饮用水中氟浓度测定方法改进及影响因素分析

提出了一种测定水中氟化物电极的洗涤方法,实验结果表明:利用稀盐酸代替蒸馏水对氟电极和参比电极进行洗涤,可以缩短电极的洗涤时间,提高工作效率3～4倍.同时对用稀盐酸洗涤电极法测定水中氟化物浓度的影响因素进行了分析.     

离子选择电极测定釜溪河水中的氟

水中氟的测定用比色法手续繁琐,采用离子选择电极测定具有选择性好,快速准确,在总离子强度调节缓冲液中,氯化钠可以调即离子强度,而柠檬酸钠可以消除Fe~(3 ),Al~(3 )的干扰。在pH值为5—6时测定较适宜。天然水中氟含量较低,地面水含氟量一般每升含0.2—0.5毫克之间,自来水中要求含氟量每升不超过1.0毫克,有些地下水含氟量较高,可达每升数毫克。水中氟含量的测定方法有茜索锆比色法,茜素络合剂比色法,对磺基苯偶氮变色酸锆比色法,用比色法测定氟,需要蒸馏或萃取等费时费事,特别是在测定微量的氟时,若蒸镏操作不严密,反而给测定结果带来较大的误差,因此令人感到检洲氟化物快速而可靠的方法颇为重要,采用离子选择电极测定微量的氟化物,方法准确、快速,简便,灵敏度高,不破环试样等优点,所以很快地得到人们的重视,在美国已将氟电极法作为水中氟化物的标准分析方法之一,本文采用标准加入法,使用上海生产PF—1型氟电极,对自贡市釜溪河水中的氟进行测定,现将方法小结如下。     

电絮凝处理油田废水初步研究

采用电絮凝法处理油田废水，考察了电流强度、PAC投加量、电极板间距和pH值对废水脱油率的影响。正交实验表明，pH值和电流强度是影响废水脱油率的两个最显著因素。在选定的条件下进行电絮凝实验，废水脱油率达到84.3％。     

氟化物污染对降水中氟离子浓度的影响分析

采用石灰滤纸法监测分析包头市区大气环境中的氟化物污染与降水中氟离子浓度的影响,结果显示,降水中氟离子与空气中氟化物浓度的变化存在着明显的正相关,该结论对于包头市空气的氟污染规律和优化监测分析研究有重要意义。     

对电解铝厂周边氟污染的环境影响评价

通过测定广西某电解铝厂周边大气、土壤和农作物中氟化物含量,对该厂周边的氟化物污染进行了评价,结果表明：电解铝厂周围大气氟污染与采样点的方位成显著相关关系;农作物玉米叶片氟污染主要来自于电解铝厂无组织排放的氟化物,而土壤中总氟含量除受大气中氟化物的影响外,还与当地的地质构造、土壤类型等因素有关,与主导风向无明显的相关关系,土壤中水溶氟含量与采样点到电解铝厂距离呈负相关。     

碱熔－蒸馏－离子选择电极法测定废钻井液中全氟

废钻井液是油气勘探开发的废弃物，目前多采用就地掩埋方式处置。准确测定废钻井液中氟化物的含量，对于评价其对环境可能造成的影响是十分必要的。选用离子选择电极法测定废钻井液中的氟时，对预处理方法进行了试验研究：试验了蒸馏－离子选择电极法、碱熔－离子选择电极法、碱熔－蒸馏－离子选择电极法。结论是：碱熔－蒸馏预处理法综合了碱熔法和蒸馏法各自的优点，能将氟从钻井液中最大程度地蒸馏出来，消除了基体对氟测定的干扰。因此，此法以回收率表示的废钻井液全氟准确度为最高并达到了文献要求，方法可靠。     

铝用炭素阳极生产废水中氟化物的治理

铝用阳极炭素生产中培烧净化系统喷淋废水氟化物超标严重,严重影响工业污水达标排放。文章通过对焙烧净化废水中氟化物治理的研究,并加以改造,达到良好的治理效果。此方法简单易行,处理效果明显,经济实用,建议在氟化物废水治理中推广应用。     

大通地区铝电解企业大气氟化物排放状况调查

随着地方经济的发展,铝电解业已成为大通地区的主要产业之一,但由此而带来的空气氟化物污染亦越来越重.2006年,据大通县环境监测站测试资料,中国铝业青海分公司周围空气氟化物年日均值浓度为19.93μg/dm3·d,比2005年上升了19.84%;桥头铝电股份有限公司周围空气氟化物年日均值浓度为18.47μg/dm3·d,比2005年上升36.7%;桥头地区平均值为9.3μg/dm3·d,分别超过《环境空气质量标准》(GB3095-1996)3.0μg/dm3·d的5.64倍、5.16倍和城市标准7.0μg/dm3·d的0.33倍.为了解和掌握大通地区铝电解企业大气氟化物排放状况,文章从铝电解企业的生产状况,尤其是氟化盐消耗情况入手,引入氟平衡原理,计算出氟排放总量,并辅以监测资料,探讨大通地区空气氟化物排放状况.文章为环境管理决策和污染损害赔偿纠纷的调处具有一定的参考作用.     

