Adsorption study of utilizing calabash <i>Crescentia cujete</i>) seed in the removal of heavy metals from industrial wastewater

Abstract

This work was carried out to assess the physicochemical parameters and removal of heavy metals from industrial wastewater by activated carbon prepared from calabash seed. Some physicochemical parameters of the wastewater that assessed are pH, temperature, and turbidity, BOD, COD, TS, TDS and TSS. Adsorption studies on the effects of contact time, pH and adsorbent doses on the removal of heavy metals were investigated. The pH and temperature of granite industrial wastewater were 7.5 and 32.5 respectively which are within the permissible limit of WHO (7-8.5 and 32 oC). The wastewater sample shows extremely high turbidity of 2.5 mg/l, biochemical oxygen demand (BOD) of 430 mg/l, chemical oxygen demand (COD) of 283 mg/l, total solid (TS) of 45 mg/l, total dissolved solid (TDS) of 655 mg/l and total suspended solid (TSS) of 965 which are above permissible limit of WHO. The maximum adsorption capacity of Zn (99%) and Fe (88%) were observed at pH 8 and 12 respectively. The pseudo-fist order and pseudo-second order kinetic models were used to fit the kinetic data of the adsorption process, and the result obtained showed that pseudo-second order kinetic model was able to fit the generated adsorption data from the heavy metals considered in this research work due to the regression coefficient R2 of 0.997 value obtained. The study reveals that granite industrial wastewater effluent is one of the industries responsible for polluting the surrounding aquatic environment.

Key words: Kinetic study, calabash seed, adsorption, heavy metals, wastewater