Effectiveness of potassium ferrate (VI) as a green agent in the treatment and disinfection of carwash wastewater

Environmental Science and Pollution Research - Carwash wastewater treatment with potassium ferrate (VI) (K2FeO4) was optimized by response surface methodology. The optimum conditions for chemical...     

Effectiveness and kinetics of ferrate as a disinfectant for ballast water

This study examined whether ferrate could meet the international standards for successful ballast water treatment, including final concentrations of less than 1 CFU/mL of Enterococci, less than 2.5 CFU/mL of Escherichia coli, and less than 1 CFU/100 mL of Vibrio cholerae. Pure cultures of E. coli, Klebsiella pneumoniae, and V. cholerae, and a mixed culture of Enterococcus faecium and E. faecilis were grown in saline solution to simulate ballast water and were treated with dosages of ferrate ranging from 0.25 to 5.0 mg/L. A ferrate dose of 5 mg/L resulted in complete disinfection of all organisms tested, and smaller dosages were also very effective. Tailing was consistently observed, and the Hom's model (1972) appeared to most accurately represent the action of ferrate on these organisms. Salinity and pH did not adversely affect results, and regrowth was not a problem. Ferrate shows good potential as an effective disinfectant in the treatment of ballast water.     

高铁酸钾预处理垃圾渗滤液

采用自制高纯度高铁酸钾预处理危废填埋场和垃圾焚烧厂的垃圾渗滤液,探讨和分析了处理效果。正交实验表明,高铁酸钾预处理危废填埋场渗滤液COD的最佳条件为:高铁酸钾与COD的初始质量浓度比为0.5、渗滤液初始pH值4.00、反应温度30℃、反应时间40 min,此时COD去除率达71.51%。此最佳条件下高铁酸钾对不同类型垃圾渗滤液的色度、SS、COD、BOD5、氨氮、总磷、重金属离子等污染因子都具有良好的去除效果,危废填埋场渗滤液经高铁酸钾预处理后可以直接进入后续生化处理系统;垃圾焚烧厂渗滤液预处理后其COD为2 861.0 mg/L,经二次预处理也可进入生化处理系统。实验结果表明,高铁酸钾对不同类型垃圾渗滤液都具有良好的预处理效果。     

Kinetic assessment of the potassium ferrate(VI) oxidation of antibacterial drug sulfamethoxazole

Sulfamethoxazole (SMX), a worldwide-applied antibacterial drug, was recently found in surface waters and in secondary wastewater effluents, which may result in ecotoxical effects in the environment. Herein, removal of SMX by environmentally-friendly oxidant, potassium ferrate(VI) (K(2)FeO(4)), is sought by studying the kinetics of the reaction between Fe(VI) and SMX as a function of pH (6.93-9.50) and temperature (15-45 degrees C). The rate law for the oxidation of SMX by Fe(VI) is first-order with respect to each reactant. The observed second-order rate constant decreased non-linearly from 1.33+/-0.08 x 10(3) M(-1)s(-1) to 1.33+/-0.10 x 10(0) M(-1)s(-1) with an increase of pH from 7.00 to 9.50. This is related to protonation of Fe(VI) (HFeO(4)(-) <==> H(+) + FeO(4)(2-); pK(a,HFeO(4)) = 7.23) and sulfamethoxazole (SH <==> H(+) + S(-); pK(a,SH)=5.7). The estimated rate constants were k(11)(HFeO(4)(-) + SH) = 3.0 x 10(4) M(-1)s(-1), k(12)(HFeO(4)(-) + S(-)) = 1.7 x 10(2) M(-1)s(-1), and k(13) (FeO(4)(2-) + SH) = 1.2 x 10(0) M(-1)s(-1). The energy of activation at pH 7.0 was found to be 1.86+/-0.04 kJ mol(-1). If excess potassium ferrate(VI) concentration (10 microM) is used than the SMX in water, the half-life of the reaction using a rate constant obtained in our study would be approximately 2 min at pH 7. The reaction rates are pH dependent; thus, so are the half-lives of the reactions. The results suggest that K(2)FeO(4) has the potential to serve as an oxidative treatment chemical for removing SMX in water.     

