Application of aluminosilicate clay mineral-based composites in photocatalysis

Aluminosilicate clay mineral (ACM) is a kind of typical raw materials that used widely in manufacturing industry owing to the abundant reserve and low-cost exploring. In past two decades, in-depth understanding on unique layered structure and abundant surface properties endows ACM in the emerging research and application fields. In field of solar-chemical energy conversion, ACM has been widely used to support various semiconductor photocatalysts, forming the composites and achieving efficient conversion of reactants under sunlight irradiation. To date, classic ACM such as kaolinite and montmorillonite, loaded with semiconductor photocatalysts has been widely applied in photocatalysis. This review summaries the recent works on ACM-based composites in photocatalysis. Focusing on the properties of surface and layered structure, we elucidate the different features in the composition with various functional photocatalysts on two typical kinds of ACM, i.e., type 1:1 and type 2:1. Not only large surface area and active surface hydroxyl group assist the substrate adsorption, but also the layered structure provides more space to enlarge the application of ACM-based photocatalysts. Besides, we overview the modifications on ACM from both external surface and the inter-layer space that make the formation of composites more efficiently and boost the photo-chemical process. This review could inspire more upcoming design and synthesis for ACM-based photocatalysts, leading this kind of economic and eco-friendly materials for more practical application in the future.     

黏土对废水中铀的吸附性能

用黏土吸附废水中的铀，考察了黏土对废水中铀的吸附性能、影响因素及黏土对铀的吸附动力学。实验结果表明，在含铀废水pH为5、铀初始质量浓度为20mg／L、黏土加入量为5g／L的条件下，振荡吸附1h后的吸附率达75．4％；黏土粒径越小，对铀的吸附量越大，粒径为0．20mm时的吸附量最高（3．24mg／g）；溶液中铀初始质量浓度与铀的吸附率成反比，与铀的吸附量成正比；黏土对铀的吸附符合Frcundlich和Langmuir吸附等温式，饱和吸附量达18．25mg/g；黏土对铀的吸附过程用Ho准二级反应动力学方程描述更合适。     

试论长江流域自然环境的演化

依据青藏高原不断抬升及第四纪红色风化壳的不同性状,论证长江流域河流网系的台阶性特征,抬升的结果使高原东侧与北部高大山系足以阻隔西北寒流的冬季入侵,同时又强化了东南湿润气流的深入与阻滞于四川盆地西部及云贵高原北侧,因而使湿润亚热带生态环境得以深入上游地区。根据江南丘陵广泛分布的第四纪红色风化壳的特征,论证了整个地区均受到新构造运动抬升的影响,并在漫长的时期里处于湿润亚热带环境,成为孑遗陆生、水生物种得以长期存活的条件,同时使长江流域形成水热资源丰富、物种多样的河流网系。     

Dibenzo-p-dioxins in the environment from ceramics and pottery produced from ball clay mined in the United States

Processed ball clay samples used in the production of ceramics and samples of the ceramic products were collected and analyzed for the presence and concentration of the 2,3,7,8-Cl substituted polychlorinated dibenzo-p-dioxins and -furans (PCDDs/PCDFs). The processed ball clay had average PCDD concentrations of 3.2 ng/g toxic equivalents, a congener profile, and isomer distribution consistent with those found previously in raw ball clay. The PCDF concentrations were below the average limit of detection (LOD) of 0.5 pg/g. The final fired ceramic products were found to be free of PCDDs/PCDFs at the LODs. A consideration of the conditions involved in the firing process suggests that the PCDDs, if not destroyed, may be released to the atmosphere and could represent an as yet unidentified source of dioxins to the environment. In addition, the PCDDs in clay dust generated during manufacturing operations may represent a potential occupational exposure.     

牛骨炭与伊/蒙黏土组配改良剂对土壤中Cd的钝化效果

农田土壤Cd污染是我国最为突出的环境问题之一,开展新型钝化修复Cd污染土壤材料的研究和技术开发对保障农产品安全及保护人体健康具有重要意义.以北京某蔬菜生产基地设施大棚Cd污染土壤为试验对象,温室条件下采用盆栽试验,研究牛骨炭与伊/蒙黏土复合组配的改良剂对Cd污染土壤的钝化效果,探讨不同配比的组配改良剂对土壤Cd有效态含量以及小白菜Cd吸收量的影响.结果表明:在污染土壤中添加1%、2%和5%的组配改良剂,可明显降低土壤有效态Cd含量及小白菜对Cd的吸收,土壤有效态Cd含量降幅最大值达42.3%,小白菜地上部分Cd含量降幅最大值达22.7%,组配改良剂中骨炭成分比例越高,钝化效果越好,尤其以添加5%组配改良剂（添加组配改良剂中牛骨炭含量为50%）对Cd的稳定化效果最佳,且不同组配改良剂处理均不会对小白菜生长产生不良影响,表明牛骨炭与伊/蒙黏土组配的改良剂在修复Cd污染土壤上具有较好的应用潜力.研究显示,牛骨炭与伊/蒙黏土组配的改良剂符合绿色修复技术的发展要求,可作为钝化修复农田重金属污染土壤的环保新材料.      