共沉积制备Pd／Cu纳米金属粒子对四氯化碳的脱氯研究

利用电化学共沉积的方法,在玻碳电极表面沉积制备了纳米尺寸的Pd／Cu二相金属粒子。采用循环伏安法研究了四氯化碳在沉积了Pd／Cu纳米粒子的电极表面的电化学还原行为。研究了纳米粒子尺寸、Pd和Cu质量比对四氯化碳还原脱氯效果的影响,并对反应机理进行了探讨。     

嘉陵江下游饮用水氟化物时空变异特征研究

饮用水中可溶性氟化物是公众摄入氟的主要途径,其含量水平影响人体健康.分别于2015～2017年的丰水期和枯水期6次随机采集监测了嘉陵江下游52个饮用水样中氟化物含量,并基于地理信息系统平台和健康风险指数法进行了评价.结果表明,该区域饮用水中氟化物浓度平均为0.20～0.25 mg/L.除2015年部分样点外,其余样点的...     

Assessment of electrocoagulation for the treatment of petroleum refinery wastewater

Batch electrocoagulation experiments were carried out to evaluate the removal of sulfate and COD from petroleum refinery wastewater using three types of electrodes: aluminum, stainless steel, and iron. The effects of current density, electrode arrangement, electrolysis time, initial pH, and temperature were investigated for two wastewater samples with different concentrations of COD and sulfate. The experimental results indicated that the utilization of aluminum, as anode and cathode, was by far the most efficient arrangement in the reduction of both the contaminants. The treatment process was found to be largely affected by the current density and the initial composition of the wastewater. Although electrocoagulation was found to be most effective at 25°C and a pH of 8, the influence of these two parameters on the removal rate was not significant. The results demonstrated the technical feasibility of electrocoagulation as a possible and reliable technique for the pretreatment of heavily contaminated petroleum refinery wastewater.     

Electrocoagulation of palm oil mill effluent as wastewater treatment and hydrogen production using electrode aluminum

Palm oil mill effluent (POME) is highly polluting wastewater generated from the palm oil milling process. Palm oil mill effluent was used as an electrolyte without any additive or pretreatment to perform electrocoagulation (EC) using electricity (direct current) ranging from 2 to 4 volts in the presence of aluminum electrodes with a reactor volume of 20 L. The production of hydrogen gas, removal of chemical oxygen demand (COD), and turbidity as a result of electrocoagulation of POME were determined. The results show that EC can reduce the COD and turbidity of POME by 57 and 62%, respectively, in addition to the 42% hydrogen production. Hydrogen production was also helpful to remove the lighter suspended solids toward the surface. The production of Al(OH)XHO at the aluminum electrode (anode) was responsible for the flocculation-coagulation process of suspended solids followed by sedimentation under gravity. The production of hydrogen gas from POME during EC was also compared with hydrogen gas production by electrolysis of tap water at pH 4 and tap water without pH adjustment under the same conditions. The main advantage of this study is to produce hydrogen gas while treating POME with EC to reduce COD and turbidity effectively.     

Fluoride removal by a continuous flow electrocoagulation reactor

Long-term consumption of water containing excessive fluoride can lead to fluorosis of the teeth and bones. Electrocoagulation (EC) is an electrochemical technique, in which a variety of unwanted dissolved particles and suspended matter can be effectively removed from an aqueous solution by electrolysis. Continuous flow experiments with monopolar aluminium electrodes for fluoride removal were undertaken to investigate the effects of the different parameters such as: current density (12.5-50A/m(2)), flow rate (150-400 mL/min), initial pH (4-8), and initial fluoride concentration (5-25mg/L). The highest treatment efficiency was obtained for the largest current and the removal efficiency was found to be dependent on the current density, the flow rate and the initial fluoride concentration when the final pH ranged between 6 and 8. The composition of the sludge produced was analysed using the X-ray diffraction (XRD) spectrum. The strong presence of the aluminium hydroxide [Al(OH)(3)] in the above pH range, which maximizes the formation of aluminium fluoride hydroxide complex [Al(n)F(m)(OH)(3n-m)], is the main reason for defluoridation by electrocoagulation. The results obtained showed that the continuous flow electrocoagulation technology is an effective process for defluoridation of potable water supplies and could also be utilized for the defluoridation of industrial wastewater.     

