Alternative adsorbent to remove Cr (VI) ions from industrial wastewater

Heavy metals which are discharged from industries in the environment with wastewater causes serious problems for the living organisms. To save the water bodies from the heavy metal contamination, many treatment processes are there. But most used is Adsorption processes where Activated Carbon is used as Adsorbent. As the activated carbon is costly, the treatment is expensive. So, low-cost alternate adsorbents are to be identified in the present scenario. The locally available agro waste material namely Teak Leaves (botanical name is Tectona Grandis) is used as low-cost adsorbent Teak leaves (TL) with pretreatment have been used to study for their potential use to remove chromium (VI) from wastewater by Adsorption. Contact time, Adsorbent dose, pH, initial Cr (VI) ions concentration and particle size have been studied for batch process. The optimum pH, agitation time, Cr (VI) ions conc. adsorbent dose and particle size were found 2.0, 75 minutes, 175 milligrams/l, 25 gm./l and 150 – 300 microns respectively at the room temperature (30 ± 2° C) and achieved 69.1 % to remove Cr (VI). Whereas, the powdered activated carbon (PAC), the removal was 78% at optimum conditions 2.0, 60 min, 125 mg/l, 15 gm/l and <75 micron respectively. The adsorption equilibrium data was used to fit into, Freundlich, Langmuir and modified Freundlich isotherm. But Freundlich isotherm fitted well compared to other two. A distinct advantage of TL as bio-sorbent is that these are locally and easily available agricultural waste and can be used with minor chemical treatment. This process is cost effective and eco-friendly. (paper)