通过表面活性剂改性氧化铝去除废水中的结晶紫染料
原文作者 Asok Adak, Manas Bandyopadhyay, Anjali Pallowast;
单位 Civil Engineering Department, Indian Institute of Technology, Kharagpur 721302, India
摘要:
十二烷基硫酸钠(SDS)是一种阴离子表面活性剂(AS),用于中性氧化铝改性表面。氧化铝表面形成胶束状结构,能够去除水环境中的有机污染物。表面活性剂改性的氧化铝(SMA)用于去除结晶紫(CV),是水生环境中公认的阳离子染料。动力学研究表明,1小时的振动时间足以达到平衡。结晶紫的去除遵循二级动力学。研究了吸附剂用量和初始浓度对去除率的影响。PH保持在6.7plusmn;0.1。可以发现SMA是非常有效的吸附剂,并且即使在高浓度(200 ppm)条件下,在优化条件下可以达到sim;99%的结晶紫去除率。其他各种参数如pH、温度的影响,不同离子的存在(Clminus;,NO3minus;,SO4minus;2,HPO4minus;2and Fe3 ),还对腐殖酸对结晶紫的去除进行了研究。在PH7.0–8.5范围内,有利于去除。可以观察到,由于阴离子和腐殖酸的存在,去除效率增加,由于阳离子的存在,去除效率降低。温度在这个过程中没有任何影响。为了检验是否有可能从实际水样中使用形状记忆合金,蒸馏水、自来水和合成废水的循环伏安法进行吸附研究。有趣的是,和使用蒸馏水相比,自来水和废水去除效率甚至更好。使用1M的氢氧化钠溶液,精馏酒精和丙酮从形状记忆合金表面解吸结晶紫是可能的。
关键词:氧化铝;十二烷基硫酸钠;表面活性剂改性氧化铝;结晶紫;去除率
1. 简介
染料是纺织工业、油漆和清漆、油墨、塑料、造纸、化妆品、皮革工业等产生废水的主要成分之一,也是染料生产所产生的废水成分。彩色染料废水是周围的生态系统的一个主要威胁。许多染料是有剧毒的。在各种染料中,结晶紫(CV)是一种被用于各种用途的知名染料:生物染色剂,皮肤病剂、兽药、抑制霉菌繁殖的家禽饲料添加剂,肠道寄生虫和真菌等也广泛应用在纺织印染、造纸印刷。它是一种诱变剂和有丝分裂的毒药。像吸附[ 1–5 ] 处理的各种技术,光催化降解[ 6–10 ],混凝沉淀法[ 11 ],化学氧化法[12,13],电化学氧化[ 14,15 ]等生物过程可以从废水中去除染料。上述过程中的许多方法是不符合成本效益原则的,因此不适合用于发展中国家。最近使用表面活性剂方法去除固体表面有机污染物引起了广泛关注。通过表面活性剂固体表面可形成胶束状的表面有溶解的有机分子内的潜在结构结构形成。这些被称为半胶束或胶束,胶束的现象称为吸附及增溶作用。在过去的二十年中,这种新的分离技术已被用于去除不同的有机化合物[ 16-19 ]。本研究旨在通过十二烷基硫酸钠(SDS)改性氧化铝对含铁废水进行处理。表面活性剂改性的氧化铝(SDS)是一种有效的吸附材料的结晶紫,即使是在一个非常高浓度的废水中也很强效,因此可以作为一个实用吸附剂处理结晶紫轴承废水。据我们所知,这是第一份报告,其中,SMA是用于染料废水的染料去除。
- 材料与方法
2.1. 试剂
BDH(AR级)行吖啶橙(ACO)、结晶紫、SDS、冰醋酸、甲苯。本研究所用的所有化学物质均为纯度高,无需进一步提纯。
2.2.吸附剂
氧化铝来自印度SRL,并作为进一步研磨、过筛等。中性化的氧化铝为 70–290ASTM,分子量为101.96,电荷零点(ZPC)为9.15。
2.3. 仪器仪表
高精度电子天平(赛多利斯GMBH)和数字pH计(DHP-500,思科 印度)分别进行称重和测量pH值。分光光度计(Spectronic公司,英国)进行吸光度测量。
2.4.分析方法
一个快速和可靠的溶剂萃取分光光度法研究了离子型表面活性剂的测定。吖啶橙(ACO)具有颜色(lambda;最大=467纳米)3,6-双(二甲氨基)啶已作为离子潜力试剂。样品溶液(10毫升)含SDS,0.1–6.0 ppm的范围内,被转移到一个25毫升分液漏斗。增加ACO (5 times; 10minus;3 M) 和冰醋酸100升。然后,加入5毫升的甲苯的混合物振荡1分钟。弃去上清液,并用分光光度计在467nm测定甲苯层的吸光度。采用分光光度法在591 nmlambda;Max在中性pH条件下测得。
2.5. 表面活性剂改性氧化铝的制备
