Chen Zicheng, Zhang Huiwen, Fan Guangyuan, He Xiangyang, He Zhibin, Zhang Lanhe
School of Chemical Engineering, Northeast Electric Power University, Jilin, Jilin Province 132012, P. R. China.
Department of Chemical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3, Canada.
ACS Omega. 2022 Jul 18;7(30):26154-26164. doi: 10.1021/acsomega.2c01648. eCollection 2022 Aug 2.
Adsorption technology based on various adsorbents has been widely applied in wastewater treatment containing phosphate. A novel diatomite adsorbent composited with ZIF-8 (CZD) was developed for removing phosphate from water in this work. The chitosan was used to pre-modify the diatomite so that ZIF-8 could be anchored on the surface of the diatomite solidly and uniformly. The diatomite composited with ZIF-8 was then used to remove phosphate in water by an adsorption process, the process variables such as adsorption time, temperature, pH, and competitive ions were investigated. The electrostatic attraction was the primary mechanism of phosphate removal. The adsorption reached equilibrium within 90 min, and its sorption capacity increased when adsorption time and temperature increased. Especially, CZD had a rapid adsorption rate and 85% of the phosphate in the solution can be adsorbed within the first 10 min. The maximum phosphate adsorption capacities of the modified diatomite reached 13.46, 13.55, and 13.95 mg/g at 25, 35, and 45 °C, respectively. The removal efficiencies of CZD for phosphate were more than 98% and even came up to 100% at 45 °C. The adsorption isotherms fit well with the Langmuir isotherm model. The Freundlich isotherm and Temkin isotherm showed that the adsorption process is physical in nature. The kinetic data of the adsorption process were fitted by the pseudo-second-order kinetics. Thermodynamic parameters indicated that the adsorption process was endothermic. This adsorbent provided an alternative for phosphate removal on account of the high adsorption efficiency in a short time. Therefore, CZD could be a promising and eco-friendly phosphate adsorbent for wastewater treatment.
基于各种吸附剂的吸附技术已广泛应用于含磷废水处理。本研究开发了一种新型的与ZIF-8复合的硅藻土吸附剂（CZD）用于去除水中的磷酸盐。壳聚糖用于对硅藻土进行预改性，以便ZIF-8能够牢固且均匀地锚定在硅藻土表面。然后将与ZIF-8复合的硅藻土用于通过吸附过程去除水中的磷酸盐，研究了吸附时间、温度、pH值和竞争离子等过程变量。静电吸引是去除磷酸盐的主要机制。吸附在90分钟内达到平衡，吸附容量随吸附时间和温度的增加而增加。特别是，CZD具有快速的吸附速率，溶液中85%的磷酸盐可在最初10分钟内被吸附。改性硅藻土在25、35和45℃下对磷酸盐的最大吸附容量分别达到13.46、13.55和13.95mg/g。CZD对磷酸盐的去除效率超过98%，在45℃时甚至可达100%。吸附等温线与Langmuir等温线模型拟合良好。Freundlich等温线和Temkin等温线表明吸附过程本质上是物理过程。吸附过程的动力学数据用准二级动力学进行拟合。热力学参数表明吸附过程是吸热的。由于该吸附剂在短时间内具有高吸附效率，为磷酸盐去除提供了一种替代方法。因此，CZD可能是一种有前景的、生态友好的用于废水处理的磷酸盐吸附剂。
