Influence of dyes, salts and auxiliary chemicals on the nanofiltration of reactive dye baths: experimental observations and model verification

The aim of this study was to investigate the effects of dyes, salts and auxiliary chemicals in reactive dye baths on the separation performance of nanofiltration membranes. A reactive dye bath was simulated for this purpose with auxiliary chemicals. A DS5-type nanofiltration membrane was used in the experimental runs. Performance of the nanofiltration membrane was evaluated by measuring permeate flux, salt and color rejections in five steps. Reactive black 5, reactive orange 16, NaCl, NaOH, Na₂SO₄, acidic acid, mollan and slipper were used to prepare synthetic dye baths. Pressures in the range of 8 to 24 bars were applied, and flow velocity was kept constant at 0.74 m/s. NaCl rejection of 20% and color rejection of more than 95% were achieved throughout the experiments. Permeate quality was satisfactory enough to recycle these effluents in reactive dyeing. Acidification ofthe original synthetic dye bath solution with HCl and H₂S0₄ decreased the membrane fouling and also increased the NaCl recovery and color rejection. Besides, using HCI instead of H₂SO₄ increased these positive effects. The effects of auxiliary chemicals were determined by using salt rejection model parameters of α and k_D in the presence of an organic ion. There was a correlation among the results of experiments and the model. The model parameters (α and k_D were also calculated for all steps.     

Decolorization of disperse and reactive dye solutions using ferric chloride

The composition of wastewater from dyeing and textile processes is highly variable depending on the dyestuff type; typically it has a high chemical oxygen demand. This study examined the decolorization of some of the most commonly used disperse and reactive dyestuffs by destabilization using ferric chloride as a coagulant. Dye removal, distributions of zeta potential, concentration of suspended solids, changes of the SCOD/TCOD ratio and distributions of SV and SVI values were investigated in this work. Compared to reactive dyes, disperse dyes have lower solubility, higher suspended solids concentrations and lower SCOD/TCOD ratios. It was concluded that disperse dye solutions are more easily decolorized by chemical coagulation than reactive dye solutions.     

Comparative removal of two textile dyes from aqueous solution by adsorption onto marine-source waste shell: Kinetic and isotherm studies

Scallop shell was used as a low-cost adsorbent for removal of two anionic textile dyes, Reactive Blue 19 (RB19) and Acid Cyanine 5 R (AC5R), from aqueous solutions. The adsorbent was characterized using inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The dye removal efficiency of scallop shell was determined as function of contact time, solution pH, initial dye concentration and adsorbent dosage. With increasing dye concentration, the adsorption of both dyes decreased, while it increased with increasing adsorbent dosage. Optimum removal of RB19 and AC5R was achieved at pH=6. Adsorption equilibrium data were well described by the Freundlich model. The maximum dye adsorption capacity of scallop shell as estimated from the Langmuir isotherm was 12.36 and 12.47 mg/g for RB19 and AC5R, respectively. The adsorption kinetic data showed excellent correlation with the pseudosecond-order model. It was concluded that scallop shell has a remarkable potential for the sorption of RB19 and AC5R and can be used for treatment of the dye contaminated wastewater.     

Treatment of a textile effluent: application of a combination method involving adsorption and nanofiltration

A combination of adsorption and nanofiltration (NF) was adopted for the treatment of a textile dyehouse effluent containing a mixture of two reactive dyes. The effluent stream was first treated in a batch adsorption process with sawdust as an adsorbent to reduce the dye concentration of the effluent by about 83% for Dye 1 and 93% for Dye 2. The effluent from the adsorption unit was passed through an NF unit for the removal of the remaining small amount of dyes and to recover the associated chemicals (mainly salt) in the effluent stream. The dyes remaining after this step were less than 1 ppm. The percentage removal of COD was greater than 99%, and the salt recovery was on the order of 90%. Equilibrium studies were carried out with synthetic solutions of the dyes (both single component as well as two-component systems) at room temperature. The adsorption rates were studied in detail using varying amounts of the adsorbent. NF of the effluent was performed in a cross-flow system using a 400 molecular weight cut-off membrane. A detailed study was carried out to observe the effect of the process parameters, namely applied pressure and bulk velocity on the process outputs such as dye rejection, COD removal, permeate flux and salt recovery. Finally, direct NF of the effluent (with the original high concentration) was undertaken, and the performance of the process was compared with the combination method. The permeate flux for the proposed combined method was found to be about twice that for the direct NF method. The dye rejection improved significantly compared to adsorption.     

