Solution Initial Dye Concentration Research Articles

Purification of Methylene Blue via Photocatalytic Nanofibrous Membranes Containing TiO2 Nanoparticles

In this paper, titanium dioxide nanoparticles were synthesized on polyacrylonitrile nanofiber membranes via a sol-gel process. Filter structure consisted of a non-woven polyurethane-carbon substrate, polyacrylonitrile nanofiber and titanium dioxide nanoparticles. The concentration of methylene blue dye solution was measured via UV radiation. The filtration efficiency was calculated via Langmuir-Hinshelwood pseudo-first order equations. The results showed that the filtration efficiency of samples using titanium dioxide under UV rays was higher than those without titanium dioxide and UV rays in both immersing and cross-flow processes. Degradation efficiency of the cross-flow system was three times higher than that of immersing method. In the cross-flow process, the effect of three variables-pressure on the membrane, initial concentration of dye solution and pH of the dye solution was studied under UV rays. The highest efficiency obtained was 90.3% by using 1.5 bar pressure, 40 μM initial concentration and pH of 4.1.

Fabrication of green device for efficient capture of toxic methylene blue from industrial effluent based on K2Zn3[Fe(CN)6]2·9H2O nanoparticles reinforced gum xanthan-psyllium hydrogel nanocomposite

In the present work, the synthesis of novel device for the efficient removal of toxic cationic dye methylene blue (MB) from aqueous fluid was carried out. The device was fabricated by in-situ incorporation of K2Zn3[Fe(CN)6]2·9H2O nanoparticles into gum semi-IPN matrix in the presence of glutaraldehyde-ammonium persulphate as crosslinker–initiator system. The effect of several reaction variables such as time, solvent, temperature, pH, crosslinker, initiator concentration and monomer concentration on the fluid uptake capacity of the candidate sample was explored. The morphological and structural properties were studied using Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction studies. Thermal stability was evaluated by thermogravimetric analysis/differential thermal analysis/differential thermogravimetric analysis. Contact time, adsorbent dose and initial concentration of dye solution were optimized for maximum dye removal and it was ...

Batch and fixed-bed adsorption of tartrazine azo-dye onto activated carbon prepared from apricot stones

This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium (qe) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) were determined and the positive value of (ΔH) 78.1 (K J mol−1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R2 ≥ 94.

Factor Analysis on Adsorption Capacity of Industrial Sludge Based Activated Carbon on Dye Removal

The use of highly structured and robust activated carbons based on non-renewable and relatively expensive starting materials such as coal is unjustified in most pollution control applications. Hence activated carbons were prepared from three industrial sludge and they are named as sugar mill sludge activated carbon (SSAC), paper mill sludge activated carbon (PSAC) and tannery industry sludge activated carbon (TSAC). These carbons were used to remove reactive red dyes from dye solution by varying the dose of carbon, contact time, initial concentration of dye solution, particle size of carbon, pH and temperature of dye solution through batch experiments and their performance was investigated. Functional groups and chemical composition of carbons and dye were analyzed through Fourier transformed infra-red (FT-IR) spectroscopy and X-ray diffraction technique respectively. The adsorption capacity of carbons on dye removal was in the order of SSAC > PSAC > TSAC, which was well correlated to porosity and surface area of adsorbent. It was concluded from the factor analysis that the variables of performance of SSAC on dye removal from different concentrations of solution with different dosages were grouped into 2 factors while the variables of performance of PSAC and TSAC on dye removal were grouped into 3 and 4 factors respectively. The identified number of factors from factor analysis on dye removal by SSAC, PSAC and TSAC was 2, 3 and 4 and reveals that the adsorption capacity of carbon is better when the number of factor is less. Keywords: Adsorption, carbons, dosage, dye, equilibrium, optimum, sludge.

Enhanced photocatalytic activity of nanocomposites of TiO2 doped with Zr, Y or Ce polyoxometalates for degradation of methyl orange dye.

