Comparison of zinc complexation properties of dissolved natural organic matter from different surface waters

The zinc binding characteristics of natural organic matter (NOM) from several representative surface waters were studied and compared. NOM samples were concentrated by reverse osmosis. The samples were treated in the laboratory to remove trace metals. Square wave anodic stripping voltammetry (SWASV) was used to study zinc complexing properties of those NOM samples at fixed pH, ionic strength, and dissolved organic carbon (DOC) concentrations. Experimental data were compared to the predictions from the Windermere Humic Aqueous Model (WHAM) Version VI. At the same pH, ionic strength, and temperature, the zinc titration curves for NOM samples from different surface water sources tested in our study almost overlapped each other, indicating similarity in zinc binding properties of the NOM. A discrete two-site model gave good fits to our experimental titration data. Non-linear fitting by FITEQL 4.0 shows that the conditional zinc binding constants at the same pH are similar for NOM from different sources, indicating that zinc complexation characteristics of the NOM used in our study do not depend on their origin and one set of binding parameters can be used to represent Zn-NOM complexation for NOM samples from those different surface water sources representing geographically diverse locations. In addition, the total ligand concentrations (L(1,T), L(2,T), and L(T)) of all NOM show no observable gradation with increasing pH (L(1,T)=2.06+/-0.80 mmol/g carbon; L(2,T)=0.12+/-0.04 mmol/g carbon; L(T)=2.18+/-0.78 mmol/g carbon), while the conditional binding constants of zinc by NOM (logK(ZnL)(c)) show a linear increase with increasing pH(logK(1)(c)(pH=6.0)=4.69+/-0.25; logK(1)(c)(pH=7.0)=4.94+/-0.10; logK(1)(c)(pH=8.0)=5.25+/-0.006; logK(2)(c)(pH=6.0)=6.29+/-0.13; logK(2)(c)(pH=7.0)=6.55+/-0.08; logK(2)(c)(pH=8.0)=6.86+/-0.023) with a slope of ca. 0.28, indicating the zinc-NOM complexes become more stable at higher pH. The WHAM VI predicted free zinc ion activities at high zinc concentrations agree with our experimental results at pH 6.0, 7.0, and 8.0. However, the zinc binding of these NOM samples is over estimated by WHAM VI at zinc concentrations below 10(-6) M at pH 8.0.     

溶出伏安法快速测定水中砷的研究

利用阳极溶出伏安法实现水体中砷含量的现场快速分析。方法检出限为0.007 mg／L,测定范围为0.03 mg／L～0.14 mg／L。该法可由单标法测定和标准添加法测定。采用单标测定,对国家标准物质的分析误差在20％以内,加标回收率在94.0％～126.2％之间;采用标添测定,对国家标准物质的分析误差在5％以内,加标回收率在93.5％～104.8％之间。对浓度为0.01、0.02、0.05、0.10 mg／L的统一样品进行测定, RSD在7.0％～18.7％之间。特别是浓度在0.05 mg／L以上时,RSD在10％以内,完全满足应急状态下As项目Ⅲ类水分析要求。完全满足应急状态下现场分析的要求。     

Behaviour and Quantification Studies of Terbacil and Lenacil in Environmental Samples Using Cyclic and Adsorptive Stripping Voltammetry at Hanging Mercury Drop Electrode

The cyclic voltammograms of terbacil and lenacil at the hanging mercury drop electrode showed a single well defined four electron irreversible peak in universal buffer of pH 4.0 for both compounds. The peak potentials were shifted to more negative values on the increase of pH of the medium, implying the involvement of protons in the electrode reaction and that the proton transfer reaction precedes the proper electrode process. The four electron single peak may be attributed to the simultaneous reduction of carbonyl groups present in 2 and 4 in pyrimidine ring of terbacil and lenacil to the corresponding hydroxy derivative. Based on the interfacial adsorptive character of the terbacil and lenacil onto the mercury electrode surface, a simple sensitive and low cost differential pulse adsorptive stripping voltammetric procedure was optimized for the analysis of terbacil and lenacil. The optimal operational conditions of the proposed procedure were accumulation potential E _acc = −0.4 V, accumulation time t _acc = 80 s, scan rate = 40 mV s⁻¹, pulse amplitude = 25 mV using a universal buffer pH 4.0 as a supporting electrolyte. The linear concentration range was found to be 1.5 × 10⁻⁵ to 1.2 × 10⁻⁹ mol/l and 1.5 × 10⁻⁵ to 2.5 × 10⁻⁸ mol/l with the lower detection limit of 1.22 × 10⁻⁹ and 2.0 × 10⁻⁸ mol/l. The correlation coefficient and relative standard deviation values are found to be 0.942, 0.996, 1.64% and 1.23%, respectively, for 10 replicants. The procedure was successfully applied for determination of terbacil and lenacil in formulations, mixed formulations, environmental samples such as fruit samples and spiked water samples.     

