Increase In Initial Dye Concentration Research Articles

Synthesis of Polyvinyl Alcohol/Maleic Acid Hydrogels by Electron Beam Irradiation for Dye Uptake

Novel polyelectrolyte hydrogels based on maleic acid (MA) and polyvinyl alcohol (PVA) were prepared in the presence of electron beams irradiation as initiator and crosslinker. PVA was used as a template for the polymerization of MA in an aqueous solution. The effect of pH on swelling behavior of the hydrogels was examined. In particular, a reversible swelling behavior between acidic and alkaline solutions was investigated. The structure, thermal properties and morphologies of PVA/MA hydrogels were characterized by FTIR, DSC and SEM, respectively. The swelling ratios of gels increased with the increase MA content, pH values, but decreased with enhanced irradiation dose. PVA/MA has been utilized as an adsorbent for the removal of two textile dyes, Reactive red SH.B and Ismative violet 2R, as model dyes from aqueous solution. Factors affecting dye sorption were extensively investigated. The adsorption capacity for dyes increased with the increase of initial dye concentration, contact time, pH, temperature and MA content in the hydrogels. The equilibrium adsorption data were modeled using Langmuir and Freundlich adsorption isotherms. The results revealed that the adsorption of dyes onto PVA/MA hydrogel fit very well with Langmuir isotherm model.

Anionic dye (acid green 25) adsorption from water by using polyaniline nanotubes salt/silica composite

Acid green 25 (AG) dye was adsorbed from water by using polyaniline nanotubes (PANI NT) salt/silica composite as adsorbent. Comparison between the removal of the dye by using PANI NT salt/silica composite and the conventional PANI salt/silica composite was investigated. This result was evidenced from the measurements of the UV-visible absorbance of AG dye solutions after different times. Experiments were conducted by varying parameters, namely initial concentration of the dye and contact time. The percentage of color removal decreased with increase in initial dye concentration. Adsorption equilibrium of color removal was reached after 60 min of contact time. Equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherms, and their constants were determined. Using the linear correlation coefficients showed that the Langmuir isotherm best fits the AG adsorption data on PANI NT salt/silica composite. The experimental data were fitted into the following kinetic models: pseudo-first-order, pseudo-second-order, and the intraparticle diffusion model. It was observed that the pseudo-second-order kinetic model described the adsorption process better than any other kinetic models. The results obtained indicate that PANI NT salt/silica composite could be employed as a much more efficient adsorbent than the conventional PANI salt/silica composite for dye removal from water.

Sonochemical Decolourisation of Reactive Blue 21 and Acid Red 114 in the Presence of TiO<sub>2</sub> and Rare Earths

The ultrasonic decolourisation of two commonly used textile dyes, Acid Red 114 (AR 114) and Reactive Blue 21 (RB 21), with different chromophoric groups, azo and phthalocyanine respectively, has been studied using TiO2 (consisting of mixture of crystalline and amorphous phases) in the presence of rare earths ions (Pr3+, Ce4+). The characterisation of TiO2 has been done through X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, diffuse reflectance spectroscopy (DRS) and N2 adsorption techniques. The decolourisation of AR 114 was faster than for RB 21 under all the experimental conditions. Almost complete decolourisation of both dyes was achieved in 5 min in the presence of US+TiO2+Ce. Ce4+ was found to be more effective than Pr3+. The decolourisation reaction followed second order kinetics. The effects of initial dye concentration and amount of TiO2 on the decolourisation of dyes have been found to be in the order; US+TiO2+Ce > US+TiO2+Pr > US+Ce > US+Pr > US+TiO2 > TiO2 >US. The decolourisation rate increased with increase in TiO2 amount and decreased with increase in initial dye concentration.

Equilibrium, Kinetics, and Thermodynamics of Methylene Blue Adsorption by Pine Tree Leaves

The adsorption capacity of pine tree leaves for removal of methylene blue (MB) from aqueous solution was investigated in a batch system. The effects of the process variables, such as solution pH, contact time, initial dye concentration, amount of adsorbent, agitation speed, salt concentration, and system temperature on the adsorption process were studied. The extent of methylene blue dye adsorption increased with increase in initial dye concentration, contact time, agitation speed, temperature, and solution pH but decreased with increased in amount of adsorbent and salt concentration. Equilibrium data were best described by both Langmuir isotherm and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity of pine tree leaves biomass was 126.58 mg/g at 30 °C. The value of separation factor, R L , from Langmuir equation and Freundlich constant, n, both give an indication of favorable adsorption. The intrapartical diffusion model, liquid film diffusion model, double exponential model, pseudo-first and second order model were used to describe the kinetic and mechanism of adsorption process. A single stage bath adsorber design for the MB adsorption onto pine tree leaves has been presented based on the Langmuir isotherm model equation. Thermodynamic parameters such as standard Gibbs free energy (ΔG 0), standard enthalpy (ΔH 0), and standard entropy (ΔS 0) were calculated.

