorption. The biomass uptake capacity is found 85 mg Cr(VI)/gm of biomass in batch mode. The influence of different experimental parameters such as pH, dose of adsorbent and Cr(VI) levels (15–200 mg/l), effect of contact time etc. on biosorption was evaluated. The adsorption data fitted well to Langmuir and Freundlich isotherm models. Kinetic experiments revealed that the dilute chromium solutions reached equilibrium within 120 minutes. It was observed that the pH had a strong effect on biosorption capacity. Desorption of Cr(VI) was successfully carried out by 0.1 N hydrochloric acid. The interference study of metals like Mn, Fe, Cu, Cd, Mo, Ni, Pb, As, Co (10mg/l) was investigated. Cd showed negative interference in this investigation.