Novel Fe/glass composite adsorbent and its property for arsenic(V) removal

An effective adsorbent for arsenic removal was synthesized by hydrothermal treatment of waste glass powder (HGP), followed by loading iron(III) oxyhydorxide on the surface of waste glass powder (GP). The ?Si-O-H group was formed on the surface of GP and the specific surface area of GP powder was slightly increased after hydrothermal treatment. FeOOH was loaded on the surface of HGP by the hydrolysis of FeCl3. The formation conditions of FeOOH were also investigated. The ability of this new adsorbent for arsenic removal was tested. The results indicate that the highest arsenic removal efficiency is about 97% for 1 mg/L As(V) solution at pH 6 and keeping time 2h.     

基于铁锰泥的除砷吸附剂性能比较及吸附机理

为解决反冲洗铁锰泥粉末吸附剂（BSPA）使用后难以泥水分离问题,将除铁锰水厂生物滤池产生的反冲洗泥制成颗粒吸附剂（GA）和磁性粉末吸附剂（MPA）,并对BSPA、GA和MPA的除砷性能进行了比较,通过SEM、TED、XRD、BET、FTIR等技术对3种材料进行了表征,寻找3种吸附剂之间除砷性能差异的根源.结果表明,BSPA、GA和MPA对As （V）的最大吸附容量分别为40.980,5.048,8.694mg/g,改性后的吸附材料GA和MPA对砷的吸附能力下降.BSPA是一种以纤铁矿为主的无定形结构混合物,并混有针铁矿和结晶度差的水铁矿,GA的XRD图谱中出现石英晶体和少量赤铁矿晶体的衍射峰,而MPA的主要成分为结晶程度较高的磁赤铁矿.3种材料中均存在有利于吸附的含羟基官能团.BSPA、MPA和GA的比表面积分别为253.150,238.660,43.803m²/g.物相改变且结晶程度增加、表面羟基减少和比表面积降低是导致GA和MPA的砷吸附容量比BSPA低的主要因素.     

载铁(β-FeOOH)球形棉纤维素吸附剂去除地下水As(Ⅴ)的研究

制备了一种载铁(β- FeOOH)球形棉纤维素吸附剂,球珠孔隙度大,强度好,活性成分铁的载入量可高达360mg/mL ,(质量分数达50%) ,活性好.研究表明,当铁含量为220mg/mL时,该吸附剂对As(V)的最大吸附量为15.6mg/mL(33.2mg/g) ,Langmuir和Freundlich方程能很好地描述吸附等温线.吸附速度较快,10h可达到吸附平衡,吸附动力学符合Lagergren二级方程.SiO₃^2- ,SO₄^2-,Cl^-干扰离子均不影响砷的去除.柱吸附实验表明,空床停留时间为5.9min ,进水As(V)浓度为500μg/L时,As(V)的穿透体积为5000BV .吸附剂可以用1.5mol·L^-1 NaOH再生,洗脱和再生效率可达90%以上.活性成分β-FeOOH形态稳定,柱操作和再生时铁无溶出.吸附剂制备方法简单,新颖,对地下水和饮用水砷去除具有较好的应用前景.     

