Application of an agro-industrial waste for the removal of As (III) in a counter-current multiphase fluidized bed

摘要

Arsenic pollution in groundwater has been identified as a major hazard in developing countries. In this purview, Karanja or Pongamia pinnata seed cake, a biodiesel residue has been proposed to being utilized to curb the arsenic menace using an agro-industrial waste. The study investigates the biosorption of As (III) onto thermally activated de-oiled karanja seed cake (TAKB) with a surface area of 19.8m(2)/g in a counter-current multiphase fluidized bed column. Experiments were designed with the aid of a full factorial central composite design to study the effect of five different process variables on the percentage adsorption of As (III). The maximum uptake capacity of the biosorbent was obtained to be 0.226mg/g which was comparable to other reported biosorbents. Multiple regression analysis was used to derive a quadratic polynomial that developed a correlation between the independent process parameters and the percentage removal of As (III) together the analysis of variance . The optimum parameters for maximum percentage removal of As (III) were determined to be an initial As (III) concentration of 0.378mg/L, gas and liquid flow rates of 0.224 and 0.074L/min, respectively, static bed height of 0.069m and the average particle size of the biosorbent as 1.73mm. Isotherm studies based on Langmuir and Freundlich models were also conducted in order to estimate the maximum sorption capacity of TAKB. A confirmatory test with groundwater at optimum conditions for real-time application was performed, and 93.17% As (III) removal was attained.