Adsorption Of Modified Activated Carbon And Red-loess For Heavy Metal Ions

Adsorption is a highly effective way to treat heavy metal wastewater, moreover, exploiting a new type low-cost sorbent is a hot research topic in the recent years. In the paper, the method of KMnO4 modification was researched to improve the properties of activated carbon (wooden activated carbon and bamboo carbon).The adsorption of modified carbons and natural mineral red loess to heavy metals was also studied. The purpose provides the basis for treating heavy metals wastewater. The main results as follows:1. The adsorption properties of modified and unmodified wooden activated carbon to Cu2+, Cd2+, Zn2+, Cr (III) and Cr (VI) were investigated. The results show that the best result achieves at 0.03mol/L KMnO4 to Cu2+, Cd2+, Zn2+ and Cr (VI), but to Cr (III), the best result achieves at 0.04mol/L KMnO4. The adsorption amount of Cu2+, Cd2+, Zn2+, Cr (III) and Cr (VI) over wood activated carbon modified with KMnO4 increases 2.7,1.4,1.2,1.43 and 1.12 times, respectively. The types of Cu2+, Cd2+ and Zn2+ adsorption rate-pH curves are"S", but"waves"and"parabola"types to Cr (III) and Cr (VI). The adsorption of Cd2+, Zn2+, Cr (III) and Cr (VI) is endothermic. The adsorption behaviors are all match to Langmuir model, but Freundlich model to Cu2+ on wood activated carbon.2. The treatment effect of modified and unmodified wooden activated carbon to Cu2+ and Zn2+ was studied using dynamic column adsorption. The effects of craftwork parameter including modification, salt effect and flow rate were researched. The results show that breakthrough curves move right obviously, the removal effect enhances. To Cu2+, the first desorption effect is better after modification, however, the adsorption property wears off along with the times of desorption. Comparing multi-species with single-specie, the adsorption to Cu2+ and Zn2+ on modified carbon is close when BV<25, but the adsorption is good in multi-species when BV<25. With an increase in ionic strength, the adsorption increase to Cu2+, but not obviously to Zn2+. The effect becomes bad Cu2+ on modified carbon with the increase of flow rate.3. The influence of KMnO4 concentration on the Cu2+ adsorption rate-pH curves was investigated. The modification with KMnO4 affected the adsorption and desorption capacity of bamboo charcoal. The results show that the Cu2+ adsorption rate-pH curves and pH50 of bamboo charcoal move to low pH after modification with KMnO4. The best result achieved at 0.04mol/L KMnO4. The modification with KMnO4 improves the adsorption rate of Cu2+ and reduces the consumption of adsorbent about doubleness than that of unmodified bamboo charcoal. The adsorption isothermals of Cu2+ over the modified and unmodified bamboo charcoal match to Langmuir model. On the same equilibrium concentration of Cu2+, the adsorption amount of Cu2+ over bamboo charcoal modified with KMnO4 increases about 53% than unmodified bamboo charcoal. Moreover, the Cu2+ adsorption capacity of the modified bamboo charcoal can be improved obviously with the increase of temperature. At 40℃, the saturated adsorption amount of Cu2+ is 1.69 times as much as that of at 25℃. The modification of bamboo charcoal with KMnO4 not only increases the adsorption capability to heavy metal ions, but also improves the ability of desorption-regeneration of bamboo charcoal.4. Red-loess treats simulated wastewater containing Pb2+, Cu2+, Zn2+, Cr (Ⅲ) and Cd2+. The influence of pH, adsorbent dose, temperature and concentrations on the adsorption and the desorption property were studied. The results indicate that the types of Pb2+, Cu2+, Zn2+, Cr(Ⅲ) and Cd2+ adsorption rate-pH curves are"S". The adsorption of Pb2+ is exothermic, while the adsorption of Cu2+, Zn2+, Cr (Ⅲ) and Cd2+ is endothermic. The adsorption behavior of Pb2+, Cu2+, Zn2+, Cr (Ⅲ) and Cd2+ onto RL is fitted to Langmuir model. The good desorption property to Pb2+, Cu2+, Zn2+ and Cd2+, but the poor property to Cr(Ⅲ) with 0.1 mol·L-1 HCl as desorption solution. Compare with other treating methods, this mean has some advantages such as low cost, craftwork simple and good treating effect and favorable application prospect.