Adsorption of dissolved Reactive red dye from aqueous phase onto activated carbon prepared from agricultural waste

The adsorption of Reactive red dye (RR) onto Coconut tree flower carbon (CFC) and Jute fibre carbon (JFC) from aqueous solution was investigated. Adsorption studies were carried out at different initial dye concentrations, initial solution pH and adsorbent doses. The kinetic studies were also conducted; the adsorption of Reactive red onto CFC and JFC followed pseudosecond-order rate equation. The effective diffusion coefficient was evaluated to establish the film diffusion mechanism. Quantitative removal of Reactive red dye was achieved at strongly acidic conditions for both the carbons studied. The adsorption isotherm data were fitted well to Langmuir isotherm and the adsorption capacity were found to be 181.9 and 200 mg/g for CFC and JFC, respectively. The overall rate of dye adsorption appeared to be controlled by chemisorption, in this case in accordance with poor desorption studies.     

铜离子和亚甲蓝在柠檬酸酯化麦草上的吸附行为

以固相酯化法制备一种具有羧基的柠檬酸改性麦草阳离子吸附剂.用批次实验法研究了不同实验条件下(pH值、吸附剂量、吸附质浓度和吸附时间)水溶液中铜离子和亚甲蓝在酯化麦草上的吸附行为.结果表明：溶液初始pH≥40时,铜离子和亚甲蓝达到最大吸附值.≥2.0 g·L^-1的酯化麦草能去除铜浓度为100 mg·L^-1溶液中96%的铜及亚甲蓝浓度为250 mg·L^-1溶液中99%的亚甲蓝.酯化麦草对铜离子和亚甲蓝的吸附符合Langmuir等温模型,其最大吸附能力分别为79.37 mg·g^-1和312.50 mg·g^-1.铜离子和亚甲蓝达到吸附平衡的时间分别为75 min和5 h,准一级和准二级反应动力学方程可分别描述酯化麦草对铜离子和亚甲蓝的吸附过程.     

Biosorption of a reactive dye (Rhodamine-B) from an aqueous solution using dried biomass of activated sludge

Low cost, locally available biomaterial was tested for its ability to remove reactive dyes from aqueous solution. Granules prepared from dried activated sludge (DAS) were utilized as a sorbent for the uptake of Rhodamine-B (Rh-B) dye. The effects of various experimental parameters (dye concentration, sludge concentrations, swelling, pretreatment and other factors) were investigated and optimal experimental conditions were ascertained. Nearly 15min was required for the equilibrium adsorption, and Rh-B dyes could be removed effectively. Dye removal performance of Rh-B and DAS increased with increasing concentrations. The acid pretreated biomass exhibited a slightly better biosorption capacity than alkali pretreated or non-pretreated biomass. The optimum swelling time for dye adsorption of the DAS within the swelling time range studied was 12h. Both the Freundlich and Langmuir isotherm models could describe the adsorption equilibrium of the reactive dye onto the activated sludge with the Langmuir isotherm showing the better agreement of the two. Second-order kinetic models confirmed the agreement.     

Utilization of ground eggshell waste as an adsorbent for the removal of dyes from aqueous solution

The adsorption of cationic basic blue 9 and anionic acid orange 51 from aqueous solution onto the calcified eggshell (ES) and its ground eggshell powder (ESP) was carried out by varying the process parameters such as agitation speed, initial dye concentration, adsorbent mass and temperature. The adsorption potential for basic blue 9 onto ESP is far lower than that for acid orange 51, mainly due to the ionic interaction between the acid dye with the sulfonate groups and the positively charged sites on the surface of ESP. The adsorption capacity of acid orange 51 onto ES is significantly smaller than that onto ESP, which is in line with their pore properties (i.e., 1 vs. 21 m(2)/g). The experimental results showed that the adsorption process can be well described with a simple model, the pseudo-second-order model. According to the equilibrium adsorption capacity from the fitting of pseudo-second order reaction model, it was further found that the Freundlich model yields a somewhat better fit than the Langmuir model in the adsorption of acid orange 51 onto ESP. In addition, an increase in adsorption temperature from 15 to 45 degrees C significantly enhances the adsorption capacity of acid orange 51 onto ESP, revealing that the adsorption should be an endothermic or chemisorption process. From the results, it is feasible to utilize the ground eggshell waste as an effective adsorbent for removal of anionic dye from aqueous solution.     

