Zhang Aijia, Liu Jing, Yang Yingju, Li Yemei
State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Sci Total Environ. 2024 Feb 20;912:168928. doi: 10.1016/j.scitotenv.2023.168928. Epub 2023 Dec 2.
Chromium is a typical toxic pollution in sewage sludge incineration flue gas. Cr removal from flue gas is a challenge due to the high toxicity and valence variability of chromium. Ca-based sorbents, including CG-CaO, CA-CaO, and CCi-CaO, were developed for Cr capture by calcining calcium D-gluconate monohydrate, calcium acetate hydrate, and calcium citrate tetrahydrate, respectively. CG-CaO, CA-CaO, and CCi-CaO exhibit better Cr removal performance than traditional CaO. CA-CaO shows superior Cr adsorption ability due to the large BET surface area and pore volume. The Cr adsorption efficiency of CA-CaO is up to 94.79 % at 1000 °C. XRD and XPS results reveal that the adsorbed Cr contains Cr(III) and Cr(VI), and exists in the form of CaCrO and CaCrO. Cr adsorption on Ca-based sorbents is mainly controlled by adsorption and oxidation mechanism. The adsorption process of Cr on different Ca-based sorbents was described by four typical adsorption kinetic models. For CaO and CG-CaO, pseudo-first order model and Elovich model are suitable for the description of Cr adsorption. For CA-CaO and CCi-CaO, pseudo-second order model, Elovich model and Weber and Morris model fit well with the experimental values of Cr adsorption, suggesting that Cr adsorption on CA-CaO and CCi-CaO is controlled by a combined mechanism of chemisorption and intraparticle diffusion. The saturated adsorption capacity of CaO, CG-CaO, CA-CaO and CCi-CaO are evaluated to be 39.77, 48.98, 102.22 and 104.52 mg/g, respectively. The effects of incineration flue gas components on Cr adsorption were also explored. O shows no obvious influence on Cr adsorption over CA-CaO. HCl, SO, NO and CO can inhibit Cr adsorption because of the competitive adsorption, and the inhibitory effect of SO is the strongest.
铬是污水污泥焚烧烟气中一种典型的有毒污染物。由于铬的高毒性和价态多变性，从烟气中去除铬是一项挑战。通过分别煅烧一水合葡萄糖酸钙、水合醋酸钙和四水合柠檬酸钙，开发了包括CG-CaO、CA-CaO和CCi-CaO在内的钙基吸附剂用于捕获铬。CG-CaO、CA-CaO和CCi-CaO表现出比传统CaO更好的铬去除性能。CA-CaO由于具有较大的BET表面积和孔体积，表现出优异的铬吸附能力。在1000℃时，CA-CaO的铬吸附效率高达94.79%。XRD和XPS结果表明，吸附的铬含有Cr(III)和Cr(VI)，并以CaCrO和CaCrO的形式存在。铬在钙基吸附剂上的吸附主要受吸附和氧化机制控制。用四种典型的吸附动力学模型描述了铬在不同钙基吸附剂上的吸附过程。对于CaO和CG-CaO，准一级模型和Elovich模型适用于描述铬的吸附。对于CA-CaO和CCi-CaO，准二级模型、Elovich模型以及Weber和Morris模型与铬吸附的实验值拟合良好，表明铬在CA-CaO和CCi-CaO上的吸附受化学吸附和颗粒内扩散的联合机制控制。CaO、CG-CaO、CA-CaO和CCi-CaO的饱和吸附容量分别评估为39.77、48.98、102.22和104.52mg/g。还探讨了焚烧烟气成分对铬吸附的影响。O对CA-CaO上的铬吸附没有明显影响。HCl、SO、NO和CO由于竞争吸附会抑制铬吸附，其中SO的抑制作用最强。