Hydrophilic polymeric membrane supported on silver nanoparticle surface decorated polyester textile: Toward enhancement of water flux and dye removal

A novel mixed matrix nanofiltration membrane was constructed by coating a casting solution containing polyvinylidene fluoride(PVDF), polyethylene glycol(PEG) as hydrophilic agent, zeolitic like framework-67(ZIF-67), ethylenediamine as cross-linking agent on Ag-nanoparticle-decorated polyester textile(PT) support(PT/AgNPs/PVDF-PEG/ZIF-67). PT/Ag-NPs/PVDF-PEG/ZIF-67 morphology, crystalline structure, surface chemical composition and hydrophilicity of PT/Ag-NPs/PVDF-PEG/ZIF-67 were fully characterized by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR) and water contact angle technique, respectively. PT/Ag-NPs/PVDF-PEG/ZIF-67 was applied in cross module set-up for removal of contaminated water containing rose bengal(RB) dye. The effect of operational parameters such as dye concentration,solution pH and flow rate on performance of PT/Ag-NPs/PVDF-PEG/ZIF-67 were investigated and optimized by central composite design(CCD). Casting solution containing 0.5 wt.% ZIF-67 as optimum value showed the good wettability, high pure water flux(PWF; 35.8 L·m~(-2)·h~(-1)), flux recovery ratio(FRR;90%), dye removal efficiency(96.41%). The selectivity factor of 12.72 and 14.42 was found to be for RB in the presence of amido black and methylene blue as interferent dyes, respectively, which showed a good selective recognition ability for RB dye.     

Nanofiltration and reverse osmosis thin film composite membrane module for the removal of dye and salts from the simulated mixtures

Nanofiltration (NF) and reverse osmosis (RO) thin film composite polyamide membrane modules were used to remove the color from the contaminated solution mixture. The feasibility of membrane processes for treating simulated mixture by varying the feed pressures (100-400 psi) and feed concentrations was studied to assess the separation performance of both NF and RO membranes. It was found that the efficiency of NF and RO membranes used in the treatment of colored water effluents was greatly affected by the presence of salts and dyes in the mixture. Color removal by NF with a high rejection of 99.80% and total dissolved solids (TDS) of 99.99% was achieved from RO by retaining significant flux rate compared to pure water flux, which suggested that membranes were not affected by fouling during the simulated wastewater process operation. The effect of varying concentrations of Na₂SO₄ salt and methyl orange (MO) dye on the performance of spiral wound membranes was determined. Increasing the dye concentration from 500 to 1000 mg/L resulted in a decrease of salt rejection at all operating pressures and for both concentrations of 5000 and 10,000 mg/L as the feed TDS. Increasing the salt concentration from 5000 to 10,000 mg/L resulted in a slight decrease in dye removal.     

Removal of methyl orange dye and Na2SO4 salt from synthetic waste water using reverse osmosis

The efficiency of reverse osmosis (RO) membranes used for treatment of colored water effluents can be affected by the presence of both salt and dyes. Concentration polarization of each of the dye and the salt and the possibility of a dynamic membrane formed by the concentrated dye can affect the performance of the RO membrane. The objective of the current work was to study the effect of varying the Na₂SO₄ salt and methyl orange (MO) dye concentrations on the performance of a spiral wound polyamide membrane. The work also involved the development of a theoretical model based on the solution diffusion (SD) mass transport theory that takes into consideration a pressure dependent dynamic membrane resistance as well as both salt and dye concentration polarizations. Control tests were performed using distilled water, dye/water and salt/water feeds to determine the parameters for the model. The experimental results showed that increasing the dye concentration from 500 to 1000 ppm resulted in a decrease in the salt rejection at all of the operating pressures and for both feed salt concentrations of 5000 and 10,000 ppm. Increasing the salt concentration from 5000 to 10,000 ppm resulted in a slight decrease in the percent dye removal. The model’s results agreed well with these general trends.     

Adsorption of anionic dyes on poly(epicholorohydrin dimethylamine) modified bentonite in single and mixed dye solutions

The performance of poly(epicholorohydrin dimethylamine) modified bentonite (EPIDMA/bentonite) as an adsorbent to remove anionic dyes, namely Direct Fast Scarlet, Eosin Y and Reactive Violet K-3R, was investigated in single, binary and ternary dye systems. In adsorption experiments in single dye solutions, the adsorption of the three dyes onto EPIDMA/bentonite was described by the Langmuir isotherm model and the pseudo-second-order kinetic model. At low dosage of EPIDMA/bentonite, preferential adsorption was observed for the dye with higher affinity to the adsorbent in mixed dye systems. The reduction in uptake of the dye with increasing equilibrium dye concentration in the isotherm and desorption in the kinetic curves were observed for the dye with lower affinity. The total amount of dyes adsorbed versus the total equilibrium dye concentrations were fitted well by the Langmuir isotherm model. The kinetics of the total adsorbed amount of dyes followed the pseudo-second-order kinetic model. The effect of the dosage of adsorbent on color removal efficiency, residual color distribution and adsorption kinetics was investigated.     

