PERIWINKLE SHELL: BASED GRANULAR ACTIVATED CARBON FOR TREATMENT OF CHEMICAL OXYGEN DEMAND (COD) IN INDUSTRIAL WASTEWATER

The present investigation was undertaken to compare the adsorption efficiency of a low cost adsorbent, periwinkle shell-based granular activated carbon (PSC) with the adsorption efficiency of the commercial activated carbon (CAC) and a ratio 1:1 mixture of PSC and CAC (PSC/CAC) with respect to uptake of the organic components responsible for the chemical oxygen demand (COD) of industrial wastewater. The influence of treatment time, adsorbent dose, pH of the media, agitation speed and adsorbent particle size on the rate of percent COD removal is evaluated. PSC has shown quite effective adsorbent capacity for COD removal with 77.5% efficiency. Though its capacity is slightly lower than that of CAC with 79% efficiency, however the low material cost makes it an attractive option for the treatment of COD. The equilibrium adsorption study can be described by the Linear, Langmuir and Freundlich models. The mechanisms of the rate of adsorption of COD were analysed using the Elovich equation and a pseudo-second-order model. The models provided a very high degree of correlation of the experimental adsorption rate data suggesting either model could be used in design applications.