Perpustakaan Digital ITB

Heavy metal pollutants normally found in industrial wastewater. Heavy metals enter into the environment due to bioaccumulation. These metals are highly toxic and disturb the ecosystems. One such heavy metal is chromium. Generally, Chromium widely used in tannery, leather, paint manufacturing, and metal plating industries. Chromium (VI) is more highly toxic and leads to carcinogenic disorders. Hence it is very important that chromium should be removed from industrial waste water before being discharged in natural water bodies and aquatic environment. In this study the pine bark (Pinus merkusii) powder was used as an adsorbent for hexavalent chromium removal from artificial wastewater, and this artificial wastewater was prepared from potassium dichromate, the objectives of this study are to investigate the feasibility of pine bark for the removal of chromium (VI), to determine the various physiochemical controlling factors affecting adsorption, and to study the mechanism of adsorption through kinetic and isotherm models. The experiment was carried out in batch mode experiment, residual Cr(VI) was analyzed by colorimetric method using 1,5 biphenyl carbazide as the complexing agent, meanwhile the pine bark adsorbent will be also characterized by BET, FTIR and SEM analysis. From the study of Cr(VI) removal in artificial wastewater it found that the maximum capacity of the adsorption obtained from the experiment 81.86 mg/g can be reached under conditions of particle size < 0.25 mm, pH = 2, contact time 26 hours, adsorbent dose 2.5 g/250 ml, room temperature and the initial concentration 1000 mg/l, and obtained from Langmuir isotherm is 81.96 mg/g For the physiochemical controlling factors it can be concluded that the very important factors are the pH and temperature because based on the experiment those two parameters has large significant for the adsorption process which lead to higher and faster removal and this also indicating that it was endothermic sorption. It was also observed that the biosorption of hexavalent chromium by pine bark is influenced by the pH of solution, initial adsorbate concentration, contact time, mixing speed and adsorbent dose. The kinetics study showed that the biosorption process followed the Lagergren’s pseuso-second order kinetics From the result of kinetics study it showed that the mostly biosorption of hexavalent chromium using pine bark are follow Ho pseudo-second order which indicated that the mechanism of this adsorption process is the rate-limiting step may be chemisorption involving valence forces through sharing or exchange of electrons between sorbent and sorbate however the isotherm study of Temkin and Dubinin – Radushkevich was oppositely confirmed that the adsorption mechanism is physical adsorption, this adsorption process may be both chemical and physical process and isotherm data also well fitted to Langmuir isotherm which means the adsorption is monolayer adsorption and there is no interaction between adsorbed molecules which means molecules of adsorbate do not lay down on another molecules of adsorbate which are already adsorbed The biosorption of hexavalent chromium by using pine bark occurs through the following mechanism: (1) Anionic adsorption of Cr(VI) on the protonated functional groups of the biosorbent in acidic solution; (2) Bioreduction of Cr(VI) to Cr(III) by functional groups of the biosorbent in acidic environment, (3) physical adsorption of hexavalent chromium to pores and surface of biosorbent.