Adsorption of methylene blue dye from aqueous solution by sugar extracted spent rice biomass

This study was aimed at using sugar extracted spent rice biomass (SRB) as a potential adsorbent to remove methylene blue (MB) dye from aqueous solution. The SRB was used without any modification. A three factor full factorial experimental design (2(3)) was employed to investigate the effect of factors (adsorbent dose, dye concentration, temperature) and their interaction on the adsorption capacity and color removal. Two levels for each factor were used; adsorbent dose (0.25-0.5g/100mL), dye concentration (25-50mg/L), and temperature (25-45°C). Initial dye concentration and adsorbent dosage were found as significant factors for the adsorption of MB dye. Langmuir isotherm (R(2)>0.998) best explained the equilibrium of MB adsorption on SRB with monolayer adsorption capacity of 8.13mg/g. The pseudo-second order model (R(2)>0.999) was best fitted to explain the adsorption kinetics. Thermodynamic investigation revealed that the adsorption process was spontaneous, endothermic, and was feasible to treat dyeing wastewater.     

A sustainable process for adsorptive removal of methylene blue onto a food grade mucilage: kinetics,thermodynamics, and equilibrium evaluation

Abstract

Adsorption of dyes onto natural materials like polysaccharides is considered a green chemistry approach for remediation of wastewater. In this work, the polysaccharide isolated from the corm of Colocasia esculenta (L.) Schott or taro tuber (CEM) was utilized for removing methylene blue (MB) from aqueous solution by batch adsorption method. The CEM adsorbent was characterized by FTIR spectroscopy, Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM). The solution pH and adsorbent dose have been found to have a significant positive correlation with the adsorptive removal efficiency of CEM for MB dye. The removal efficiency of CEM was found to be 72.35% under the optimum conditions; 20?mg/L initial concentration of dye, 120?mg of adsorbent dose, solution pH 8.5, 311.2?K temperature and 80?min contact time. The adsorption of MB onto CEM followed best the Freundlich isotherm and pseudo-second-order kinetics. The adsorption was thermodynamically favorable and was endothermic in nature. The desorption/adsorption data justifiably indicated the reuse capability of CEM adsorbent for MB adsorption. Hence, CEM may be regarded as an eco-friendly and cost-effective natural adsorbent for MB dye removal from aqueous solution.     

Removal of Astrazon Yellow 7GL from aqueous solutions by adsorption onto wheat bran

Adsorption kinetic and equilibrium of a basic dye (Astrazon Yellow 7GL) from aqueous solutions at various initial dye concentration (50-300 mg/l), pH (4-10), adsorbent dosage (2-8 g/l), particle size (354-846 microm) and temperature (30-50 degrees C) on wheat bran were studied in a batch mode operation. The result showed that the amount adsorbed of the dye increased with increasing initial dye concentration and contact time, whereas particle size and pH had no significant affect on the amount of dye adsorbed by the adsorbent. A comparison of kinetic models on the overall adsorption rate showed that dye/adsorbent system was best described by the pseudo second-order rate model. The removal rate was also dependent on both external mass transfer and intra-particle diffusion. The low value of the intraparticle diffusivity, 10(-11) cm2/s, indicated the significant influence of intraparticle diffusion on the kinetic control. The adsorption capacity (Q0) calculated from the Langmuir isotherm was 69.06 mg/g for at pH 5.6, 303 K for the particle size of 354 microm. The experimental data yielded excellent fits with Langmuir and Tempkin isotherm equations. Different thermodynamic parameters showed that the reaction was spontaneous and endothermic in nature.     

Fabrication of hybrid biosorbent nanoscale zero-valent iron-Sargassum swartzii biocomposite for the removal of crystal violet from aqueous solution

A novel nanoscale zero-valent iron-Sargassum swartzii (nZVI-SS) biocomposite was synthesized and evaluated for its ability to adsorb crystal violet (CV) from aqueous solutions. Involvement of various functional groups of the biosorbent in preferential adsorption of cationic dye was observed using Fourier transform infrared (FTIR) spectroscopy. Morphological changes occurring on the biocomposite materials were characterized using scanning electron microscopy (SEM). Significant increase (～90%) in the biosorption of cationic dye was observed with gradual increase in pH of the medium from 3 to 12. The effect of biosorbent concentration, initial pH, temperature, agitation rate, adsorption time, and initial dye concentration was studied for the biosorption of CV using nZVI biocomposite. During the optimization study, maximum biosorption capacity was observed at pH of 8. At various initial CV concentrations (20–100 mg/L), attainment of batch sorption equilibrium was observed within 120 min of reaction time. The Langmuir isotherm model expressed high coefficient of determination (R² = 0.999). The maximum dye uptake of 200 mg/g was reported at pH 8. Kinetics and temperature profiles were evaluated and reported. Desorption study was carried out with 0.1 M HCl. Investigations proved that nZVI-SS is an excellent biosorbent for the sequestration of CV in aqueous media.     

