Enhancement of cadmium ion sorption capacity of lignocellulosic biosorbent by sulfonation

摘要: Water contaminated by heavy metals remains a serious environmental and public health problem. Cadmium is a toxic heavy metal that not only causes choking, abdominal pain, anemia, renal dysfunction, and diarrhea, but also has been listed as a carcinogen by the EPA (Gaballah and Kibertus, 1998). Among current technologies used to reduce the amount of heavy metals in water, applications and studies of adsorption method with bio-sorbents have been expanded because of their low cost.(Gaballah and Kibertus 1998; Reddad et al., 2002). Pinyon juniper and modified pinyon juniper have been used as sorbents for removal of heavy metal (Min et al., 2002). In general, raw lignocellulosic bio-sorbents were modified by various methods to increase their sorption capacities because metal ion binding by lignocellulosic bio-sorbents is believed to take place through chemical functional groups such as carboxyl, amino, or phenolics. In this study, sulfonic sites were introduced into juniper wood as new binding sites for cadmium ions. Accordingly, the objectives of this study are 1) to assure that sulfonation enhances the cadmium ion sorption capacity of lignocellulosic biosorbents using sorption tests, and 2) to reasonably explain the improvement of sorption capacity by sulfonation by observing changes in functional groups on the surfaces of the sorbents.