用有机膨润土吸附处理含铬(Ⅵ)废水的研究

采用溴化十六烷基三甲铵(CTMAB)对天然膨润土进行了有机改性处理,并在静态条件下,进行了有机膨润土对含Cr(Ⅵ)工业废水的吸附试验.研究了CTMAB浓度、有机膨润土用量、废水pH值、搅拌时间等因素对Cr(Ⅵ)去除率的影响,确定了用有机膨润土处理含Cr(Ⅵ)废水的适宜条件.结果表明,有机膨润土能有效地除去废水中的Cr(Ⅵ),其最佳工艺条件为废水pH值3.0～5.0、搅拌时间约30 min、有机膨润土用量10 g/L,按该工艺条件对含Cr(Ⅵ)35 mg/L左右的废水进行处理,铬的去除率达到98.0%以上,处理后的水样中Cr(Ⅵ)含量小于0.50 mg/L,达到国家排放标准.     

煤矸石/膨润土复合微珠的制备及其对Cu~(2+)和亚甲基蓝的吸附研究

将煤矸石粉和膨润土粉按不同比例混合并加入粘结剂球磨后,利用喷雾干燥法制备了煤矸石/膨润土不同比例的复合球坯体,再通过煅烧得到煤矸石/膨润土复合空心微珠。研究了微珠的预处理温度、用量、吸附时间以及染料与Cu2+浓度对废水中亚甲基蓝及重金属离子Cu2+的吸附性能。研究表明,煤矸石/膨润土复合微珠为多孔结构,成球好。经600℃煅烧后的复合配比为1∶1的复合微珠,在投加量为2g/L时对80mg/L的Cu2+的吸附量和去除率分别为39.94mg/g和99.85%,在投加量为6g/L时对100mg/L的亚甲基蓝的吸附量和去除率为7.85mg/g和47.07%。伪二级动力学方程和Langmuir吸附等温模型更适合描述它们的吸附过程,易吸附并且是单层吸附,复合微珠对Cu2+吸附效果明显,对亚甲基蓝也有一定的去除效果。     

聚二甲基二烯丙基氯化铵/偶联剂改性膨润土对苯酚的吸附研究

采用阳离子聚电解质聚二甲基二烯丙基氯化铵(PDMDAAC)和硅烷偶联剂(KH550)对钙基膨润土进行改性,得到有机改性膨润土.研究发现,PDMDAAC和KH550成功负载在膨润土表面,其结构没有发生改变.以苯酚为吸附对象,采用该有机改性膨润土对其进行模拟吸附,当有机改性膨润土的投加量为2g/L,吸附时间20min,pH...     

巯基改性SBA-15的制备及其对Cr6+的吸附

环境中存在的重金属铬对人体健康有严重的危害, 本研究采用水热共缩聚法制备了一种对Cr ⁶⁺有较高吸附能力的介孔材料SBA-15-SH。经红外光谱证实, 通过使用改性硅源3-巯丙基三甲氧基硅烷, 对SBA-15成功实现了巯基改性。经扫描电子显微镜(SEM)和透射电子显微镜(TEM)观察, 所制备的材料呈棒状, 具有均匀的孔道结构, 孔径约为7 nm。将制备材料用于重金属Cr ⁶⁺的吸附, 研究了吸附时间、环境温度、Cr ⁶⁺溶液pH和初始浓度以及吸附剂用量对吸附剂吸附性能的影响。研究表明: 该材料吸附Cr ⁶⁺的平衡吸附时间约10 min, 吸附过程符合Langmuir方程与伪二级动力学模型。当Cr ⁶⁺溶液pH为4.0、吸附温度在25~45 ℃时, 介孔材料SBA-15-SH对Cr ⁶⁺吸附量最大, 达到6.85 mg/g。将本方法用于自来水和工业废水中Cr ⁶⁺的吸附, 回收率介于95%~105%之间。     

超声波改性有机膨润土及其对苯的吸附研究

为了提高有机膨润土对苯的吸附能力,采用超声波辐照处理膨润土改性合成有机膨润土.通过研究不同的改性条件对苯吸附量的影响,获得了最佳工艺条件为:超声处理时间20min、固液比1:10、十六烷基三甲基溴化铵(HTAB)加量120mmol/100g及超声波功率600 W.在此条件下制备的有机膨润土对苯的吸附平衡研究表明,在开始30rain内吸附非常快,吸附150min后基本达到吸附平衡,其对苯的吸附量达51.28mg/g.     

