Adsorption of cationic dye textile wastewater using Clinoptilolite: isotherm and kinetic study

The releasing of dye-contained effluents has become an objectionable problem in these decades. Thus, the aim of the present work was to evaluate the potential of the acid-treated Clinoptilolite for Methylene Blue (MB) dye removal from aqueous solution. In this experimental-lab study, the dye adsorption onto acid-treated Clinoptilolite was carried out in batch adsorption system. Brunauer-Emmet-Teller (BET) analysis, Scanning Electron Microscopy (SEM), XRF analysis and X-ray diffraction (XRD) were utilized to characterize the acid-treated Clinoptilolite. The effect of some parameters on adsorption efficiency including pH, adsorbent dosage, initial dye concentration and contact time were studied. The isotherm and kinetic study were applied to describe the data obtained from the dye adsorption process. The results indicated that increasing the studied parameters had direct and positive effect on the dye adsorption efficiency. The results showed that higher dye adsorption efficiency was observed at pH=10, adsorbent dosage of 0.5 g/L, dye concentration of 50 mg/L and contact time of 90 min. the isotherm and kinetic studies are better described by pseudo-second kinetic model and Langmuir isotherm model. It can be concluded that acid-treated Clinoptilolite can be used as an effective adsorbent to remove the MB dye from aqueous solution.     

Polypropylene/clay nanocomposite: kinetic and thermodynamic of dyeing with various disperse dyes

The preparation of polypropylene/clay nanocomposite fibers is interesting from the point of dyeability. This paper investigated the kinetics and the thermodynamic parameters of polypropylene/nanoclay dyeing with three disperse dyes as common dyestuffs for non-polar polymer (C.I. Disperse Blue 60, C.I. Disperse Red 324, and C.I. Disperse Yellow 211). The physicochemical parameters of dyeing are calculated in terms of sorption isotherm, standard affinity, enthalpy and entropy changes, and diffusion coefficient as well as activation energy of the diffusion. The sorption of disperse dye on polypropylene/nanoclay composite shows the linear isotherm. The value of dyeing rate constant and diffusion coefficient of dye molecules increases with the dyeing temperature. The standard affinity of Disperse Red 324 to polypropylene/nanoclay fiber is higher than the two other dyes due its higher partially polarity.     

Agave sisalana,a biosorbent for the adsorption of Reactive Red 120 from aqueous solution

The textile industry is one of the largest producers of dye effluent. Treatment of these effluents has to be cost effective hence a number of precursors have been studied as a viable alternative adsorbent. Sisal fibre was converted to activated carbon by chemical methods. Sisal fibre was activated with different activating agents such as H₃PO₄, HCl, HNO₃, NaOH and KOH. The adsorption of Reactive Red 120 (RR 120) dye onto sisal fibre activated carbon (SFAC) from aqueous solution was investigated. Adsorption experiments were carried out at different dye concentrations, initial solution pH and carbon dosage. Batch adsorption studies were carried out using activated carbon produced using phosphoric acid yielded better carbon as it good results in terms of Methylene Blue number and Iodine number. These carbons were used to study the batch adsorption studies. Methylene Blue number and Iodine number of SFAC were found to be 240 mg/g and 855 mg/g, respectively. The BET surface area of the carbon was 885 m²/g. The batch experiments adsorption isotherm studies fitted well to Langmuir isotherm and the adsorption capacity was found to be 110 mg/g. Adsorption kinetics data were tested using pseudo-first-order and pseudo-second-order models. Kinetic studies showed that the adsorption data followed a pseudo-second-order reaction.     

Functionally Modified Cellulose Nanocrystals as an Adsorbent for Anionic Dyes

Cellulose nanocrystal was modified with poly(N,N-diethy-laminomethyl methacrylate) to prepare an adsorbent containing amine groups for removing anionic dyes from waste water. The prepared adsorbent was characterized by Fourier-transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The adsorption was affected by various factors, such as the contact time, adsorbent dosage, dye solution pH value, initial dye concentration, and ionic strength. The results revealed that amine functional groups mainly contribute to the adsorption of azo dyes (AO7). The adsorbent showed pseudo-second-order adsorption kinetics, indicating that the dye molecules were chemisorbed on the adsorbent. The adsorption isotherm was found to fit better with the Langmuir isotherm model than with the Freundlich isotherm model.     

