不同氧化剂去除饮用水中溶解性Mn~(2+)的比较研究

用KMnO_4、ClO_2、NaClO、Na_2S_2O_8、KHSO_5及O_3等水处理中常见的氧化剂去除水中的Mn⁽²⁺⁾,考察了投加量、联合投加、紫外光照、pH和共存离子等对Mn(2+),考察了投加量、联合投加、紫外光照、pH和共存离子等对Mn⁽²⁺⁾去除率的影响。结果表明,KMnO_4和O_3对溶解的Mn(2+)去除率的影响。结果表明,KMnO_4和O_3对溶解的Mn⁽²⁺⁾有很好的去除效果,当KMnO_4与Mn(2+)有很好的去除效果,当KMnO_4与Mn⁽²⁺⁾投加比为2∶3时,反应30 min后,Mn(2+)投加比为2∶3时,反应30 min后,Mn⁽²⁺⁾下降至0.006 mg/L;O_3流量0.6 L/min,5 min后Mn(2+)下降至0.006 mg/L;O_3流量0.6 L/min,5 min后Mn⁽²⁺⁾下降至0.056 mg/L。KMnO_4和O_3在弱碱性条件下去除效果更佳。ClO_2有一定去除效果。采用UV辐射,在UV254/ClO_2、UV254/KHSO_5、UV254/Na_2S_2O_8系统中,当氧化剂与Mn(2+)下降至0.056 mg/L。KMnO_4和O_3在弱碱性条件下去除效果更佳。ClO_2有一定去除效果。采用UV辐射,在UV254/ClO_2、UV254/KHSO_5、UV254/Na_2S_2O_8系统中,当氧化剂与Mn⁽²⁺⁾摩尔比分别为8∶5,4∶1和4∶1时,对起始Mn(2+)摩尔比分别为8∶5,4∶1和4∶1时,对起始Mn⁽²⁺⁾浓度在0.8(2+)浓度在0.8⁰.9 mg/L的模拟水样,Mn0.9 mg/L的模拟水样,Mn⁽²⁺⁾可分别下降至0.006,0.006,0.001 mg/L,均优于国家标准。单用NaClO处理,在较短反应时间条件下,效率较低,若UV254/NaClO联用,则亦有较好去除效果。KHSO_5/KMnO_4与Mn(2+)可分别下降至0.006,0.006,0.001 mg/L,均优于国家标准。单用NaClO处理,在较短反应时间条件下,效率较低,若UV254/NaClO联用,则亦有较好去除效果。KHSO_5/KMnO_4与Mn⁽²⁺⁾比例为5∶2时,Mn(2+)比例为5∶2时,Mn⁽²⁺⁾下降至0.06 mg/L,较单个投加效果显著提高。     

Mn~(2+)掺杂BaGdF_5:Yb/Er上转换纳米粒子的制备及其表征

本文通过一锅法制备出聚乙二醇(PEG)稳定的Mn~(2+)掺杂的BaGdF_5:Yb/Er纳米粒子(NPs)。傅里叶变换红外光谱证明PEG被成功修饰在Mn~(2+)掺杂的BaGdF_5:Yb/Er纳米粒子表面。透射电镜(TEM)结果说明:逐渐增加Mn~(2+)掺杂的含量,纳米粒子的尺寸大约从20 nm转变到10 nm;X射线衍射(XRD)证明Mn~(2+)掺杂的含量X%(X=0,10,20,30,40,50)变化,纳米粒子的晶体结构并无明显变化;荧光光谱证明;Mn~(2+)掺杂可以提高纳米粒子的上转换荧光强度。     