氯化锌催化活化制备中孔活性炭及其对Cr6+的吸附性能

为进一步提高活性炭对废水中Cr⁶⁺的吸附能力,采用氯化锌对市售微孔活性炭粉进行催化活化,制成了中孔活性炭,并研究了中孔活性炭对Cr⁶⁺的吸附性能。通过单因素试验优选了中孔活性炭吸附Cr⁶⁺的工艺参数;研究了中孔活性炭吸附Cr⁶⁺的吸附动力学和吸附等温线,并进行了再生吸附试验。结果表明:向100 mL Cr⁶⁺初始浓度为100 mg/L的重铬酸钾溶液中投加0.1 g中孔活性炭,控制温度为35℃,pH=2,3 h即可达吸附平衡,此时吸附效果最佳,最大吸附量达93.7 mg/g;中孔活性炭对Cr⁶⁺的吸附遵循二级动力学规律,符合Langmuir吸附等温式;吸附/再生循环2次后,中孔活性炭吸附能力保持不变,循环5次后,活性炭对Cr⁶⁺的吸附量为初始吸附量的75%,碳损失率为6.5%。     

改性膨润土对溶液中Co2+、Mn2+的吸附研究

以膨润土为原材料,盐酸为改性剂,制备改性膨润土。研究了改性膨润土的制备条件,其对重金属Co2+、Mn2+的吸附性能及对苯二甲酸(PTA)工业中的副产品对甲苯甲酸对吸附的影响。实验结果表明,盐酸的最佳改性浓度为1.5mol/L,改性膨润土在40℃的吸附能力最好,可达到12～14mg/g,经过热力学分析得出,改性膨润土对钴离子、锰离子的吸附方式均符合Langmuir吸附模型,PTA工业中的副产品对甲苯甲酸对吸附没有影响。     

钠基膨润土对废水中Ni2+,Cu2+的吸附效果

为了提高膨润土吸附废水中Ni2+,Cu2+的效果,对其改性制备了钠基膨润土,考察了吸附时间、废水pH值以及Ni2+和Cu2+初始浓度对自制钠基膨润土吸附Ni2+,Cu2+效果的影响,分析了吸附等温线,并探讨了吸附机理。结果表明:钠基膨润土对Ni2+,Cu2+都有较好的吸附性能;初始阶段(前10 min)吸附很快,之后随时间延长吸附量提高甚微;pH值为6.2时,处理后的水质即可达国家排放标准;随着Ni2+,Cu2+初始浓度增加,去除率先增加后降低,而吸附量迅速增加,Ni2+和Cu2+初始浓度分别为25 mg/L和40 mg/L时,钠基膨润土对Ni2+,Cu2+的去除率均可达98.6%;钠基膨润土对Ni2+,Cu2+的吸附等温线符合Freundlich吸附等温式。     

KOH作用下稻壳制备高比表面积活性炭的研究

以稻壳为原料、KOH为活化剂,制备了高比表面积活性炭,研究了活化剂用量、活化温度和活化时间对活性炭吸附性能的影响.研究结果表明,活化剂与稻壳的质量比为3:1,在800℃活化1h,制得的活性炭碘吸附值为1520.32mg/g,亚甲蓝吸附值为3442.50mg/g,比表面积为2027.42m2/g.SEM和XRD观察发现,干馏过程及活化过程的共同作用使活性炭产生多孔结构.     

无机改性膨润土制备及吸附苯酚废水的研究

以膨润土为原料,Fe(OH)<'2+>为改性剂,制备了无机改性膨润土吸附剂,研究了该吸附剂对苯酚废水的吸附性能,结果表明:在温度为30℃,pH为8左右,废水初始浓度为100mg/L,吸附剂用量为10g/L,吸附时间为50min,苯酚的去除率可达到92%以上.     

