湿法磷酸净化脱砷的研究现状

随着食品、医药及电子行业的不断发展，磷酸及磷酸盐的市场需求量不断增大，并且对磷酸的品质要求也越来越高，尤其是对湿法磷酸中砷杂质的要求，湿法磷酸中砷的含量将直接影响其在磷精细化工领域的应用，因此湿法磷酸中砷的高效、安全去除是亟待解决的一大难题。本文主要对湿法净化磷酸脱砷技术的研究情况进行综述，比较了几种湿法净化磷酸脱砷工艺的优缺点，介绍了较常见的化学沉淀法、结晶法，以及新兴的电沉积法、垂直区域熔融法和微反应器脱砷工艺的应用前景，并指出这些新兴的脱砷工艺将成为今后湿法磷酸的净化脱砷的发展方向，如能解决将这些脱砷工艺在实际中的问题，将会对磷酸工业的发展提供一个更有力的支持。     

硝酸脱除褐煤粉煤灰中的砷

基于砷在褐煤粉煤灰中的赋存状态,建立了酸法脱除粉煤灰中部分砷的新方法,考察了反应温度、时间、pH值等对脱砷率的影响. 结果表明,褐煤灰中的砷大多富集在煤灰表面并以砷酸钙等砷酸盐形式存在,脱砷率与pH值和反应温度成反比. 综合考虑脱砷率、溶损率等因素,确定酸法最优脱砷条件为pH=1、反应温度20℃、反应时间1 h,此时脱砷率为66.34%.     

Equilibrium and dynamic studies of the removal of As(III) and As(V) from contaminated aqueous systems using a functionalized biopolymer

BACKGROUND: A study of the removal of arsenic from a sample of actual groundwater using crosslinked xanthated chitosan is described. RESULTS: Removal of As(III) and As(V) was studied at pH 7.5 under equilibrium and dynamic conditions. The equilibrium data were fitted to Langmuir and Freundlich adsorption models and the various model parameters evaluated. The monolayer adsorption capacity from the Langmuir model for xanthated chitosan flakes (XCF) (As(V) 20.0 ± 0.56 mg g^?1; As(III) 33.0 ± 0.32 mg g^?1) were lower than obtained for xanthated chitosan granules (XCB) (As(V) 36.0 ± 0.52 mg g^?1; As(III) 48.0 ± 0.45 mg g^?1). Adsorption of As (V) was unaffected by the presence of other anions while in the case of As(III) the presence of sulfate and silicate caused a 26.5–50.9% decrease in adsorption. A sample (940 bed volumes) of a groundwater spiked with 200 µg L^?1 As(V) treated with XCF in column experiments reduced the arsenic concentration to < 10 µg L^?1. The adsorbent was also successfully applied for the removal of total inorganic arsenic down to < 10 µg L^?1 from real samples of arsenic‐contaminated groundwater. CONCLUSION: Xanthated chitosan was an efficient adsorbent for the removal of both forms of arsenic from groundwater under near neutral conditions. The presence of sulfur and the amino groups resulted in increased adsorption capacity of the sorbent. Copyright © 2012 Society of Chemical Industry     

KTA-2型脱砷剂在炼厂丙烯精制中的工业应用

介绍了锦西石化公司15万t/a聚丙烯装置丙烯脱砷流程,结合KTA-2型脱砷剂的实际应用过程及生产运行数据,对KTA-2型丙烯脱砷剂在炼厂丙烯精制中的工业应用进行了总结。工业应用表明:KTA-2型脱砷剂具有较好的脱砷活性,精制丙烯中含砷化合物的质量分数小于20×10-9,脱砷率达99.1%以上,满足高效催化剂对丙烯中砷含量要求;KTA-2型脱砷剂具有较高的砷容,穿透砷容(w)可达10%。     

高比表面积羟基氧化铁的脱砷性能

利用羟基氧化铁的吸附特性可以有效脱除水体中的重金属,考察在不同条件下的脱砷效果。采用浆态床脱除法进行评价实验,主要考察废液砷含量、p H、温度、羟基氧化铁浓度和震荡时间等对脱砷率的影响。结果表明,废液砷含量和p H对脱砷率影响较小,时间、温度及羟基氧化铁浓度对脱砷率影响较大,羟基氧化铁浓度为影响脱砷效果的主要因素,整体来看,脱除率较高。在羟基氧化铁浓度为150 mg·m L-1、震荡时间1 h和温度50℃条件下,可将初始砷含量176.00 mg·L-1的废水降至砷含量为5.46 mg·L-1。     

