稻壳对三种染料的吸附性能研究

用稻壳吸附剂对甲基紫、孔雀绿、维多利亚蓝三种染料废水进行吸附实验,研究了室温条件下染料溶液pH值、稻壳吸附时间、染料初始浓度等因素对吸附效果的影响。在室温条件下稻壳对三种染料具有较好的吸附脱色效果,当pH=6时脱色率最高;稻壳对三种染料的吸附符合准二级反应动力学模型,较好符合Langmiur等温线方程。     

竹炭对碱性品红的吸附性能研究

研究了竹炭对碱性品红染料的吸附性能,考察了竹炭用量、竹炭粒径、吸附时间、pH值、温度和染料浓度等因素对吸附效果的影响。实验结果表明,脱色率随着竹炭用量的增加而增大,竹炭粒径的减小而增加,用200~300目竹炭处理25 mg/L的碱性品红溶液,当加入量为4 g/L时,吸附平衡时间为10 h,脱色率为90.1%;在不改变碱性品红结构的pH范围内(pH<9),脱色率均大于74%;溶液温度升高,脱色率增大,但随着染料浓度增加,温度对脱色率的影响越来越小;Langmuir等温方程比Freundlich等温方程更适合于描述竹炭对碱性品红的吸附行为。     

生物炭和活性炭吸附水中典型染料的研究

用竹屑生物炭和活性炭对染料废水中常见甲基橙进行对比吸附实验。考察吸附时间、甲基橙初始浓度、温度等因素对吸附效果的影响。同时对吸附剂表面进行FTIR、SEM、Bohem滴定法等检测,进一步探究吸附剂表面的化学性质。结果表明:竹屑生物炭比活性炭有更高的表面芳香度和更多种类和数量的含氧官能团,因此,竹炭对甲基橙的吸附效果比活性炭更好。活性炭的等温吸附行为比较符合Langmuir模型(R20.98),竹屑生物炭的吸附行为与Langmuir和Freundlich模型的拟合度都比较高(R20.95),说明竹屑生物炭吸附性能受物理化学等多方面因素的影响。活性炭的动力吸附行为较符合准一级动力学模型(R20.95),竹屑生物炭更符合二级动力学模型(R20.95)。两种吸附剂对甲基橙的吸附量均随着温度的升高而增加,热力学参数ΔG00,ΔH00,ΔS00,说明两种吸附剂对甲基橙的吸附是自发吸热的过程。     

表面改性硅藻土吸附水中活性艳红的研究

以硅藻土为基质,在高锰酸钾溶液中通过化学方法制备了负载型锰氧化物改性硅藻土吸附剂,并利用该吸附剂对染料活性艳红进行吸附脱色实验。实验结果表明,当c(KMnO4)为0.15mol/L时,改性硅藻土吸附剂对染料艳红的η可达96%。当吸附体系pH为4～6时,吸附效果最好。对吸附结果用Langmuir和Freundlich等温方程描述时,发现Langmuir方程能更好地描述吸附行为,相关系数达到0.998。     

制革固体废弃物的吸附特性

分别研究了含铬废革屑和含单宁废革屑对染料和金属离子的吸附特性.结果表明：含铬废革屑对酸性染料和直接染料具有较强的吸附能力,而对碱性染料的吸附能力较弱;含单宁废革屑对Au3+、U6+、Th4+及Hg2+具有较强的吸附能力.含铬废革屑对染料的吸附平衡符合Langmuir方程;含单宁废革屑对Cu2+、U6+、Pb2+和Hg2+的吸附平衡符合Freundlich方程,而对Au3+及Th4+的吸附平衡符合Langmuir方程,因此含单宁废革屑对不同的金属离子可能具有不同的吸附机理.含铬废革屑对染料的吸附动力学以及含单宁废革屑对金属离子的吸附动力学均符合拟二级速度方程.含铬废革屑固定床对染料具有良好的吸附特性,固定床易再生和重复使用.含单宁废革屑固定床对Au3+的吸附量很大,但不易再生;而吸附其他金属离子后则容易再生,而且其吸附性能变化不大.     

