Removal of hexavalent chromium Cr (VI) from Aqueous Solution using Adsorption onto Modified alder Sawdust: A Study of Equilibrium and Kinetics

A huge volume of wastewater from household، agriculture and industrial sources is released into the environment، which contains high level concentration of organic and inorganic materials such as hydrocarbonic solvents، heavy metals، insecticides and dyes. Heavy metals are one of the most important pollutants discharged by industries such as the electroplating and have adverse effects on environment and human health. Heavy metals such as chromium are found in plating wastewater and is harmful for human health and environment. The purpose of present study was to investigate the adsorption of heavy metals such as chromium onto modified alder sawdust by formaldehyde، sulfuric acid and sodium bicarbonate، as a cheaper adsorbent. This research was an experimental-laboratory type which investigated the removal of hexavalent chromium from aqueous solution by using modified alder sawdust with variation contact time، initial Cr (VI) concentrations pH and adsorbent dose in batch system، the residual Cr (VI) concentration was analyzed by 1،5-diphenylcarbazide method by a spectrophotometer at a wavelength of 540 nm. Then، the results were analyzed by Excel software. Results showed the removal efficiency was decreased by increasing of pH and initial chromium concentration. Also، the results showed the removal efficiency was increased by increasing of adsorbent dose and contact time. Experimental isotherms and kinetic models were assessed by pseudo-first-order and pseudo-second-order kinetics and Langmuir and Freundlich isotherms models. The results show that the data were explained acceptably by pseudo-second-order kinetics and Langmuir isotherms models، respectively. The results showed that the removal of hexavalent chromium from aqueous solution can be done by using modified alder sawdust، both at lower cost and more effectively.