Dissolved organic matter and arsenic removal with coupled chitosan/UF operation

Long time uptake arsenic will cause cancers and blackfoot disease. There are still several million people suffering from drinking arsenic contaminated water. This work studied the performance of coupled chitosan/UF for arsenic removal and the influence of dissolved organic matter on arsenic removal with UF operation. Humic acid representing dissolved organic matter was fractionated into five groups of molecular sizes by gel filtration chromatography. Arsenic rejection by UF under the experimental condition is only 10%. In the presence of humic compounds, the arsenic removal of 22% is obtained. DOM with apparent molecular weight > 35,000 Da is the principle component responsible for chelating arsenic and thereafter being rejected by UF membrane. The combined interactions of humic compounds, chitosan, and arsenic enable a 65% arsenic rejection by UF. The results presented here enable our understanding of the complicated mechanisms involved in chitosan/UF/DOM/arsenic system.     

MIEX-DOC~离子交换树脂的饮用水除砷研究

对新型阴离子交换树脂MIEX-DOC的除砷性能进行了研究,考察了该树脂除砷容量、对三价砷[As(Ⅲ)]和五价砷[As(Ⅴ)]的去除能力、不同离子和水体pH值对树脂除砷[包括As(Ⅲ)和As(Ⅴ)]效率的影响。结果表明,MIEX-DOC树脂对人工配制高砷水(0.1mg.L-1)的除砷容量约为0.0051mg.mL-1;对As(Ⅲ)和As(Ⅴ)的去除能力相当;常见的共存离子对树脂除砷效率有抑制或促进影响;不同pH值下,MIEX-DOC树脂除砷效率不同,但对0.1mg.L-1的高砷水的除砷效率均达到50%以上。对农村高砷水的实地中试研究表明,当源水砷浓度约为0.1mg.L-1时,出水砷浓度低于0.05mg.L-1,达到《生活饮用水卫生标准》(GB 5749-2006)的农村小型集中式供水和分散式供水水质指标。成本分析结果表明,采用国产MIEX-DOC净水设备的除砷效果与进口设备相当,但除砷成本较低(0.56元.t-1),在我国农村高砷饮用水处理中有一定应用潜力。     

MIEX—DOC离子交换树脂的饮用水除砷研究

对新型阴离子交换树脂MIEX—DOC@的除砷性能进行了研究,考察了该树脂除砷容量、对三价砷[As（m）]和五价砷[As（V）]的去除能力、不同离子和水体pH值对树脂除砷[包括As（Ⅲ）和As（V）]效率的影响。结果表明,MIEX-DOC~树脂对人工配制高砷水（O．1mg·L-1）的除砷容量约为0．0051mg·mL-1;对As（Ⅲ）和As（V）的去除能力相当;常见的共存离子对树脂除砷效率有抑制或促进影响;不同pH值下,MIEX—DOC@树脂除砷效率不同,但对0．1mg·L-1的高砷水的除砷效率均达到50％以上。对农村高砷水的实地中试研究表明,当源水砷浓度约为0．1mg·L-1时,出水砷浓度低于0．05mg·L-1达到《生活饮用水卫生标准》（GB5749—2006）的农村小型集中式供水和分散式供水水质指标。成本分析结果表明,采用国产MIEX-DOC净水设备的除砷效果与进口设备相当,但除砷成本较低（0．56元·t-1）,在我国农村高砷饮用水处理中有一定应用潜力。     