Chromium fractionation in semi-arid soils amended with chromium and tannery sludge

We studied Cr fractionation in three semi-arid soils (cultivated, under-the-canopy, and outside-the-canopy soils). The soils were amended with: Cr3+, Cr6+, tannery sludge, Cr3++tannery sludge, and Cr6++tannery sludge and all soils were incubated for 30 and 120 days at 25 degrees C. The Cr in three semi-arid soils was fractionated using sequential extraction (Tessier scheme). Data of Cr fractionation were used to find the correlations with microbial activities determined in previous work. The microbial activities: CO2-C evolved, dehydrogenase activity and nitrification were determined in the same soils amended with the same treatments. Tannery sludge was added at 0.0125 g g(-1) soil and Cr3+ or Cr6+ at 250 microg g(-1) soils. After 120 days of incubation, higher values of concentration of Cr were found in the residual fraction in the three soils amended with all the treatments, except cultivated and outside-the-canopy soils amended with Cr6++tannery. The non-residual fraction tended to decrease with time except in cultivated and outside-the-canopy soils amended with Cr6++tannery sludge. CO2-C evolved was significantly correlated (p<0.05 and p<0.001) with fractions bound to: Mn oxides, Fe oxides organic matter at 30 and 120 days of incubation (from r=0.827 to 0.979). Dehydrogenase activity was correlated with fractions bound to Fe oxides and bound to organic matter, and nitrification with fraction bound to organic matter at 30 days of incubation (r=0.874, 0.959, and 0.803, respectively). These results suggest that even in a sparingly available Cr fraction in semi-arid soils has effect on microbial activities.     

沸石及膨润土对水泥-铬渣体系中Cr(Ⅵ)浸出的影响

本文研究了沸石及膨润土对水泥-铬渣体系中Cr(Ⅵ)浸出的影响。结果表明:沸石和膨润土对Cr(Ⅵ)的浸出有较好的效果,在pH=3,掺量为30%的条件下,28d龄期掺入沸石和膨润土的硬化体中Cr(Ⅵ)浸出浓度分别下降了82%及63%,沸石的效果优于膨润土。雨淋的自然养护条件会导致体系中Cr(Ⅵ)的浸出浓度减少近一倍。同时,硬化体抗压强度随着掺量的增加而下降,膨润土对强度的不利影响大于沸石。     

有机/无机纳米复合相变储能材料的制备

利用十六烷基三甲基溴化铵（CTAB）嵌入到具有层状结构的膨润土层间,使膨润土层间得到改必,通过交换反应,使三羟甲基丙烷和新戊二醇嵌入膨润土层间而制得有机／无机纳米复合相变储能材料,利用X射线衍射（XRD）和差示扫描量热法（DSC）对制得有机／无机纳米复合相变储能材料进行了表征。     

凹凸棒石黏土-腐植酸复合吸附剂吸附Cr(Ⅵ)的性能研究

为促进凹凸棒石黏土-腐植酸复合吸附剂在水处理中的应用,用酸改性的甘肃靖远凹凸棒石黏土和天祝褐煤提取的腐植酸制备出凹凸棒石黏土-腐植酸复合吸附剂,通过SEM、XRD、FT-IR等分析方法对复合吸附剂的结构进行了表征,考察了物料配比及吸附时间、pH值、温度、投加量和初始浓度对Cr(Ⅵ)吸附率的影响。结果表明:靖远凹凸棒石黏土最佳酸改性条件为盐酸5 mol/L,酸化时间120 min,酸用量固液比为1∶10。当Cr(Ⅵ)的起始浓度为0.1 g/L,体积为50 m L,复合吸附剂用量为1.2 g,吸附时间为6 h,p H值为6,温度25℃,酸改性的凹凸棒石黏土与腐植酸的最佳复合比为1∶3时,复合吸附剂对Cr(Ⅵ)的吸附率达到91.7%。复合吸附剂对Cr(Ⅵ)的吸附满足Freundlich模型。在25~45℃条件下,吸附过程ΔG <0、ΔS=87.46 J/(mol·K)、ΔH=-21.2 kJ/mol,表明该吸附是一个自发、熵增、放热的过程。     

