Rice Straw/Sewage Sludge-Based Composite Activated Carbon: Its Some Basic Properties and Adsorption Effect for Cr (VI)

In this study, the rice straw/sewage sludge-based composite activated carbon (RS-SCAC) was prepared from the mixture of sewage sludge and rice straw. Some basic properties of RS-SCAC, i.e., yield, iodine number, contents of heavy metals, surface functional groups, and leaching toxicity, were characterized. Furthermore, the adsorption performance of RS-SCAC for Cr (VI) was investigated. For RS-SCAC, the yield was moderate, and the iodine number was higher than that of the sewage sludge-based activated carbon (SBAC). RS-SCAC contained a variety of heavy metals, and Zn, Fe, and Cu had the relatively high content. The surface of RS-SCAC was rich in functional groups, especially for -OH, -COOH, and -COH, which was helpful for the adsorption of polar solute. For all heavy metals except Zn in RS-SCAC, the leaching concentrations were below the limits for identifying hazardous wastes, which indicated that RS-SCAC was relatively safe. Compared with SBAC, RS-SCAC had the better adsorption effect for Cr (VI). The results indicated that RS-SCAC can be used as a safety and efficient adsorbent for Cr (VI).