铁改性杭锦土吸附剂对水中砷的去除研究

为提高天然杭锦土对水溶液中砷的吸附性能,采用氯化铁（FeCl₃·6H₂O）浸渍天然黏土矿物杭锦土（HJ）,制备表面负载铁氧化物的铁改性杭锦土除砷吸附剂（FHJ）.通过比表面积（BET）和扫描电镜（SEM）分析技术对材料进行表征以观察其微观形貌特点,通过X射线光电子能谱分析（XPS）和傅里叶红外光谱（FTIR）技术测定材料组成及化学基团,以初步探究材料吸附除砷机理.通过批试验考察FHJ投加量、初始pH、共存离子及腐殖酸浓度对FHJ除砷效能的影响.结果表明:①当铁负载比在0~50wt%范围内时,FHJ对溶液中As（Ⅴ）吸附容量随着铁负载比的增加而增加,最佳铁负载比为33wt%,此时铁与杭锦土的理论质量比为1:3.②BET分析结果表明经铁改性后,杭锦土比表面积显著增加,由71.14 m2/g增至158.50 m2/g;SEM分析显示,经改性后杭锦土表面形貌发生明显变化,结合Mapping图表明铁被有效负载到杭锦土表面.③批试验结果表明,As（Ⅴ）去除率随着FHJ投加量的增加而升高;溶液pH对As（Ⅴ）去除率有较大的影响,pH的降低有利于FHJ对砷酸盐的吸附.④FHJ除砷性能受溶液中共存离子CO₃2-、SiO₃2-影响较大,但受Cl-、SO₄2-、NO₃-及腐殖酸影响程度比较小.⑤吸附动力学过程符合准二级动力学模型,Freundlich等温吸附模型可更好地描述FHJ吸附除砷行为（R2=0.999）.⑥XPS分析结果显示,铁氧化物主要以FeOOH和Fe₂O₃的形态负载于杭锦土表面,FTIR表明FeOOH的羟基基团同As（Ⅴ）发生吸附作用,在FHJ除砷过程中,化学吸附是主要的吸附除砷机理.研究显示,铁改性杭锦土除砷效果良好,具有一定的应用潜力.      

铁锰复合氧化物吸附去除五价锑性能研究

对比研究了铁锰复合氧化物(FMBO)、羟基氧化铁(FeOOH)和二氧化锰(MnO₂)吸附去除五价锑(Sb(V))的性能.结果表明FMBO对Sb(V)具有很好的吸附性能,在pH=5.0的条件下,最大吸附容量达到1.05 mmol·g^-1,略高于FeOOH (0.82 mmol·g^-1)及远高于MnO₂ (0.43 mmol·g^-1);采用Freundlich模型可以很好地描述Sb(V)在FMBO的吸附行为(R² = 0.98).就吸附动力学而言,假二级动力学可很好地描述Sb(V)在FMBO (R² = 0.93)和MnO₂表面的吸附过程(R² = 0.96),而Sb(V)在FeOOH表面的吸附过程可用Elovich模型拟合 (R² = 0.94).Sb(V)的吸附量随着pH值的升高而降低;磷酸盐显著抑制了Sb(V)的吸附,而硫酸盐和碳酸盐影响不大.提高体系离子强度可促进Sb(V)在FMBO表面的吸附,推断Sb(V)在FMBO表面形成内层络合物后被吸附去除.     

天然菱铁矿改性及强化除砷研究

我国高砷地下水分布广泛,经济、高效地饮用水除砷技术受到广泛关注.静态批实验采用资源丰富、价格便宜的天然菱铁矿为主要原材料,考虑灼烧温度、时间及添加黏合剂等因素确定最优改性条件使除砷效果达到最佳.结果表明,在加铝量为10 mg.g-1、350℃下恒温灼烧90 min后造粒达到强度要求并除砷效果较优.25℃、固液比为0.5 g∶50 mL、As(Ⅲ)和As(Ⅴ)初始浓度为5 mg.L-1时,吸附后溶液中残留As浓度均<10μg.L-1.静态吸附批实验结果表明,25℃时,接触反应时间为12 h可达到吸附平衡,吸附过程较好地符合Lagergren假二级吸附速率方程;最优改性天然菱铁矿对砷的吸附规律可用Langmuir和Freundlich等温吸附模型很好地描述,As(Ⅲ)、As(Ⅴ)饱和吸附容量分别可以达到1 039、1 026μg.g-1.结合XRD、SEM等研究方法和比表面及孔结构分析初步探讨天然菱铁矿改性以及除砷的主要机制.分析表明,改性后天然菱铁矿比表面积大幅度增大,孔径减小,且在表面活化生成一层圆球状的含Fe(Ⅱ)和Fe(Ⅲ)的化合物.改性天然菱铁矿是一种值得进一步研究并实际应用的除砷材料.     

