SnS2/α-Al2O3对酸性废水中汞离子的去除机制

基于硫化物与汞亲和性较强的特性,构建了SnS₂/α-Al₂O₃复合型除汞吸附剂材料.实验结果表明,该复合材料对Hg²⁺的最大吸附容量可达950mg/g,其吸附效果不受pH值（酸性pH=1~6）影响,汞浓度为65mg/L时,均能达到近100%的汞去除效率.同时,吸附过程不会受其他金属离子（Cd²⁺、Cr³⁺、Zn²⁺、Cu²⁺、Pb²⁺、Ni²⁺、Co²⁺等）的强烈干扰,汞浓度为1mmol/L条件下,汞的去除速率及效率均未有很大差距.吸附过程未有大量Sn²⁺析出,证明了该复合材料的酸性稳定性.通过吸附动力学以及吸附机制研究表明,该吸附过程为单层化学吸附.通过盐酸溶液浸泡洗涤,可以实现SnS₂/α-Al₂O₃复合材料的再生和循环使用.     

Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation

This study focuses on the effects of p H and fluoride at different molar ratios of fluoride to Al(R F:Al) on the removal of cadmium(Cd~(2+)) and phosphate by Al coagulation. Fluoride at R F:Al≥ 3:1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high R F:Al of 10:1 whereas at lowered R F:Al(i.e., ≤ 6:1), an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at p H 7 and 8 and that of phosphate at p H 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated R F:Al. The Al fluoride interactions include the formation of Al–F complexes and the adsorption of fluoride onto Al(OH)_3 precipitates, i.e., the formation of Al(OH)n F m. Al–F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower p H. Al–F complexes at high R F:Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low R F:Al shows little effect on Al coagulation behavior towards Cd~(2+)and phosphate, and the spent defluoridation adsorbent,i.e., aluminum(Al) hydro(oxide) with adsorbed fluoride at R F:Al of below 0.1:1, may be reclaimed as a coagulant after being dissolved.     

湖泊营养物参照状态建立方法研究

建立生态分区内各类型湖泊营养物的参照状态是营养物基准制定过程中最为核心的内容之一。在系统分析和评价国外确定湖泊营养物参照状态的若干种方法,包括参照湖泊法、湖泊群体分布法、三分法、回归分析等几种统计学方法以及模型推断和古湖沼学重建方法后,文章根据总磷（total phosphorus,TP）、总氮（total nitrogen,TN）、叶绿素a（chlorophyll a,Chl-a）和塞氏透明度（Secci depth）等四项指标的历史监测数据,应用若干统计学方法建立了巢湖的营养物基准参照状态。通过互相之间的比较分析以及长江中下游湖区古湖沼学重建数据的验证,推荐采用湖泊群体分布法5％点位对应的值作为巢湖营养物基准的参照状态。因此,巢湖营养物参照状态阈值范围为总磷0．023～0．27mg·L^-1,总氮O．62～0．63mg·L^-1,叶绿素aO．65～0．67mg·m^-1,塞氏透明度0．65-0．72m。     

Removal of elemental mercury with Mn/Mo/Ru/Al2O3 membrane catalytic system

In this work, a catalytic membrane using Mn/Mo/Ru/Al₂O₃ as the catalyst was employed to remove elemental mercury (Hg⁰) from flue gas at low temperature. Compared with traditional catalytic oxidation (TCO) mode, Mn/Al₂O₃ membrane catalytic system had much higher removal efficiency of Hg⁰. After the incorporation of Mo and Ru, the production of Cl₂ from the Deacon reaction and the retainability for oxidants over Mn/Al₂O₃ membrane were greatly enhanced. As a result, the oxidization of Hg⁰ over Mn/Al₂O₃ membrane was obviously promoted due to incorporation of Mo and Ru. In the presence of 8 ppmv HCl, the removal efficiency of Hg⁰ by Mn/Mo/Ru/Al₂O₃ membrane reached 95% at 423 K. The influence of NO and SO₂ on Hg⁰ removal were insignificant even if 200 ppmv NO and 1000 ppmv SO₂ were used. Moreover, compared with the TCO mode, the Mn/Mo/Ru/Al₂O₃ membrane catalytic system could remarkably reduce the demanded amount of oxidants for Hg⁰ removal. Therefore, the Mn/Mo/Ru/Al₂O₃ membrane catalytic system may be a promising technology for the control of Hg⁰ emission.