Sorption of copper (II) ions by pine sawdust

The sawdust of Calabrian pine was used as sorbent for the removal of Cu(II) ions from aqueous solution of copper sulfate pentahydrate (CuSO₄.5H₂O) at different concentrations, pHs and temperatures. The results showed that about 65–81% of Cu(II) ions in the solution could be adsorbed on the sawdust. The percentage of adsorped Cu(II) ions onto the sawdust increased with increasing initial concentration. Kinetic studies indicated that the sorption process followed the first order reversible kinetic model. It was also determined that the sorption process obeyed the Freundlich isotherm. Furthermore, the sorption thermodynamic was investigated in detail.     

Cr(VI) removal from aqueous solution by activated carbon coated with quaternized poly(4-vinylpyridine)

A composite sorbent (GAC-QPVP) was prepared by coating poly(4-vinylpyridine) onto a granular activated carbon, followed by cross-linking and quaternization processes. The sorbent was characterized by scanning electron microscopy, point of zero charge measurement, and BET analysis. Batch experiments with variable pH, ionic strength, and concentrations of Cr(VI), sorbent, and competing anions were conducted to evaluate the selective sorption of Cr(VI) from aqueous solutions. The results showed that Cr(VI) sorption rates could be described by a reversible second-order kinetics, and equilibrium uptake of Cr(VI) increased with decreasing pH, decreasing ionic strength, and increasing sorbent concentration. The estimated maximum equilibrium uptake of chromium was 53.7 mg/g at pH = 2.25, 30.7 mg/g at pH = 3.65, and 18.9 mg/g at pH = 6.03, much higher than the maximum capacity of PVP-coated silica gel, an adsorbent for Cr examined previously. When compared with the untreated granular activated carbon, sorption onto GAC-QPVP resulted in much less Cr(VI) reduction and subsequent release of Cr(III). The effect of phosphate, sulfate, and nitrate was minor on the selective sorption of Cr(VI). An ion exchange model that was linked with aqueous speciation chemistry described Cr(VI) sorption reasonably well as a function of pH, ionic strength, and Cr(VI) concentration. Model simulations suggested that sorbed Cr(VI) was partially reduced to Cr(III) on the sorbent when pH was less than 4. The presence of Cr(III) on the sorbent was confirmed by the X-ray photoelectron spectroscopic analysis. Overall, the study has demonstrated that GAC-QPVP can effectively remove Cr(VI) from aqueous solutions under a wide range of experimental conditions, without significant Cr(III) release associated with the virgin GAC treatment.     

A research on electrochemical salt-free dyeing with KN reactive dyes: process optimization studies

Four types of KN-type reactive dyes, C.I.Reactive Blue 19, C.I.Reactive Violet 5, C.I.Reactive Red 111, and C.I.Reactive Blue 21, were employed to study the dyeing process in electrochemical route. Effects of the applied voltage, the amount of anionic groups (sulfuric group) in the molecular structure of the dyes, dyeing temperature, dying time, fixation time were studied to explore the optimum process parameters in lab. The results showed that K/S values of the fabric dyed with C.I.Reactive Blue 19, C.I.Reactive Violet 5, and C.I.Reactive Blue 21were increased than those of the conventional route by 3.6, 9.4, and 12.6%, respectively, under the optimum conditions. Meanwhile, COD values of the dyeing raffinate were reduced by 37.89, 45.67, and 52%, respectively, while the fastness properties had no remarkable differences from traditional dyeing.     

Removal of a wide range of dyes using 4-methyl-2-(naphthalen-2-yl)-N-propylpentanamide-functionalized ethoxy-silica and raw silica

The present research offers a comparative study on the character of the performance of dye removal using either functionalized silica or raw silica gel as adsorbents. First, these supports were characterized in terms of FT-IR and SEM analyses. Then, four different dye solutions were checked for the adsorption phenomenon: Eriochrome Black B (an acid dye), Methylene Blue (a basic dye), Direct Yellow 50 (a direct dye), and Reactive Blue 49 (a reactive dye). Experimental data revealed a dependence on the experimental conditions. Functionalized silica presented a higher removal of dyes than the raw silica. Among the four studied dyes, the highest capacity removal was achieved with Eriochrome Blue Black B (140 mg g^?1) using functionalized silica as adsorbent. This value was reduced to 55 mg g^?1 for raw silica. Further, kinetic and thermodynamic investigations of Eriochrome were discussed. Results gleaned from this study suggest that the functionalized silica could be considered as an efficient candidate to treat colored waters.     