高铁酸钾法去除水中1,1-DCE

选取水中常见的1,1-DCE为目标污染物,通过间歇实验探讨了目标化合物在以高铁酸钾为氧化剂的情况下,不同反应条件下的去除效果、反应动力学以及反应机理。实验结果表明,不同pH值对高铁酸钾去除1,1-DCE的反应速率影响很大,在pH=3时去除效果最好;反应符合一级动力学方程,去除速率随温度升高而增大,且活化能Ea为28.52 kJ/mol,表明温度对高铁酸钾的氧化性有很大影响;反应的ΔH*>0,ΔS*G*>0;以NaNO3调节反应体系的离子强度,当离子强度为0~0.2 mol/L时,高铁酸钾去除1,1-DCE的反应速率随离子强度的增大而减小。通过对实验机理的分析看出,高铁酸钾法去除卤代烃机理为氧化及吸附共存。     

Reduction of ferrate(VI) and oxidation of cyanate in a Fe(VI)-TiO2-UV-NCO- system

The aqueous photocatalytic degradation of cyanate (NCO(-)), which is a long-lived neurotoxin formed during the remediation of cyanide in industrial waste streams, was studied in the ferrate(VI)-UV-TiO2-NCO(-) system. Kinetics measurements of the photocatalytic reduction of ferrate(VI) were carried out as a function of [NCO(-)], [ferrate(VI)], [O(2)], light intensity (I(o)), and amount of TiO2 in suspensions at pH 9.0. The photocatalytic reduction rate of ferrate(VI) in the studied system can be expressed as -d[Fe(VI)]/dt=kI(o)(0.5) [NCO(-)] [TiO2]. The rate of photocatalytic oxidation of cyanate with ferrate(VI) was greater than the rate in the analogous system without ferrate(VI). The possibility of involvement of reactive ferrate(V) species for this enhancement was determined by studying the reactivity of ferrate(V) with NCO(-) in a homogeneous solution using a premix pulse radiolysis technique. The rate constant for the reaction of ferrate(V) and NCO(-) in alkaline medium was estimated to be (9.60+/-0.07) x 10(2) M(-1) s(-1), which is much slower than the ferrate(VI) self-decomposition reaction (k approximately 10(7) M(-1) s(-1)). An analysis of the kinetic data in the Fe(VI)-UV-TiO2-NCO(-) system suggests that ferrate(V) is not directly participating in the oxidation of cyanate. Possible reactions in the system are presented to explain results of ferrate(VI) reduction and oxidation of cyanate.     

聚硅基复合氯化铁絮凝剂的制备及其在采油废水处理中的应用

采用硅酸钠制备聚硅酸,探讨了活化pH、活化剂、硅酸钠浓度(以SiO_2质量分数计)及聚合温度等因素对聚硅酸稳定性的影响.利用聚硅酸及氯化铁制备聚硅基复合氯化铁(PSiF),并通过正交试验分析了活化pH、Si/Fe(摩尔比)、OH/Fe(摩尔比)、制备时间对PSiF絮凝性能的影响.综合考虑絮凝性能、稳定性以及经济性等因素,确定PSiF适宜的制备条件为SiO_2质量分数2%～3%;活化pH为2～3;Si/Fe为0.50～0.75;OH/Fe为0.50～0.75;制备时间为0.5 h;聚合温度低于25℃.对比PSiF、PAC、FeCl_3对采油废水的处理效果,PSiF除浊、除COD效果以及经济性最好,是一种应用前景广阔的新型絮凝剂.     

新型混凝剂在废水处理中的应用研究

自行研发出一种新型混凝剂,它能广泛应用于印染废水、生活污水和餐饮废水等的处理。经过一步强化混凝处理后,各种废水的COD、色度和浊度等均有良好的去除效果。混凝污泥可以再生重复利用。     

新型混凝剂在废水处理中的应用研究

自行研发出一种新型混凝剂，它能广泛应用于印染废水、生活污水和餐饮废水等的处理。经过一步强化混凝处理后，各种废水的COD、色度和浊度等均有良好的去除效果。混凝污泥可以再生重复利用。     

Removal of fluoride from water by using a coagulant (inorganic polymeric coagulant)

Environmental Science and Pollution Research - Excess fluoride (F) ion of drinking water is a major problem in many areas of India and causes harmful effects such as dental and skeletal fluorosis....     

