Utilization Of Native Botanic Material As Sorbent For Removal Of Heavy Metals From Wastewater

Heavy metals are the kinds of poisonous substance that can contaminate river water, a dram of heavy metals can bring sigma effect of toxicity, heavy metals can do harm to people's health by many ways, and it' s toxicity mainly show the harm by receding people's resistibility. All heavy metals are poisonous substance that cannot be decreased by degradation, and will be adsorbed and be accumulated by food cycle, and eventually people will be poisoned chronically. Detecting, and prevention and curing heavy metals in water are always the hotspots in the study of environment science. Techniques in treating the heavy wastewater were exploitured and meliorated, such as physical, chemic, biologic and so on. Biosorption of heavy metal is a new potential technology to treat wastewater containing heavy metal. It has many outstanding advantages: selectivity of heavy metal ions from the low concentration wastewater, high efficiency, wide range of pH and temperature, low investment and recovery of some precious metals. Some low cost botanic materials had directly been used as sorbent for heavy metals in aqueous solution, which included wheat straw,maize cob, maize stalk, rice husk, barley husk, wood chip, palm fruit bunch, sawdust, bark, leaf, coir pith, banana pith, bagasse pith and aquatic plants. For a developing nation as China, new, economical and highly effective treatment technologies of heavy metals wastewater were urgently neede.On the foundation of the former experimental conclusions, in this paper, Peanut hull, rice bran and sawdust were used to adsorb Pb(â…¡) ,Zn(â…¡),Cu(â…¡) from simulated wastewater. The influencing factors to the yield of absorption were systematically studied and the best reacting conditions were optimized, and studied the adsorption function mechanism.The experiments results showed that three types of sorbents have high sorption efficiency when the initial metal ion concentration is low, the peanut hull is the best of the three adsorption. Then the continued experiments investigate the absorption activity of peanut hull was affected by the adsorption time, pH values, the amount of peanut hull addition. The results demonstrated that use peanut hull adsorb Pb(â…¡) ,Zn(â…¡),Cu(â…¡) could achieve equilibrium during very sort time. The pH of the aqueous solution is indeed an important parameter in sorption process. The low-pH values, too much sorbent, resulting in a reduced metal uptake by the sorbent. The adsorpton capacity decreased in the order of Pb(â…¡)>Zn(â…¡)>Cu(â…¡). The adsorption isotherms for Pb(â…¡),Zn(â…¡),Cu(â…¡) were found to obye Langmuir adsorption model.Although peanut hull is an attractive option for the treatment of low-concentration metal ion wastewater, peanut hull has much water-soluble organic pigment, when immersion with water, colored matter flow outlet. The water which treatmented by peanut hull have to treatment again, cause resource and energy waste. Modified peanut hull with acid-formaldehyde solution, modified peanut hull could blocking the outflow of colored substances, maintain the active ingredients and increased chemical stability of peanut hull. Use removal of lead in water as a reference standard, Discussion of the modified peanut shells of heavy metal adsorption preparation process, achieve the optimum conditions of Preparation for modified peanut hull.In this paper modified bark was studied, and its performance for heavy metal ion adsorption was evaluated. Experimental results show that the optimum conditions of preparation for sodium hydroxide concentration, the dose of epichlorohydrin, temperature are0.5mol/L, 30ml per 5g bark, 60℃. Comparison of Cu²⁺ adsorption between crude barks and modified ones, modified ones are better. modified bark could blocking the outflow of colored substances, maintain the active ingredients and increased chemical stability of bark.