The synergistic effect of polyoxometalate (POM) and metal-doped TiO2 (metal = Zr, Y and Ce) was examined, to fabricate nanocomposites with enhanced photocatalytic activities toward the degradation of methyl orange (MO), as a model textile dye. A series of new nanocomposites, containing different loading amounts of H9Na3[WZn3(H2O)2(ZnW9O34)2].24H2O (HZnW) (10-30%) on each of the metal-doped TiO2 nanoparticles, were synthesized using impregnation method. The morphology and crystal phase of the as-prepared nanocomposites were investigated by various characterization techniques: Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray analysis and diffuse reflectance spectroscopy, indicating that the HZnW and metal-doped TiO2 had been successfully incorporated into the nanocomposite structure. The effects of parameters such as loading amount of HZnW, catalyst dose, pH and initial concentration of dye solution were investigated on the degradation kinetics and it was interestingly found that the prepared nanocomposites could efficiently degrade the MO dye in 5-7 min under UV light irradiation. The best results were obtained for the HZnW-Zr-TiO2 among the different nanocomposites. Also, control studies showed the superior photocatalytic properties of composites compared to that of the individual components. The facile preparation and their improved photocatalytic activities suggest that these materials can have a promising future for water and wastewater purifications.

Removal of reactive dyes from their aqueous solutions using Moringa oleifera seeds and Grewia venusta peel

Moringa oleifera seeds (MOS) and Grewia venusta peel (GVP) were used in this study as biosorbents. The adsorption behaviours on two dyes were investigated through batch experiments. The best conditions for the maximum indigo carmine removal (99%) were found to be at pH 2, with 0.5g of GVP and 150 mg/L as initial concentration of dye solution. In the same conditions at pH 5, the maximum removal was 85% when using MOS. The equilibrium adsorption data were fitted with the Freundlich model when using MOS (R2 = 0.9968) and Langmuir model when using GVP (R2 = 0.9957). In a methyl orange case, the adsorption capacity of MOS is 31.25 mg g−1 and the one of GVP is 5.78 mg g−1. In an indigo carmine case, the adsorption capacity of MOS is 91.74 mg g−1 and the one of GVP is 188.68 mg g−1. This study contributed to a better understanding of methyl orange and indigo carmine dyes removal process from aqueous media by M. oleifera seeds and highlighted the sorption properties of G. venusta peel which is rarely used as absorbents in adsorption process. According to the obtained results, MOS and GVP may be potentially used in industry as natural biosorbents for textile dying wastewater treatment.

Fly ash as low cost adsorbent for treatment of effluent of handmade paper industry-Kinetic and modelling studies for direct black dye

The handmade paper industry utilizes quantum of dyes for making bright colored handmade paper used for wedding cards, fancy and decorative paper, etc. A study has been conducted on adsorption of direct black dye (used extensively in handmade paper industry to make black colored handmade paper) on fly ash obtained from thermal power plant of Yamuna Nagar. The effluent has been characterized for pH, suspended solids, total solids and chemical oxygen demand. The batch and column studies have been conducted on the adsorption of direct black dye solution of different concentrations on fly ash at varying pH, dosage of fly ash, temperature, contact time, particle size fractions of fly ash and initial concentration of dye solution. In batch studies, it was observed that the experimental data fit well with Langmuir adsorption isotherm in comparison to Freundlich and Temkin isotherms. The maximum adsorption capacity of 76.33 mg/g was achieved at 318 K in batch studies. The column experimental data fitted well to Yoon–Nelson model and Thomas model in comparison to Bohart–Adams model. The maximum adsorption capacity of 45.54 mg/g in column study was obtained for 2.4 cm bed height, 150 ppm inlet concentration and 1.6 mL/min flow rate of dye solution. The calculations of thermodynamic parameters indicate that the adsorption of black dye on fly ash is spontaneous and endothermic in nature and follows first order kinetics with rate constant of 0.201 min−1. It has been found that fly ash is a potential low cost adsorbent to treat effluent of handmade paper industry. The exhausted fly ash can be further reused as filler in paper making and hence can offer a viable closed loop solution in curbing pollution from this predominantly small sector industry.

