Abstract:

Excessive discharge of phosphate will cause eutrophication of water body and pose a great threat to water environment safety. As a non-renewable resource, phosphate has significant recycling value. In order to obtain an adsorbent with low cost and excellent performance to effectively recover phosphate from wastewater, alginate-like exopolymers (ALE) was extracted from the residual sludge by high-temperature sodium carbonate method, and FeCa-ALE hydrogel composite was constructed. The microstructure and functional group characteristics of FeCa-ALE were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Static adsorption experiments showed that FeCa-ALE had good adsorption performance for phosphate, and the actual maximum adsorption capacity was 15.92mg/g at pH of 9. Pseudo-second-order kinetics, Elovich kinetic and Freundlich isotherm model could well describe the adsorption process of FeCa-ALE with respect to phosphate, indicating that the adsorption process was mainly dominated by heterogeneous chemical adsorption. The test of adsorption performance under the real water environment showed that FeCa-ALE with the characteristic of environmentally friendly and biodegradable, could resist the salinity inhibition effect to some extent and remove phosphate from real wastewater.

Key words: alginate-like exopolymers, phosphates, adsorption kinetics, adsorption thermodynamics, adsorption mechanism

摘要：

磷酸盐的过度排放会造成水体富营养化，对水环境安全构成极大威胁，而磷作为一种不可再生资源，具有重大的回收价值。为获得成本低廉、性能优异的吸附剂，有效回收废水中的磷酸盐，采用高温碳酸钠法从剩余污泥中提取类藻酸盐多聚物（alginate-like exopolymers，ALE），制备了FeCa-ALE水凝胶复合材料。利用扫描电子显微镜（SEM）、X射线光电子能谱（XPS）及傅里叶变换红外光谱（FTIR）等表征手段对FeCa-ALE微观形貌及官能团特性进行了分析。静态吸附实验表明，FeCa-ALE对磷酸盐表现出良好的吸附性能，且pH为9时的最大吸附量为15.92mg/g。拟二级动力学模型、Elovich动力学模型和Freundlich等温模型能很好地描述FeCa-ALE对磷酸盐的吸附过程，说明该吸附过程以非均相化学吸附为主。在实际水环境条件下的吸附性能测试表明，绿色环保、易生物降解的FeCa-ALE在一定程度上可抵抗盐度抑制效应，可用于实际废水中磷酸盐的去除。

关键词: 类藻酸盐多聚物, 磷酸盐, 吸附动力学, 吸附热力学, 吸附机理