聚硅酸阳离子絮凝剂处理印染废水

以工业废弃物为主要原料,经过同时聚合制备聚硅酸阳离子絮凝剂(PSiC)。实现硅酸缩合自聚、铁铝离子羟化聚合以及硅与铁铝离子聚合同步交互进行。利用PSiC处理印染废水,研究PSiC去除浊度、色度和和UV254的性能,分析其除污染机理。结果表明,PSiC处理印染废水时最佳投放量为80 mg/L,此时浊度和色度去除率分别达到50%和90%。废水pH为7、PSiC投加量80 mg/L时对印染废水UV254的去除率为65%。pH和投加量过大或过小都会降低PSiC去除UV254的效果。在混凝搅拌初期UV254迅速下降,停止搅拌后又略有所上升。沉淀初期UV254稍有波动,沉降10 min后基本趋于稳定。     

Enhanced removal of lead(II) and cadmium(II) from water in alum coagulation by ferrate(VI) pretreatment.

A laboratory study demonstrated that ferrate pretreatment significantly enhanced lead and cadmium removal in alum coagulation, under the conditions of natural surface water. The enhancement of lead removal was approximately 21 to 37% by ferrate pretreatment at a dosage of 1 to 5 mg/L. The enhanced removal of cadmium by ferrate pretreatment at a dosage of 1 to 5 mg/L exceeded the removal by alum coagulation alone 2-to 12-fold. Cadmium is much more difficult to remove than lead in alum coagulation. The performance of ferrate in enhancing the removal of lead and cadmium in alum coagulation was better than that of ferric chloride. The removal of lead and cadmium was highly pH-dependent, following the general trend of higher pH being related to higher removal. Satisfactory removal of cadmium could be expected by ferrate pretreatment combined with adjusting the pH of the water.     

Kinetics of the oxidation of sucralose and related carbohydrates by ferrate(VI)

The kinetics of the oxidation of sucralose, an emerging contaminant, and related monosaccharides and disaccharides by ferrate(VI) (Fe(VI)) were studied as a function of pH (6.5-10.1) at 25°C. Reducing sugars (glucose, fructose, and maltose) reacted faster with Fe(VI) than did the non-reducing sugar sucrose or its chlorinated derivative, sucralose. Second-order rate constants of the reactions of Fe(VI) with sucralose and disaccharides decreased with an increase in pH. The pH dependence was modeled by considering the reactivity of species of Fe(VI), (HFeO(4)(-) and FeO(4)(2-)) with the studied substrates. Second-order rate constants for the reaction of Fe(VI) with monosaccharides displayed an unusual variation with pH and were explained by considering the involvement of hydroxide in catalyzing the ring opening of the cyclic form of the carbohydrate at increased pH. The rate constants for the reactions of carbohydrates with Fe(VI) were compared with those for other oxidant species used in water treatment and were briefly discussed.     

Hydrous ferric oxide nanoparticles hosted porous polyethersulfone adsorptive membrane: chromium (VI) adsorptive studies and its applicability for water/wastewater treatment

In this present study, adsorptive membranes for Cr(VI) ion removal were prepared by blending polyethersulfone (PES) with hydrous ferric oxide (HFO) nanoparticles (NPs). The effects of HFO NPs to PES weight ratio (0–1.5) on the physicochemical properties of the resultant HFO/PES adsorptive membranes were investigated with respect to the surface chemistry and roughness as well as structural morphologies using different analytical instruments. The adsorptive performance of the HFO NPs/PES membranes was studied via batch adsorption experiments under various conditions by varying solution pH, initial concentration of Cr(VI), and contact time. The results showed that the membrane made of HFO/PES at a weight ratio of 1.0 exhibited the highest adsorption capacity which is 13.5 mg/g. Isotherm and kinetic studies revealed that the mechanism is best fitted to the Langmuir model and pseudo-second-order model. For filtration of Cr(VI), the best promising membranes showed improved water flux (629.3 L/m² h) with Cr(VI) ion removal of 75%. More importantly, the newly developed membrane maintained the Cr(VI) concentration below the maximum contamination level (MCL) for up to 9 h.