Dye removal from colored‐textile wastewater using chitosan‐PPI dendrimer hybrid as a biopolymer: Optimization,kinetic, and isotherm studies

Preparation of a biopolymer chitosan‐polypropylene imine (CS‐PPI) as a biocompatible adsorbent and its reactive textile dyes removal potential were performed. Chemical specifications of CS‐PPI were determined using Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR. The surface morphology of the CS‐PPI surface was characterized by scanning electron microscopy. Results confirmed that the linkages between the NH₂ groups of PPI dendrimer and carboxylic groups of modified Chitosan were accomplished chemically. Two textile reactive dyes, reactive black 5 (RB5) and reactive red 198 (RR198), were used as model compounds. A response surface methodology was applied to estimate the simple and combined effects of the operating variables, including pH, dye concentration, time contact, and temperature. Under the optimal values of process parameters, the dye removal performance of 97 and 99% was achieved for RB5 and RR198, respectively. Furthermore, the isotherm and kinetic models of dyes adsorption were performed. Adsorption data represented that both examined dye followed the Langmuir isotherm. The adsorption kinetics of both reactive dyes were satisfied by pseudo‐second order equation. Based on this study, CS‐PPI due to having high adsorption capacity (6250 mg/g for RB5 and 5882.35 mg/g for RR198), biocompatibility and ecofriendly properties might be a suitable adsorbent for removal of reactive dyes from colored solutions. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

From pollutant to solution of wastewater pollution: Synthesis of activated carbon from textile sludge for dye adsorption

Adsorption is an important process in wastewater treatment,and conversion of waste materials to adsorbent offers a solution to high material cost related to the use of commercial activated carbon.This study investigated the adsorption behaviour of Reactive Black 5(RB5)and methylene blue(MB)onto activated carbon produced from textile sludge(TSAC).The activated carbon was synthesized through chemical activation of precursor followed with carbonization at 650°C under nitrogen flow.Effects of time(0–200 min),pH(2–10),temperature(25–60°C),initial dye concentration(0–200 mg·L~(-1)),and adsorbent dosage(0.01–0.15 g)on dye removal efficiency were investigated.Preliminary screening revealed that TSAC synthesized via H_2SO_4activation showed higher adsorption behaviour than TSAC activated by KCl and ZnCl_2.The adsorption capacity of TSAC was found to be 11.98 mg·g~(-1)(RB5)and 13.27 mg·g~(-1)(MB),and is dependent on adsorption time and initial dye concentration.The adsorption data for both dyes were well fitted to Freundlich isotherm model which explains the heterogeneous nature of TSAC surface.The dye adsorption obeyed pseudo-second order kinetic model,thus chemisorption was the controlling step.This study reveals potential of textile sludge in removal of dyes from aqueous solution,and further studies are required to establish the applicability of the synthesized adsorbent for the treatment of waste water containing toxic dyes from textile industry.     

光催化降解活性染料K-GL的动力学及其盐效应

以分散态纳米TiO2为光催化剂,在鼓泡流化床光催化反应器中对活性翠兰K-GL染料溶液进行光催化降解实验研究。通过改变光催化剂投入量、染料溶液的初始浓度和Na2SO4与NaCl的掺加,探讨了影响光催化降解K-GL的因素,运用Langrmuir-Hinshelwood动力学方程对染料降解动力学规律进行了研究。结果表明,TiO2光催化降解活性翠兰K-GL的反应遵循准一级反应动力学方程,且表观反应速率表常数随活性翠兰溶液初始浓度的升高而降低;反应的催化剂最佳投入量为0.122g/L;光催化体系中的Na2SO4对于染料K-GL的降解表现出明显的促进作用,在较低浓度下,Na2SO4的最佳添加量为0.104mol/g,且随着其浓度的升高,表观反应速率常数随之增大;而掺加不同浓度的NaCl对光催化降解K-GL有抑止作用。     