Decolourization of Rhodamine B from aqueous solution by electrochemical oxidation using graphite electrodes

This study investigated the colour removal efficiency of Rhodamine B (RhB) by electrochemical oxidation. The influences of various operating variables such as current density (from 5 to 25 mA/cm2), initial concentration of dye solution (from 50 to 250 mg/L), initial pH of solution (3, 5, 7, 9), the stirrer speed (150–300 rpm) and the concentration of electrolytes (0.025–0.10 M NaCl) on removal efficiency were explored in a batch mode treatment to achieve a higher removal capacity. The results obtained with synthetic wastewater revealed that the most effective removal of dye could be achieved when the pH was kept neutral. The results showed that the colour removal increases with the increase in applied current density, NaCl concentration, while it was found to decrease with the increase in initial dye concentration. The complete (100%) colour removal has been achieved under the optimal experimental conditions such as NaCl concentration of 0.05 M, applied current density of 15 mA/cm2, initial pH 7.0, stirrer speed of 200 rpm and electrolysis time of 40 min. The result of UV–vis spectrum analysis confirms the removal of colour from RhB aqueous solution at the short treatment time. In addition, the increase of current intensity, in the range of 0.6–2.0 A, enhanced the treatment rate. The method was found to be highly efficient and relatively fast compared to conventional treatment techniques.

Solar degradation of malachite green using nickel-doped TiO2 nanocatalysts

Malachite green (MG) is one of the most used dyes in textile industries. The aim of this research work was to degrade MG, a model dye, using nickel-doped TiO2 nanocatalysts. Nickel-doped TiO2 nanocatalysts were fabricated under mild hydrothermal conditions (p = autogenous, T = 100°C, and t = 12 h). Nickel oxide and n-butylamine were used as dopant and surface modifier, respectively. The samples dried were characterized using powder X-ray diffraction, zeta potential, SEM, and electron diffraction X-ray analysis. The batch experiments of MG degradation were performed under UV light and sunlight irradiation. The effect of operational parameters including nanocatalyst dosage, pH, contact time, initial concentration of dye solution, and light source were investigated systematically. It was found that nickel-doped TiO2 nanocatalysts had better solar degradation efficiency compared with bare TiO2 under both UV light and sunlight irradiation. The optimum solar degradation efficiency for MG dye solution was achieved at pH 8, nanocatalyst dosage = 1.2 g/l, contact time = 120 min, and initial dye concentration = 250 mg/l.

Adsorption of tannery anionic dyes by modified kaolin from aqueous solution

There are significant amounts of unused dyes remaining in wastewater from dyeing industry. The release of these effluents causes abnormal coloration of surface waters and there is a risk of toxicity. This research involved the efficient adsorption of anionic dyes (Coriacide Bordeaux 3B, Derma Blue R67, and Coriacide Brown 3J) used in tanning industry by local natural and treated clays; DD3 and KT2, a low-cost material abundant in highly weathered soils from Algerian East. The activated kaolins were characterized by chemical analyses, X-ray diffraction, and fourier transform IR scanning electron microscopy to obtain information about their structure and surface texture. The adsorption kinetics was investigated using the parameters such as contact time, clay nature, solution initial dye concentration, and acid activation. The adsorption capacity of all three dyes on local kaolinite clays exceeds 90% observed after 40–80 min. Compared with the adsorption experiments on Bentonite, the results show that kaolin has the best adsorption capacity for anionic dyes under the experimental conditions of this work.

