Zhong Zhenxing, Yu Guowen, Mo Wenting, Zhang Chunjie, Huang Hao, Li Shengui, Gao Meng, Lu Xiejuan, Zhang Beiping, Zhu Hongping
School of Environmental Science and Engineering, Huazhong University of Science and Technology Wuhan 430074 China
Department of Urban Construction, Wuchang Shouyi University Wuhan 430064 China.
RSC Adv. 2019 Apr 3;9(18):10425-10436. doi: 10.1039/c8ra10400j. eCollection 2019 Mar 28.
In this work, a novel Fe-modified coconut shell biochar (Fe-CSB) was synthesized and utilized to remove phosphate from aqueous solution. Characterization results confirmed that the iron in the Fe(iii)-impregnated CSB existed mainly in the amorphous phase, as ferrihydrite and amorphous hydroxide, which substantially enhanced the phosphate adsorption. Batch experiments indicated that phosphate adsorption on the Fe-CSB was highly dependent on the pH, the humic acid, and temperature, while it was less affected by the nitrate. Phosphate adsorption by the CSB and Fe-CSB could be well described by the pseudo -th order and Langmuir-Freundlich models. The fitting of the experimental data with the intra-particle diffusion model revealed that surface adsorption and inner-sphere diffusion were involved in the phosphate adsorption process, and that the latter was the rate-controlling step. Batch adsorption experiments and post-adsorption characterization results revealed that the phosphate adsorption by Fe-CSB was primarily governed by four mechanisms: ligand exchange, electrostatic attraction, chemical precipitation, and inner-sphere complexation. This work demonstrated that the modified Fe-CSB is an environmentally friendly and cost-effective bioretention medium and could open up new pathways for the removal of phosphorus from stormwater, as well as solve the problem of waste biomass pollution.
在本研究中，合成了一种新型铁改性椰壳生物炭（Fe-CSB）并用于去除水溶液中的磷酸盐。表征结果证实，负载Fe(iii)的CSB中的铁主要以无定形相存在，即水铁矿和无定形氢氧化物，这大大增强了磷酸盐的吸附。批量实验表明，Fe-CSB对磷酸盐的吸附高度依赖于pH值、腐殖酸和温度，而受硝酸盐的影响较小。CSB和Fe-CSB对磷酸盐的吸附可以用准二级动力学模型和Langmuir-Freundlich模型很好地描述。实验数据与颗粒内扩散模型的拟合结果表明，磷酸盐吸附过程涉及表面吸附和内球扩散，且后者是速率控制步骤。批量吸附实验和吸附后表征结果表明，Fe-CSB对磷酸盐的吸附主要受四种机制控制：配体交换、静电吸引、化学沉淀和内球络合。本研究表明，改性后的Fe-CSB是一种环境友好且经济高效的生物滞留介质，可为雨水除磷开辟新途径，同时解决废弃生物质污染问题。