载钠硅碳羟基磷灰石的制备及其对水中As(Ⅴ)的吸附特性

由于自然和人为活动导致自然水体和土壤被As（砷）污染,严重危及生态环境并已受到广泛关注.为实现更大程度地去除含As废水的新型吸附材料,以废弃蛋壳为原材料,采用超声波法制备多孔状且较大比表面积的Na-Si-CHAP[Ca_10-xNa_x（PO₄）_6-y-z（SiO₄）_z（CO₃）_y（OH）_2-α,载钠硅碳羟基磷灰石],深入分析去除含As（Ⅴ）废水的吸附特性.通过BET比表面积、扫描电镜（SEM）、EDX（能量色散X射线光谱）、X-射线衍射（XRD）等手段对样品进行表征,并进一步探讨了pH、吸附时间、初始ρ[As（Ⅴ）]以及反应温度等因素对吸附效果的影响.结果表明:在pH为6.0、作用时间为60 min、反应温度为313 K等优化条件下,0.2 g Na-Si-CHAP对100 mL 30 mg/L含As（Ⅴ）废水的去除率和平衡吸附容量分别为96.53%和14.48 mg/g.Langmuir等温吸附模型较好地拟合了吸附试验数据,313 K下相关系数（r2）高达0.998 0,饱和吸附容量达46.73 mg/g,明显高于其他同类材料;准二级动力学模型可较好地描述该吸附行为,相关系数高达0.999 9;热力学参数△G（吉布斯自由能变）、△H（焓变）和△S（熵变）的计算值显示,该吸附过程为自发吸热过程.研究显示,Na-Si-CHAP作为一种吸附剂,对含As（Ⅴ）的去除效果明显优于同类材料.      

磁性吸附材料CuFe2O4吸附砷的性能

根据Cu(Ⅱ)和Fe(Ⅲ)都对砷有较强的亲和性,制备了同时含有Cu(Ⅱ)和Fe(Ⅲ)的、可用磁分离方法进行分离回收的磁性吸附材料CuFe₂O₄,并对其进行了表征及吸附砷的性能研究.结果表明,该吸附剂对砷的吸附能力与溶液pH有关,在弱酸性及中性条件下,吸附砷的能力最强,而对As(V)的吸附能力比对As(Ⅲ)更强些,在平衡浓度为10μg/L时,其吸附容量可达10mg/g左右,可以很容易地将水中浓度为1～20mg/L的As(V)降到10μg/L以下.实验考察了几种无机阴离子对吸附砷的影响,表明较高浓度(砷浓度的20倍)的硫酸盐对As(Ⅲ)和As(V)的吸附均有一定影响,盐酸盐及磷酸盐则影响不明显;负载的As(V)可较容易地用0.1mol/L NaOH洗脱下来,使吸附剂再生,而As(Ⅲ)则难以洗脱,这与2种价态砷的吸附机理不同有关.     

Removal of arsenate and arsenite from aqueous solution by waste cast iron

The removal of As(III) and As(V) from aqueous solution was investigated using waste cast iron, which is a byproduct of the iron casting process in foundries. Two types of waste cast iron were used in the experiment: grind precipitate dust (GPD) and cast iron shot (CIS). The X-ray diffraction analysis indicated the presence of Fe0 on GPD and CIS. Batch experiments were performed under different concentrations of As(III) and As(V) and at various initial pH levels. Results showed that waste cast iron was effective in the removal of arsenic. The adsorption isotherm study indicated that the Langmuir isotherm was better than the Freundlich isotherm at describing the experimental result. In the adsorption of both As(III) and As(V), the adsorption capacity of GPD was greater than CIS, mainly due to the fact that GPD had higher surface area and weight percent of Fe than CIS. Results also indicated the removal of As(III) and As(V) by GPD and CIS was influenced by the initial solution pH, generally decreasing with increasing pH from 3.0 to 10.5. In addition, both GPD and CIS were more effective at the removal of As(III) than As(V) under given experimental conditions. This study demonstrates that waste cast iron has potential as a reactive material to treat wastewater and groundwater containing arsenic.     