酚醛树脂-腐殖酸钠复合材料性能及其对水体中Mn~(2+)的吸附效应

将改性腐殖酸钠与酚醛树脂制备成酚醛树脂-磺化腐殖酸钠复合材料,探讨复合材料对水体中Mn⁽²⁺⁾的吸附效应。结果表明,酚醛树脂-磺化腐殖酸钠复合材料孔洞明显增加,亲水性降低,官能团增多,其孔容、比表面积比腐殖酸钠提高了3.00,1.22倍,而N、C、S、H元素的占比则分别增加了2.15,2.04,1.24,0.59倍。在投加量20 g/L、pH 5、室温吸附时间2 h条件下,复合材料对Mn(2+)的吸附效应。结果表明,酚醛树脂-磺化腐殖酸钠复合材料孔洞明显增加,亲水性降低,官能团增多,其孔容、比表面积比腐殖酸钠提高了3.00,1.22倍,而N、C、S、H元素的占比则分别增加了2.15,2.04,1.24,0.59倍。在投加量20 g/L、pH 5、室温吸附时间2 h条件下,复合材料对Mn⁽²⁺⁾浓度为10 mg/L的水体中Mn(2+)浓度为10 mg/L的水体中Mn⁽²⁺⁾的吸附率达到92.68%。Freundlich模型比Langmuir模型能更好的拟合酚醛树脂-磺化腐殖酸钠复合材料对水体中Mn(2+)的吸附率达到92.68%。Freundlich模型比Langmuir模型能更好的拟合酚醛树脂-磺化腐殖酸钠复合材料对水体中Mn⁽²⁺⁾的等温吸附过程,其吸附过程为多层吸附,Mn(2+)的等温吸附过程,其吸附过程为多层吸附,Mn⁽²⁺⁾最大饱和吸附容量比腐殖酸钠提高了5.99倍,达到13.49 mg/g。酚醛树脂-磺化腐殖酸钠复合材料对水体中Mn(2+)最大饱和吸附容量比腐殖酸钠提高了5.99倍,达到13.49 mg/g。酚醛树脂-磺化腐殖酸钠复合材料对水体中Mn⁽²⁺⁾具有明显的吸附固定效果。     

饮用水中嗅味物质去除技术研究进展

饮用水中异嗅异味不仅影响了感官性状,还降低了饮用水水质。介绍了饮用水中的嗅味物质的分类方法和去除技术,特别是常见的两种嗅味物质土臭素和2-甲基异莰醇的典型去除工艺。并分析了吸附处理、化学氧化、生物处理和联用技术的去除效果及优缺点,指出了嗅味物质去除技术的发展方向。     

饮用水中三氯乙酸的紫外光降解研究

饮用水中高致癌物风险物三氯乙酸,普遍存在且难以去除。采用紫外光光降解可在较短时间内去除饮用水中高浓度的三氯乙酸,150 min内去除率达到72%。结果表明,这是一种高效、环保、简便的去除方法。其光降解反应符合一级反应动力学模型。实验还考察了水样品pH及常见离子Mn2+、NO2-、NO3-和Fe3+对降解率的影响。     

水中Ni~(2+)在粒状沸石/活性炭复合材料上的吸附研究

采用廉价的煤矸石为主要原料,添加一定量的沥青粉制备了沸石NaA/活性炭粒状复合材料,并以此作为吸附剂,研究了水溶液中Ni~(2+)在该复合材料中的吸附行为,考察溶液的初始浓度、吸附时间和pH对吸附的影响.结果表明溶液较高的pH值有利于Ni~(2+)在吸附剂上的吸附;随Ni~(2+)初始浓度的增大复合材料的吸附量增大,而Ni~(2+)的去除率随之减小;Ni~(2+)在复合材料上的吸附接近Langmuir-Freundlich等温吸附模型,反映了吸附表面的多相性及两类吸附中心在复合材料上的共存性;吸附速率遵循准二级吸附动力学模型.     

饮用水中腐植酸对人体健康的影响及去除方法

在概述腐植酸的结构及其在水处理中的应用的基础上,着重阐述了腐植酸可与水处理中的氯反应生成致癌物质及其对人体的危害,并详细介绍了目前国内外去除腐植酸的主要方法,包括活性炭吸附法、光化学催化氧化法、光电化学法、强化混凝、臭氧氧化、膜技术等。对比可知,膜分离技术净化去除效果最好,已成为目前的研究热点,同时指出了使用单一处理法的一些不足之处。     

Acidithiobacillus ferrooxidans去除水中Ni~(2+)、Mn~(2+)、Cd~(2+)机理的研究

以从粤北大宝山酸性矿山废水(AMD)分离出具有的Acidithiobacillus ferrooxidans(A.f菌)为研究对象,采用原子吸收分光光度法和X射线衍射分析技术,研究A.f菌对水中Ni~(2+)、Mn~(2+)、Cd~(2+)的去除和钝化机理。实验结果显示,A.f菌与重金属离子共培养7 d后,其对Ni~(2+)、Mn~(2+)、Cd~(2+)的去除率分别为18.52%、31.63%、36.05%,X射线衍射分析显示Ni~(2+)、Mn~(2+)、Cd~(2+)与次生矿物晶体内的构晶离子Fe~(3+)间的类质同象作用不明显;A.f菌成因次生矿物对Ni~(2+)、Mn~(2+)、Cd~(2+)的吸附容量分别达130.26、74.99、78.36 mg/kg,可能与A.f菌次生高铁矿物纳米颗粒表面富含OH~-、SO_4~(2-)等高吸附能位点的强静电相互作用密切相关。     