粉煤灰中重金属元素砷的赋存状态与分离方法

粉煤灰中重金属元素在环境中的迁移转化和累积效应是粉煤灰综合利用过程中面临的壁垒问题，明晰粉煤灰中重金属元素的赋存状态并探索一种高效脱除方法是解决粉煤灰大宗利用的关键。利用改进的BCR连续提取法发现，粉煤灰中重金属元素砷的水溶态和酸可溶态占比较高，证明重金属砷容易在环境中迁移，从而影响周边环境。基于粉煤灰中重金属砷的赋存状态特征，建立了硫酸一步脱除重金属元素砷的新方法，考察了硫酸浓度、反应温度和反应时间对重金属砷脱除率的影响。结果表明，砷的脱除率随硫酸浓度增大而增大，随反应温度升高而降低，随反应时间增加而增大。综合考虑重金属砷的脱除率、粉煤灰中常量元素的损失率和球形颗粒的破坏程度，确定硫酸一步法脱除粉煤灰中重金属砷的最佳条件为硫酸溶液物质的量浓度2.0 mol/L、反应温度20℃、反应时间60 min，此时重金属砷的脱除率达75.21%。     

除砷技术现状与进展

介绍了砷的危害及污染状况，着重介绍了除砷的各种方法，最后总结了目前除砷技术的不足，并就现状提出展望。     

饮用水除砷吸附剂的研究进展

砷在水体中主要以As(Ⅲ)和As(Ⅴ)的无机酸形式存在,对人体的危害很大,吸附法是国内外研究最广泛的饮用水除砷技术之一.详细说明了饮用水除砷的吸附剂类型,指出:复合材料效率高、费用低,目前应用最为广泛;纳米材料与砷结合后性质稳定,除砷效率最高,是今后的主要发展方向;生物吸附材料以其高吸附率、低成本成为研究的热点.     

铁铝复合氧化物吸附砷氟性能实验研究

采用共沉淀法制备了复合铁铝氧化物吸附剂,并对其表面ξ电位和砷氟共存时除砷氟性能进行了初步研究。ξ电位表明铁铝复合氧化物pHzpc在9.0附近;铁铝复合氧化物对砷氟共存溶液中As(V)和F-均表现出很强的吸附能力,决定F-的去除率的是铝含量;该吸附剂对砷氟共存溶液As(V)在广谱pH范围内具有很高的去除能力,对F-在pH为6~7之间时去除率最高;砷氟共存溶液中As(V)对F-具有竞争吸附作用。     

Arsenic removal through adsorption, sand filtration and ultrafiltration: In situ precipitated ferric and manganese binary oxides as adsorbents

This study proposes a process consisting of in situ precipitated ferric and manganese binary oxides (FMBO) adsorption, sand filtration, and ultra-filtration (UF) for arsenic removal. Bench scale studies indicate that the FMBO shows higher capability of removing arsenic than hydrous ferric precipitate (HFO) and hydrous manganese oxide (HMO). This is ascribed to the combined effects of oxidizing As(III) and adsorbing As(V) for FMBO. The continuous experiments indicate that this process is effective for arsenic removal. In the presence of 0.624 mg/L As(III), when the Fe(II) dosage is 3 mg/L and the KMnO₄ dosage is equivalent to the sum of As(III) and Fe(II), the residual As concentration is as low as 29.2 μg/L. The adsorption of arsenic onto FMBO is fast, and the hydraulic retention time (HRT) of 45 s is enough for the adsorption unit. Sand filtration leads to more than 90% of arsenic removal, and UF further removes the particulate arsenic that passes through the sand filter. During the backwashing of the sand filter, the maximal aqueous arsenic concentration is 0.105 mg/L (at 150 s), and the dissolution of arsenic from FMBO is neglectable. The main operating cost of this process is as low as 0.355 RMB/m³, which is acceptable in rural areas for arsenic removal in engineering.     

Use of ArsenXnp,a hybrid anion exchanger,for arsenic removal in remote villages in the Indian subcontinent