物料干燥在60◦C 24小时氧化铝从而获得被称为表面活性剂改性的氧化铝作为吸附剂去除结晶紫。2升的SDS溶液在20000 ppm的浓度,氧化铝(200克)振荡24小时。氯化钠的剂量为2500 ppm,pH值为4.4plusmn;0.1。摇匀后,弃去上清液,氧化铝最初用自来水彻底冲洗,最后用蒸馏水。然后材料在60◦C下干燥24小时,获得氧化铝,被称为表面活性剂改性的氧化铝作为吸附剂去除结晶紫。
2.6. 实验研究
该批次进行的实验,在25plusmn;2◦C使用结晶紫在蒸馏水配制合成的样品,150转的搅拌速度机械振动。处理研究与样本含有200 ppm结晶紫。这样的高浓度往往可以在工业废水中发现[ 4 ]。吸附平衡时间发现使用200 ppm的初始浓度和吸附剂的结晶紫(SMA)6 g/L溶液,pH值为6.7plusmn;0.1,振荡时间从0 -105 min,平衡时间变为1小时,用于进一步的研究。实验进行了吸附剂剂量的影响研究。结晶紫溶液(20毫升)与不同的吸附剂剂量为200 ppm的初始浓度(0–20 g/L)振荡1小时,pH为6.7plusmn;0.1。进行实验观察在氧化铝表面活性剂覆盖的影响。表面活性剂对氧化铝表面的数量从0变化到111.6 mg/g进行研究,观察数值的影响(2.6–10.8范围内)。通过加入HCl或NaOH维持溶液的pH值。不同的干扰物质的影响(0–1500 ppm,添加NaCl)、硝酸盐(0–1000 ppm,加入硝酸钠),硫酸(0–500 ppm,添加硫酸钠)、磷酸氢二铵(0–500 ppm,加入K2HPO4)、铁(0–60 ppm的Fe3 ,添加Fe2(SO4)[ 3 ]),镁(0–125 ppm,添加MgSO4·7H2O),腐殖酸(0–10 ppm)的研究。所有吸附剂用量为4 g / L,除硫酸、铁和镁为3 g/L,初始浓度为200 ppm的结晶紫和pH值为6.7plusmn;0.1。在200 ppm的浓度在15–35◦C初始结晶紫的范围内研究了温度的影响,pH值在6.7plusmn;0.1,吸附剂量为4 g/L。
采用循环伏安、水处理和综合处理的废水,对其进行了测定,并对其进行了测定。对于自来水系统,吸附剂的剂量从0到6 g / L的变化,初始浓度为200 ppm的结晶紫和振动时间为60 min的结晶紫去除人工合成废水吸附剂的剂量为0~–8 g/L和动力学进行了研究,找到平衡时间。
- 结果与讨论
3.1 氧化铝吸附在氧化铝上的吸附及SMA的制备
获得吸附等温线,以了解在氧化铝表面上的平衡分布的钠的性质。氯离子的存在和PH值的降低一般都会增加氧化铝的吸附容量。
Fig. 1. Adsorption isotherm of SDS on alumina.
因此,对吸附等温线研究氯化钠的浓度保持在2500 ppm和溶液的pH值保持在4.4plusmn;0.1加入盐酸中获得最佳的表面覆盖。最初的SDS的浓度变化范围从0到40,000 ppm。吸附剂的剂量固定100g/ L。SDS对带正电荷的氧化铝表面的吸附发生以形成根据SDS浓度单层或双层而形成。在这些情况下,吸附等温线,一般情况下,分为四个特征区域[ 20 ]。在氧化铝表面上的吸附等温线,在本试验中,也可分为四个区域(图1)。出现在一个很低的平衡浓度的区域(3.37 ppm以下SDS)。从区域I到II半胶束或胶束浓度表示的过渡。从区域II到 III的过渡是30.2 ppm的平衡浓度(1times;10minus;4 m)的SDS。对应于III、IV区过渡的平衡浓度为8839 ppm(3times;10minus;2 m)。一般来说,过渡区Ⅲ~Ⅳ期发生以上的CMC(10minus;3到10minus;2 m)。从等温线研究的最大吸附量为111.6 mg/g,它发生时的初始浓度为20000 ppm,SDS的吸附量为100 g/L的条件用于SMA的制备。氧化铝200克振荡24小时与2 L SDS 20000 ppm浓度的溶液。氯化钠的剂量为2500 ppm,pH值为4.4plusmn;0.1。摇匀后,去除上清液,氧化铝开始先用自来水彻底清洗,最后用蒸馏水。最后氧化铝可以被作为SMA,60◦C 干燥24小时。
3.2 去除结晶紫动力学研究
进行动力学研究,找出SMA品种吸收平衡时间。在这项研究中,初步的结晶紫浓度固定在200 ppm,6 g/L溶液的pH值为6.7plusmn;0.1,温度的吸附量为25plusmn;2◦C,振动时间为0~105分钟。
Fig. 2. Kinetic plot for the removal of crystal violet (CV) from distilled water, synthetic textile wastewater and tap water.