液体染料在牛皮箱板纸染色中的应用特性

叙述了液体染料的应用特性,并对阴、阳离子直接染料的染色特性进行分析,阴离子直接染料用在牛皮箱板纸上总的染色成本稍低,耐光性稍好;而阳离子直接染料在调色过程、换色相时较便利。     

Removal of ionic dyes from water by solvent extraction using reverse micelles

Several methods (e.g., UV/H2O2 oxidation, adsorption, flocculation-precipitation) are normally employed to remove dye from water. A new technique based on liquid/liquid extraction using reverse micelles is proposed whereby recovery of solvent and reuse of dye is possible. Experiments were conducted by mixing a known quantity of dye in aqueous phase and solvent-containing surfactants in a simple mixer. The separation of solvent phase, containing encapsulated dye in reverse micelles, from aqueous phase due to gravity results in separation of dye from water. The removal of different ionic dyes (e.g., eosin yellow, methylene blue, malachite green, methyl orange, orange G) from aqueous phase in the presence of different cationic and anionic surfactants [e.g., sodium dodecylbenzene sulfonate, sodium bis(2-ethylhexyl) sulfosuccinate, hexadecyltrimethylammonium bromide, and cetyl pyridinium chloride] in different solvents (e.g., amyl alcohol, benzyl alcohol, methyl benzoate, and isooctane) were studied by conducting experiments. The percentage removal of dye from aqueous phase increases with the decrease in dye concentration or with the increase in surfactants concentration. Furthermore, the percentage COD removal of dye is increased with the increase in surfactant concentration. The nature of solvent has minimal effect on percentage removal of dye. The ratio of solventto aqueous phase volume required for the removal of dye decreases with the increase in surfactant concentration. It is possible to back-extract dye into aqueous phase and recover solvent by using counterionic surfactants. The separation of aqueous phase from the aqueous-phase solvent dispersion is faster for amyl alcohol as compared to benzyl alcohol and methyl benzoate. A theoretical model based on ion-exchange reaction between surfactants and dye is used to analyze the experimental data.     

Sorption of ciprofloxacin and oxytetracycline zwitterions to soils and soil minerals: influence of compound structure

Oxytetracycline (OTC) zwitterions sorbed to a greater extent than ciprofloxacin (CIP) zwitterions onto goethite and soils with moderate-to-low effective cation exchange capacities (ECEC < 10 cmol(c)/kg) because adjacent pairs of hydroxyl groups on the OTC molecule (absent in CIP) facilitated greater surface complexation to soil metal oxides and aluminosilicate edge sites. CIP sorbed to a higher extentthan OTC onto aluminosilicates and onto soils with "high" ECEC values (>10 cmol(c)/kg). The sorption of heterocyclic compounds structurally similar to CIP indicated that both positive charge localization on the cationic amine and the extent of charge delocalization to the heterocyclic ring influenced molecular orientation within the montmorillonite interlayers, van der Waals interactions, and the potential for sorption. The sorption of compounds structurally similar to OTC revealed that greater positive charge localization on the cationic amine facilitated sorption to montmorillonite, whereas ortho substituted anionic and cationic groups on a zwitterionic molecule resulted in unfavorable Coulombic interactions between the anionic moiety and the negatively charged surface and hindered sorption. Thus, greater CIP zwitterion sorption to aluminosilicates and "high" ECEC soils resulted from greater distance between the anionic and cationic groups, which maximized Coulombic attraction to the surface.     

Effect of surfactants on the survival and sorption of viruses

There is an increasing concern about the protection of groundwater from contamination by enteric viruses and the prevention of outbreaks of waterborne diseases. Knowledge of survivability and transport of viruses from their point of origin is necessary to determine their potential effects on the neighboring groundwater systems. The distribution of virus is, in turn, dependent on the physical and chemical compositions of the surrounding soil and subsurface systems. For the present study, we have determined the effects of different surfactants (cationic, anionic, nonionic, and biological) and natural organic matter (NOM) on bacteriophages. Results indicated that surfactants and NOM adversely affect phage survival in binary systems, with surfactants being the most harmful. Studies with ternary systems also showed that the presence of surfactants reduced sorption of phages on sorbents either by occupying available sorption sites on the sorbent material or by displacing the sorbed phages from the sorbent surface. Water contact angles of the selected phages and different sorbent surfaces have been measured. Experimental data demonstrated that the sorption of hydrophobic viruses was favored by hydrophobic sorbents, while the sorption of hydrophilic viruses was favored by hydrophilic sorbents.     