Dye removal from colored textile wastewater using acrylic grafted nanomembrane

In this paper, the dye removal ability of the acrylic grafted polysulfone nanomembrane using ultraviolet radiation was studied to remove dyes from colored textile wastewater. Acrylic acid was used to modify polysulfone ultrafiltration membrane. The effect of different operating parameters such as pressure, salt concentration and chemical structure of dyes was evaluated. Data indicated that the photografted membrane has acceptable performance both in terms of flux and rejection. The dye rejection and hydraulic permeability were 86–99.9% and 7.6 L m^{− 2} h^{− 1} bar^{− 1}, respectively. It was found that the rejection of dyes decreased with salt concentration due to a decrease of the Donnan effect. Also, the low molecular weight dyes and highly charged dyes were more sensitive in the presence of salts. Addition of 80 mM Na₂SO₄ in dye solution decreased the dye rejection more than 15%. The rejection enhancement for all cases was negligible by increasing driving pressure from 1 to 4 bar. Dyes with low charger were more sensitive to operating pressure than that of dyes with higher charges. All findings supported that acrylic grafted nanomembrane is potentially capable to separate dyes from colored textile effluent.     

The adsorption of malachite green (MG) as a cationic dye onto functionalized multi walled carbon nanotubes

Synthetic dyes are widely used by several industries to color their products. The discharge of colored wastewater into the hydrosphere causes serious environmental problems. We used functionalized multi wall carbon nanotubes as an adsorbent for the adsorption of cationic dye, malachite green, from aqueous solution. Based on information provided by the Iranian Research Institute of Petroleum Industry, carbon nanotubes are produced using a chemical vapor deposition (CVD) technique. These as-received MWCNTs were functionalized by acid treatment. The remaining dye concentration was read by UV-visible absorption spectroscopy at maximum adsorption wavelength. The effect of different operational parameters such as contact time, pH of solution, adsorbent dose and initial dye concentration were studied. The results showed that by increasing of contact time, pH and adsorbent dose the removal of dye increased, but by increasing initial dye concentration, the removal efficiency decreased. Adsorption isotherms and kinetics behavior of f-MWCNTs for removal of malachite green was analyzed, and fitted to various existing models. The experimental data were well correlated with the Langmuir isotherm with a maximum adsorption capacity (q _m ) and regression coefficient (R²) of 142.85 mg/g and 0.997, respectively. The results of this study indicate that functionalized multi wall carbon nanotubes can be used as an effective adsorbent for the removal of dyes.     

Performance evaluation of a continuous flow immobilized rotating tube photocatalytic reactor (IRTPR) immobilized with TiO2 catalyst for azo dye degradation

Photocatalytic oxidation is becoming an attractive technique for the degradation of hazardous organic contaminants. Reactor design plays an important role in the treatment efficiency. A novel immobilized photocatalytic reactor presented in this paper, consists of TiO₂ coated rotating PVC tubes in a continuous flow reactor; irradiated with UV lamps. Using reactors in series approach, the effects of key parameters—initial dye concentration, rotational speed, pH and flow rate, on color removal were evaluated for reactive red dye. Low initial concentration and acidic pH favored the dye removal. Rate of color removal increased with speed initially but remained constant at higher speed. Though the effect of flow rate was complex, in combination with initial concentration it had a significant effect on the energy consumption. Langmuir–Hinshelwood type kinetic model fitted the decolorization kinetic well and the rate constants were evaluated. 90–99.99% color removal and 55–70% TOC removal were obtained depending on operating conditions.     

Fenton试剂-浸没式生物滤池处理模拟染料生产废水试验研究

作者采用Fenton试剂预处理和浸没式生物滤池联合法处理含盐较高的模拟染料生产废水,考察了Fenton试剂预处理对染料结构的破坏作用和染料液可生化性的改善作用及浸没式生物滤池对预处理后溶液CODCr的去除过程和处理效果.实验结果表明,Fenton试剂预处理能有效破坏染料分子的结构,色度去除率可达99%;预处理后染料液的可生化性得到显著改善;浸没式生物滤池对预处理后的染料废水CODCr的去除效果稳定,平均去除率达到64%,且具有一定的抗冲击负荷能力.     