Significance of iron compounds in chemical and electro‐oxidation treatment of sugar industry wastewater: Batch reaction

Industrialization plays a major role in a nation's growth. However, with an increase in industrial activities, pollution levels are also increasing. Among all industries, the sugar‐processing industry is one that requires large amounts of water to process the sugar, and, consequently, it discharges large amounts of water as effluent. Highly polluted wastewater brings changes to the physicochemical characteristics of the surrounding environment. Iron compounds have had a significant impact when they are used in wastewater treatment in various applications, including when they are used to minimize the pollution levels in sugar industry wastewater (SIWW). To minimize the pollutant levels from SIWW, iron compounds have been key for uses in treatments involving chemical and electro‐oxidation. Two different methodologies of electrocoagulation and chemical coagulation have been used to treat SIWW. In electrocoagulation, an iron plate is used as an electrode material under specific operating conditions. Ferrous sulfate and ferric chloride have been used as chemical coagulants at various pH and mass loading levels. The use of iron metals shows an 82% reduction in chemical oxygen demand (COD) and an 84% reduction in color at the optimum condition of pH 6, an electrode distance of 20 millimeters, and a current density of 156 square centimeters. As a chemical coagulant, iron salt (ferrous sulfate) provides a reduction of 77% COD and a 91% reduction of color at pH 6 and a 40‐millimole mass loading. Electrochemical treatment using iron was found to be suitable to treat SIWW. The sludge generated after treatment can be burned or composted with the possible recovery of some of the treatment costs.     

浅谈水质中氟化物的分析方法

经过长期的工作实践,笔者总结出能够大大提高水中氟化物测定效率及准确度的操作方法。即在使用离子选择电极法测量水中氟化物时,首先要保证试验用的去离子水的纯净度,同时确保电极清洗到260mv以上,再开始试验,最后在绘制标准曲线时保证斜率的绝对值在（58±1）之间。     

Effect of salt solution treatment on impurity removal: A case study on phosphogypsum

This study gives a brief demonstration of impurity removal efficiency upon salt solution treatment of phosphogypsum (PG). The experimental set up has been designed according to a multi-variable Box–Behnken Design (BBD) with stirring time, solid: liquid (PG:salt solution) ratio and temperature as the conducted in various salt solutions. PG sample has been treated with sea water, 5% NaCl and 10% NaCl solutions according to the BBD matrix. Fluoride (F), copper (Cu), manganese (Mn), and nickel (Ni) amounts in the PG sample have been measured upon pre- and post-treatment with salt solutions. Among other operating conditions, temperature has been the dominant factor on fluoride removal efficiency, and responses for the factors determined in the experiment runs indicated that a significant correlation could be established between temperature and fluoride removal, sea water being the most efficient salt solution. Higher copper, manganese, and nickel removal efficiencies have been observed in single salt NaCl solution systems however no significant correlation could be established between factors. Results indicate that pre-treatment of PG located near coastal regions with sea water can be a cost-effective approach and applicable on industrial scale when fluoride removal is of importance.     

The removal of lignin and phenol from paper mill effluents by electrocoagulation

This study aims to investigate the treatment of paper mill effluents using electrocoagulation. Removal of lignin, phenol, chemical oxygen demand (COD) and biological oxygen demand (BOD) from paper mill effluents was investigated at various current intensities by using different electrodes (Al and Fe) and at various electrolysis times (1.0, 2.5, 5.0 and 7.5min). It was observed that the experiments carried out at 12V, an electrolysis time of 2min and a current intensity of 77.13mA were sufficient for the removal of these pollutants with each electrode. The removal capacities of the process using an Al electrode were 80% of lignin, 98% of phenol, 70% of BOD, and 75% of COD after 7.5min. Using an Fe electrode the removal capacities were 92%, 93%, 80% and 55%, respectively. In addition, it was found that removal of lignin, phenol, BOD and COD increased with increasing current intensity. In the experiments carried out at different current intensities, higher removal can be explained through a decrease in intra-resistance of solution and consequently an increase at the transfer speed of organic species to electrodes. It was also found that Al electrode performs higher efficiency than Fe electrode except for COD removal. However, the time required for removal of BOD was more than that of COD. The results suggest that electrocoagulation could be considered as an effective alternative to paper mill effluents treatment.     

Review of fluoride removal from drinking water

Fluoride in drinking water has a profound effect on teeth and bones. Up to a small level (1–1.5 mg/L) this strengthens the enamel. Concentrations in the range of 1.5–4 mg/L result in dental fluorosis whereas with prolonged exposure at still higher fluoride concentrations (4–10 mg/L) dental fluorosis progresses to skeletal fluorosis. High fluoride concentrations in groundwater, up to more than 30 mg/L, occur widely, in many parts of the world. This review article is aimed at providing precise information on efforts made by various researchers in the field of fluoride removal for drinking water. The fluoride removal has been broadly divided in two sections dealing with membrane and adsorption techniques. Under the membrane techniques reverse osmosis, nanofiltration, dialysis and electro-dialysis have been discussed. Adsorption, which is a conventional technique, deals with adsorbents such as: alumina/aluminium based materials, clays and soils, calcium based minerals, synthetic compounds and carbon based materials. Studies on fluoride removal from aqueous solutions using various reversed zeolites, modified zeolites and ion exchange resins based on cross-linked polystyrene are reviewed. During the last few years, layered double oxides have been of interest as adsorbents for fluoride removal. Such recent developments have been briefly discussed.