改性凹凸棒石对高温炉内PbCl_(2)蒸气的吸附研究:实验和理论计算

Adsorption of PbCl_(2) vapor in high temperature furnace by modified attapulgite:Experimental and theoretical calculations

通过酸活化和负载磁性纳米铁氧体复合改性方式获得改性凹凸棒石,探究其在不同烟气氛围中吸附炉内半挥发性重金属PbCl_(2)蒸气的适用性,结合FT-IR、BET和XRD等表征手段以及DFT理论计算深入探究其对PbCl_(2)蒸气的吸附机理。结果表明,酸活化通过分解原矿中杂质提高表面活性位点占比,复合改性后铁基氧化物与凹凸棒石晶格氧形成的双活性吸附位点显著增强了其PbCl_(2)吸附容量,质量比为1∶2的Fe/HP2样品吸附容量最高达67.62(mg PbCl_(2)/g吸附剂)。当高温烟气中含有O_(2)、SO_(2)和少量H_(2)O时,会提升复合改性凹凸棒石的PbCl_(2)吸附容量。DFT理论计算表明,H_(2)O、O_(2)、SO_(2)和PbCl_(2)在ATT(110)表面均发生化学吸附,同时证明了H_(2)O通过共吸附作用促进PbCl_(2)在ATT(110)和Fe/ATT(110)表面的吸附。PbCl_(2)在H_(2)O分子形成的吸附氧位点的吸附弱于在晶格氧位点的吸附,在Fe/ATT(110)表面会优先与晶格氧位点和铁氧化物团簇中氧位点双活性位点通过强相互作用成键。

The modified attapulgite was obtained by acid activation and loaded magnetic nano-ferrite composite modification. The applicability of attapulgite in the adsorption furnace of semi-volatile heavy metal PbCl_(2)vapor in different flue gas atmosphere was explored. Besides, the adsorption mechanism of PbCl_(2)vapor was investigated by combining FT-IR, BET, XRD and DFT theoretical calculation. The results show that acid activation increases the proportion of surface-active sites by decomposing impurities in the original ore, and the double active adsorption sites formed by the composite modified iron-based oxides and attapulgite lattice oxygen significantly enhance the adsorption capacity of PbCl_(2). The maximum adsorption capacity of Fe/HP2 samples with the mass ratio of 1∶2 is67.62(mg PbCl_(2)/g adsorbent). When the high-temperature flue gas contains O_(2), SO_(2)and a small amount of H_(2)O, it can enhance the adsorption capacity of modified attapulgite. In addition, DFT theoretical calculations show that H_(2)O, O_(2), SO_(2)and PbCl_(2)all undergo chemisorption on the surface of ATT(110), and it also demonstrates that H_(2)O promotes the adsorption of PbCl_(2)on the surface of ATT(110) and Fe/ATT(110) through co-adsorption. Weaker adsorption of PbCl_(2)at the adsorbed oxygen sites formed by H_(2)O molecules instead of at the lattice oxygen sites can be preferentially bond to double active sites(the lattice oxygen sites and the oxygen site) in the iron oxide clusters through strong interactions on the Fe/ATT(110) surface.