     

K2FeO4去除水体中的邻仲丁基4,6-二硝基苯酚

以水体中的邻仲丁基4,6-二硝基苯酚(DNBP)为研究对象,考察了K2FeO4在不同温度、pH和共存成分等条件下对其去除效果。结果表明,K2FeO4去除水体中DNBP所需的适宜pH为6.0~7.0,适宜温度在25~35℃,且K2FeO4与DNBP摩尔比大于20:1时,DNBP降解率大于90.0%。水体pH接近中性时,共存成分NH4Cl、NaCl、NaNO3和MnCl2对K2FeO4去除DNBP的影响很小。此外,K2FeO4与DNBP摩尔比较大时,DNBP的准一级动力学降解速率常数k与pH的关系符合Gauss模型。     

Preliminary studies of the oxidation of arsenic(III) by potassium ferrate

The Pollutant Standards Index (PSI) was developed in the USA to give the public an overall assessment of the air quality on a regular basis. Currently, the PSI does not include the synergistic effects of the major air pollutants. Synergism applies when the damage caused by two or more pollutants, either to human health or property, is greater than the effect or damage caused by each individual pollutant acting alone. The purpose of this work is to develop a methodology that would take into account the synergistic effects of the priority air pollutants, and therefore give us a better understanding of the severity of the damage caused by these pollutants. The equation suggested is D(P1,P2,P3,P4,P5) = C1^A C2^B C3^C C4^D C5^E. If it is assumed that the weight constants A to E are equal to one (all pollutants contribute equally to the damage), the equation becomes D (P1,P2,P3,P4,P5) = K·C1·C2·C3·C4·C5 where the constant K represents a conversion factor between the PSI scale and the new Synergistic Theory scale. The value of K is to be determined experimentally by finding the threshold value in the synergistic scale and dividing the threshold value of the PSI scale (100) by this number K = 100/SSC1_threshold where SS_threshold is the Synergistic Scale threshold value.     

Evaluation of Al30 polynuclear species in polyaluminum solutions as coagulant for water treatment

Polyaluminum coagulant with a content of 76.8% of Al30 (PACAl30) was prepared. Its coagulation behaviors were compared with high Al13 content polyaluminum coagulant (PACAl13) and AlCl3. The species stability was studied using Al-Ferron method and 27Al NMR. The coagulation performances were investigated by studying the rate of flocs development, the turbidity removal efficiency and charge neutralization capacity under fixed pH conditions and uncontrolled pH conditions. The effect of pH on coagulation was also studied. The results show that PACAl30 are stable for using as coagulant. PACAl30 causes less pH depression than PACAl13. The charge neutralization capacity of PACAl30 is slightly lower than that of PACAl13 at pH6.8 and higher at pH 6.5. PACAl30 achieves the most effective turbidity removal in these three coagulants. And it acts effectively within a much broader dosage range and a wider pH range when compared with PACAl13. PACAl30 achieves the highest turbidity removal due to its strong flocs formation capacity. The results verify that Al30 is another highly active coagulation/flocculation species for turbidity removal.     

Preparation of macromolecular heavy metal coagulant and treatment of wastewater containing copper.

Many treatment technologies for wastewater containing heavy metals have been developed in recent years, but these technologies have some disadvantages, such as poor removing efficiency and complex operation. For this reason, a macromolecular heavy metal coagulant polyethyleneimine-sodium xanthogenate (PEX) was prepared by grafting a xanthogenate group to polyethyleneimine. It was determined that PEX has the function of removing both turbidity and copper ions. It was also determined that copper ions and turbidity have a cooperative removal effect with each other in the process of treating wastewater containing both turbidity and copper ions by PEX. The investigation showed that PEX is an amphoteric polyelectrolyte. At lower pH values, the amino groups of the macromolecule are electrically positive; therefore, turbidity is removed because of electroneutralization coagulation; at higher pH values, both amino groups and xanthogenic radical groups contribute to the removal of heavy metals, as a result of chelation. Compared with traditional chemical precipitation by calcium oxide and coagulation by an ordinary inorganic coagulant, PEX showed obvious advantages, for example, removing both turbidity and copper ions, higher removal efficiency, lower suitable pH value, and higher floc settlement velocity.