Modified activated carbon with interconnected fibrils of iron-oxyhydroxides using Mn2 + as morphology regulator, for a superior arsenic removal from water

The arsenic removal efficiency of iron-modified activated carbons depends greatly on the number of available iron oxide surface sites, which are given by the surface area of the anchored particles. In this sense, aiming the generation of an adsorbent with superior arsenic adsorption capacity, we developed a protocol to anchor interconnected fibrils of iron oxyhydroxides, using Mn^2 + as a morphology regulator. The protocol was based on a microwave-assisted hydrothermal method, using bituminous based activated carbon and both Fe^2 + and Mn^2 + ions in the hydrolysis solution. The elemental analysis of modified carbons revealed that Mn does not anchor to the carbon. However, when Mn is included in the hydrolysis solution, the iron content in the activated carbon increased up to 3.5?wt%, without considerable decreasing the adsorbent surface area. Under specific hydrothermal conditions, the Mn^2 + promoted the formation of iron oxide nanoparticles shaped as interconnected fibrils. This material showed a superior arsenic adsorption capacity in comparison to similar iron modified activated carbons (5?mg As/g carbon, at 2?mg As/L), attributed to the increase in quantity and availability of active sites located on the novel interconnected fibrils of iron oxyhydroxides nanostructures.     

Effects of solution chemistry on arsenic(Ⅴ) removal by low-cost adsorbents

Natural and anthropogenic arsenic （As） contamination of water sources pose serious health concerns, especially for small communities in rural areas. This study assessed the applicability of three industrial byproducts （coal fly ash, lignite, and green waste compost） as the low-cost adsorbents for As（V） removal under various field-relevant conditions （dissolved oxygen, As（V）/Fe ratio, solution pH, and presence of competing species）. The physico-chemical properties of the adsorbents were characterized by XRD, XRF, FT-IR, and NMR analysis. Batch experiments demonstrated that coal fly ash could provide effective As（V） removal （82.1%-95%） because it contained high content of amorphous iron/aluminium hydroxides for As（V） adsorption and dissolvable calcium minerals for calcium arsenate precipitation. However, the addition of lignite and green waste compost was found unfavourable since they hindered the As（V） removal by 10%-42% possibly due to dissolution of organic matter and ternary arsenate-iron-organic matter complexes. On the other hand, higher concentrations of dissolved iron （comparing As（V）/Fe ratios of 1：1 and 1：10） and dissolved oxygen （comparing 0.2 and 6 mg/L） only marginally enhanced the As（V） removal at pH 6 and 8. Thus, addition of dissolved iron, water aeration, or pH adjustment became unnecessary because coal fly ash was able to provide effective As（V） removal under the natural range of geochemical conditions. Moreover, the presence of low levels of background competing （0.8 or 8 mg/L of humic acid, phosphate, and silicate） imposed little influence on As（V） removal, possibly because the high adsorption capacity of coal fly ash was far from exhaustion. These results suggested that coal fly ash was a potentially promising adsorbent that warranted further investigation.     

CTAC改性活性炭去除水中砷(V)的柱实验吸附和再生研究

为了开发一种能有效去除水中砷的吸附材料, 研究了十六烷基三甲基氯化铵(CTAC)改性活性炭后, 活性炭对水中五价砷As(V)的去除效果.研究中利用动态小柱实验(Rapid small-scale column test, RSSCT)探讨了CTAC改性后活性炭对砷的吸附能力、影响吸附能力的因素和活性炭再生方法.结果表明, CTAC改性能有效提高活性炭对As(V)的吸附.活性炭对As(V)的吸附受溶液pH、空床接触时间、进水中砷浓度及水中其他离子存在的影响.另外, 1 mol·L^-1的盐酸能有效对吸附穿透后的活性炭进行再生,再生后的活性炭可以重复使用.同时,柱实验中对出水CTAC的检测结果表明, CTAC和活性炭的结合非常稳定.     