可以观察到,1小时的接触时间很充足,已达到平衡(图2)。从1/Ce可以得出结论,由SMA除去结晶紫,遵循二级动力学(图3)。
3.3. 吸附剂用量对品种的去除效果的影响
由于吸附剂剂量对结晶紫的去除效果显著,所以研究这个参数的影响。吸附剂的剂量为0~20 g/L,初步的结晶紫浓度添加在不同蒸馏水中,分别为100、200和400 ppm。该溶液的PH值保持在6.7plusmn;0.1.。温度固定在25plusmn;2℃,振动时间为1 h,100、200和400 ppm的初始浓度结晶紫最佳吸附剂用量分别为3,6,12 g / L的。在适当的条件下,可以达到99%的去除效率(图4)。未经处理的氧化铝只能达到6%使用6 g/L吸附剂剂量从水环境移除结晶紫、染料初始浓度为200 ppm,1 h的振荡时间(图5)。
3.4. 表面活性剂覆盖对氧化铝的影响
进行实验,观察在氧化铝表面活性剂覆盖对结晶紫去除的影响。在这项研究中,初步的结晶紫浓度固定为200 ppm,6 g/L溶液的pH值为6.7plusmn;0.1,温度的吸附量为25plusmn;2℃.振荡时间为60分钟。
Fig. 3. Plot of reciprocal of final crystal violet (CV) concentration after its removal from distilled water, synthetic textile wastewater and tap water with reference to time.
Fig. 4. Effect of adsorbent dose on CV uptake by SMA.
表面活性剂的覆盖范围从0到111.6mg/g不等。可以看到,随着表面活性剂覆盖的增加结晶紫增加,增长率逐渐增加减少(图6)。这是由于,在—表面活性剂覆盖的增加,在形成的双层结构氧化铝表面有多品种分子的数目可以容纳,因此去除效率逐渐衰减。在表面活性剂的覆盖率是最佳的对应饱和高点[ 21 ]。
3.5. PH值对去除率的影响
含水介质的pH值是一个重要的因素,可能会对吸附质的吸收产生影响。两个吸附和吸附剂的化学特性随pH变化。在2.6–10.8内看到的pH值的影响。通过加入HCl或NaOH维持溶液的pH值。在较高的pH值结晶紫变为无色还可以再加入酸进行回收。在这项研究中,初步的结晶紫浓度固定为200 ppm,3 g/L温度的吸附量为25plusmn;2◦C.振动时间为1h,图7显示的结晶紫增加去除随pH值到8,然后逐渐下降。随着PH值的增加,分子的自由端(在氧化铝上的双层结构,如图8所示)变为负电荷[ 5 ],并与阳离子染料的反应,产生更大的去除效果。但pH值大于9.15的SDS分子解吸从氧化铝表面并产生更少的去除效应。
3.6. 不同干扰物质对结晶紫的影响
不同阴离子的影响,即Clminus;, NO3minus; 和 HPO4minus;2如图9所示,SO4minus;2效果如图10所示。总的趋势是在阴离子的存在下,去除效率增加。不同的金属离子,如Mg2 和Fe3 的作用是如图10和11。研究比较的基础上进行Fe3 、Mg2 的影响的对比。由于硫酸对结晶紫去除干扰,当Fe2(SO4)3、MgSO4作为添加盐硫酸根离子的影响也必须考虑。因此,Fe2
剩余内容已隐藏,支付完成后下载完整资料
Removal of crystal violet dye from wastewater by
surfactant-modified alumina
Asok Adak, Manas Bandyopadhyay, Anjali Pallowast;
Civil Engineering Department, Indian Institute of Technology, Kharagpur 721302, India
Received 2 August 2004; accepted 3 January 2005
Abstract
Sodium dodecyl sulfate(SDS),an anionic surfactant(AS)was used for the surface modification of neutral alumina. Micelle-like structures are formed on the surface of alumina,which are capable of removing organic pollutants from water environment.The surfactant-modified alumina (SMA) was used for the removal of crystal violet (CV), a well-known cationic dye from aquatic environment. The kinetic studies showed that 1 h shaking time was sufficient to achieve the equilibrium. The removal of CV followed the second order kinetics. Studies were conducted to see the effects of adsorbent dose and initial CV concentration on the removal of CV using SMA. The pH was maintained at
6.7plusmn;0.1. SMA was found to be very efficient adsorbent, and sim;99% efficiency could be achieved under optimised conditions for the removal of CV when present even at a high concentration (200 ppm). The effects of various other parameters such as pH, temperature, the presence of different ions (Clminus;, NO3minus;, SO4minus;2, HPO4minus;2 and Fe3 ), and humic acid on the CV removal were also studied. The pH in the range of 7.0–8.5 favours the removal. It was observed that the removal efficiency was increased due to the presence of anions and humic acid and was decreased due to the presence of cations. Temperature had no effect in this process. To test whether the removal of CV was possible from real water using SMA, the adsorption study was conducted using CV spiked samples using distilled water, tap water and synthetically prepared wastewater. It was interesting to note that the removal efficiency was even better for tap water and much better for wastewater when compared to that using distilled water. Desorption of CV from the SMA surface was possible using 1M sodium hydroxide solution, rectified spirit and acetone.copy; 2005 Elsevier B.V. All rights reserved.
