Wu Lu, Liu Feng, Long Rui, Luo Pei, Xiao Run-Lin, Chen Xiang, Wu Jin-Shui
Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Huan Jing Ke Xue. 2019 Feb 8;40(2):677-684. doi: 10.13227/j.hjkx.201805020.
To screen the optimal absorbents for P removal from agricultural wastewater, the P adsorption capacity of bentonite, red soil, and slag was studied using synthetic wastewater. Combing the properties of three adsorbents measured by SEM, XDS, and BET methods, the isothermal adsorption, adsorption kinetics, and Ca release capacity were analyzed to elucidate the mechanisms of P adsorption. The results showed that the P adsorption capacity of slag was higher than that of bentonite and red soil, and the Langmuir isotherm model was able to better fit the adsorption data (>0.96). The P theoretical saturation sorption capacity of slag was higher (16.87 mg·g) than that of bentonite (1.21 mg·g) and red soil (0.92 mg·g) (<0.05). The results for adsorption kinetics indicated that slag rapidly removed 95.6% of P from 10 mg·L solution, and the Elovich equation fit the data well (=0.812). The adsorption kinetics of P on bentonite and red soil were better described by the pseudo-second-order kinetic equation (=0.982 and 0.959, respectively). The Ca release capacity of slag (10.46 mg·g) was significantly higher compared to bentonite (0.31 mg·g) and red soil (0.03 mg·g) (<0.05). The P adsorption capacity of red soil was 0.26 mg·g when the pH value was 3, and it decreased as the pH values increased. At the initial pH of 7.0, the P adsorption capacity of bentonite was about 0.01 mg·g, lower than 0.04 mg·g at pH 3, and 0.05 mg·g at pH 11. The initial pH value had little effect on the P adsorption capacity of slag. The P-loaded bentonite, red soil, and slag were effectively regenerated by using CaCl solution, and bentonite was easier to reuse compared to red soil and slag. The key factors affecting the P adsorption capacity of the three adsorbents were physical and chemical properties, such as crystal structure and the content of metal ions, Ca release capacity, and initial pH. These findings demonstrated that slag was a better choice for P removal compared to bentonite and red soil and could be used as an effective P adsorbent for agricultural wastewater treatment.
为筛选从农业废水中去除磷的最佳吸附剂，采用合成废水研究了膨润土、红壤和矿渣的磷吸附容量。结合通过扫描电子显微镜（SEM）、X射线衍射仪（XDS）和比表面积分析仪（BET）方法测得的三种吸附剂的性质，分析了等温吸附、吸附动力学和钙释放容量，以阐明磷吸附的机制。结果表明，矿渣的磷吸附容量高于膨润土和红壤，朗缪尔等温线模型能够更好地拟合吸附数据（>0.96）。矿渣的磷理论饱和吸附容量较高（16.87 mg·g），高于膨润土（1.21 mg·g）和红壤（0.92 mg·g）（<0.05）。吸附动力学结果表明，矿渣能快速从10 mg·L溶液中去除95.6%的磷，埃洛维奇方程能很好地拟合数据（=0.812）。磷在膨润土和红壤上的吸附动力学用准二级动力学方程能更好地描述（分别为=0.982和0.959）。矿渣的钙释放容量（10.46 mg·g）明显高于膨润土（0.31 mg·g）和红壤（0.03 mg·g）（<0.05）。当pH值为3时，红壤的磷吸附容量为0.26 mg·g，随着pH值升高而降低。在初始pH为7.0时，膨润土的磷吸附容量约为0.01 mg·g，低于pH 3时的0.04 mg·g和pH 11时的0.05 mg·g。初始pH值对矿渣的磷吸附容量影响较小。负载磷的膨润土、红壤和矿渣用氯化钙溶液能有效再生，与红壤和矿渣相比，膨润土更易于重复使用。影响这三种吸附剂磷吸附容量的关键因素是物理和化学性质，如晶体结构、金属离子含量、钙释放容量和初始pH。这些研究结果表明，与膨润土和红壤相比，矿渣是去除磷的更好选择，可作为处理农业废水的有效磷吸附剂。