生活垃圾填埋场渗滤液处理研究

对国内某大型垃圾填埋场渗滤液处理进行了试验研究.研究结果表明,采用吹脱→厌氧UBF→A-SBR工艺是行之有效的,各项指标均达到了<生活垃圾填埋污染控制标准>(GB16889-1997)三级排放标准,其中CODCr、BOD5、NH3-N和TN去除率分别达到了95%、99%、99.5%和97%.     

微电解-吹脱-SBR法处理DSD酸生产废水

针对DSD酸废水难降解,高氨氮,高色度以及含盐的特点,设计了微电解-吹脱-SBR工艺。试验结果表明,该工艺对DSD酸废水有较好的处理效果。当炭铁比1.6,采用曝气加搅拌方式微电解50min,在pH为11～12,气水体积比为4000条件下吹脱6h,在溶解氧浓度为3mg/L条件下,SBR法生化反应6h,最终该工艺对COD、NH4+-N、色度去除率分别约为86.5%,95.3%和97%。     

超声波吹脱技术处理高浓度氨氮废水试验研究

采用超声波吹脱技术对高浓度NH3 N废水进行了处理试验。试验结果表明 ,废水采用超声波辐射以后 ,NH3 N的吹脱效果明显增加 ,与传统吹脱技术相比 ,NH3 N的去除率增加了 1 7%—1 64%。经超声吹脱处理后的废水 ,NH3 N完全可以达到国家排放标准     

炼化酸性水中含硫化合物在汽提过程中的转化规律研究

对炼化酸性水中含硫化合物在汽提过程中的转化规律进行了详细研究,发现酸性水中硫化物高达4317 mg/L,占总硫负荷的75.6%,但是其他含硫化合物如硫代硫酸根(2240 mg/L)、亚硫酸根(64 mg/L)、硫氰酸根(21 mg/L)、硫酸根(21 mg/L)以及有机硫化合物也不容忽视。汽提处理对硫化物、硫代硫酸根和部分有机硫化合物的去除效果显著,净化水中硫化物仅余3.6 mg/L,但总硫负荷高达162 mg/L,以硫代硫酸根(123 mg/L)和有机硫化合物(48.4 mg/L)为主,并残留大量多环类有机硫化合物,是影响污水场安全、高效、平稳运行的潜在不利因素。     

含硫污水单塔汽提脱硫装置长周期运行探讨

通过对排水车间含硫污水单塔汽提脱硫装置运行状况的分析，提出目前装置中存在的影响装置长周期运行的一些问题，初步探讨了问题出现的原因，并从含硫污水预处理系统工艺优化、单塔汽提冷进料原料污水选择、单塔塔盘浮阀改造等方面分别提出相应的解决方案，有效延长装置的安全平稳运行周期。     

污水汽提装置的改造方案

对含硫污水双塔汽提装置中存在的能耗高、可操作性差等问题进行了深入分析，并在此基础上提出了技术改进方案。     

四氢呋喃废水的降解特性

对医药及化工生产中含四氢呋喃废水近年来的大量出现,研究了四氢呋喃废水的生物降解特性。结果表明:厌氧单基质条件下,四氢呋喃对厌氧消化产生轻微的抑制作用,浓度达到200mg/L时,厌氧微生物受到明显抑制,产气量急剧减少。厌氧共基质条件下,四氢呋喃浓度的增加反而有利于四氢呋喃的降解。四氢呋喃废水BOD5/COD为0.096,属好氧难降解污染物质,但其对好氧微生物无抑制,其原因在于四氢呋喃具有强的挥发性,曝气吹脱12h时COD去除率高达84%。