LAQV-REQUIMTE, Departamento de Ciências e Tecnologia da Biomassa, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
LAQV-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
J Hazard Mater. 2017 Jan 5;321:173-182. doi: 10.1016/j.jhazmat.2016.09.006. Epub 2016 Sep 6.
The present work aims to assess the efficiency of chars, obtained from the gasification and co-pyrolysis of rice wastes, as adsorbents of Cr from aqueous solution. GC and PC chars, produced in the gasification and co-pyrolysis, respectively, of rice husk and polyethylene were studied. Cr removal assays were optimised for the initial pH value, adsorbent mass, contact time and Cr initial concentration. GC showed a better performance than PC with about 100% Cr removal, due to the pH increase that caused Cr precipitation. Under pH conditions in which the adsorption prevailed (pH<5.5), GC presented the highest uptake capacity (21.1mg Cr g char) for the following initial conditions: 50mg Cr L; pH 5; contact time: 24h;L/S ratio: 1000mLg. The pseudo-second order kinetic model showed the best adjustment to GC experimental data. Both the first and second order kinetic models fitted well to PC experimental data. The ion exchange was the dominant phenomenon on the Cr adsorption by GC sample. Also, this char significantly reduced the ecotoxicity of Cr solutions for the bacterium Vibrio fischeri. GC char proved to be an efficient material to remove Cr from aqueous solution, without the need for further activation.
本工作旨在评估由稻废物的气化和共热解得到的炭作为水溶液中 Cr 的吸附剂的效率。研究了在稻壳和聚乙烯的气化和共热解中分别产生的 GC 和 PC 炭。优化了初始 pH 值、吸附剂质量、接触时间和 Cr 初始浓度对 Cr 去除的测定。由于 pH 值升高导致 Cr 沉淀，GC 的性能优于 PC，可实现约 100%的 Cr 去除。在吸附占主导地位的 pH 条件下（pH<5.5），对于以下初始条件，GC 表现出最高的 Cr 吸收能力（21.1mg Cr g 炭）：50mg Cr L；pH 5；接触时间：24h；L/S 比：1000mLg。准二级动力学模型对 GC 实验数据的拟合效果最好。一级和二级动力学模型均能很好地拟合 PC 实验数据。离子交换是 GC 样品吸附 Cr 的主要现象。此外，这种炭还显著降低了 Cr 溶液对发光菌 Vibrio fischeri 的生态毒性。GC 炭被证明是一种从水溶液中去除 Cr 的有效材料，无需进一步活化。