饮用水中有机磷农药的去除技术研究进展

重点介绍了饮用水中有机磷农药的去除技术的研究进展,包括:常规处理工艺、臭氧/活性炭深度处理工艺、高级氧化工艺对有机磷农药的去除效果及去除机制。常规饮用水处理工艺不能安全有效地去除有机磷农药;作为常规处理工艺补充,臭氧/活性炭深度处理工艺、高级氧化工艺是目前的研究热点。但这两种工艺过程中机磷农药降解形成的高毒中间产物(P=O结构)生成和降解机制研究明显不足,同时也未对其提出有效的控制方法。今后的研究应当更多的关注于饮用水中有机磷农药去除技术的安全性。     

氧化法去除饮用水中亚硝酸盐氮的研究

考察了NaClO、氯胺T、H_2O_2及单过硫酸氢钾复合盐4种氧化剂的投加量、pH、温度、反应时间和紫外光照对去除亚硝酸盐氮的影响与机制。结果表明,NaClO与NO_2~-N比为1∶1时去除率达到94.31%,效果比其他几种更好,去除率随NaClO投加量的增加而增加;NaClO在弱酸性条件下去除效果最佳;氯胺T对NO_2~-N的去除效果也比较明显,其原理与NaClO一样。UV_(254)/H_2O_2和UV_(254)/单过硫酸氢钾复合盐与NO_2~-N比例为5∶1时去除率分别为93.06%和98.2%,去除效果显著提高。     

氧化法去除饮用水中亚硝酸盐氮的研究

考察了NaClO、氯胺T、H_2O_2及单过硫酸氢钾复合盐4种氧化剂的投加量、pH、温度、反应时间和紫外光照对去除亚硝酸盐氮的影响与机制。结果表明,NaClO与NO_2^-N比为1∶1时去除率达到94.31%,效果比其他几种更好,去除率随NaClO投加量的增加而增加;NaClO在弱酸性条件下去除效果最佳;氯胺T对NO_2-N比为1∶1时去除率达到94.31%,效果比其他几种更好,去除率随NaClO投加量的增加而增加;NaClO在弱酸性条件下去除效果最佳;氯胺T对NO_2^-N的去除效果也比较明显,其原理与NaClO一样。UV_(254)/H_2O_2和UV_(254)/单过硫酸氢钾复合盐与NO_2-N的去除效果也比较明显,其原理与NaClO一样。UV_(254)/H_2O_2和UV_(254)/单过硫酸氢钾复合盐与NO_2^-N比例为5∶1时去除率分别为93.06%和98.2%,去除效果显著提高。     

Removal of turbidity from drinking water using natural coagulants

The ability of three plant materials, seeds such as Moringa oleifera, Strychnos potatorum and Phaseolus vulgaris, to act as natural coagulants was tested using synthetic turbid water formulated to resemble the drinking water. An improved and alternative method for the extraction of the active coagulant agent M. oleifera, S. potatorum, P. vulgaris seeds was developed and compared with the conventional water extraction method. In the new method the seeds were extracted using different solvents of NaCl and NaOH to extract the active coagulant agent from natural coagulants. In addition, ultrasound was investigated as a potential method to assist the extraction process. Batch coagulation experiments were conducted to evaluate the performance of the extracted coagulant achieved through various schemes. The optimum turbidity removal at different values of initial synthetic wastewater turbidity from 100 to 500 NTU was investigated. Sodium chloride at 0.5 M was found to provide a high turbidity removal of >99% compared to NaOH and distilled water extract. Among these three coagulant M. oleifera seed extracts is the highest performance in turbidity removal. The optimum coagulant dosage showed the coagulation with blended coagulant M. oleifera, S. potatorum and P. vulgaris. The study was carried out for initial turbidity of the sample such as 100 NTU (low), 250 NTU (medium) and 500 NTU (high). For the natural coagulant dosage was found to be 250–1000 mg/L respectively. It was found that the percentage of removal is highest in M. oleifera.     

