Liu Peng, Liu Li, Li Yanling, Zhou Zhengzhong, Huhe Taoli, Lei Tingzhou
Jiangsu Province Biomass Energy and Materials Laboratory, Nanjing 210042, China.
National-Local Joint Engineering Research Center of Biomass Refining and High-Quality Utilization, Institute of Urban and Rural Mining, Changzhou University, 21 Gehu Middle Rd, Changzhou, Jiangsu 213164, China.
ACS Omega. 2021 Aug 18;6(34):22301-22310. doi: 10.1021/acsomega.1c02998. eCollection 2021 Aug 31.
Carbon-alumina composites are prepared for the efficient removal of Cr(VI) from wastewater. Pristine and acid-treated alumina dross (AD and AAD) are copyrolyzed with pine sawdust to form the respective composites, ADPC and AADPC. Excellent absorption properties with Cr(VI) removal efficiency of 95.08% are demonstrated at 60 °C for an initial concentration of 6 μg/mL. The composites combine the merits of char, which provides a high surface-to-volume ratio with abundant functional groups on the surface, and alumina, which provides metal ions for coprecipitation. Carbon structures of pine, char, and composite were analyzed semiquantitatively using C NMR by a curve-fitting method. Cr(VI) adsorption is accurately described with chemisorption by the Langmuir isotherm model and a pseudo-second-order kinetic model. The results show that AADPC has more alcohol hydroxyl groups substituted to glucosyl units in amorphous cellulose assigned to the peak at 80 ppm and hemicellulose assigned to peaks at 97 and 101 ppm. Also, it has more phenolic groups in lignin distributed at syringyl units assigned to peaks at 129 and 146 ppm. These oxygen-containing functional groups have a significant influence on Cr(VI) adsorption and reduction to Cr(III) governed by the mechanisms of diffusion, adsorption, complexation, reduction, and coprecipitation. The results of this work provide a new direction for the reuse of biomass and industrial solid wastes to fabricate higher value-added products, i.e., adsorption materials for Cr(VI) removal and stabilization.
制备了碳-氧化铝复合材料，用于高效去除废水中的Cr(VI)。将原始的和酸处理过的氧化铝废渣（AD和AAD）与松木锯末共热解，以形成相应的复合材料ADPC和AADPC。在60℃下，对于初始浓度为6μg/mL的Cr(VI)，该复合材料表现出优异的吸附性能，去除效率达95.08%。该复合材料兼具炭的优点（提供高的比表面积且表面有丰富的官能团）和氧化铝的优点（提供用于共沉淀的金属离子）。采用曲线拟合方法通过13C NMR对松木、炭和复合材料的碳结构进行了半定量分析。Cr(VI)的吸附可以用Langmuir等温线模型和伪二级动力学模型进行化学吸附准确描述。结果表明，AADPC在80ppm处归属于无定形纤维素中取代到葡糖基单元上的醇羟基以及在97和101ppm处归属于半纤维素的醇羟基更多。此外，它在129和146ppm处归属于紫丁香基单元的木质素中的酚羟基更多。这些含氧官能团对Cr(VI)的吸附以及通过扩散、吸附、络合、还原和共沉淀机制将其还原为Cr(III)有显著影响。这项工作的结果为生物质和工业固体废物的再利用提供了一个新方向，即制造更高附加值的产品，也就是用于去除和稳定Cr(VI)的吸附材料。