Many of the arsenic removal units operating in remote villages of West Bengal, India now use a hybrid anion exchanger (HAIX) which are essentially spherical anion exchange resin beads containing dispersed nanoparticles of hydrated ferric oxide (HFO). HAIX, now commercially available as ArsenX^np, offers a very high selectivity for sorption of oxyanions of arsenic due to the Donnan membrane effect. The sorption columns used in the field for removal of arsenic are either single column or split-column design. The sorption columns allow flow of atmospheric oxygen, thereby promoting oxidation of dissolved Fe(II) species of arsenic-contaminated raw water to insoluble Fe(III) oxides or HFO particulates. Apart from the usual role played by the sorbents like ArsenX^np or activated alumina towards arsenic removal, HFO particulates also aid in the treatment process. Each unit is attached to a hand-pump driven well and capable of providing arsenic-safe water to three hundred (300) households or approximately one thousand villagers. No chemical addition, pH adjustment or electricity is required to run these units. On average, every unit runs for more than 20,000 bed volumes before a breakthrough of 50 μg/L of arsenic, the maximum contaminant level in drinking water in India, is reached. In addition to arsenic removal, significant iron removal is also achieved throughout the run. Upon exhaustion, the media is withdrawn and taken to a central regeneration facility where 2% NaCl and 2% NaOH solution are used for regeneration. Subsequently, the regenerated resin is reloaded into the well-head sorption column. Following regeneration, the spent solutions, containing high arsenic concentration, are transformed into solids residuals and contained in a way to avoid any significant arsenic leaching. Laboratory investigations confirmed that the regenerated ArsenX^np is amenable to reuse for multiple cycles without any significant loss in capacity.     

铜冶炼烟气制酸酸性废水处理新工艺研究

介绍了处理铜冶炼烟气制酸酸性废水生产白砷和氯化钙的新工艺研究.试验确定了除酸时中和液最佳pH值为4.0,除砷时最佳pH值为9.0,回收砷时钙砷物质的量比最佳值为2.0.该工艺流程简单、处理成本低、产渣量少,可以回收有价金属.工艺过程中产出的白砷和氯化钙分别符合工业白砷三级品和工业氯化钙V型指标.处理后的废水各项指标均符合国家排放标准.     

脱砷剂研究进展

介绍了近年来国内外报道的用于石脑油和柴油的加氢脱砷剂，用于石脑油和汽油的低温脱砷剂，用于乙烯和丙烯的氧化物脱砷剂的研究进展和工业使用状况及其发展前景。     

改性粉煤灰处理低浓度含砷含氨氮废水

在冶金和采矿等行业里,排放废水中的砷和氨氮均存在不同程度的超标。本实验采用粉煤灰对砷和氨氮进行深度处理。考察了不同改性方法对粉煤灰除砷和氨氮的处理效果。实验结果表明： NaOH＋FeCl3复合改性的粉煤灰对两种污染物都有较好的去除效果,废水中含砷2 mg/L,含氨氮50 mg/L,复合改性粉煤灰的投加量为20 g/L,废水pH为6,搅拌1 h,砷和氨氮的去除率分别达到83.33%和82.48%,出水满足《污水综合排放标准》（GB8978-1996）中砷和氨氮的排放要求。     

含砷饮用水处理技术综述

分析归纳了各种含砷饮用水处理技术,重点阐述了混凝沉淀法在处理饮用水中砷的研究进展,对吸附法、离子交换法等五种其他饮用水除砷技术进行了分析,并比较了各种除砷技术的优缺点,指出其适用条件。     

Removal of Arsenic from Wastewaters by Airlift Electrocoagulation: Part 3: Copper Smelter Wastewater Treatment

The arsenic content in wastewater is of major concern for copper smelters. A typical complex wastewater treatment is needed with a combination of chemical and physical processes. Electrocoagulation (EC) has shown its potential for arsenic removal due to the formation of ferric hydroxide-arsenate precipitates. This work evaluates the feasibility of EC as a treatment process at various stages during conventional copper smelter wastewater treatment – with a focus on arsenic. The reactor used is a batch airlift electrocoagulator. The results showed that raw copper smelter wastewater was difficult to treat for arsenic and heavy metals with EC, mainly due to the very low pH. On the other hand, after a preliminary Ca(OH)₂ treatment for sulphate and heavy metal removal, arsenic could be removed totally by EC. In addition, EC could also be applied as a final remediation control tool for arsenic since the national threshold value for wastewater discharge could rapidly be reached when the conventional method did not clean the wastewater sufficiently.     

KTA-2型常温脱砷剂在小本体聚丙烯装置的应用

分析了引起聚丙烯装置异常波动的原因,并确定是丙烯原料中杂质砷含量偏高所致.将原干燥塔内的分子筛更换为KTA-2型常温脱砷剂作为脱砷塔使用.脱砷装置投用后,降低了催化刘、活化剂的消耗量,提高了反应的稳定性,取得了较好的效果.