全再生型地聚物新材料及其固封有机物污染土的多尺度研究

With the academic thought of "using wastes to treat contaminants for sustainability", a new type of waste-based geopolymer material synthesized from three abundant industrial wastes/byproducts, such as fly ash (FA), red mud (RM), and rice husk ash (RHA), is developed as the next-generation solidification/stabilization (S/S) agent of organic contaminants (OC). As advances of our previous studies,the synthesis parameters of geopolymers based on RM, FA, and RHA will be further finely tuned to produce geopolymer binders with optimized mechanical properties (e.g., adhesion, compressive strength), low porosity/permeability, high immobilization capacity, and good workability for in-situ S/S implementation. To uncover the fundamental science on geopolymer-OC interactions, molecular simulation methods based on density functional theory (DFT) and classical simulation methods relying on geometric optimization methods are firstly employed to generate the molecular models of geopolymer, which will be used to obtain insights into the stabilization mechanisms of common OC molecular scale trapped/adsorbed in geopolymer's cage-like structural units. Then, nano/micro test techniques are applied to characterize the microstructure (including porosity) and chemical composition of the S/S materials, providing insights to the immobilization mechanisms (e.g., physical encapsulation in pores/cracks and physic-chemical adsorption to the geopolymer surface/interface). Finally, the multi-scale adsorption model based on thermodynamic theories and multi-scale leaching model based on microporomechanics are built up, establishing the foundamental theoretical framework of geopolymeric S/S of organic contaminants. This project will generate scientific and technological impacts on multifaceted sustainability, and it is also addresses a combination of global issues, including CO2 emission and climate change, energy conservation, waste recycling and reduction for "green" manufacturing, and environmental protection. Therefore, this project will have great economic, environmental, and societal impacts.

针对当前资源短缺、能耗过大、废料堆积和环境污染的问题与困境，基于"用废料治理污染，以实现资源再生、环境保护和可持续发展"的系统化解决思路，研制一种全部采用工业废料和副产品(包括赤泥、粉煤灰、稻壳灰等)制备合成的全再生型地聚物新材料，并将其用于有机物污染土的固化/封存处理，以发展一种污染土处理新技术。在申请人已有研究基础上，开发封存效率更高、施工性能更好的高性能再生地聚物制备技术；采用分子模拟方法揭示地聚物将有机污染物封装在其笼状分子结构中的科学机理；通过纳/微观结构测试与化学表征，阐释在地聚物凝胶界面及微细观孔隙、裂隙中吸附、封存有机污染物的物理与化学机制；基于热力学吸附理论和微观孔隙力学理论，建立多尺度固封模型和渗流模型，以此构建地聚物固化/封存有机物污染土技术的基础理论框架。本项目将为利用材料再生技术来消解环境问题的研究提供示范，并为地聚物替代水泥用于新一代污染土固封技术奠定理论基础。

当前，资源、能源和环境问题是全人类共同面临的严峻挑战，解决途径之一是通过科技手段，重建物质、能量循环系统，实现资源再生和循环利用。本项目针对资源短缺、能耗过大、废料堆积和环境污染等问题，开发了一种全部采用工农业废料和副产品 (包括粉煤灰、矿渣、赤泥、粉煤灰、稻壳灰等) 制备合成的全再生型地聚物新材料，并将其用于原位固化/封存有机物污染土治理技术。本项目为综合解决资源、能源、环境问题提供了一种“用废料治理污染，以实现资源再生、环境保护和可持续发展”的新思路。. 实验研究：通过配比优化，制备了多种类型的高强、高耐久地聚物材料，包括粉煤灰基地聚物，以及粉煤灰-矿渣、粉煤灰-矿渣-赤泥、粉煤灰-矿渣-赤泥-稻壳灰/硅藻土等复合地聚物材料。实验结果表明，粉煤灰基地聚物强度可达60MPa以上，粉煤灰-矿渣基地聚物最高强度可达120MPa以上，赤泥、稻壳灰/硅藻土改性地聚物的强度亦可稳定在40MPa以上。耐久性对比实验表明，地聚物比水泥耐高温、耐盐腐蚀，同时收缩性更低。采用异构烷烃和氯代烃分别代表低密度 (轻于水) 和高密度 (重于水) 有机污染物，采用石英砂作为土，配制了不同配比的有机物污染土试样；基于自行设计的实验测试方法，测试了地聚物固封污染土的渗滤性能。.微观结构测试与表征：通过SEM、XRD、EDXS、NMR、FTIR等微观结构测试方法，探讨了地聚物强度的化学结构和微观基础。通过等温吸附实验，测定了有机污染物的吸附动力学参数。. 微观力学性能测试：通过纳米压痕实验，测试了各配比地聚物材料微观各相的力学特性，并结合微观结构测试进行了统一分析。. 分子动力学模拟：基于Materials Studio软件，建立了典型地聚物的分子模型，并开展了微观力学性能和吸附过程的分子动力学模拟。. 渗滤理论：基于分子模拟、微观结构测试和吸附试验，建立了有机污染物在地聚物中的微观分布模型和吸附模型；采用微观孔隙力学方法，建立了地聚物固封污染土中的多尺度渗滤模型；基于渗滤实验结果建立半经验唯象渗滤模型。