紫外光接枝丙烯酸亚麻织物阳离子染料染色热力学

采用阳离子染料碱性玫瑰精对紫外光接枝丙烯酸的亚麻织物进行染色,采用Langmuir、Freudlich、Nernst三种模型对紫外光接枝丙烯酸亚麻织物染色的吸附等温线进行模拟,计算亲和力、染色热、染色熵等热力学参数。结果表明,阳离子染料碱性玫瑰精上染紫外光接枝丙烯酸亚麻织物的吸附等温线属于Langmuir型,其亲和力随着温度的升高而增大,染色热和染色熵均是正值,因此,随着温度的升高,阳离子染料碱性玫瑰精从染液向纤维转移的趋势越大,即推动力越大,该染色反应为吸热反应,并且,阳离子染料碱性玫瑰精上染紫外光接枝丙烯酸亚麻织物引起物系紊乱度增大。     

氮掺杂纤维素基碳气凝胶对染料吸附的影响

采用尿素改性与冷冻干燥法相结合的方式制备了可循环使用的氮掺杂纤维素基气凝胶,并对该气凝胶进行碳化得到氮掺杂纤维素基碳气凝胶(N-CCA)。分析了N-CCA的形貌和结构特征,并对废水中阳离子染料亚甲基蓝(MB)和阴离子染料刚果红(CR)的吸附性能进行了研究。SEM、XRD、氮气吸附脱附仪测试结果表明,经过尿素改性后,纤维素基碳气凝胶形貌发生重组,孔隙结构更加紧密,石墨化程度降低,比表面积增加,有利于提高染料去除能力。通过紫外可见分光光度计测试表明,改性后的N-CCA对阳离子染料MB的吸附能力略微下降,但对阴离子染料CR的吸附能力提升明显,从改性之前的87.12mg/g增加到360.63 mg/g。N-CCA材料具有选择性吸附性解,循环使用5次,CR去除率保持在98%以上。     

Polypyrrole-coated cotton fabrics used for removal of methylene blue from aqueous solution

PPy-coated cotton fabric was prepared in situ chemical polymerization using blends of anionic and cationic surfactants as soft template and investigated as adsorbent to remove dyes in the printing and dyeing wastewater. The PPy-coated fabric was characterized by scanning electronic microscopy and fourier transform infrared spectrum. It was found that the fiber and fabric surfaces were coated by PPy nanoparticles with diameters less than 100 nm which were quite loose and well formed as a three-dimensional network. Dye adsorption experiments demonstrated that the PPy-coated fabric could effectively remove MB dye and the decoloration capacity of MB solution could reach up to 95.6%. Factors influencing the adsorption of MB, e.g. ionic strength, solution pH, contact time, and adsorption mass, were systematically investigated. The adsorption capacity for MB dye increased gradually as its initial concentration increased. The batch experimental results suggested that the PPy-coated fabric could be used as an efficient sorbent to remove dyes in textile effluents.     

Acid dyeing of linen fabrics using gemini cationic surfactants

Three novel gemini cationic surfactants were synthesized and their structures confirmed by ¹H-NMR analysis. The interaction of C.I. Acid Violet 1 dye with gemini cationic surfactants in aqueous solution was investigated by UV-Vis spectroscopy at the λ_max of the acid dye–cationic surfactants. The dyeing behavior of the acid dye–cationic surfactants and their fastness properties were investigated. It was observed that the aggregation of surfactant and dye takes place at low concentrations far below 1 g/l. The further addition of surfactant resulted in an absorption spectrum characteristic of fully saturated acid dye in the cases of the 16–2-16 and 16–3-16 surfactants at 1 g/l, and in the case of the 10–3-10 surfactant 1.2 g/l. The results also showed bathochromic shifts for the acid dye followed by significant increase in the λ_max at the optimum concentrations of these surfactants. The dyeability of linen fabric with acid dye–gemini cationic surfactants increased as the electrostatic interactions between the surfactant head groups and the anionic nature of the acid dye increased, but the hydrophobic interactions decreased at higher temperature. The fastness to washing and rubbing improved by increasing the alkyl length of the gemini surfactants from 10–3-10 to 16–2-16 and 16–3-16, although the spacer length had no effect.     

Effects of linear alkylbenzene sulfonate on the sorption of Brij 30 and Brij 35 onto aquifer sand

