Effectiveness of Activated Groundnut Shells to Remove Chromium from Tannery Wastewater

Abstract

This paper presents results of the investigation of Chromium III removal from tannery wastewater using groundnut shells under laboratory scale batch experiments. The effects of pH, contact time, particle size and dosage of the adsorbent on the adsorption of Cr (III) were studied. Determination of Chromium ion concentration in the wastewater was done using Atomic Absorption Spectrophotometer (AAS). Results show that removal mechanism is dominantly adsorption, which is dependent of the physical and chemical characteristics of the material. The main constituent of groundnut shell is carbon, potentially making it suitable for making activated carbon for adsorption experiments. From the initial concentration of 6.643 ppm, optimum Cr (III) removal was obtained at pH of 4, particle size of 0.25mm, contact time of 180 minutes and adsorbent dosage of 20g, with highest efficiency of 98.013%, corresponding to final concentration of 0.132ppm. The adsorption process was found to obey the Freundlich adsorption isotherm with R2 being 0.9613. Overall, the adsorption capacity of the activated groundnut shell was found to be 2.6172mg/g which ensures that they can be used for the removal of Chromium III from tannery wastewater.