Hu Po-Yu, Hsieh Yung-Hsu, Chen Jen-Ching, Chang Chen-Yu
Department of Environmental Engineering, National Chung-Hsing University, Taichung 402, Taiwan.
J Colloid Interface Sci. 2004 Apr 15;272(2):308-13. doi: 10.1016/j.jcis.2003.12.058.
"Manganese-coated sand" is a type of silica medium coated with manganese oxides, formed from the sorption of manganese oxides during long-term filtration via the process of rapid sand filtration, followed by aeration in a water treatment plant. Locally available manganese-coated sand, both for packing and as a byproduct of filtration processes for water treatment plants in Taiwan, was found to be a low-cost and promising adsorbent for removal of Mn(2+) from raw water. This study was conducted to build the basic data for coating hydrated manganese oxide on the sand surface to utilize the adsorbent properties of the coating and the filtration properties of the sand. In this study, gas adsorption porosimetry and scanning electron microscopy analyses were used to investigate the surface properties of the coated layer. An energy dispersive X-ray (EDAX) technique of analysis was used to characterize metal adsorption sites on a manganese-coated sand surface. Results indicated that manganese-coated sand had more micropores and higher specific surface area, owing to attachment of manganese sand. Manganese ions penetrated into the micropores and mesopores of manganese oxide on a sandy surface; regeneration of manganese-coated sand could be achieved by soaking with pH < 2.0 acid solution. Results of EDAX analysis showed that the interfacial layer constructed the interface of manganese-coated sand. Acid and alkali resistance tests interpret a wide application range of pH for manganese-coated sand, and general temperature conditions do not affect the performance of this sand. Manganese-coated sand is potentially suitable for application as a packed bed for treatment of heavy metals from water. The results of this study can also benefit plant operational capacity data for engineering design.
“锰砂”是一种涂覆有锰氧化物的硅质介质，它是在水处理厂通过快速砂滤过程进行长期过滤期间，由锰氧化物的吸附作用形成的，随后进行曝气。在台湾，发现可用于填充的本地锰砂以及作为水处理厂过滤过程副产品的锰砂，是一种低成本且有前景的吸附剂，可用于从原水中去除Mn(2+)。本研究旨在建立在砂表面涂覆水合锰氧化物的基础数据，以利用涂层的吸附性能和砂的过滤性能。在本研究中，采用气体吸附孔隙率测定法和扫描电子显微镜分析来研究涂层的表面性质。使用能量色散X射线（EDAX）分析技术来表征锰砂表面的金属吸附位点。结果表明，由于锰砂的附着，锰砂具有更多的微孔和更高的比表面积。锰离子渗透到砂质表面锰氧化物的微孔和中孔中；通过用pH < 2.0的酸性溶液浸泡可以实现锰砂的再生。EDAX分析结果表明，界面层构成了锰砂的界面。耐酸碱测试表明锰砂的适用pH范围很广，一般温度条件不会影响这种砂的性能。锰砂有可能适合用作处理水中重金属的填充床。本研究结果也可为工程设计的工厂运行能力数据提供参考。