透析对施氏矿物微观结构及其砷吸附能力的影响

探讨透析对施氏矿物微观结构和砷吸附能力的调控,对高效合成施氏矿物,进而将其应用于含砷地下水处理具有重要意义.本研究在利用FeCl_3·6H_2O与Na_2SO_4合成施氏矿物的基础上,用截留分子量100000 Da和20000 Da透析袋分别对施氏矿物透析10 d与20 d,探究了透析过程对施氏矿物产生量、比表面积、孔体积、平均孔径等矿物特征的影响,并考察了透析前后施氏矿物对废水中砷的吸附去除效果.研究结果表明,透析过程可显著提高矿物的合成量,增加矿物比表面积及孔体积,增加矿物的平均孔径.施氏矿物在截留分子量100000 Da与20000 Da透析袋中透析20 d,矿物产生量分别增加70.70%与79.84%;比表面积分别增加68.75%与45.85%;其中微孔(2 nm)比表面积增加439.90%与395.11%,中孔(2～50 nm)比表面积增加30.63%与9.96%;孔体积分别增加332.79%与287.25%,其中微孔体积增加491.61%与419.92%,中孔体积增加了220.36%与211.95%,透析后矿物平均孔径增长了214.77%与244.31%;矿物对污水中砷的吸附去除能力提高65.60%与64.74%.本研究结果可为化学合成施氏矿物改性并将其应用于地下水除砷领域提供必要的参数支撑.     

Removal of trace arsenic（V） and phosphate from water by a highly selective ligand exchange adsorbent

The ligand exchange adsorbent could be used to remove the toxic arsenic(V) and phosphate efficiently from water even in the presence of foreign anions and possible to apply in chemical industry.     

Characteristics and model studies for fluoride and arsenic adsorption on goethite

Fluoride and arsenic are major anionic elements of concern in drinking water treatment. The effects of contact time, pH, surface loading and ionic strength on adsorption of fluoride and As(V) were investigated using batch methods. Adsorption of fluoride and As(V) onto goethite obeyed a pseudo second-order rate law. Through experimental data and adsorption kinetic analysis, the affinity of As(V) onto goethite was stronger than fluoride. Fluoride and As(V) uptake by goethite all decreased with pH increasing at the same surface loading; however, ionic strength had slight influence on their adsorption. A surface sites-species model was used to quantify the adsorption of fluoride and As(V) onto goethite as function of pH and surface loading. This model can satisfactorily predict their adsorption characteristics with several adsorption constants.     

Review on heterogeneous oxidation and adsorption for arsenic removal from drinking water

The long term exposure of arsenic via drinking water has resulted in wide occurrence of arsenisim globally, and the oxidation of the non-ionic arsenite (As(III)) to negatively-charged arsenate (As(V)) is of crucial importance for the promising removal of arsenic. The chemical oxidants of ozone, chlorine, chlorine dioxide, and potassium permanganate may achieve this goal; however, their application in developing countries is sometimes restricted by the complicate operation and high cost. This review paper focuses on the heterogeneous oxidation of As(III) by solid oxidants such as manganese oxide, and the adsorption of As(V) accordingly. Manganese oxide may be prepared by both chemical and biological methods to achieve good oxidation performance towards As(III). Additionally, manganese oxide may be combined with other metal oxides, e.g., iron oxide, to improve the adsorption capability towards As(V). Furthermore, manganese oxide may be coated onto porous materials of metal organic frameworks to develop novel adsorbents for arsenic removal. To achieve the application in engineering works, the adsorbents granulation may be achieved by drying and calcination, agglomeration, and the active components may also be in situ coated onto the porous materials to maintain the oxidation and adsorption activities as much as possible. The novel adsorbents with heterogeneous oxidation and adsorption capability may be carefully designed for the removal of arsenic in household purifiers, community-level decentralized small systems, and the large-scale drinking water treatment plants (DWTPs). This review provides insight into the fundamental studies on novel adsorbents, the development of innovative technologies, and the demonstration engineering works involved in the heterogeneous oxidation and adsorption, and may be practically valuable for the arsenic pollution control globally.     

