XAFS study of starch-stabilized magnetite nanoparticles and surface speciation of arsenate

It has been shown that starch can effectively stabilize nanoscale magnetite particles, and starch-stabilized magnetite nanoparticles (SMNP) are promising for in situ remediation of arsenic-contaminated soils. However, a molecular level understanding has been lacking. Here, we carried out XAFS studies to bridge this knowledge gap. Fe K-edge XAFS spectra indicated that the Fe-O and Fe-Fe coordination numbers of SMNP were lower than those for bare magnetite particles, and these coordination numbers decreased with increasing starch concentration. The decrease in the average coordination number at elevated stabilizer concentration was attributed to the increase in the surface-to-volume ratio. Arsenic K-edge XAFS spectra indicated that adsorbed arsenate on SMNP consisted primarily of binuclear bidentate (BB) complexes and monodentate mononuclear (MM) complexes. More BB complexes (energetically more favorable) were observed at higher starch concentrations, indicating that SMNP not only offered greater adsorption surface area, but also stronger adsorption affinity toward arsenate.     

γ-射线辐照法改善城市污水厂剩余污泥厌氧消化特性的研究

采用γ-射线辐照法对城市污水厂剩余污泥进行预处理，从固体组分、可溶性组分及厌氧产气量等角度来探讨γ-射线辐照法改善城市污水厂剩余污泥厌氧消化特性的可行性。结果表明，经γ-射线辐照处理后，污泥的平均粒径减小，在辐照剂量为6．51-30．75kGy范围内，粒径的减小率达30％-50％；可溶性有机组分随着辐照剂量升高而增加，当辐照剂量为19．4kGy时，SCOD增加率达552．5％；与未辐照相比，污泥经2．48、6．51、11．24kGy辐照处理后，厌氧消化累计产气量分别增加8．89％、19．74％和35．81％。γ-射线辐照法是一种有效的改善污泥厌氧消化特性的方法，11．24kGy左右的剂量可作为污泥预处理的最佳剂量。     

铁炭法处理高浓度难降解表面活性剂废水的研究

就铁炭法对高浓度难降解拉开粉（阴离子表面活性剂）废水的处理效果进行了接近工业化的动态模型实验研究，结果表明酸化铁炭工艺对橡胶工业拉开粉废水具有显著的去除效果。在Fe：C=2：1，pH=4，停留时间60min，曝气量0．1m^3／h时，拉开粉（BX）和COD的总去除率分别约为80％和45％。     

催化湿式氧化中负载型催化剂的稳定性与应用

催化剂在应用过程中必须具有良好的催化活性和稳定性.优化制备的CuO/γ-Al2O3催化剂用于处理高浓度难降解的乳化液废水时具有良好的催化活性,在200℃时反应2 h,TOC去除率为81.3%,比未加催化剂的湿式氧化提高了14.9%.该催化剂对分散兰废水具有更高的活性和稳定性:在220℃反应1.5 h后,COD和TOC去除率分别为68.8%和56.5%,比非催化氧化分别提高了18.7%和18.9%.     

Effect of soil characteristics on Cd uptake by the hyperaccumulator Thlaspi caerulescens

The influence of soil characteristics on the phytoremediation potential of Thlaspi caerulescens is not well understood. We investigated the effect of soil pH and Cd concentration on plant Cd uptake on one soil type, and the variation in Cd uptake using a range of field contaminated soils. On soils with total Cd concentrations of 0.6-3.7 mg kg(-1), T. caerulescens (the Ganges ecotype) produced greater biomass in the pH range 5.1-7.6 than at pH 4.4. The highest plant Cd concentration (236 mg kg(-1)) and Cd uptake (228 microg pot(-1)) were observed at pH 5.1. On soils with total Cd concentrations of 2.6-314.8 mg kg(-1), shoot Cd concentrations were 10.9-1,196 mg kg(-1). Multiple regression analysis indicated that higher Cd in soil, low pH (within the range of >5) and coarser texture were associated with higher Cd concentration and Cd uptake by T. caerulescens.     

Ozonation of Cationic Red X-GRL in aqueous solution: degradation and mechanism

Ozonation of the azo dye Cationic Red X-GRL was investigated in a bubble column reactor at varying operating parameters such as oxygen flow rate, temperature, initial Cationic Red X-GRL concentration, and pH. The conversion of dye increased with the increasing of pH and oxygen flow rate. As the reaction rate constant and the volumetric mass transfer coefficient increase while the ozone equilibrium concentration decreases with the temperature, there is a minimum conversion of dye at 25 degrees C. The increasing of initial dye concentration leads to a decreasing conversion of dye while the ozonation rate increases. The formation of intermediates and the variation of pH, TOC, and nitrate ion during ozonation were investigated by the use of some analytical instruments such as GC/MS, GC, and IC. The intermediates of weak organic acids lower the pH value of the solution. The probable degradation mechanism of the Cationic Red X-GRL in aqueous solution was deliberated with the aid of Molecular Orbital calculations. The N(12)-C(13) site in Cationic Red X-GRL, instead of the N(6)-N(7) site, is found to be the principal site for ozone cycloaddition in the degradation processes. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one is converted into an amine compound, and the remaining four are transformed into two molecules of nitrogen.     

绿色饲料的地位及其生产与研究进展

分析了绿色饲料生产发展趋势及绿色饲料生产已经探索形成的若干有效模式 ,以黄淮海平原青刈黑麦研究为例 ,从青刈黑麦高产栽培技术体系研究、加工技术研究、生产系统评价等方面阐述了青刈黑麦的生产与研究进展 ,为我国绿色饲料产业化建设提供了思路。     

Multilevel air quality evolution in Shenyang: Impact of elevated point emission reduction

Visibility observed at different altitudes is favorable to understand the causes of air pollution. We conducted 4-years of observations of visibility at 2.8 and 60 m and particulate matter(PM) concentrations from 2015 to 2018 in Shenyang, a provincial city in Northeast China. The results indicated that visibility increased with the increasing height in winter(especially at night), and decreased with height in summer(especially at the daytime). PM concentration exhibited opposite vertical variati...     

曝气浸没固定生物膜反应器处理化粪池出水

研究了以丝瓜络作为生物膜载体的曝气浸没固定生物膜反应器在处理化粪池出水时的可行性以及运行性能。结果表明,丝瓜络生物膜反应器可以在2周内成功启动;水力停留时间(HRT)对COD和氨氮的去除效果有显著影响,在水力停留时间为4 h的条件下,系统对COD和氨氮的去除率分别达到了78.5%和96.4%。另外,系统有较强抗有机污染物冲击负荷的能力,当COD和氨氮的进水浓度分别为59.3 mg/L和15.9 mg/L时,系统对有机污染物的去除效果较佳,去除率分别达到了80.0%和98.9%。