Biological treatment of wastewater containing an azo dye using mixed culture in alternating anaerobic/aerobic sequencing batch reactors

The performance of one stage anaerobic/aerobic processes for the biological treatment of synthetic wastewaters containing Acid Red 18 was studied. In addition, a method for evaluating dye mineralization using lumped parameters was investigated. The selected initial dye concentrations were 0, 35, 70, 140, and 280 mg/L, in reactors R1 ∼ R5, respectively. This study showed that average COD removal was not lower than 85% while the remaining COD originated from Acid Red 18 and its degradation products. The majority of the dye removal occurred in the anaerobic phases and the aerobic phase contributions were insignificant. The kinetics data of dye removal showed that the increase in initial dye concentration (35 ∼ 280 mg/L) caused a decrease in first-order kinetic rate constants (0.0593 ∼ 0.0384/h). The overall mineralization of AR 18 dye was at least 44, 35, 13, and 0% in R2 ∼ R5, respectively. Increase in initial dye concentrations had no significant effect on sludge characteristics.

Enhancing Adsorption of Dyes onto Clay in Bubble Column Adsorber

Herein, we studied the adsorption of acid dye onto Yemen natural clay in a bubble column adsorber. In addition, the effect of different parameters such as air flow rate, initial dye concentration and clay mass on the adsorption using clay has been investigated. The external and internal mass transfers were analyzed based on external mass transfer and intra-particle diffusion models. Our results showed that the calculated external mass transfer coefficient increased with the increase in air flow rate and mass of clay, but decreased with the increase in initial dye concentration. For the external mass transfer, different coefficient variables can be correlated by the following dimensionless correlation: Sh/Sc0.33 = 261.65 (F)0.165 (C0)-0.743 (m)-0.311. The intra-particle diffusion coefficient, KP, was found to increase with the increase in air flow rate and initial dye concentration, and with the decrease in the mass of clay. For the intra-particle diffusion, the studied variables can be correlated by the e...

Papaya (Carica papaya L.) Leaf Powder: Novel Adsorbent for Removal of Methylene Blue from Aqueous Solution

Batch sorption experiments were carried out to investigate the potentiality of papaya leaf powder (PLP) for the removal of methylene blue (MB) from aqueous solution. The effects of various experimental parameters, such as adsorbent dose, initial solution concentration, contact time, and solution pH were also studied. The amount of dye adsorbed was found to increase with increase in initial dye concentrations. Papaya leaf adsorbs MB better in basic medium. The adsorption equilibrium data fitted well in the Langmuir isotherm equation with a monolayer sorption capacity of 512.55 mg g−1. The kinetics of MB adsorption onto papaya leaf was examined using the pseudo-first and pseudo-second order and unified approach kinetic models. The adsorption kinetics followed the pseudo-second order kinetic model, but the rate constant was found to depend on initial dye concentration. The unified approach model described the equilibrium and kinetics well. The forward and backward rate constants were determined from the unified approach model.

Kinetics and isotherm studies of methylene blue adsorption onto polyaniline nanotubes base/silica composite

A cationic dye, such as methylene blue (MB), was adsorbed from water by using polyaniline nanotubes (PANI NTs) base/silica composite as adsorbent. Experiments were conducted by using the UV–visible spectroscopy and by varying parameters namely: initial concentration of MB and contact time. The percentage of color removal decreased with increase of initial dye concentration. Equilibrium data were fit to Langmuir isotherm. The Langmuir isotherm fits best the MB adsorption data on PANI NTs base/silica composite.The kinetic models: pseudo first order, pseudo-second order and the intraparticle diffusion models were applied to the experimental data. It was observed that pseudo-second order kinetic model described the adsorption process better than any other kinetic models. Results obtained indicate that PANI NTs base/silica composite could be employed as an efficient adsorbent much more than the conventional PANI base/silica composite powder for dye uptake.

