Mekonnen Dereje Tadesse, Alemayehu Esayas, Lennartz Bernd
School of Chemical Engineering, Jimma Institute of Technology, Jimma University, Jimma P.O. Box 378, Ethiopia.
Faculty of Agricultural and Environmental Sciences, University of Rostock, Justus von-Liebig Weg 6, 18059 Rostock, Germany.
Materials (Basel). 2021 Sep 22;14(19):5466. doi: 10.3390/ma14195466.
The excessive discharge of phosphate from anthropogenic activities is a primary cause for the eutrophication of aquatic habitats. Several methodologies have been tested for the removal of phosphate from aqueous solutions, and adsorption in a flow-through reactor is an effective mechanism to reduce the nutrient loading of water. This research aimed to investigate the adsorption potential of leftover coal material to remove phosphate from a solution by using continuous flow fixed-bed column, and analyzes the obtained breakthrough curves. A series of column tests were performed to determine the phosphorus breakthrough characteristics by varying operational design parameters such as adsorbent bed height (5 to 8 cm), influent phosphate concentration (10-25 mg/L), and influent flow rate (1-2 mL/min). The amorphous and crystalline property of leftover coal material was studied using XRD technology. The FT-IR spectrum confirmed the interaction of adsorption sites with phosphate ions. Breakthrough time decreased with increasing flow rate and influent phosphate concentration, but increased with increasing adsorbent bed height. Breakthrough-curve analysis showed that phosphate adsorption onto the leftover coal material was most effective at a flow rate of 1 mL/min, influent phosphate concentration of 25 mg/L, and at a bed height of 8 cm. The maximal total phosphate adsorbed onto the coal material's surface was 243 mg/kg adsorbent. The Adams-Bohart model depicted the experimental breakthrough curve well, and overall performed better than the Thomas and Yoon-Nelson models did, with correlation values (R) ranging from 0.92 to 0.98. Lastly, leftover coal could be used in the purification of phosphorus-laden water, and the Adams-Bohart model can be employed to design filter units at a technical scale.
人为活动中过量排放的磷酸盐是水生栖息地富营养化的主要原因。人们已经测试了多种从水溶液中去除磷酸盐的方法，而在流通式反应器中进行吸附是减少水体营养负荷的有效机制。本研究旨在通过使用连续流固定床柱来研究剩余煤料从溶液中去除磷酸盐的吸附潜力，并分析所得的穿透曲线。进行了一系列柱试验，通过改变操作设计参数，如吸附剂床层高度（5至8厘米）、进水磷酸盐浓度（10 - 25毫克/升）和进水流量（1 - 2毫升/分钟），来确定磷的穿透特性。使用X射线衍射（XRD）技术研究了剩余煤料的非晶态和晶态特性。傅里叶变换红外光谱（FT - IR）证实了吸附位点与磷酸根离子的相互作用。穿透时间随流速和进水磷酸盐浓度的增加而减少，但随吸附剂床层高度的增加而增加。穿透曲线分析表明，在流速为1毫升/分钟、进水磷酸盐浓度为25毫克/升、床层高度为8厘米时，剩余煤料对磷酸盐的吸附效果最佳。煤料表面吸附的最大总磷酸盐量为243毫克/千克吸附剂。亚当斯 - 博哈特模型很好地描述了实验穿透曲线，总体表现优于托马斯模型和尹 - 尼尔森模型，相关系数（R）在0.92至0.98之间。最后，剩余煤料可用于净化含磷水，并且亚当斯 - 博哈特模型可用于在技术规模上设计过滤单元。