Catalytic ozonation with non-polar bonded alumina phases for treatment of aqueous dye solutions in a semi-batch reactor

Semi-batch experiments were conducted to investigate the effects of catalyst type, pH, initial dye concentration and production rate of ozone on the catalytic ozonation of the dyes, namely Acid Red-151 (AR-151) and Remazol Brilliant Blue R (RBBR). The used catalysts were alumina, 25% (w/w) perfluorooctyl alumina (PFOA), 50% (w/w) PFOA and 100% (w/w) PFOA. The results showed that the overall percent dye removal after 30 min of the reaction was not affected significantly by the catalyst type. However, highest COD reduction was achieved by ozonation with alumina for AR-151, and 100% PFOA for RBBR at pH 13. The behavior of COD reduction with the increasing amount of perfluorooctanoic (PFO) acid amount can be explained by the enhancement of catalytic activity of PFOA with alkyl chains. For both of the dyes, the highest dye and COD removals were reached at pH 13. The overall dye reduction after 30 min of ozonation was almost independent of the initial dye concentration at relatively low values while at the higher concentrations, it changed with the initial dye concentration for both of the dyes. Similarly, COD reduction changed on a limited scale with the increasing initial dye concentration from 100 mg/L to 200 mg/L; however, an increase of initial dye concentration to 400 mg/L decreased the COD reduction significantly. All the studied production rates of ozone were sufficient to provide almost 100% dye removal in 30 min, whereas the COD removal percentage was increased gradually by the increasing ozone input to the reactor. The reaction kinetics for the ozonation of each dye with and without catalyst was investigated and discussed in the paper.     

Effect of Color and Surfactants on Nanofiltration for the Recovery of Carpet Printing Wastewaters

Abstract

Carpet printing wastewater (CPW) was spiked with metal‐complex dyes at concentrations of 10 and 30 mg/L to investigate the effect of feed color on separation performance of nanofiltration (NF). The rejection was excellent; 98–100% for color and COD under all spiking conditions. Although the flux decline increased with increasing dye concentration, the concentration polarization was the main cause of the flux decline. The effect of surfactants on NF separation performance was also investigated by preparing synthetic wastewaters with dyes and auxiliary chemicals. The presence of a non‐ionic penetrant did not adversely affect the color rejection whereas the COD rejection was reduced from 100% to 91%. Furthermore, fouling became dominant when surfactants were used.     

Linear alkylbenzene sulfonates in the prevention of vagrant dye pick-up on polyester textile fabric during laundering

The unwanted pick-up of low levels of vagrant dyes during washing of textile fabrics can be a significant contributor to long-term polyester appearance degradation. Fabric appearance loss from pick-up of small quantities of a standard yellow dye are measured on both optically brightened and unbrightened polyester. Linear alkylbenzene sulfonate (LAS) surfactant micelles act as effective dye scavengers, reducing the level of dye pick-up by the fabric substantially. The efficacy of LAS as a dye scavenger is quantified as a function of alkyl chain length and use concentration. Dye scavenging ability per unit weight of LAS increases with increasing molecular weight and decreasing critical micelle concentration (cmc). Dye scavenging of up to 80% of the transferable dye is achieved at high LAS concentrations. Results with C₉, C₁₁, C₁₃ and C₁₅ single homolog alkyl chain lengths, and with several mixed chain length blends are presented. Presented at the AOCS symposium on “Surfactants in Textiles,” New Orleans, May 1981.     

胶原多肽基表面活性剂对染料废水的泡沫分离性能

以结晶紫溶液模拟染料废水,研究了胶原多肽基表面活性剂(CBS)对染料废水的泡沫分离性能。通过单因素实验考察了pH、气速、表面活性剂质量浓度、泡沫相与液相高度比(H_F/H_L)、染料初始浓度、乙醇添加量等因素对废水中染料分离的影响。结果表明,CBS适用于碱性条件下染料废水的泡沫分离;随着气速的升高,染料的去除率增加,但富集比降低;随着CBS用量的增加,染料的去除率先增加而后降低,富集比随CBS用量的增加而降低;当泡沫相高度与液相高度比为3左右时,染料去除率较高;添加适量的乙醇对泡沫分离是有利的;在较佳的分离条件下,染料的去除率可达80%,富集比达到16。上述研究结果表明,胶原多肽基表面活性剂可用于染料废水的泡沫分离。     

Investigation of Reactive Red Dye 198 removal using multiwall carbon nanotubes in aqueous solution

The present study evaluates the performance of multiwalled carbon nanotubes (MWCNTs) for removing Reactive Red Dye 198 (RR198) from the color wastewater. In this study, the influence of pH, adsorbent dose, initial dye concentration, and contact time on the RR198 adsorption by MWCNTs was investigated. The results showed increasing the dye concentration from 20 to 200 mg/L, removal efficiency decreased from 99.62% to 66.99%. Moreover, by increasing the pH from 3 to 10, the efficiency of dye removal decreased from 76.34% to 54.98%. Freundlich isotherm and pseudo-second-order kinetic model were the best models for describing the adsorption reactions.