稀土废水处理技术及资源化利用研究进展

详细综述了国内外稀土废水处理技术及综合利用进展,并提出化学沉淀法-电还原法作为稀土废水后续处理,旨在回收稀土氧化物的同时,进一步降低氨氮的浓度,无论从环境还是经济角度考虑,都有现实及深远的意义。     

催化湿式氧化乐果农药废水及催化剂的研究

通过共沉淀法制备了用于湿式氧化乐果农药废水的Cu/Mn复合氧化物催化剂,研究了沉淀剂种类、沉淀温度、焙烧温度和活性组分配比等因素对Cu/Mn复合氧化物催化剂的活性及稳定性的影响,确定了最佳制备条件,利用BET比表面积测定和XRD对催化剂进行了表征。结果表明:优化条件制备的Cu/Mn复合氧化物催化剂催化湿式过氧化氢氧化处理乐果农药废水时,具有较高的催化活性和稳定性。催化剂用量以6 g/L,反应温度80℃,过氧化氢加入量为12.0 g/L,反应时间60 min,COD去除率为89.5%,活性组分溶出量较小。     

钛基IrO2-RuO2阳极电解处理亚甲基蓝溶液

采用钛基IrO2-RuO2为阳极材料,不锈钢为阴极材料,NaCl质量浓度为10 g/L的溶液为电解液,对亚甲基蓝溶液进行电化学处理。实验结果表明:处理初始质量浓度为25 mg/L的亚甲基蓝溶液,电解电流0.050 A,电解20 min后亚甲基蓝去除率达95%;处理初始质量浓度为100 mg/L的亚甲基蓝溶液,电解电流0.100 A,电解30 min后亚甲基蓝去除率达98%。随着电解时间和电解电流的增加,亚甲基蓝去除率均增大。     

Adsorption of Pb, Cd to Fe, Mn oxides in natural freshwater surface coatings developed in different seasons

Metal oxides( Fe, Mn oxides) in natural surface coatings(biofilms and associated minerals) are believed to play a significant role n the fate and transport of trace metal in aquatic environments. Seasonal variation of Fe, Mn oxides and organic materials in surface oatings, which were developed periodically on glass slides in Nanhu Lake, Jilin Province, China over the time frame of three seasons,was investigated in order to understand the influence of metal oxides on Pb and Cd adsorption to heterogeneous surface coating materials(biofilm). Pb and Cd adsorption was measured under controlled laboratory conditions( mineral salts solution with defined speciation, ionic trength 0.05 mol/L, 25~C and pH 6.0). The classical Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb nd Cd adsorption to the surface coatings. In general, components in the surface coatings varied greatly with seasons altering and btained higher concentrations in summer while the content of iron oxides always exceeded that of manganese oxides. Correlation nalyses between the maximum adsorption of Pb and Cd and components in the surface coatings developed periodically indicated that Pb hase association with Mn oxides and Cd phase association with Fe oxides as well as Mn oxides were statistically significant. Effect of Mn xides on Cd adsorption was confirmed in view of its higher content in the surface coatings. The importance of ferromanganese oxides for b and Cd adsorption to the natural surface coatings developed in different seasons was evidenced.     

Ti基和Mn基介孔催化剂活化过硫酸钠降解有机污染物的反应机制

为获得高效活化过硫酸盐降解有机污染物的环境友好Ti基介孔催化剂,在无光照条件下对比了介孔氧化钛(AM-TiO₂)和介孔氧化锰(M-MnO₂)两种催化剂活化过硫酸钠(PDS)降解四环素(TC)和罗丹明B(RhB)的过程.同时,通过结构表征、电子自旋共振谱仪(ESR)光谱、密度泛函理论计算和中间产物分析等,首次详细探明了两种介孔催化剂活化PDS降解有机污染物过程机制的差异.结果表明,与传统M-MnO₂催化剂类似,在无光照条件下AM-TiO₂也能有效活化PDS降解TC和RhB.但两种催化剂活化PDS过程中产生的活性物种存在显著差异.AM-TiO₂活化PDS过程中产生的·OH和·SO₄^-等自由基数量要少于M-MnO₂活化PDS的过程,但AM-TiO₂活化过程可以产生丰富的¹O₂参与污染物的降解.因此,AM-TiO₂活化PDS降解污染物...     

铁、铝氧化物和土壤对苄嘧磺隆的吸附

用平衡吸附法研究了苄嘧磺隆在两种土壤(广州赤红壤、湖南红壤)和两种人工合成氧化物(针铁矿、铝氧化物)中的吸附,以及pH对吸附的影响.结果表明:(1)用Langmuir,Freundlich和Temkin等温方程描述供试样品对苄嘧磺隆的吸附,其中Freundlich吸附等温方程拟合的结果较佳.在苄嘧磺隆的实验浓度范围内和一定的pH条件下,吸附苄嘧磺隆的量随其浓度的升高而增加,其顺序为:铝氧化物＞湖南红壤＞针铁矿＞广州赤红壤.(2)苄嘧磺隆在供试样品中的吸附量随溶液pH值的升高而减小.     

砷在金属氧化物/水界面上的吸附机制Ⅱ.电荷分布多位络合模型模拟

利用电位滴定表征了铁铈氧化物(Fe-Ce)的表面电荷特性,并使用电荷分布多位络合模型(CD MUSIC)进行了模拟,得到Fe-Ce材料的表面位质子结合常数为5.8,位密度为23.2个·nm-2,高于大多数铁氧化物的表面位密度.在Fe-Ce表面特性参数的基础上,进一步使用CDMUSIC模型对系列pH(5～9)下As(Ⅴ)在Fe-Ce表面的等温吸附实验进行了模拟.结果表明,单齿单核单质子化形态≡FeOAsO3H1.5-和双齿双核非质子化形态≡Fe2O2AsO22-共存于吸附后的Fe-Ce表面,它们的结合常数分别为31.5和34.2,电荷分布值(f)分别为0.25和0.50.使用以上模型参数,对pH 3.5～10.5范围内2种表面络合形态分布趋势进行了预测.结果表明,在偏酸性条件下,≡ FeOAsO3H1.5-形态占主导;而≡Fe2O2AsO22-形态主要存在于偏碱性的范围.     

Selective extraction and separation of Fe, Mn oxides and organic materials in river surficial sediments

In order to investigate the adsorption mechanism of trace metals to surficial sediments （SSs）, a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials （OMs） in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH .HCl （0.1 mol/L） ＋ HNO3 （0.1 mol/L）, （NH4）2C2O4 （0.2 mol/L） ＋ H2C2O4 （pH 3.0）, and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09%--3.36% for the hydroxylamine hydrochloride treatment, 80.63%- 101.09% for the oxalate solution extraction, and 94.76%-102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation ofFe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.