蛋壳膜吸附脱色处理水溶性染料

以蛋壳膜作吸附剂,对曙红等4种不同结构的水溶性染料分子的单水溶液进行吸附脱色研究。探讨了蛋壳膜用量、溶液pH值、吸附时间及温度对吸附脱色的影响。结果表明：蛋壳膜对水溶性染料的吸附宜在酸性条件下进行,在最佳条件下,蛋壳膜对曙红、铬黑T的脱色率达95%以上,对亚甲基蓝和甲基紫吸附效果不理想,说明蛋壳膜本身对含甲基类染料吸附能力较低。此研究利用了废弃的蛋壳膜,解决染色废液的处理问题,对于蛋壳膜的开发利用以及染料废水的脱色处理寻找到了新的途径。     

阴-阳离子有机膨润土对甲基橙的吸附性能

以阴、阳离子表面活性剂复合改性膨润土制备出了阴-阳离子有机膨润土;研究了甲基橙在阴-阳离子有机膨润土上的吸附行为,结果表明：阴-阳离子有机膨润土吸附染料甲基橙的速率和吸附量均较大,其吸附动力学行为遵循Langmuir方程所描述的规律。平衡吸附量qe与平衡浓度Ce之间关系符合Freundlich和Langmuir等温吸附方程。且阴-阳离子有机膨润土对染料甲基橙的吸附效果要好于活性炭,可代替活性炭用于染料废水吸附脱色处理。     

阴-阳离子有机膨润土对甲基橙的吸附性能

以阴、阳离子表面活性剂复合改性膨润土制备出了阴-阳离子有机膨润土;研究了甲基橙在阴-阳离子有机膨润土上的吸附行为,结果表明:阴-阳离子有机膨润土吸附染料甲基橙的速率和吸附量均较大,其吸附动力学行为遵循Langmuir方程所描述的规律.平衡吸附量qe与平衡浓度Ce之间关系符合Freundlich和Langmuir等温吸附方程.且阴-阳离子有机膨润土对染料甲基橙的吸附效果要好于活性炭,可代替活性炭用于染料废水吸附脱色处理.     

粉煤灰对活性艳红溶液的吸附脱色处理

以活性艳红染料模拟废水为研究对象,考察粉煤灰对染料废水的吸附脱色作用,考察了粉煤灰的加灰量、吸附时间、吸附温度、废水pH值及初始浓度对活性艳红脱色率的影响。实验表明,废水初始浓度越低,吸附时间越长,脱色效果越好,当吸附时间达60 min时,脱色率趋于稳定;随着粉煤灰加入量的增加,脱色率呈上升趋势,对于100 mg/L的染料溶液,当粉煤灰用量为60 g/L时,染料溶液脱色率可达95%;粉煤灰脱色效果受pH值影响很大,碱性条件下粉煤灰的脱色率较高,酸性条件下次之,中性条件下最差,最佳pH值为10。脱色率随温度的升高而下降,但影响不大。     

含铬革废屑-壳聚糖-戊二醛对酸性红B1的吸附研究

用含铬革废屑,壳聚糖及戊二醛交联聚合制备了处理酸性废水染料的吸附材料,并用差式扫描量热(DSC)对其热稳定性进行表征;用酸性红染料B1模似酸性废水染料,用分光光度法考察了交联剂戊二醛用量,吸附时间,pH对染料脱色效果的影响.研究表明,戊二醛交联剂的用量对材料的热稳定性及对酸性废水的脱色均有不同程度的影响.在20℃,壳聚糖:含铬废革屑:戊二醛量比为1:4:1时,可得到一个热稳定性好的吸附材材料,其脱色率可迭99.4%以上.在pH为5.5～6时,脱色率可达99.5%以上.而且材料再生性好,其脱附率可达到90%以上.该材料对酸性红B1实际废水有良好的吸附效果,脱附率仍可达到90%以上.     

A Comparative Study Between the Adsorption Behavior of Activated Carbon Fiber and Modified Alginate I. Basic Dyes Adsorption

Activated carbon fibers and modified alginate were prepared by using a cheap precursor material. The adsorption behavior of these materials was studied toward basic dyes. It was found that the most effective factor in the adsorption process onto ACF is the high surface area followed by a little assist of the carboxylic groups on the surface. On the contrary, only the carboxylic groups created on the modified alginate (MA) will govern the adsorption behavior of MA. The equilibrium time for ACF in the adsorption of basic dyes was found to be 37 min, whereas in MA it was 70 min. The difference in the adsorption rate between ACF and MA was attributed to the difference in their structure features. Langmuir and Freundlich isotherm models were tested in the study to compare their applicability with the adsorption systems used. The result revealed that the adsorption of basics dyes onto ACF and MA fit very well with both Langmuir and Freundlich isotherms. The adsorption of basic dyes onto ACF follows the micropore-filling mechanism, whereas in MA, the adsorption is done via a physicochemical interaction between the dyes molecules and the carboxylic groups onto MA.     