Castor bean (Ricinus communis L.) presscake from biodiesel production: An efficient low cost adsorbent for removal of textile dyes

Castor bean (Ricinus communis L.) presscake, a byproduct derived from the biodiesel production process, was used in natura (CN) and thermally treated (CT) form as a natural and low-cost adsorbent for the removal of the dyes malachite green (MG) and tropaeolin (TP). The CN and CT were characterized by elemental analysis, infrared spectroscopy (FTIR), N2 adsorption/desorption and zeta potential. The effects of initial dye solution concentration, adsorbent mass/adsorbate volume ratio, initial pH of dye solution and contact time on MG and TP adsorption were studied using batch-type experiments a 25°C. The equilibrium adsorption was analysed by Langmuir, Freundlich, Sips, dual site Sips (DSS) and Dubinin–Radushkevich (D–R) isotherms. Kinetics data were evaluated by pseudo-first order and pseudo-second order models. The adsorption data of MG and TP dyes onto CN and CT were best fitted to the dual site Sips model. The maximum adsorption capacities were 37.10, 33.54, 18.60 and 55.98mgg−1 for the systems MG/CN, MG/CT, TP/CN and TP/CT, respectively. Pseudo-second order gives the better correlation to predict the kinetic process. The thermodynamic aspects were analysed.

The facile preparation of 5,10,15,20-tetrakis(4-carboxyl phenyl) porphyrin-CdS nanocomposites and their photocatalytic activity

Abstract The 5,10,15,20-tetrakis (4-carboxyl phenyl)-porphyrin-functionalized CdS nanocomposites (H2TCPP-CdS NCs) were successfully prepared by a facile one-step method under mild conditions and were extensively characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, UV–vis diffuse reflectance. Rhodamine B (RhB) dye, a common industrial pollutant, was used as a model pollutant to study its photocatalytic activity under exposure to solar light. The results showed that the as-prepared H2TCPP-CdS NCs exhibited enhanced photocatalytic activity for the degradation of RhB dissolved in water under exposure to solar light. The degradation efficiency of RhB catalyzed by the H2TCPP-CdS NCs under exposure to solar light is higher than when exposed to UV light. The degradation and decolorization of RhB were influenced by different amounts of porphyrin in preparation of H2TCPP-CdS NCs, the amount of catalyst, and the initial concentration of dye solution and pH. Moreover, the recycling experiments confirmed the relative stability and reutilization of the catalyst.

Silica Gel as an Adsorbent in the Removal of Cationic Blue X-Bl from Aqueous Solutions and its Regeneration by UV-Fenton Oxidation

The removal of cationic Blue X-BL in aqueous solution by adsorption of silica gel was investigated. Effects of pH, initial concentration of dye solution and temperature on the adsorption of Cationic Blue X-BL onto silica gel were studied. When the initial concentration of the blue dye was 100 mg/dm3, silica gel is 0.6 g at pH 9.3 and at 303 K, adsorption reached equilibrium after 2 h with the final adsorption quantity 16.38 mg/g. Fenton reaction with UV light was applied in the regeneration operation of silica gel which can transmit most of the UV light. The concentration of Fe2+ and H2O2 was evaluated and when the concentration of Fe2+ and H2O2 were 0.05 mmol/dm3 and 0.132 mol/dm3, the first, second, third and forth regeneration efficiency were 84.68 %, 82.05 %, 65.26% and 50.73 %, respectively. In order to improve the regeneration capacity and silica gels reuse times, acid washing was introduced in the forth regeneration after Fenton reaction, which can enhance the regeneration efficiency to 92.19%.