不同炭基两性黏土对紫色土吸附Cu2+的影响

为了探究不同炭基两性黏土材料对紫色土吸附Cu²⁺的影响,将0%、50%和100% CEC十二烷基二甲基甜菜碱（两性）修饰膨润土分别负载于旱生和水生空心莲子草生物炭上制得炭基两性黏土,然后将其以1%和2%（质量比）添加到紫色土中形成供试研究土样。批量处理法研究pH、离子强度和温度处理对各供试土样吸附Cu²⁺的影响,并分析最适环境条件下土样对Cu²⁺的等温吸附和热力学特征。结果表明：（1）pH在2~5范围内,各供试土样对Cu²⁺的吸附量均与pH呈正相关关系。随着离子强度的增大,供试土样对Cu²⁺的吸附量均先增加后减少,以0.1 mg/L最高。10℃~40℃范围内,土样对Cu²⁺的吸附均表现为增温正效应。（2）在pH=5,离子强度0.1 mg/L和40℃条件下,土样对Cu²⁺的吸附等温线符合Langmuir模型,最大吸附量（q_m）保持在160.79~247.12 mmol/kg之间。添加1%和2%炭基两性黏土后土样q_m分别为紫色土的1.35~1.74倍和1.57~2.02倍。选择旱生炭基两性黏土和2%材料添加比例下土样对Cu²⁺的吸附量较大。（3）热力学参数结果显示各供试土样对Cu²⁺的吸附是自发、吸热和熵增的反应过程。     

Some engineering aspects of homoionized mixed clay minerals

Many studies have been conducted to investigate thephysicochemical behavior of pure clay minerals and predicttheir engineering performance in the field. In this study, thephysicochemical properties of an artificial mixture of differentclay minerals namely, 40-50% montmorillonite, 20-30% illite and 10-15% kaolin were investigated. The mixture was homoionized with sodium, Na⁺; calcium, Ca²⁺; andaluminum, Al³⁺. The engineering properties studied wereconsistency limits, sediment volume, compressibility behavior,and hydraulic conductivity. The results revealed that theliquid, plastic and shrinkage limits of soil increased withincreasing cation valence. The hydraulic conductivity of thesoil also increased with an increase in the valence of thecation at any given void ratio. Aluminum and sodium treatedclays had the highest and the lowest modified compressionindex values, respectively. Furthermore, trivalent cationsaturated clayey soil consolidates three times faster thanthat of monovalent and two times faster than that of divalent.These properties of the soils determined were, in general,similar to those of kaolinite rather than those ofmontmorillonite. The comparison of the results obtained withthe published data in the literature revealed that thephysicochemical behavior of the tested clay soil was, ingeneral, similar to that of kaolinite.     

云南潞西上芒岗红色粘土型金矿地质特征

潞西上芒岗红色粘土型金矿赋存于下二叠统岩溶面之上的第三、第四系红色粘土层中 ,矿体形态受地形控制明显 ,呈似层状。品位较高 ,规模中等 ,适合于露天开采。矿体的红土化作用不彻底 ,去硅富铁铝能力低 ,常见高岭石与伊利石共生。矿石中石英、褐铁矿、粘土矿物为主要载金矿物。成矿物质来自燕山中晚期形成的中侏罗勐嘎组中段与二叠系的沙子坡组的断层接触破碎带内的卡林型金矿。在湿热条件下 ,金发生活化、迁移、富集 ,在潜水面附近成矿。     

咸淡水界面上含水介质的水敏感性研究

在野外水文地质调查的基础上,采集大沽河下游咸水入侵区砂样,通过室内渗流柱咸淡水驱替试验,分别研究了盐度突变和渐变条件下咸淡水界面上含水介质的水敏感性.研究结果表明,在盐度突变条件下含水多孔介质的渗透系数下降了50.0%,而在盐度渐变条件下渗透系数只下降了25.1%,溶液盐浓度递减速率越快则渗透性降低程度越大;随着渗透时间的延长,渗透系数可降低1～3个数量级,且渗透性的降低具有不可逆性.另外,本区渗透性发生变化主要是由伊利石、高岭石和绿泥石这些非膨胀性粘粒在渗流柱内迁移和沉积引起的.     

垃圾填埋场衬垫封盖系统稳定性实验方法研究

生活垃圾填埋场已经成为处理城市生活垃圾的一个重要手段,在修建过程中衬垫封盖系统的稳定性不可避免地成为一个需要解决的问题,本文总结了国外学者研究的方法、手段和成果,为国内学者提供有价值的参考。