Removal of anionic dyes from aqueous solutions by adsorption of chitosan-based semi-IPN hydrogel composites

Semi-IPN hydrogel composites for dye adsorption studies were prepared via photopolymerization of poly(ethylene glycol) (PEG) macromer and acrylamide (AAm) monomer in the presence of chitosan (CS). Swelling properties and kinetics of the hydrogel composites were investigated in aqueous solution and Acid Red 18 (AR 18) solution. The adsorption studies showed that the adsorption capacity for AR 18 increased with the increase of initial dye concentration and chitosan content in the hydrogels, but decreased with the increase of pH and ionic strength of dye solutions. Absorption kinetics of AR 18 followed pseudo second-order kinetic model at pH 2.0. The adsorption capacities for Acid Orange 7 (AO 7), Methyl Orange (MO) and Basic Violet 14 (BV 14) were also examined at pH 2.0, and the equilibrium adsorption data of AR 18, AO 7 and MO well fitted the Langmuir isotherm. The hydrogel composites could be potentially used as absorbents for anionic dye removal in wastewater treatment process.

Adsorption of Remazol Brilliant Blue R on activated carbon prepared from a pine cone

In this work the activated pine cone was investigated as adsorbent to remove Remazol Brilliant Blue R from aqueous solution. The effects of various experimental parameters such as initial dye concentration, contact time, temperature, adsorbent dose and pH were examined. The adsorption of Remazol Brilliant Blue R from aqueous solution was increased with the increase in initial dye concentration, contact time, temperature, adsorbent dose but decreased with the increase in the pH. The results in this study indicated that the activated pine cone was an attractive candidate for removing Remazol Brilliant Blue R.

Equilibrium Uptake and Bioaccumulation of Basic Violet 14 Using Submerged Macrophyte Hydrilla verticillata

AbstractThe percentage removal and uptake capacity of Basic Violet 14 using Hydrilla verticillata with living biomass was studied under batch conditions. The survival of H. verticillata was studied using the chlorophyll content in the living biomass. Bioaccumulation of Basic Violet 14 using H. verticillata was tested by varying the wet sorbent dosage (0.5–2.5 g), initial pH (3–8), and initial dye concentrations (5–25 mg L−1). The results show that the plant was effectively accumulating the Basic Violet 14 dye. The uptake capacity of Basic Violet 14 dye was observed as 5.9 and 21.3 mg g−1 at the initial dye concentration of 5 and 25 mg L−1, respectively, for a biomass of 5 g L−1 (wet weight) at pH 7.0 for 144 h. In general, the plant growth was found to be normal at lower concentrations and showed higher removal efficiency. It was also observed that removal efficiency of H. verticillata was found to decrease with increase in initial dye concentration. The biomass sample surface was analyzed using SEM imaging and functional groups present in the biomass were analyzed using FTIR. The equilibrium uptake capacity was analyzed by Langmuir and Freundlich isotherms. The equilibrium data was found to be fit well to both Langmuir and Freundlich isotherm models with higher coefficient of determination.

Adsorption of Cationic Dye (Methylene Blue) from Water Using Polyaniline Nanotubes Base

Polyaniline nanotubes (PANI NTs) base has been utilized as an adsorbent for the removal of cationic dyes such as methylene blue (MB) from aqueous solution. This observation was evidenced from the measurements of quartz crystal microbalance (QCM) and UV−visible spectroscopy. Experiments were conducted by varying parameters of initial concentration of MB and contact time. The percentage of color removal decreased with the increase of initial dye concentration. Adsorption equilibrium of the dye was reached after 120 min of contact time. Equilibrium data were fit to Langmuir, Freundlich, and Tempkin isotherms, and their constants were determined. The linear correlations coefficient showed that the Langmuir isotherm best fits the MB adsorption data on PANI NTs. The pseudo-first-order, pseudo-second-order, and the intraparticle diffusion kinetic models were applied to the experimental data. It was observed that the pseudo-second-order kinetic model described the adsorption process better than any other kinetic model. Results obtained indicate that PANI NTs could be employed as an efficient adsorbent much more than the conventional PANI powder for dye removal from water.

