Adamczuk Agnieszka, Sofinska-Chmiel Weronika, Jozefaciuk Grzegorz
Institute of Agrophysics PAS, Doswiadczalna 4 Str., 20-290 Lublin, Poland.
Analytical Laboratory, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie Sklodowska University, Maria Curie Sklodowska Sq. 3, 20-031 Lublin, Poland.
Materials (Basel). 2020 Nov 26;13(23):5381. doi: 10.3390/ma13235381.
One of the ways to recycle millions of tons of fly ash and chitin wastes produced yearly is their utilization as low-cost sorbents, mainly for heavy metal cations and organic substances. To improve their sorption efficiency, fly ashes have been thermally activated or modified by chitosan. We aimed to deeply characterize the physicochemical properties of such sorbents to reveal the usefulness of modification procedures and their effect on As(V) adsorption. Using low temperature nitrogen adsorption, scanning electron microscopy, mercury intrusion porosimetry, potentiometric titration and adsorption isotherms of As(V) anions, surface, pore, charge and anion adsorption parameters of fly ash activated at various temperatures, chitosan, and fly ash modified by chitosan were determined. Arsenate adsorption equilibrium (Langmuir model), kinetics (pseudo-second order model) and thermodynamics on the obtained materials were studied. Neither temperature activation nor chitosan modifications of fly ash were necessary and profitable for improving physicochemical properties and As(V) adsorption efficiency of fly ash. Practically, the physicochemical parameters of the sorbents were not related to their anion adsorption parameters.
每年回收数百万吨粉煤灰和几丁质废料的方法之一是将它们用作低成本吸附剂，主要用于吸附重金属阳离子和有机物质。为了提高它们的吸附效率，粉煤灰已通过热活化或用壳聚糖改性。我们旨在深入表征此类吸附剂的物理化学性质，以揭示改性程序的有用性及其对As(V)吸附的影响。通过低温氮吸附、扫描电子显微镜、压汞法、电位滴定和As(V)阴离子吸附等温线，测定了在不同温度下活化的粉煤灰、壳聚糖以及壳聚糖改性粉煤灰的表面、孔隙、电荷和阴离子吸附参数。研究了所得材料上砷酸盐的吸附平衡（朗缪尔模型）、动力学（伪二级模型）和热力学。对于改善粉煤灰的物理化学性质和As(V)吸附效率而言，粉煤灰的温度活化和壳聚糖改性既无必要也无益处。实际上，吸附剂的物理化学参数与其阴离子吸附参数无关。