Removal of metals and anions from drinking water by ion exchange

Five organic and two inorganic ion exchangers were evaluated for the removal of metals and anions from water of two drilled wells. Sodium titanate (CoTreat) and a chelating aminophosphonate resin were the most efficient exchangers in removing transition metals from the total of 1800 bed volumes processed. CoTreat was the best for almost all of the transition metals. The breakthrough level of manganese was below 1% with CoTreat even when its concentration in the feed water was high (1 mg/l). The weak acid cation resin took up transition metals relatively efficiently. Somewhat unexpectedly, the cation exchangers also removed arsenic from water. Arsenic may have been sorbed on iron species, which again was adsorbed and filtered by the exchanger beds. Most of the cation exchangers took up calcium and magnesium at low processing capacities (<400 BV), and the strong base anion resin took up nitrate, bromide and sulphate very efficiently below 700 bed volumes. Neither chloride nor fluoride was taken up by the exchangers tested.     

大梯度磁滤器对饮用水中有害物质的去除

介绍了大梯度磁滤处理饮用水的工作原理及工艺过程，分析了对水中污染物质的去除效果     

Removal of fluoride from drinking water by adsorption onto alum-impregnated activated alumina

The ability of the alum-impregnated activated alumina (AIAA) for removal of fluoride from water through adsorption has been investigated in the present study. All the experiments are carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH 2–8), adsorbent dose (0.5–16 g/l), initial fluoride concentration (1–35 mg/l) has been investigated to determine the adsorption capacity of AIAA. The adsorbent dose and isotherm data are correlated to the Bradley equation. The efficacy of AIAA to remove fluoride from water is found to be 99% at pH 6.5, contact time for 3 h, dose of 8 g/l, when 20 mg/l of fluoride is present in 50 ml of water. Energy-dispersive analysis of X-ray shows that the uptake of fluoride at the AIAA/water interface is due to only surface precipitation. The desorption study reveals that this adsorbent can be regenerated following a simple base–acid rinsing procedure, however, again impregnation of the regenerated adsorbent (rinsed residue) is needed for further defluoridation process.     

Removal of iron from drinking water by electrocoagulation: Adsorption and kinetics studies

The present study provides an electrocoagulation process for the removal of iron from drinking water with aluminum alloy as the anode and stainless steel as the cathode. The studies were carried out as a function of pH, temperature and current density. The adsorption capacity was evaluated with both the Langmuir and the Freundlich isotherm models. The results showed that the maximum removal efficiency of 98.8% was achieved at a current density of 0.06 A dm⁻², at a pH of 6.5. The adsorption of iron preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules. The adsorption process follows second-order kinetics. Temperature studies showed that adsorption was endothermic and spontaneous in nature.     

Removal of DDT in drinking water using nanofiltration process

The removal of DDT[(1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane)] with synthetic waters was carried out on a nanofiltration (NF) pilot unit. The influence of initial DDT concentration, pH, flux and recovery on the removal of DDT was studied. The presence of humic acid and some inorganic (CaCl₂, NaCl, and CaSO₄) matters was also tested in the experiment. The removal percent and that of their adsorption on the membrane have been calculated. The results reveal that DDT was easy to be adsorbed on the membranes and the higher the applied pressure the more rapidly saturation of the membrane was achieved. At the initial concentration of 77 μg/L, the equilibrium for DDT adsorption can be achieved in 30 min. With the initial DDT concentration from 5 to 20 μg/L, the removal percent was from 95 to 85%. On condition that recovery was not changed, higher flux can lead to low rejection of DDT. On the other hand, low recovery can have a high rejection when the fluxes were the same. Humic acid can hinder DDT from passing through the membrane by adsorption and inorganic matter (NaCl, CaCl₂ and CaSO₄) can improve the removal percent by reducing the pore size of the membrane.     

Removal of manganese from water supplies intended for human consumption: a case study

In the Volcano Etna area (Sicily) a substantial part of groundwater, used for potable purpose, has concentrations of metals (vanadium, iron and manganese) higher than the maximum contaminant levels (MCLs) set by European and National regulations (European Directive 98/83 and D.Lgs. 31/2001). Specifically, high levels of manganese, up to 1810 μg/l, significantly exceeding the maximum contaminant level (MCL = 50 μg/l), were detected in groundwaters currently used as drinking water supply upwelled from the Etna Volcano aquifer. The paper presents the results of the manganese removal process by potassium permanganate oxidation followed by flocculation, settling and filtration. Batch tests were carried out varying pH, oxidant doses and polyelectrolytes. Two different filters (35 μm and 0.45 μm mesh) were tested as a final step of the treatment. Significant removal (up to 95%) was achieved by addition of polyelectrolytes at pH 8.5, with a 0.5 stoichiometric dose of oxidant and final filtration through 35 μm mesh filter.