A comparison study on Acid Red 119 dye removal using two different types of waterworks sludge

This study aims to compare the performance of two waterworks sludge samples, ferric chloride sludge (FCS) and polyaluminium chloride sludge (PACS), as coagulants to remove Acid Red 119 (AR119) dye from aqueous solution. A series of batch experiments were performed to investigate the effect of initial pH, coagulant dosage and initial dye concentration on coagulation/flocculation process efficiency. Results showed that the dye removal was strongly pH-dependent and followed the same trend for both coagulants, increasing steadily with decreasing initial pH in the range of 3-12. With the increase of coagulant dosage, the dye removal efficiency increased and no re-stabilization phenomenon was observed. However, the coagulant dosage needed for the maximum dye removal efficiency was much lower for FCS (150 mg dried sludge/L) in compare with PACS (5.5 g dried sludge/L). It seems that both charge neutralization and sweep flocculation mechanisms were involved in removal of AR119 using FCS and PACS. With the increase of initial dye concentration, Q (the amount of the removed dye per unit mass of coagulant) steadily increased and reached to a maximum value of 0.96 mg dye/mg sludge and 0.029 mg dye/mg sludge for FCS and PACS, respectively. FCS was more effective than PACS for AR119 dye removal due to the higher amount of dye removed per unit mass of sludge.

Photocatalytic activity of surface fluorinated TiO 2-P25 in the degradation of Reactive Orange 4

Photocatalytic activity of surface fluorinated TiO 2-P25 (F-TiO 2-P25) in the degradation of a chlorotriazine azo dye Reactive Orange 4 (RO 4) under ambient conditions was investigated in this study. Characterization of F-TiO 2-P25 reveals that the catalyst has a strong absorption in the UV range and the presence of F atom in the catalyst. The degradation rate of RO 4 with surface fluorinated TiO 2-P25 is three times faster than bare TiO 2-P25. The quantum yield of UV/TiO 2-P25 process is largely decreased by the increase of initial dye concentration, whereas in UV/F-TiO 2-P25 process, the influence of initial dye concentration is less. Surface fluorination of TiO 2-P25 enhanced the adsorption of RO 4 dye, while improving overall degradation rate. The optimum operating conditions of UV/F-TiO 2-P25 process for efficient degradation are reported.

Removal of Brill Red 5B from an aqueous solution using Cicca acida biomass

AbstractThe biosorption of Brill Red 5B from an aqueous solution, using Cicca acida plant's leaves was investigated in a batch system with the influence of pH (1–6), temperature (25–35°C) and initial dye concentration (10–100 mg/L). Maximum biosorption was observed at initial pH of 2.0, temperature of 30°C and at the initial dye concentration of 100 mg/L. Batch biosorption kinetic was studied using the pseudo first and pseudo‐second‐order rate equations. From the result, it was observed that pseudo‐second‐order rate expression fitted the experimental data well when compared to pseudo first order kinetic model. The intra‐particle diffusion coefficient (Ki) and effective diffusion coefficient (Di) values obtained for the sorption of Brill Red 5B using C. acida plant's leaves were found to be increased with increase in initial dye concentration.

Degradation of C.I. Acid Orange 7 by ultrasound enhanced heterogeneous Fenton-like process

The effect of ultrasonic power density, goethite addition, hydrogen peroxide concentration, initial pH, hydroxyl radical scavenger, and initial dye concentration on the decolorization of C.I. Acid Orange 7 by ultrasound/goethite/H 2O 2 process was investigated. The results showed that the decolorization rate increased with power density, goethite addition, and hydrogen peroxide concentration, but decreased with the increase of initial dye concentration. The ultrasonic power density, goethite addition, and initial dye concentration have little effect on decolorization efficiency after 30 min reaction, while the increase of hydrogen peroxide concentration results in the increase of decolorization efficiency. There existed an optimal initial pH to achieve the highest decololrization rate and decolorization efficiency. The presence of hydroxyl radical scavenger would inhibit the decolorization reaction. Only less than half of total organic carbon (TOC) was removed after 90 min reaction, indicating more aggressive conditions are required to achieve the complete mineralization than those employed to simply break the chromophore group.

Photocatalytic degradation of Allura red and Quinoline yellow with Polyaniline/TiO2 nanocomposite

A series of polyaniline/TiO2 (PANI/TiO2) composites has been prepared from aniline and TiO2 under various polymerization conditions. Among these conditions are the concentrations of aniline, ammonium persulfate, HCl, sodium dodecyl sulfate, and the amount of TiO2. More composites were obtained by replacing HCl with H2SO4, H3PO4, and HNO3 as dopant acids. Scanning electron microscopy, UV/vis-diffuse reflectance spectroscopy, FTIR and TGA were used to characterize some of these composites. The rate of degradation of dyes with these composites followed first-order kinetics in the dye concentration. The activity of the composite towards the degradation process differs according to the experimental polymerization conditions. The activity increased with the increase in the concentration of aniline monomer and persulfate, but decreased with increasing the concentration of HCl, sodium dodecyl sulfate, and the amount of TiO2. The activity of composites formed in the presence of different acids followed the order H2SO4>H3PO4>HCl>HNO3. The rate of composite/dye interaction was enhanced with the UV-irradiation, increasing load of composite, and temperature. It was retarded with the increase in initial dye concentration and pH. The activation parameters were determined and a plausible mechanism was proposed.