Biosorption of reactive dye by waste biomass of Nostoc linckia

Potential of spent biomass of a cyanobacterium, Nostoc linckia HA 46, from a hydrogen bioreactor was studied for biosorption of a textile dye, reactive red 198. The waste biomass was immobilized in calcium alginate and used for biosorption of the dye from aqueous solution using response surface methodology (RSM). Kinetics of the dye in aqueous solution was studied in batch mode. Interactive effects of initial dye concentration (100-500 mg/L), pH (2-6) and temperature (25-45 °C) on dye removal were examined using Box-Behnken design. Maximum adsorption capacity of the immobilized biomass was 93.5 mg/g at pH 2.0, initial concentration of 100 mg/L and 35 °C temperature, when 94% of the dye was removed. Fourier transform infrared (FT-IR) studies revealed that biosorption was mainly mediated by functional groups like hydroxyl, amide, carboxylate, methyl and methylene groups present on the cell surface.     

Adsorption of cationic dye from aqueous solutions by date pits: Equilibrium,kinetic, thermodynamic studies,and batch adsorber design

The retention profile of methylene blue from aqueous solutions onto the solid adsorbent date pits has been investigated in a batch system. The characterization and adsorption efficiency for methylene blue was evaluated using date pits. Fourier Transform Infra-Red, Scanning Electron Microscope, Brunauer–Emmett–Teller analysis were performed to determine the characteristics of the material. The effect of contact time, initial dye concentration, adsorbent dosage, temperature, and solution pH were investigated. The adsorption was found to increase with increasing time, decreasing concentration of dye, decreasing temperature and increasing dosage up to equilibrium values which was 20 min, 25°C, and 0.1 g adsorbent, respectively. The adsorption was favorable at high and low pH (pH 3, pH 7). The adsorption equilibrium data were best fitted by Freundlich isotherm. The adsorption kinetics was found to follow the pseudo second order kinetic model. Thermodynamic parameters such as free energy, enthalpy, and entropy were calculated and found to be ?4.6 kJ/mole, ?7.9 kJ/mole, and ?11.8 kJ/mole, respectively. The thermodynamic parameters of the uptake of methylene blue onto the date pits indicated that, the process is exothermic and proceeds spontaneously at low temperature. A single stage batch adsorber was designed for adsorption of methylene blue by Date Pits based on optimum isotherm.     

Utilization of modified silk cotton hull waste as an adsorbent for the removal of textile dye (reactive blue MR) from aqueous solution

Carbon prepared from silk cotton hull was used to remove a textile dye (reactive blue MR) from aqueous solution by an adsorption technique under varying conditions of agitation time, dye concentration, adsorbent dose and pH. Adsorption depended on solution pH, dye concentration, carbon concentration and contact time. Equilibrium was attained with in 60 min. Adsorption followed both Langmuir and Freundlich isotherm models. The adsorption capacity was found to be 12.9 mg/g at an initial pH of 2+/-0.2 for the particle size of 125-250 microm at room temperature (30+/-2 degrees C).     

Biosorption of reactive dyes by dried activated sludge: equilibrium and kinetic modelling

The biosorption of reactive dyes (Reactive Blue 2 - RB2 and Reactive Yellow 2 - RY2) onto dried activated sludge was investigated. The dye binding capacity of biosorbent was shown as a function of initial pH, initial dye concentration and type of dye. The equilibrium data fitted very well to both the Freundlich and Langmuir adsorption models. The results showed that both the dyes uptake processes followed the second-order rate expression.     

Sorption of Acid Blue 9 Using Hydrilla verticillata Biomass—Optimization,Equilibrium, and Kinetics Studies

In the present study, the parameters, temperature, adsorbent dose, contact time, adsorbent size, and agitation speed were optimized for Acid Blue 9 removal from aqueous medium by Hydrilla verticillata biomass using response surface methodology (RSM). The optimum conditions for maximum removal of Acid Blue 9 from an aqueous solution of 100 mg/L were as follows: temperature 30.63°C, adsorbent dose 2.88 g/L, contact time 180 min, adsorbent size 120 mesh (0.124 mm), and agitation speed 237.39 rpm. At these optimized conditions, batch adsorption experiments were conducted to study the effect of pH and initial dye concentration for the removal of Acid Blue 9 dye. The optimum initial pH and initial dye concentration values for Acid Blue 9 removal were found to be 3.0 and 100 mg/L, respectively. Kinetic and equilibrium studies were carried out for the experimental results. From the kinetic studies it was found that pseudo-second-order kinetics suits the system well. From the equilibrium studies, the Freundlich isotherm fits the data well.     

Removal of Cr(VI) from aqueous solutions by adsorption onto hazelnut shell activated carbon: kinetic and equilibrium studies

The adsorption Cr(VI) from aqueous solutions onto hazelnut shell activated carbon was carried out by varying the parameters such as pH, initial Cr(VI) concentration and temperature. The experimental data fitted well to the pseudo first-order kinetic model and then the rate constants were evaluated. The Langmuir isotherm provided the best correlation for Cr(VI) onto the activated carbon. Adsorption capacity was calculated from the Langmuir isotherm as 170 mg/g at an initial pH of 1.0 for the 1000 mg/l Cr(VI) solution. Thermodynamic parameters were evaluated and the adsorption is endothermic showing monolayer adsorption of Cr(VI).     

