Studies on catalytic reduction of nitrate in groundwater

Catalytic reduction of nitrate in groundwater by sodium formate over the catalyst was investigated. Pd-Cu/γ-Al₂O₃ catalyst was prepared by impregnation and characterized by brunauer-emmett-teller (BET), inductive coupled plasma (ICP), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). It was found that total nitrogen was effectively removed from the nitrate solution (100 mg/L) and the removal efficiency was 87%. The catalytic activity was affected by pH, catalyst amount used, concentration of sodium formate, and initial concentration of nitrate. As sodium formate was used as reductant, precise control in the initial pH was needed. Excessively high or low initial pH (7.0 or 3.0) reduced catalytic activity. At initial pH of 4.5, catalytic activity was enhanced by reducing the amount of catalyst, while concentrations of sodium formate increased with a considerable decrease in N₂ selectivity. In which case, catalytic reduction followed the first order kinetics. Translated from Acta Scientiae Circumstantiae, 2006, 26(4): 567–571 [译自: 环境科学学报]     

异烟酸——吡唑啉酮光度法测定水中氰化物方法的探讨

在用异烟酸-吡唑啉酮光度法测定水中氰化物时，用氢氧化钠代替，N，N-二甲基甲酰胺作为溶剂，配制吡唑啉酮作试验，结果表明，改进法代替标准法是可行的，且改进后的显色剂较原显色剂稳定。     

城市污水厂二级生物处理出水氯消毒影响因素研究

进行了城市污水厂二级生物处理出水氯消毒影响因素研究,结果表明:对次氯酸钠,二氧化氯消毒效果影响最大的是pH,其次是有机氮,COD,氨氮的影响相对较小。运用Selleck-Collins公式对数据进行分析。     

钢铁厂冷轧废水污泥中铬回收实验研究

钢铁厂冷轧废水污泥中含有10%以上的铬、20%以上的铁和1.5%以上的锌(均以质量分数计).为了从污泥中回收铬,首先研究了污泥中铬的形态,确定为Cr(Ⅲ);然后以碳酸钠为氧化助剂,将污泥与碳酸钠按一定比例混合后焙烧,再用水浸取.研究了碳酸钠的添加量、焙烧温度和时间、浸取时间和浸取方式对铬回收率的影响.研究表明,每克干污泥中添加0.6 g或以上碳酸钠,在固定床上700 ℃焙烧4 h以上,可实现60%以上的总铬浸出率,残渣为Fe2O3基脱硫剂原料.     

碱法草浆黑液厌氧处理中钠的抑制作用

试验了烧碱法草浆黑液中，钠在厌氧过程中的抑制特性。研究表明，钠盐抑制作用强度为：氯化钠＞木素钠＞硫酸钠＞硅酸钠。相对产甲烷率ＰＭ（Ｉ）和钠浓度Ｉ的关系，可用ＰＭ（Ｉ）＝［１＋（Ｉ／Ｋｉ）＾ａ］＾－１拟合，污泥经过驯化，对钠的耐受能力可提高。     

水相催化芳香氯化物脱氯研究

通过把起相转移作用的聚乙二醇（PEG）链，键合到硅胶上，再将聚乙烯吡咯烷酮（PVP）络合双金属Pd-Cu后负载其上，制成一种新型双负载双金属催化剂PVP－PdCl2/SiO2-PEG600,以甲酸钠为氢转移试剂，在水相催水芳香氯化物脱氯，当反应温度80℃左右，n(Pd):n(Cu）=2:1，反应介质pH值11．7左右时，具有较高的催化脱卤活性，催化剂不但易于制备，便于分离，且具有良好的重复使用性能，经重复使用六次，转化率仍在70％以上。     

硫酸铝废渣生产硅酸钠的研究

讨论以硫酸铝废渣经水洗，碱萃取生产硅酸钠的最佳工艺条件，所得硅酸钠产品，符合国家规定．本生产工艺不仅解决了环保问题，还综合利用了资源，具有可观的经济效益．     

高效吸收氧化法处理炼油工业恶臭气体研究

以碳酸钠溶液为吸收液,对苯二酚为催化荆,研究了对炼油企业硫化氢恶臭气体的吸收氧化效果,考察了吸收氧化的影响因素、再生方法及再生效果。结果表明：高效氧化吸收法处理硫化氢恶臭气体效果很好,吸收液可循环使用。     

土壤悬浮液中五氯酚钠（PCP-Na）的分析方法研究

探索了利用紫外分光光度法测定土壤悬浮液中五氯酚钠的方法。采用紫外可见分光光度计,选定在波长255．6nm处测定土壤悬浮液中五氯酚钠的含量,所得线性回归方程为Y=0．0287X＋0．0022,相关系数r=0．9999,检测限为0．016mg／L,加标回收率为93．357％～95．907％,实验结果表明此法简单、快速,准确性较高。     

Toxic effect of sodium perfluorononyloxy-benzenesulfonate on Pseudomonas stutzeri in aerobic denitrification,cell structure and gene expression

• OBS inhibited the growth of P. stutzeri and destroyed its structure. • OBS was toxic to the aerobic denitrification process of P. stutzeri. • OBS induced the production of ROS in P. stutzeri. • OBS affected the expression of key genes involved in denitrification and SOD. The toxicities of sodium perfluorononyloxy-benzenesulfonate (OBS) to animals and plants are similar to those of perfluorooctane sulfonate. However, the mechanism of its toxicity to aerobic denitrifying bacteria is still unclear. In the present study, the ecotoxicity of OBS on an aerobic denitrifying strain, Pseudomonas stutzeri, was evaluated. The results showed that a dosage of OBS clearly affected the growth and aerobic denitrification of P. stutzeri. When compared with an unamended control, the degradation efficiency of the total nitrogen decreased by 30.13% during exposure to 200 mg/L of OBS, and the complete degradation time of nitrate-nitrogen was delayed by 4 h. The lactate dehydrogenase and superoxide dismutase produced by the bacteria increased with the concentration of OBS, and reactive oxygen species were also detected by confocal laser scanning microscope imaging. Transmission electron microscope imaging revealed chromosome deformation of the cells and damage to cell content; moreover, outer membrane vesicles were secreted from the bacteria, which was the important detoxification mechanism of P. stutzeri to OBS. Expression of the genes involved in aerobic nitrification and oxidative stress were also changed under OBS stress, which further confirmed the toxicity of OBS to P. stutzeri. This study reveals the environmental exposure risk of OBS from the perspective of microorganisms.