Keywords: Alumina; Sodium dodecyl sulfate; Surfactant-modified alumina; Crystal violet; Removal
1. Introduction
Dyes are the one of the major constituents of the wastewater produced from many industries related to textile, paint and varnishes, ink, plastics, pulp and paper, cosmetics, tannery etc., and also to the industries, which produce dyes. Colored dye effluents pose a major threat to the surrounding ecosystem. Many of the dyes are extremely toxic. Among various dyes, crystal violet (CV) is a well-known dye being used for various purposes: a biological stain, a dermatological agent, a veterinary medicine, an additive to poultry feed to inhibit propagation of mold, intestinal parasites and fungus etc. It is also extensively used in textile dying and paper printing. It is a mutagen and mitotic poison. Various treatment technologies like adsorption [1–5], photodegradation [6–10], coagulation flocculation [11], chemical oxidation [12,13], electrochemical
oxidation [14], biological process [15] etc. are available for the removal of dye from the wastewater.
Many of the above mentioned processes are not costeffective and hence are not suitable for being applied in(SDS) modified alumina. The surfactant-modified alumina(SMA) is found to be an efficient adsorbing material for CV even when it is present at a very high concentration in the wastewater and hence can be used as a practical adsorbent for the treatment of CV bearing wastewater. To the best of our knowledge this is the first report where SMA is being used for dye removal from dye bearing wastewater.
developing countries. Very recently removal of organic contaminants using surfactant-modified solid surface has drawn much attention. The solid surface can be modified by surfactant to form micelle like structures on its surface having the potential to solubilize organic molecules within the structures formed. These micelles are called hemimicelle or admicelle and the phenomenon is called adsolubilization. For the last two decades this new separation technology has been used for the removal of different organic compounds[16–19]. The present study aims towards the removal of CV from CV bearing wastewater by sodium dodecyl sulfate (SDS) modified alumina. The surfactant-modified alumina(SMA) is found to be an efficient adsorbing material for CV even when it is present at a very high concentration in the wastewater and hence can be used as a practical adsorbent for the treatment of CV bearing wastewater. To the best of
our knowledge this is the first report where SMA is being used for dye removal from dye bearing wastewater.
- Materials and methods
2.1. Reagents
Acridine orange (ACO), CV, SDS, glacial acetic acid, toluene were from BDH (AR grade) and were used as received.All other chemicals used in this study were of high purity and used without further purification.
2.2. Adsorbents
Alumina was from SRL, India and was used as such without further grinding and sieving. The granulation of neutral alumina was 70–290 mesh ASTM, molecular weight is 101.96 and zero point charge (Zpc) was 9.15.
2.3. Instrumentation
A high precision electrical balance (Sartorious GMBH) and a digital pH meter (DHP-500, SICO, India) were used for weighing and for pH measurement respectively. A spectrophotometer (Thermo Spectronic UV1, UK) was used for absorbance measurement.
2.4. Analytical method
A rapid and reliable solvent extraction spectrophotometric method has been developed for the determination of anionic surfactant (AS). Acridine orange (ACO) chemically known as 3,6-bis (dimethylamino) acridine having a colour(lambda;max = 467n
剩余内容已隐藏,支付完成后下载完整资料
资料编号:[286577],资料为PDF文档或Word文档,PDF文档可免费转换为Word
课题毕业论文、外文翻译、任务书、文献综述、开题报告、程序设计、图纸设计等资料可联系客服协助查找。