Kinetic and Equilibrium Studies of Cr(VI) Biosorption by Dead <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> Biomass

Many studies have been carried out on the biosorption capacity of different kinds of biomass. However, reports on the kinetic and equilibrium study of the biosorption process are limited. In our experiments, the removal of Cr(VI) from aqueous solution was investigated in a batch system by sorption on the dead cells of Bacillus licheniformis isolated from metal-polluted soils. Equilibrium and kinetic experiments were performed at various initial metal concentrations, pH, contact time, and temperatures. The biomass exhibited the highest Cr(VI) uptake capacity at 50°C, pH 2.5 and with the initial Cr(VI) concentration of 300 mg/g. The Langmuir and Freundlich models were considered to identify the isotherm that could better describe the equilibrium adsorption of Cr(VI) onto biomass. The Langmuir model fitted our experimental data better than the Freundlich model. The suitability of the pseudo first-order and pseudo second-order kinetic models for the sorption of Cr(VI) onto Bacillus licheniformis was also discussed. It is better to apply the pseudo second-kinetic model to describe the sorption system.     

Immobilization of blue green microalgae on loofa sponge to biosorb cadmium in repeated shake flask batch and continuous flow fixed bed column reactor system

Summary An indigenous strain of blue green microalga, Synechococcus sp., isolated from wastewater, was immobilized onto loofa sponge discs and investigated as a potential biosorbent for the removal of cadmium from aqueous solutions. Immobilization has enhanced the sorption of cadmium and an increase of biosorption (21%) at equilibrium was noted as compared to free biomass. The kinetics of cadmium biosorption was extremely rapid, with (96%) of adsorption within the first 5 min and equilibrium reached at 15 min. Increasing initial pH or initial cadmium concentration resulted in an increase in cadmium uptake. The maximum biosorption capacity of free and loofa immobilized biomass of Synechococcus sp. was found to be 47.73 and 57.76 mg g⁻¹ biomass respectively. The biosorption equilibrium was well described by Langmuir adsorption isotherm model. The biosorbed cadmium was desorbed by washing the immobilized biomass with dilute HCl (0.1 M) and desorbed biomass was reused in five biosorption–desorption cycles without an apparent decrease in its metal biosorption capacity. The metal removing capacity of loofa immobilized biomass was also tested in a continuous flow fixed-bed column bioreactor and was found to be highly effective in removing cadmium from aqueous solution. The results suggested that the loofa sponge-immobilized biomass of Synechococcus sp. could be used as a biosorbent for an efficient removal of heavy metal ions from aqueous solution.     

Comparison of biosorption properties of different kinds of fungi for the removal of Gryfalan Black RL metal-complex dye

Three kinds of filamentous fungi (Rhizopus arrhizus, Trametes versicolor, Aspergillus niger) were tested for their ability to adsorb Gryfalan Black RL metal-complex dye as a function of pH, temperature and dye concentration. R. arrhizus and T. versicolor exhibited the maximum dye uptake at pH 2.0 and at 25 degrees C while A. niger performed the highest dye biosorption at pH 1.0 and at 35 degrees C. Sorption capacity of each biosorbent increased with increasing initial dye concentration. Among the three fungi, R. arrhizus was the most effective biosorbent showing a maximum dye uptake of 666.7 mg g(-1). The Langmuir model described the equilibrium data of each dye-fungus system accurately in the concentration and temperature ranges studied. Kinetic analysis indicated that both adsorption kinetics and internal diffusion played an important role on controlling the overall adsorption rate for each fungus. Thermodynamic analysis verified that A. niger biosorption was endothermic while the others were exothermic.     

Biosorption of mercury from aqueous solution by Ulva lactuca biomass

The mercury biosorption onto non-living protonated biomass of Ulva lactuca, as an alternative method for mercury removal from aqueous solutions, was investigated. Batch equilibrium tests showed that at pH 3.5, 5.5 and 7 the maxima of mercury uptake values, according to Langmuir adsorption isotherm, were 27.24, 84.74 and 149.25 mg/g, respectively. The ability of Ulva lactuca biomass to adsorb mercury in fixed-bed column, was investigated as well. The influence of column bed height, flow rate and effluent initial concentration of metal was studied. The adsorbed metal ions were easily desorbed from the algal biomass with 0.3 N H₂SO₄ solution. After acid desorption and regeneration with distilled water, the biomass could be reused for other biosorption assays with similar performances.