原位载铁中孔活性炭吸附As和天然有机物效能

采用配煤、原位浸渍和两步活化法制备了4种原位载铁活性炭（FGL1/2/3/4）,并以空白炭C-GL为基础的表面铁浸渍后改性炭（Fe-GL-2/3/4）为对照,研究了原位载铁炭对水中As和腐植酸（HA）的同步吸附效能.结果表明,炭化料原位载铁促进了比表面积（S_BET）和中孔结构的发育.其中,原位载铁炭FCL4（载铁量6.51%）在45Å~480Å的范围内的中孔容积（V_mes）比C-GL增加了0.1146cm³/g;而后改性载铁则造成S_BET和V_mes的显著降低.原位载铁同时促进了表面碱度的增加,保证了中性条件下更好的As离子吸附能力;FCL4对As（Ⅲ）和As（V）的Langmuir最大吸附量（L-Q_max）分别达到2.566和2.825mg/g.原位载铁炭进一步发育的中孔结构促进了对HA（<10mg DOC/L）的吸附效能,FGL4对HA的Langmuir最大吸附量（Q_HA）达到46.25mg DOC/g.As-HA共存体系内FGL4对各组分的吸附容量有所降低,但As（Ⅲ）和As（V）的吸附容量仍达到2.325和2.675mg/g.     

脱硫石膏基羟基磷灰石对Cu2+吸附性能的研究

以燃煤电厂废弃物脱硫石膏(FGD)为主要原料,利用水热合成法制备羟基磷灰石(FGD-HA),利用XRD和SEM对FGD-HA的物相组成和微观形貌进行了分析和观察.通过静态吸附实验研究了吸附动力学、吸附等温线以及吸附热力学.结果表明,伪二级动力学模型相关系数为0.9998,是描述FGD-HA吸附Cu2+的最佳动力学模型,Cu2+在FGD-HA上的吸附平衡符合Langmuir等温线模型(R2=0.9846),热力学表明此吸附是自发吸热的过程.利用响应面分析法对Cu2+的吸附条件进行优化,得出投加量3.11g/L、pH值4.96、温度22.09℃、Cu2+初始浓度24.75mg/L为最佳吸附条件,此条件下Cu2+去除率预测值为100%,相同条件下开展的验证实验结果为97.4%,与预测值相接近说明模型的选择是实际可行的.     

有机酸在金属氧化物上的吸附对催化臭氧氧化的影响

以苯甲酸(BA)、邻苯二甲酸(PA)、商品腐殖酸(CHA)和反渗透法提取的松花江水腐殖酸(SHA)为目标物,研究了臭氧氧化及羟基氧化铁(FeOOH)和二氧化铈(CeO₂)为催化剂时的吸附与催化臭氧氧化去除这些有机物的效果.结果表明,BA在FeOOH表面没有吸附,FeOOH对BA催化氧化的去除率比臭氧单独氧化高45%;PA在FeOOH上的吸附使其溶液中的浓度减少了5%,此时FeOOH对PA的氧化没有催化作用.CeO₂有助于催化臭氧氧化在其表面吸附较强的PA,且对氧化产生的草酸根有催化去除作用,但对不吸附在其表面的BA没有催化臭氧氧化作用.CeO₂对腐殖酸的吸附比FeOOH强,其催化臭氧氧化去除腐殖酸的作用比FeOOH更显著;当无机阴离子和腐殖酸竞争金属氧化物表面的吸附位时,催化作用受到抑制.     

Modification of a magnetic carbon composite for ciprofloxacin adsorption

A magnetic carbon composite, Fe₃O₄/C composite, was fabricated by one-step hydrothermal synthesis, modified by heat treatment under an inert atmosphere (N₂), and then used as an adsorbent for ciprofloxacin (CIP) removal. Conditions for the modification were optimized according to the rate of CIP removal. The adsorbent was characterized by Fourier transform infrared spectroscopy, X-ray diffraction measurements, vibrating-sample magnetometry, scanning electron microscopy, transmission electron microscopy, and N₂ adsorption/desorption isotherm measurements. The results indicate that the modified adsorbent has substantial magnetism and has a large specific area, which favor CIP adsorption. The effects of solution pH, adsorbent dose, contact time, initial CIP concentration, ion strength, humic acid and solution temperature on CIP removal were also studied. Our results show that all of the above factors influence CIP removal. The Langmuir adsorption isotherm fits the adsorption process well, with the pseudo second-order model describing the adsorption kinetics accurately. The thermodynamic parameters indicate that adsorption is mainly physical adsorption. Recycling experiments revealed that the behavior of adsorbent is maintained after recycling for five times. Overall, the modified magnetic carbon composite is an efficient adsorbent for wastewater treatment.