具有光催化活性的新型坡缕石吸附材料的制备及性能研究

Adsorption is used in wastewater treating to remove heavy metal ions or organic pollutants, which is the most simple, convenient and efficient method. As the number of adsorption sites for common adsorbents is limited, they aren’t unsuited to treat wastewater simultaneously containing heavy metal ions and organic pollutants. A novel adsorbent research is becoming more and more important. The palygorskite are used as adsorbent in recently years, but its adsorption capacity needs to be improved. In order to improve adsorption capacity for heavy metal and photodegradation organic pollutants at the same time, photocatalyst is added to palygorskite. Three types of palygorskite adsorbent with photocatalytic property are prepared to use palygorskite, semiconductor photocatalyst, water quenched slag and chitosan as material. The paper research content mainly includes three parts as follows. The first part, Ti4+, Zn2+ or Fe3+ is introduced to acid-treated palygorskite by ion exchange method and is roasted to obtain TiO2, ZnO or -Fe2O3 modified palygorskite. The second part, semiconductor materials as photocatalyst is supported by palygorskite or palygorskite/chitosan composite material using one-pot synthesis, such as hydrothermal, precipitation and direct reduction method. The third part, precursor of photocatalyst are supported on palygorskite/water quenched slag composite material by ultrasonic processing and are roasted to get clay/water quenched slag with photocatalytic property. The adsorptive selectivity of function material is studied for heavy metal ions in wastewater. And photocatalytic active group of function material also is investigated for organic pollutants. It can explain the adsorption mechanism including measurement of the acidity of solution before and after adsorption or changes of surface morphology of palygorskite function material are observed. This study provides the theoretical basis for the application of the adsorption material of palygorskite in the fields of environmental protection, metallurgy and so on. Meanwhile, it is very important to promote the deep processing of non-metallic minerals. It has become a new economic growth point for economic development in Gansu.

吸附法是处理含重金属离子或有机物废水中常用方法，具有简单、方便、高效等特点。普通吸附剂遇到同时含有金属离子、有机物废水时，有限的吸附活性位点达不到处理要求，急待开发高效、适用范围广的复合型材料。粘土吸附剂是国内外研究的热点之一，实际应用中存在吸附量低的缺点。本研究工作以甘肃坡缕石粘土为基材，引入光催化剂，旨在制备即提高重金属离子的吸附量又能光降解有机物的复合材料。具体内容：1.Ti4+、Zn2+、Fe3+等柱撑酸化坡缕石，高温焙烧得到含催化成分的坡缕石；2.采用水热或沉积焙烧的一锅法，制备坡缕石/半导体复合材料；3.水淬渣与坡缕石、光催化剂前驱体复配，焙烧制成双功能材料。重点研究功能材料对金属离子的吸附选择性、光催化降解的机理，通过对吸附前后体系pH、材料微观形貌的变化，闸明新材料的吸附机理、光催化活性基团。该研究对坡缕石基质的吸附材料在环保等领域的应用提供理论依据，同时促进地方经济发展。

粘土吸附剂处理水中有机染料具有简单、方便、经济等优点，是国内外研究的热点之一，但实际应用中存在吸附量低、二次污染等缺点，研制既具有吸附性又避免二次污染的功能材料是研究者追求的目标。本研究工作以甘肃坡缕石粘土（PGS）为基材，引入光催化剂，构建了一系列具有光催化活性的坡缕石吸附材料用于水中有机污染物的处理。分别制备了g-C3N4/ PGS、PGS/ZnO-MgO-X2O3（X：Al、Cr、Bi）、PGS/CdS基（CdS/ZnO-ZnFe2O4、CdS/ZnS、CdS-Al）、PGS /Cd0.5Zn0.5S基（MoO3/Cd0.5Zn0.5S、Bi2WO6/ Cd0.5Zn0.5S、Cd0.5Zn0.5S/Zn-Fe LDH）及PGS /尖晶石型XIn2S4（X：Mg、Cd、Ca、Mn）复合材料，研究了复合材料在可见光下对甲基橙（MO）、罗丹明B（RhB）、孔雀石绿（MG）、结晶紫（CV）、亚甲基蓝（MB）、酸性品红（AF）、盐酸四环素的光降解及Pd2+、Cu2+的吸附行为。研究表明：坡缕石与比表面积较大的光催化剂（g-C3N4、MgIn2S4、CdS-Al等）组成的复合材料中可转移催化剂吸光后生成的光生电子，降低了光生电子、空穴的复合率，体系中光催化氧化还原反应的次数增加，染料光降解率增大；而在半导体光催化活性较高（MoO3/Cd0.5Zn0.5S、CdS/ZnO-ZnFe2O4、Bi2WO6/Cd0.5Zn0.5S 、Cd0.5Zn0.5S/Zn-Fe LDH、CdS-ZnS）的复合材料中可提高染料的吸附性能；PGS/ZnO-MgO-Al2O3利用表面带正电荷在吸附阴离子染料的同时光催化降解阳离子染料。光降解反应中，g-C3N4/PGS、50%PGS@Cd0.5Zn0.5S/Zn-Fe LDH体系以.OH为活性基团，降解MB、CV，降解率为96.5%、97.5%；PGS/ZnO-MgO-Bi2O3、20％PGS@ CdS/CdIn2S4、PGS(PEI)/CaIn2S4利用•O2-催化降解MG、RhB、MO，降解率为97.6%、99.1%、96.9%。同时，太阳光下，这些复合材料对混合染料进行可光催化降解。该研究对坡缕石基质的吸附材料在环保等领域的应用提供理论依据，同时促进地方经济发展。