IOSR Journal of Applied Chemistry (IOSR-JAC) e-ISSN: 2278-5736.Volume 9, Issue 7 Ver. I (July 2016), PP 74-85 www.iosrjournals.org DOI: 10.9790/5736-0907017485 www.iosrjournals.org 74 |Page Adsorption of Lead (II) from Aqueous Solution using Activated Carbon Prepared from Raffia Palm (Raphia Hookeri) Fruit Epicarp Ghogomu, J. N 1 , Muluh, S. N 1 , Ajifack, D. L 1 , Alongamo, A.A.B 1 , Noufame, D. T 1 1 (Department of Chemistry,Faculty of Science, University of Dschang, P.O. Box 6, Dschang, Cameroon) Abstract: Activated carbons from raphia hookeri fruit epicarps obtained by chemical activation using ZnCl 2 (CAZn), H 3 PO 4 (CAH) and KOH (CAK) were utilized for the removal of lead (II) ion from aqueous solution. Samples were characterized by FTIR, Boehm method, pHpzc, iodine number, bulk density and surface area. Batch adsorption experiments were performed to study the effects of contact time, solution pH, adsorbent mass and initial adsorbate concentration at 27 o C. Optimal conditions from equilibrium studies were as follows: contact times of 80 minutes for CAZn and CAH and 100 minutes for CAK, pH = 6 for all samples, adsorption capacities of 66.37 mg/g for CAZn, 56.30 mg/g for CAH and 28.0 for CAK. Adsorption was modeled using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. Equilibrium data were best represented by Langmuir isotherm model with monolayer adsorption capacities of 72.62 mg/g, 58.62 mg/g and 12.16 mg/g for CAZn, CAH and CAK respectively. Adsorption kinetics was via pseudo-first order, pseudo-second order, Elovich and intra-particle diffusion models. Kinetic studies revealed that the adsorption process followed pseudo-second order model. Raphia hookeri based activated carbons (CAZn and CAH) are shown to be promising materials for the adsorption of lead(II) ions from aqueous solutions. Keywords: Activated carbon, Adsorption, Chemical activation, Lead (II) ions, Raphia hookeri. I. Introduction The problem of water contamination is neither new nor limited to a particular geographical area. Eco- toxicity specifically from wastewater contaminated with dyes, hydrocarbons and heavy metals from various manufacturing processes has become a serious environmental issue in recent years. Unlike organic pollutants, the majority of which are susceptible to biological degradation, these heavy metals do not degrade into harmless end products and their presence in streams and lakes leads to bioaccumulation in living organisms causing health problems in animals, plants, and human beings [1,2]. Lead (Pb), a heavy metal, has recently gained increasing attention owing to its high toxicity to living organisms [3]. Lead ions are taken into the body via inhalation, ingestion or skin absorption. Lead accumulates mainly in bones, brain, kidney and muscles and may cause many serious disorders like anaemia, kidney diseases etc. Lead is also known to cause mental retardation, reduces haemoglobin reproduction necessary for O 2 transport and it interferes with normal cellular metabolism. Lead equally has damaging effects on the body’s reproductive and central nervous system [4]. As a result of these, environmental regulatory boards often spell out limitations as to the maximum concentration of lead in natural water and for wastewater discharge. The current U.S. Environmental Protection Agency (EPA) and World Health Organization (WHO) standard for lead in wastewater and drinking water is 0.5 and 0.05 mg/L, respectively [5]. Several treatment methods have been suggested, developed and used to remove heavy metals from wastewater, some of which include: chemical precipitation, ion exchange, membrane separation, complexation, adsorption, solvent extraction and distillation [6] are all geared towards greater amelioration of the quality of water/environment [7]. Amongst these methods, adsorption which is reported in this study has shown high potentials and simplicity in the depollution of industrial wastewater, especially in the elimination of lead [8]. Nevertheless, its efficiency depends largely on the adsorbent (cost, availability, and its regeneration) put together. The cost of preparing activated carbon from agricultural wastes is negligible when compared to the cost of commercial activated carbon. Present day researchers have utilized different low-cost materials as adsorbents which at times are less efficient. [9] prepared militia ferruginea plant leaves-based activated carbon for the sorption of Pb(II) ions in aqueous solution with a maximum adsorption capacity of about 3.3 mg/g of Pb(II) from a model based on the Freundlich adsorption isotherm. According to [10] maximum adsorption of Pb(II) ions by phosphoric acid activated carbon prepared from fluted pumpkin seed shell was of the order of 14.29 mg/g of adsorbent. In another study, [11], investigated on the adsorption performance of H 3 PO 4 treated Nipa Palm Nut (NPN) based activated carbon for the uptake of Pb(II) and reported a monolayer adsorption capacity of 125 mg/g via the Langmuir model. On their own part, [12] showed that the maximum monolayer adsorption capacity of Pb(II) ions from aqueous solution using palm shell activated carbon was 13.4 mg/g. All these results show that