Application of Modified Water Nut Carbon as a Sorbent in Congo Red and Malachite Green Dye Contaminated Wastewater Remediation

Batch and column adsorption experiments were conducted to investigate the removal of dyes from wastewater by water nut modified carbon (WNMC). Acidic pH was favorable for adsorption for Congo red dyes and basic pH was favorable for the adsorption for Malachite green dyes. The surface property of the sorbent was characterized by scanning electron microscopy and Fourier transform infrared techniques. The adsorption process was found to be endothermic and spontaneous. Different models of adsorption were used to describe the kinetics data and to calculate the corresponding rate constants of WNMC surfaces for dyes adsorption. A mechanism of dyes adsorption associating chemisorption processes is presented allowing the discussion of the variations in adsorption behavior of the material. These data suggested that WNMC are promising materials for dyes sorption. The data were in good agreement with bed depth service time model.     

Dyes Adsorption from Aqueous Solutions by Chitosan

In this study the ability of chitosan to remove acid, basic, reactive, and direct dyestuffs by adsorption was studied. The effect of several factors influencing dye adsorption such as dye concentration, grain size, pH, and temperature were investigated. Desorption of dyes at different pH was also examined. It was shown that the adsorption capacities of chitosan were comparatively high for acid and direct dyes and that the adsorption was controlled by the acidity of the solution. The kinetics of adsorption were found to be of pseudo second order. Batch isotherm studies showed that adsorption of dyes from aqueous solution by chitosan was described by the Langmuir equation.     

A molecularly imprinted polymer via a salicylaldiminato‐based cobalt(III) complex: A highly selective solid‐phase extractant for anionic reactive dyes

A novel molecularly imprinted polymer based on tert‐butyl acrylate (MIP‐BA) was fabricated with the assistance of a cobalt(III)‐based catalyst bearing an N‐salicylidene isopropylamine ligand [(SPA)₂CoCl]. After initiation with methyl aluminoxane, the catalyst system was found to be active toward the polymerization of tert‐butyl acrylate (t‐BA) in the presence of a polar template (Cibacron reactive red dye) and divinylbenzene (DVB) as a crosslinker. Polymerization experiments, including those of t‐BA, t‐BA, and DVB and t‐BA and dye, were also carried out. Isolated blank polymers and MIP‐BA were analyzed with a variety of techniques, including differential scanning calorimetry, thermogravimetric analysis, gel permeation chromatography, infrared spectroscopy, nuclear magnetic resonance, and ultraviolet–visible spectroscopy. In general, the complex showed moderate polymerization activity and produced high‐molar‐mass poly(tert‐butyl acrylate); however, a decrease in the monomer conversion was observed upon the addition of the dye and/or the crosslinker. The effect of imprinting was obvious when the adsorption capacity of MIP‐BA measured at pH 6 for red dye (the imprinted molecule) was increased from 9.2 to 90.4 mg/g after imprinting. Competitive adsorption studies revealed that the dye‐imprinted polymer enabled the efficient uptake of red dye, even in the presence of blue and yellow dyes that had similar chemical structures to the imprinted molecule. The selectivity coefficients were 43 and 36 with respect to the blue and yellow dyes, respectively. The proposed polymerization procedure could be extended to other anionic polar reactive dyes and polar reactive polymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Chemically modified sunflower stalks as adsorbents for color removal from textile wastewater

Quaternary ammonium groups were chemically grafted onto sunflower stalks in order to improve their adsorption performance to anionic species in wastewater. The chemically modified sunflower stalks were evaluated as adsorbents for two basic dyes (Methylene Blue and Basic Red 9) and two direct dyes (Congo Red and Direct Blue 71) in aqueous solutions by using equilibrium isotherms and kinetic adsorption. Before the modification, sunflower stalks exhibited relatively low adsorption to the direct dyes but very high adsorption to the basic dyes. The modified sunflower stalks showed increased adsorption to the anionic dyes, but slightly reduced adsorption to the cationic dyes, due to the existence of quaternary ammonium ions on the surface of the residues. The maximum adsorption capacities of two direct dyes on the modified sunflower stalks are 191.0 and 216.0 mg g for Congo Red and Direct Blue 71 at 50°C, respectively, which were at least four times higher than that of the unmodified residues. The adsorption rates of two direct dyestuffs are much higher on the modified residues than on the unmodified ones. Within 30 min, about 80% of direct dyes were removed from the solutions by the residues. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1841–1850, 1999     

Removal of basic and acid dyes from aqueous solutions by a waste containing boron impurity

In this study, batch experiments were carried out for the sorption of basic blue 41 (BB 41), and acid blue 225 (AB 225) onto boron waste (BW) from boron enrichment plant. The operating variables studied are the initial dye concentration, contact time, solution pH, and adsorbent dosage. The experimental equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that the adsorption behavior of AB 225 and BB 41 could be described well reasonably by Langmuir and Temkin isotherms, respectively. Kinetics studies indicated that the adsorption of both dyes follow pseudo-second-order kinetics. The sorption of basic dye increased at high pH values, whereas the opposite was true for acidic dye. The results indicate that BW could be employed as low-cost alternatives to the commercially available adsorbents in wastewater treatment for the removal of acid and basic dyes.     