黄原酸化膨润土的制备及脱除亚甲基蓝的性能研究

对膨润土进行改性制得黄原酸化膨润土(XB),通过FT-IR、TG、SEM、粒度分析对XB进行了表征,结果表明,碳硫键接到了膨润土表面,使其亲水性降低,表面积增大。通过XB对亚甲基蓝的吸附试验,表明XB是一种环境友好型吸附剂。考察了亚甲基蓝初始浓度、吸附时间、温度、pH值、吸附剂用量对其吸附性能的影响。结果表明:在25℃,pH=7～8,亚甲基蓝初始浓度100mg/L,XB用量为2g/L,吸附30min时,XB对亚甲基蓝的脱色率达到99.93%,处理后废水可达标排放。     

Solidification and leaching behaviours of Cr6+ in sludge ceramsite

Making lightweight ceramsite with sewage sludge is a new effective approach for disposal of sludge. However, there is a concern as to whether the heavy metals such as Cr6+ in sewage sludge can be solidified in ceramsite after sintering. The configuration of Cr6+ in ceramsite was analyzed by X-ray diffraction (XRD) and leaching tests were conducted to determine the effects of sintering temperature, pH and H2O2 concentration on the stabilization of Cr6+ in ceramsite. The results show that leaching of Cr6+ changes little at temperatures above 900 degrees C, and both pH and H2O2 concentration have some effects on the leaching of Cr6+. Leaching test results indicate that Cr6+ is stabilized in ceramsite and cannot be easily released to the environment again as secondary pollution, which eliminates the concern for its application. XRD analysis of ceramsite sintered at 1000 degrees C reveals that the main compounds of Cr6+ in ceramsite are Cr2O3 and FeCrO4. The test results provides a better understanding of the factors that affect the mobility of Cr6+, and show it is a safe way to make ceramsite with sludge as an additive.     

In situ stabilization of chromium(VI) in polluted soils using organic ligands: the role of galacturonic, glucuronic and alginic acids

Laboratory batch sorption and column experiments were performed to investigate the role of organic ligands such as galacturonic, glucuronic and alginic acids (main constituents of bacterial exopolymeric substances (EPS)) on Cr(VI) uptake and transport in heterogeneous subsurface media. Our batch sorption experiments demonstrate the addition of galacturonic, glucuronic and alginic acids to soils enhances Cr(VI) uptake by soil at pH values <7.7 depending on the concentration of the ligand and pH used. The enhanced Cr(VI) uptake at pH values <7.7 may be explained through either the catalytic reduction of Cr(VI) to Cr(III) by the surface-bound organic matter/Fe oxides and/or the dissolved metal ions (e.g., Fe(III)) from the soil. On the other hand, organic ligands have no or little effect on Cr(VI) uptake under highly alkaline pH conditions since the catalytic Cr(VI) reduction decreases with increasing pH. Similarly, the results from column experiments show that, depending on the concentration of organic ligands, the Cr(VI) breakthrough curves were significantly retarded relative to the organic acid-free systems at pH 7.6. A significant portion of Cr(VI) initially added to the feed solution was not readily recoverable in the effluent, indicating Cr(VI) reduction in columns, most probably catalyzed by surface-bound metal-oxides (e.g., Fe oxides) or dissolved metal ions such as Fe(II; III). The overall results suggest that EPS constituents such as glucuronic, galacturonic and alginic acids may play a significant role on Cr(VI) stabilization in subsurface systems under acidic to slightly alkaline pH conditions.     

Optical study of the reduction of hexavalent chromium by iron-based nanoparticles

In this paper, a simple method was presented to measure the concentration change in the Cr(VI)-contained waste water during treatment by nanoparticles, based on its optical absorption spectral evolution which exhibits a good linear relationship between the absorbance of the peak at 348 nm and Cr6+ ion concentration. The iron and Fe/Pd bimetal nanoparticles were prepared and used for removal of Cr6+ in waste water. It has been found that presented method for concentration determination based on optical spectral evolution is effective and flexible. The nanoparticles have higher efficiency than normal iron powders and Fe/Pd bimetallic nanoparticles show faster removal of the Cr6+ than iron nanoparticles. The study is of importance in environmental remediation or pollution treatment of heavy metal ions in water and even soil.