Coagulation/flocculation of dye-containing solutions using polyaluminium chloride and alum

This study aims to compare the performance of Polyaluminium Chloride (PAC) and alum as coagulants to remove a specific type of dye (Acid Blue 292 (AB292)) from dye-containing solution. For this purpose, the influence of pH, coagulant dosage, coagulant aids (kaolinite and bentonite), and initial dye concentration on dye removal efficiency were examined. According to the results, removal of AB292 was absolutely dependent on the pH variations. The maximum dye removal occurred when pH was 7 and 5 for PAC and alum, respectively. Both coagulants efficiently removed the dye (about 85%) with a relatively low dosage (40 mg/l) in their optimum pH range. By adding kaolinite as a coagulant aid, the removal efficiencies tended to increase, especially for lower dosages of PAC and alum. With the increase of initial dye concentration, PAC and alum represented different behaviors. In the case of PAC, Q (the amount of the removed dye per unit mass of coagulant) increased at first and reached to a maximum value, 2.1 mg dye/mg PAC, and then decreased rapidly. While for alum, Q steadily increased with the increase of dye concentration and reached to 2.8 mg dye/mg alum. No reduction of Q occurred for alum with the increase of dye concentration in the range of 25-250 mg/l.

Degradation studies of Rhodamine B in the presence of UV/H 2O 2

The photo-oxidation of Rhodamime B was carried out in the presence of H 2O 2 using UV light. The effects of dye concentration, pH, H 2O 2 dose and irradiation time were studied. These parameters strongly influenced the degradation of the dye. As expected, the increase of initial dye concentration decreased the percentage decoloration. Likewise increasing H 2O 2 concentration also increased the dye decoloration upto a certain limit after which it starts decreasing. The optimum operating conditions of the method were found to be [Dye] = 10 μM; [H 2O 2] = 1.67 mM at pH 7. Under these conditions, a maximum of 73% decoloration of the dye was achieved. The decoloration pattern obeyed the first-order kinetics and was used to calculate apparent rate constants for dye decoloration. The actual breakdown of the dye was confirmed using HPLC and GC/MS analyses. Preliminary results show that the low molecular weight aliphatic alcohols and acids are some of the degradation products of Rhodamine B. The influence of dye assisting chemicals such as NaCl, NaNO 3, Na 2SO 4 and Na 2CO 3 on photodecoloration of the dye was also investigated. Addition of these chemicals inhibited the percent decoloration as well as the rate of dye degradation. The reaction mechanism is discussed in terms of OH • radical scavenging by these ions.

The Study of Sorption of Toxic Basic Dyes from Aqueous Solutions on H2O 2 Treated Recycled Wool-based Nonwoven Material and Related Toxicity Analysis

The aim of this study was to investigate the potential use of recycled wool-based nonwoven material for removal of basic dyes C.I. Basic Yellow 28 and C.I. Basic Red 46 from aqueous solutions. To improve the sorption properties, the recycled wool-based nonwoven material was treated with hydrogen peroxide. The sorption capacity, the sorption kinetics, and the influence of initial dye concentration and pH on the sorption were studied. The acute toxicity of dyes was evaluated using a ToxAlert® 100 biological test, which is based on inhibition of the bioluminescence of Vibrio fischeri . The percent of inhibition ( %I) before and after the sorption, 50 % effective concentration ( EC50) and toxicity units ( TU) were determined. The results indicated that recycled wool-based nonwoven material can be used as an efficient sorbent for removal of investigated basic dyes. Hydrogen peroxide treatment considerably improved the sorption properties of the material for both dyes. The sorption kinetics of dyes on the hydrogen peroxide treated material obeyed pseudo-second order kinetic model. The Freundlich sorption isotherm was found to represent well the experimental sorption data. The increase of initial dye concentration and pH positively affected the sorption of basic dyes. An ion exchange mechanism of dye sorption was confirmed by desorption studies. The toxicity decreased after the sorption of both dyes.