Preparation of poly (acrylic acid) containing core‐shell type resin for removal of basic dyes

BACKGROUND: A core‐shell type carboxylic acid modified resin was prepared and dye sorption characteristics of the resin were investigated. The resulting grafted resin material has been shown to be an efficient sorbent for removal of basic dyes from water as a result of the carboxylic acid group's affinity towards basic dye molecules. RESULTS: The resin was characterized using Fourier transform infrared spectroscopy (FT‐IR) and titrimetric methods. The basic dyes (methylene blue and crystal violet) were removed by contacting the swollen resin with aqueous dye solutions at room temperature. The adsorption capacities of resin were determined by colorimetric analysis of the residual dye content in the adsorption medium, which gave capacities for methylene blue and crystal violet of 300 and 250 mg g^?1 resin, respectively. The prepared resin is also able to remove basic dyes completely from dilute aqueous dye solutions. Batch kinetic sorption experiments determined that a pseudo‐second‐order rate kinetic model was applicable. CONCLUSION: Flexibility of the polymer side chains is expected to provide pseudo‐homogeneous reaction conditions and easy accessibility of the functional groups involved. The adsorbents are expected to have the advantage of mobility of the grafted chains in the removal of basic dyes from aqueous mixtures. The resin has potential as an adsorbent for removal of basic dyes for use over a wide pH range. Copyright © 2011 Society of Chemical Industry     

Removal of textile dyes from aqueous solutions by natural phosphate as a new adsorbent

The objective of this study was to investigate the ability of natural phosphate (NP) to remove textile dyes from aqueous solutions. The adsorption of methylene blue (MB) as a reference molecule for the adsorption studies of organic molecules, basic yellow 28 (BY 28) and reactive yellow 125 (RY 125) representatives of two families of textile dyes was studied in a batch mode. The experimental results show that NP can totally remove MB and BY 28, whereas a low adsorption affinity was found in the case of RY 125. The adsorption rate data were analysed using the pseudo-first order kinetics of Lagergren and the pseudo second order model to determine adsorption rate constants. The isotherms of adsorption data were analyzed by various adsorption isotherm models. The adsorption was temperature- and pH-dependent with a high adsorption capacity of MB and BY 28 in the basic range and a high adsorption of RY125 in an acidic range.     

A study on the adsorption of some cationic dyes onto acrylamide/itaconic acid hydrogels

Summary Acrylamide/itaconic acid (AAm/IA) hydrogels prepared by irradiating with radiation were used in experiments on the adsorption of some cationic dyes such as basic red 9 (BR 9), basic green 4 (BG 4), cresyl violet (CV), and basic blue 20 (BB 20). Adsorption of the cationic dyes onto AAm/IA hydrogels is studied by batch adsorption technique. In the experiments of the adsorption, Langmiur type adsorption in the Giles classification system was found. Monolayer coverages for AAm/IA hydrogel-dye systems were calculated by using B point method. Adsorption studies indicated that monolayer coverages of AAm/IA hydrogel by these dyes were increased with following order; BB 20>CV>BR9>BG 4.     

Chitosan intercalated montmorillonite: Preparation, characterization and cationic dye adsorption

Chitosan intercalated montmorillonite (Chi-MMT) was prepared by dispersing sodium montmorillonite (Na⁺-MMT) into chitosan solution at 60 °C for 24 h. The Chi-MMT was characterized by XRD, XRF and FT-IR. The intercalation was accomplished via the ion-exchange of Na⁺ ions with –NH₃⁺ of chitosan, resulting in the expansion of d₀₀₁ from 1.42 nm of Na⁺-MMT to 2.21 nm of Chi-MMT. The chitosan content in the Chi-MMT measured by TGA was about 17 mass%. The adsorption capacity of Chi-MMT was investigated in comparison with the starting Na⁺-MMT and chitosan using three different cationic dyes, i.e. basic blue 9 (BB9), basic blue 66 (BB66) and basic yellow 1 (BY1). The Chi-MMT showed the highest adsorption capacity in the range of 46–49 mg/g when the initial dye concentration was 500 mg/L, being equivalent to 92–99 wt.% of dye removal. The adsorption capacities of Chi-MMT for all basic dyes increased with an increase of initial dye concentration. An increase of adsorption capability of Chi-MMT was attributed to the existence of intercalate-chitosan. It could enlarge the pore structure of Chi-MMT, facilitating the penetration of macromolecular dyes, and also electrostatically interact with the applied dyes. These results indicated the competency of Chi-MMT adsorbent for basic dye adsorption.