The Kinetics of the Adsorption Process of Cr (VI) in Aqueous Solution Using Neem Seed Husk (Azadirachta indica) Activated Carbon

Abstract

The aim of this research is the study of physico-chemical properties activated carbon prepared from agricultural by product such as Neem Seed Husk (NSH) which is abundantly available in our environment The Activated Carbon (AC) was prepared using H3PO4 as activating agent and carbonized at 300°C for two hours. The results shows that the activated process was successful and can compete favorably with commercial activated carbon. The prepared activated carbon was characterized using Fourier Transform Infrared Spectrophotometer (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersion X-ray (EDX) and Thermogravimetric Analysis (TGA). The percentage removal of Cr(VI) increased with increase in process parameters such as adsorbent dose, time and temperature while there was a decrease with increase in pH and Initial concentration. It was established from the results that activated carbon produced from Neem seed husk has adsorption capacity which could remove 99.75% Cr (VI) at optimum process conditions (pH-2.0, Cr(VI) concentration-10 mg/L, adsorbent dose 0.5 g/L, Temperature 70 c and contact time 30 mins.). Thus, the adsorption method using activated carbon produced from biomass was used effectively for removing Cr(VI) in a stock solution, seems to be an economical and worthwhile alternative over other conventional methods, because of it availability, low price and multi-purposes. The adsorption data fitted well into Freundlich and Langmuir with correlation coefficient (R2) 0.9522 and 0.9403 respectively. The kinetics of the adsorption process was tested through pseudo-first-order and pseudo-second-order models. The pseudo-second-order kinetic model provided the best correlation for with (R2) 0.993, while the pseudo-first-order was found to be 0.928. The study provided an effective use of low-cost activated carbon as a valuable source of adsorbents for the removal of Cr(VI) ions from aqueous solution.