氢氧化钙沸石的设计及其对沥青VOCs的抑制

Design of Ca（OH）2-incorporated zeolite and its inhibition effect on bitumen VOCs

针对沥青加热、搅拌、摊铺和服役过程中持续挥发性有机化合物(VOCs)排放带来的环境污染以及对施工人员的健康威胁等问题,开展了沥青VOCs的抑制效果研究。通过对沥青VOCs抑制研究方法的调研和总结,明确了抑制沥青VOCs从源头控制的方法最为可行有效,故确立以具有优良孔道结构的沸石材料作为沥青VOCs抑制剂。基于VOCs吸附机理和水热合成法中氢氧化钙的掺入能够加速沸石晶体的生长并使表面更加粗糙的原理,设计合成了具有多孔吸附和内部结晶水挥发降低拌合温度双重功效的氢氧化钙沸石基沥青VOCs抑制剂。随后通过扫描电子显微镜(SEM)、热重(TG)测试,从抑制剂表面形貌、热重稳定性和沥青最佳拌和温度3个方面确定了用于沥青VOCs抑制的氢氧化钙沸石合成时所需的最佳铝钙比。沥青VOCs难收集,且目前中国沥青VOCs的定量分析仍处于探索阶段,故采用全封闭系统热裂解-气相色谱-质谱联用仪分析,减少收集沥青VOCs过程中由于环境因素造成的误差,并分别从裂化温度和裂化时间分析,开展氢氧化钙沸石对沥青VOCs抑制效果的研究。研究结果表明:铝钙比(物质的量比,下同)为1∶2的氢氧化钙沸石具有最佳的沥青VOCs抑制效果,此时氢氧化钙沸石对沥青VOCs的综合抑制效率可达37.18%;同时由于氢氧化钙沸石的吸附特性与催化特性的复合作用,导致不同温度及热裂解时间下,其对沥青VOCs的抑制效率不同。

Amid to continuous volatile organic compounds(VOCs)emissions during heating,agitation,paving,and service have resulted in non-negligible environmental pollution and health threats to construction workers,the inhibition effect of asphalt VOCs was conducted.Through the investigation and summary of the research methods of the asphalt VOCs inhibition,it was clear that the method of controlling asphalt VOCs from the source was the most feasible and effective.Therefore,a zeolite material with excellent pore structure was established as an inhibitor of asphalt VOCs.Based on the adsorption mechanism of the VOCs and the principle that the incorporation of calcium hydroxide in hydrothermal synthesis can accelerate the growth of zeolite crystals and roughen their surface,Ca(OH)2-incorporated zeolite-based asphalt VOCs inhibitors with porous adsorption and internal crystal water volatilization to reduce the mixing temperature were designed and synthesized.The optimal ratio of aluminum to calcium was determined from three aspects,surface morphology,thermos-gravimetric stability,and optimal mixing temperature of the asphalt using SEM and TG tests.Given the difficulty of collecting asphalt VOCs and the quantitative analysis of China’s asphalt VOCs remains in an exploration stage,a full-closed system pyrolysis-gas chromatography-mass spectrometer was used to reduce the errors caused by environmental factors during the process of collecting asphalt VOCs.Pyrolysis temperature and pyrolysis time analysis were conducted to assess the inhibitory effect of calcium hydroxide zeolite on asphalt VOCs.The results show that the Ca(OH)2-incorporated zeolite with an aluminum-to-calcium ratio of 1∶2 has the best inhibitory effect on asphalt VOCs.The comprehensive inhibitory efficiency of the calcium hydroxide zeolite on asphalt VOCs can reach 37.18%.At the same time,because of the combination of the adsorption characteristics and catalytic properties of the Ca(OH)2-incorporated zeolite,the inhibitory efficiency of the asphalt VOCs is different under different temperatures and pyrolysis times.4 tabs,11 figs,35 refs.