Adsorption characteristics for the removal of a toxic dye, tartrazine from aqueous solutions by a low cost agricultural by-product

Application of saw dust for the removal of an anionic dye, tartrazine, from aqueous solutions has been investigated. The experiments were carried out in batch mode. Effect of the parameters such as pH, initial dye concentration and temperature on the removal of the dye was studied. Equilibrium was achieved in 70min. Maximum adsorption of dye was achieved at pH 3. Removal percent was found to be dependent on the initial concentration of dye solution, and maximum removal was found to be 97% at 1mg/L of tartrazine. The removal increases from 71% to 97% when the initial concentration of dye solution decreases from 15mg/L to 1mg/L. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The (Langmuir) adsorption capacity of the adsorbent is found to be 4.71mg/g at 318K. Kinetic modeling of the process of removal was carried out and the process of removal was found to follow a pseudo second order model and the value of rate constant for adsorption process was calculated as 2.7×10−3gmg−1min−1 at 318K. The thermodynamic parameters such as change in free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were determined and the negative values of ΔG° indicated that the process of removal was spontaneous at all values of temperatures. Further, the values of ΔH° indicated the endothermic nature of the process of removal.

Fast and Efficient Removal of Cationic Dyes From Aqueous Solution by Collagen-Based Hydrogel Nanocomposites

A series of collagen-based hydrogel nanocomposites were prepared and applied as dye adsorbents. The certain variables affecting the dye adsorption such as initial concentration of dye solution, pH value, contact time and montmorilonite content were investigated to achieve maximum removal of Methylene Green (MG) and Crystal Violet (CV) from aqueous solutions. The experimental data showed that more than 90% of the maximum adsorption capacities of the optimized sample for MG and CV were achieved within the initial 10 min. Three isotherm models were carried out to describe adsorption capacity of the adsorbents.

Removal of methylene blue from aqueous solution by sorption on lignocellulose-g-poly(acrylic acid)/montmorillonite three-dimensional cross-linked polymeric network hydrogels

Batch lignocellulose-g-poly(acrylic acid)/montmorillonite (LNC-g-PAA/MMT) hydrogel nanocomposites were applied as adsorbents. The nanocomposites were characterized by FTIR, XRD, SEM, and TEM. The results showed that montmorillonite (MMT) could react with the monomers and change the structure of polymeric network of the traditional superabsorbent materials, an exfoliated structure was formed in the nanocomposites. The effect of process parameters such as MMT content (wt%), contact time (t), initial concentration of dye solution (C0), adsorption temperature (T), and pH value (pH) of the dye solution for the removal of methylene blue (MB) from aqueous solution were also studied. The results showed that the adsorption capacity for MB increased with increasing contact time, initial dye concentration, and pH value, but decreased with increasing MMT content and temperature. The adsorption kinetics were better described by the pseudo-second-order equation, and their adsorption isotherms were better fitted for the langmuir equation. By introducing 20 wt% MMT into LNC-g-PAA polymeric network, the obtaining hydrogel composite showed the high adsorption capacity 1994.38 mg/g and economic advantage for MB. The desorption studies revealed that the composite provided the potential for regeneration and reuse after MB dye adsorption, which implied that the composite could be regarded as a potential adsorbent for cationic dye MB removal in a wastewater treatment process.

Use of orange peel ash for removal of direct black 22 dye from aqueous environments

Background & objectives: The treatment of textile industries wastewater due to excessive coloring matter and pollution is one of the environmental health experts concerns. As, adsorption is one of the effective process in colorfully wastewater treatment. The aim of this study was surveying about introducing an inexpensive and available adsorbent capability, orange peel ash, in removal of Direct Black 22 Dye from aqueous environments. Material & Methods: In this study, orange peel ash was produced in vitro. The elimination of direct black 22 was studied in aqueous solution in a batch system by the adsorbent. Therefore, the effect of operational parameters such as contact time, pH, initial concentration of soluble dye Direct Black 22 and the adsorbent dosages were investigated. Measurements were performed using a UV-Visible spectrophotometer at a wavelength of 585.5 nm. Finally, adsorption isotherm and kinetic analyses were carried out. Results: data showed high selectivity and efficiency of orange peel ash to rapidly remove the color from solution and equilibrium was achieved within 90 minutes. Maximum removal of color (95.2%) was observed at pH=2. Adsorption efficiency was reduced with increasing initial concentration of dye solution and decreasing the adsorbent dose. Adsorption isotherm studies revealed the binding occurred within surface and correlated with the Freundlich model. Kinetic models indicated a correlation between the adsorption processes with the pseudo second kinetic model. Conclusion: pH affects the cell surface and on physical-chemical reactions and adsorption sites. At low concentrations of color soluble, adsorption sites absorbed dye more easily, but at higher concentrations colored ions must be penetrated into the inner places. According to the results, the carbon obtained from orange peel as an agricultural product, showed good performance for Direct Black 22 dye.

