This study investigates the feasibility of coating cationic polydiallydimethyl ammonium chloride (PDDA) onto mesoporous acid-treated fly ash (AFA) and its capacity to adsorb phenol from aqueous solution. The PDDA-FA and its AFA substrate were characterized using a scanning electron microscope with energy-dispersive x-ray spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy and thermogravimetric analysis (TGA) to ascertain successful film coating. Batch adsorption studies were carried out to evaluate the effects of solution pH, initial concentration, adsorbent dosage, contact time, shaking speed and temperature on the removal of phenol using PDDA-FA and AFA. Characterization revealed that the coating of cationic polyelectrolyte film onto FA introduced surface polarity which enhanced the mass transfer of phenol to the PDDA-FA surfaces. Importantly, the results showed that synthesized PDDA-FA is 4-fold more efficient than precursor AFA in removing phenol from aqueous solution. The sorption equilibrium isotherm of adsorbent was described by Freundlich, Langmuir and Temkin models. The adsorption rate of both adsorbents followed the pseudo-second-order kinetic model, while the thermodynamic studies of PDDA-FA sorption of phenol indicated a favorable endothermic and physical adsorption mechanism. The PDDA-FA also has a higher adsorption capacity than other reported modified FA. In conclusion, an ultrathin coating of fly ash with cationic polyelectrolyte offers a viable potential as an alternative adsorbent from waste. This work has the advantages of cleaner production of adsorbents from waste, and wastewater decontamination.

这项研究调查了在中孔酸处理的粉煤灰（AFA）上涂覆阳离子聚二烯丙基二甲基氯化铵（PDDA）的可行性及其从水溶液中吸附苯酚的能力。PDDA-FA及其AFA底物使用具有能量色散X射线光谱仪（SEM-EDX），傅立叶变换红外光谱仪（FTIR），拉曼光谱仪和热重分析（TGA）的扫描电子显微镜进行表征，以确定成功的薄膜涂层。进行了批量吸附研究，以评估溶液pH，初始浓度，吸附剂量，接触时间，振荡速度和温度对使用PDDA-FA和AFA去除苯酚的影响。表征表明，FA上的阳离子聚电解质薄膜涂层引入了表面极性，从而增强了苯酚向PDDA-FA表面的质量转移。重要的是，结果表明，从水溶液中去除苯酚，合成的PDDA-FA比前体AFA的效率高4倍。Freundlich，Langmuir和Temkin模型描述了吸附剂的吸附平衡等温线。两种吸附剂的吸附速率均遵循拟二级动力学模型，而PDDA-FA吸附苯酚的热力学研究表明其具有良好的吸热和物理吸附机理。PDDA-FA还具有比其他报道的改性FA更高的吸附能力。结论，带有阳离子聚电解质的粉煤灰超薄涂层提供了可行的潜力，可以作为废物的替代吸附剂。这项工作的优点是可以更清洁地从废物中生产吸附剂，并对废水进行净化处理。