Surfactant sorption is of considerable importance to environmental applications, including surfactant flushing to mobilize hydrophobic contaminants; effects of surfactants on the transport of dissolved contaminants, microorganisms, and colloids through porous media; and bioremediation of hydrophobic organic compounds, as well as understanding the fate and transport of surfactants as environmental contaminants themselves. Although most sorption studies consider pure surfactants, commercial detergent formulations typically consist of mixtures of nonionic and anionic surfactants. In this study, the effects of varying concentrations of the anionic surfactant linear alkylbenzene sulfonate (LAS) on micelle formation and sorption behavior of the two commonly used nonionic surfactants Brij 30 and Brij 35 onto aquifer sand were examined. A strong linear relationship was observed between the critical micelle concentration (CMC) of the Brij surfactants and the concentration of LAS in the mixture, with the CMC decreasing with increasing concentration of LAS. The relative change in CMC as a function of the LAS concentration was identical forthe two Brij surfactants, indicating that LAS interacted with their common alkyl chains. Sorption isotherms were developed for Brij 30 and Brij 35 present as single surfactants in an aqueous solution as well as when present with LAS. Although LAS had minor effects on the maximum sorption plateaus of the Brij surfactants, Brij sorption at was significantly enhanced as a function of the LAS concentration for Brij aqueous concentrations below the CMC. Application of a multi-interaction isotherm model indicated that the formation of surface aggregates (e.g., hemimicelles) decreased with increasing LAS concentration. Overall, these results provide insight into the complex sorption behavior of surfactant mixtures.     

凹凸棒石粘土对水溶性染料的吸附脱色研究

研究凹凸棒石粘土对几种水溶性染料的吸附脱色作用,并对其中脱色效果较明显的亚甲基蓝和弱酸艳蓝RAW进行深入探讨.结果表明,凹凸棒石粘土对两种染料的吸附均可在短时间内达到平衡;振荡有利于吸附,而温度、pH值对两种染料的吸附均无显著影响;适当增加染液浓度可以提高凹凸棒石粘土的吸附量,相同条件下凹凸棒石粘土对亚甲基蓝的吸附能力高于弱酸艳蓝RAW.除活性染料外,凹凸棒石粘土对其它染料的脱色性能均优于活性炭.     

Polyethylenimine-modified fungal biomass as a high-capacity biosorbent for Cr(VI) anions: sorption capacity and uptake mechanisms

Heavy metal pollution in the aqueous environment is a problem of global concern. Biosorption has been considered as a promising technology for the removal of low levels of toxic metals from industrial effluents and natural waters. A modified fungal biomass of Penicillium chrysogenum with positive surface charges was prepared by grafting polyethylenimine (PEI) onto the biomass surface in a two-step reaction. The presence of PEI on the biomass surface was verified by FTIR and X-ray photoelectron spectroscopy (XPS) analyses. Due to the high density of amine groups in the long chains of PEI molecules on the surface, the modified biomass was found to possess positive zeta potential at pH below 10.4 as well as high sorption capacity for anionic Cr(VI). Using the Langmuir adsorption isotherm, the maximum sorption capacity for Cr(VI) at a pH range of 4.3-5.5 was 5.37 mmol/g of biomass dry weight, the highest sorption capacity for Cr(VI) compared to other sorbents reported in the literature. Scanning electronic microscopy (SEM) provided evidence of chromium aggregates formed on the biomass surface. XPS results verified the presence of Cr(III) on the biomass surface in the pH range 2.5-10.5, suggesting that some Cr(VI) anions were reduced to Cr(III) during the sorption. The sorption kinetics indicated that redox reaction occurred on the biomass surface, and whether the converted Cr(III) ions were released to solution or adsorbed on the biomass depended on the solution pH. Sorption mechanisms including electrostatic interaction, chelation, and precipitation were found to be involved in the complex sorption of chromium on the PEI-modified biomass.     

Photosensitized oxidation of substituted phenols on aluminum phthalocyanine-intercalated organoclay

Bentonite modified with cationic surfactant, cetyltri-methylammonium bromide (CTMA), was an effective sorbent for organic pollutants in water. To make the sorbent recyclable, aluminum phthalocyanine (AIPc), a representative photosensitizer for generation of singlet oxygen, was inserted successfully into the interlamellar space of CTMA-modified bentonite. Under visible light (lambda > 450 nm) irradiation, the composite catalyst exhibited a remarkable activity for degradation of the recalcitrant pollutants phenol, 4-chlorophenol, 4-nitrophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol in an aerated aqueous medium. The initial rate of the heterogeneous photoreaction was found to increase with the initial amount of the substrate sorption onto the catalyst, the kinetics following the Langmuir-Hinshelwood equation. Loading of AIPc into the organoclay led to slight expansion of the clay basal spacings from 1.82 to 2.15 nm, but the sorption capacity was decreased notably. The optimal loading of AIPc was about 0.25 wt %. The result demonstrates thatthe surfactant-modified bentonite not only offers a hydrophobic zone for enrichment of organic contaminants but also provides a flexible environment for destruction of the sorbed pollutants by singlet oxygen generated in situ. It was noted, however, that during four repeated experiments, both the sorption and the degradation rate of 2,4,6-trichlorophenol were gradually decreased, due to some intermediates formed and sorbed onto the catalyst surface.