Application of activated carbon derived from ‘waste’ bamboo culms for the adsorption of azo disperse dye: Kinetic, equilibrium and thermodynamic studies

The utilization of activated carbon derived from 'waste' bamboo culms (BAC) for the removal of Disperse Red 167 (DR167), an azo disperse dye, was investigated. Studies of the properties of the adsorbent, the effect of contact time, the initial pH of the solution, the initial concentration of the dye solution and temperature indicated that a low initial pH or concentration of dye solution favors the adsorption process; temperature exerts a greater effect on the removal of azo disperse red 167 dye from aqueous solution. Kinetic and isotherm data were fitted to five non-linear kinetic and nine non-linear isotherm equations. In addition, the fits were evaluated in terms of the non-linear coefficient, Chi-square test, Marquardt's percent standard deviation error function and small-sample-corrected Akaike Information Criterion (AICc) methodology. The results showed that the AICc analysis was the best statistical tool for analyzing the data, the intra-particle diffusion and the pseudo-first-order models played important roles in the controlling rate step, and the Temkin equation best described the BAC isotherm data. Furthermore, the thermodynamic analysis indicated that the adsorption was a spontaneous, endothermic, entropy-increasing and physical process. Two types of commercial activated carbon, Filtrasorb 400 and Filtrasorb (F400 and F300), were used as contrast adsorbents. The contrast experiments revealed that BAC exhibits similar properties to F400 and F300. The utilization of bamboo wastes as carbon precursors is feasible.

Recyclable thin TiO2-embedded rubber sheet and dye degradation

A new method for the preparation of thin rubber sheet embedded with TiO2 from natural rubber latex is presented. This method – simple and inexpensive – is based on the use of TiO2 powder (Degussa P25) mixing with small amount of natural rubber latex (60% HA) followed by vacuum filtration through a sintered glass to form a thin paper-like and flexible sheet. The characteristic of this thin and flexible TiO2 sheet (FT sheet) thus formed was studied by X-ray diffractometer (XRD) and scanning electron microscopy/energy dispersive X-ray spectrometer (SEM/EDS) techniques. The photocatalytic activity of FT sheet was evaluated using indigo carmine (IC) dye as a model for the organic dye pollutant in water. The results showed that the FT sheet containing TiO2 5wt% has the highest degradation efficiency than sheets containing higher TiO2 concentrations. The effects of pH and initial concentration of dye solution on the photodegradation were also investigated. Kinetics of the photocatalytic degradation was of the first-order reaction. The used FT sheet can be recovered and reused with no decline in the photodegradation efficiency over a long-term usage.

Photocatalytic degradation of reactive black-5 dye using TiO2-impregnated activated carbon

The photocatalytic degradation of reactive black-5 (RB-5) dye was studied using hydrothermally prepared TiO2 impregnated on activated carbon (AC) (20%, 40% TiO2:AC). Photodegradation efficiency of the prepared TiO2:AC catalysts were studied and compared with the commercial TiO2 (P25). These catalysts were characterized by using X-ray diffraction and scanning election microscope techniques. The experimental results showed that the effect of TiO2 impregnation on AC helped to optimize the amount of TiO2 impregnated and the amount of catalyst used for the reaction. The effect of different parameters, such as the initial concentration of dye solution and the catalyst amount, on the rate of photodegradation was also studied. The reduction in the chemical oxygen demand (88%) proves the mineralization of the RB-5 dye along with the colour removal.