Biosorbent Size Research Articles

Kinetic and thermodynamic modeling for the removal of Direct Red-31 and Direct Orange-26 dyes from aqueous solutions by rice husk

The present study deals with the utilization of an inexpensive agro-industrial waste rice husk for the removal of Direct Red-31 and Direct Orange-26 from aqueous solutions in a batch mode. Experiments were carried out as function of pH, biosorbent dose, particle size of biosorbent, initial dyes concentration, contact time and temperature. The equilibrium biosorption data were analyzed by Langmuir, Freundlich, Temkin, Doubinin–Radushevich (D–R) and Harkins–Jura isotherm models. The results indicated that the Langmuir model provided the best correlation of the experimental data for both dyes. The biosorption kinetic data were modeled using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic equations. It was observed that the pseudo-second-order kinetic equation could explain the biosorption kinetics of dyes on rice husk. Thermodynamic parameters such as enthalpy change (ΔH°), entropy change (ΔS°) and free energy change (ΔG°) were also investigated. Free energy change showed that biosorption of Direct Red-31 and Direct Orange-26 was spontaneous at all studied temperatures (30–70 °C). Surface adsorption of both the dyes at specific binding sites was confirmed through and Fourier Transform infrared spectroscopic (FT-IR) analysis. The changes in surface morphology of rice husk before and after adsorption was investigated through scanning electron microscopy (SEM). It was implied that rice husk may be suitable as an adsorbent for removal of direct dyes from aqueous solutions.

Biosorption of a model basic dye onto Pinus brutia Ten.: Evaluating of equilibrium, kinetic and thermodynamic data

The potential of pine cones as a natural biosorbent was investigated for adsorptive removal of Basic Red 46 (BR 46) from aqueous solutions. Various physico-chemical parameters were studied such as solution pH, biosorbent dosage, biosorbent size, dye concentration, temperature, contact time and ionic strength. The equilibrium data fitted well with the Langmuir isotherm. The monolayer sorption capacity was found as 73.53 mg g −1. Kinetic data were best described by the pseudo-second order model. The thermodynamic studies indicated that the biosorption reactions were spontaneous and endothermic. Activation energy was calculated as 32.33 kJ mol −1. The BR 46 was desorbed from the pine cones with 0.1 M HCl solution. The recovery for the dye was found to be higher than 90%. Thus, this study demonstrated that the pine cones could be used as a low-cost biosorbent for the treatment of the wastewater streams bearing dye.

Adsorptive removal of direct textile dyes by low cost agricultural waste: Application of factorial design analysis

This research work involved the use of factorial experimental design technique to investigate the biosorption of Everdirect Orange-3GL and Direct Blue-67 dyes from aqueous solution on rice husk. A 5 3 full factorial experimental design was employed to study the effect of three factors: initial dye concentration, biosorbent dose and pH at five levels. The efficiency of rice husk for dyes removal has been determined after 3 h of treatment at 30 °C using suitable size of biosorbent (0.255 mm). Main and interaction effects were analyzed by analysis of variance (ANOVA), F-test and P-values to define most important process variables affecting the dyes biosorption. The statistical model was best fitted with high coefficient of determination ( R 2 = 0.999) for Everdirect Orange-3GL and Direct Blue-67 dyes. The most significant variable was thus found to be pH for both the dyes. FT-IR studies showed that hydroxyl functional groups participated in the biosorption of dyes.

Equilibrium, kinetic and thermodynamic studies of Acid Orange 52 dye biosorption by Paulownia tomentosa Steud. leaf powder as a low-cost natural biosorbent

The biosorption of Acid Orange 52 onto the leaf powder of Paulownia tomentosa Steud. was studied in a batch adsorption system to estimate the equilibrium, kinetic and thermodynamic parameters as a function of solution pH, biosorbent concentration, dye concentration, biosorbent size, temperature and contact time. The Langmuir, Freundlich and Temkin isotherm models were used for modeling the biosorption equilibrium. The experimental equilibrium data could be well interpreted by the Temkin and Langmuir isotherms with maximum adsorption capacity of 10.5 mg g −1. In order to state the sorption kinetics, the fits of pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion kinetic models were investigated. It was obtained that the biosorption process followed the pseudo-second order rate kinetics. Thermodynamic studies indicated that this system was exothermic process. The results revealed that P. tomentosa leaf powder could be an efficient biosorbent for the treatment of wastewater containing Acid Orange 52.

Efficacy of Daucus carota L. waste biomass for the removal of chromium from aqueous solutions

In the present study the removal of Cr(III) and Cr(VI) using Daucus carota L. (carrot) waste biomass was investigated from aqueous solutions. Biosorption studies were determined as a function of contact time, pH, initial metal ion concentration, biosorbent size and biosorbent dose. Maximum uptake capacity of D . carota L. waste biomass for Cr(III) (86.65 mg/g) and Cr(VI) (88.27 mg/g) was observed at pH 1 and 5 respectively. Optimum biosorbent dose (0.1 g), biosorbent size (0.250 mm), initial concentration (100 mg/L), temperature (30 °C) and contact time (240 min) gave maximum biosorption. The sorption isotherms followed the Langmuir type suggesting monolayer sorption character. A high degree of correlation coefficient was obtained for the second-order kinetic model. To evaluate the effect of pretreatment on Cr(III) and Cr(VI) uptake by D . carota L., the waste biomass was physically as well as chemically pretreated. Maximum Cr(III) and Cr(VI) uptake was observed with acetone and Moringa oleifera extract pretreated D . carota L. waste biomass. The results also demonstrate that chromium uptake capacity of D . carota L. waste biomass was comparatively higher than most of early reported work.

Potencial de biossorção do zinco pela macrófita egeria densa

Neste trabalho, foi estudada a capacidade de biossorção da macrófita aquática Egeria densa seca na remoção do íon zinco. Os testes cinético e de equilíbrio foram realizados em sistema de batelada com temperatura, agitação e pH controlados. Os resultados obtidos na cinética de biossorção demonstram uma rápida remoção do zinco (II), com tempo de equilíbrio em torno de 45 minutos e taxa de remoção superior a 70%. O modelo cinético de pseudo-segunda ordem foi o que melhor representou os dados experimentais. No estudo do equilíbrio, verificou-se que o modelo de Langmuir ajustou-se melhor aos dados experimentais, com capacidade máxima de sorção de 0,92 mequiv g-1 e razão entre as taxas de sorção e dessorção de 0,829 L g-1 em pH 5. Os resultados obtidos demonstram que a macrófita E. densa tem potencial para ser utilizada em sistemas de tratamento de efluentes industriais.

Pb(II) biosorption from hazardous aqueous streams using Gossypium hirsutum (Cotton) waste biomass

Studies on the biosorptive ability of Gossypium hirsutum (Cotton) waste biomass outlined that smaller size of biosorbent (0.355 mm), higher biomass dose (0.20 g), 5 pH and 100 mg/L initial Pb(II) concentration were more suitable for enhanced Pb(II) biosorption from aqueous medium. The Langmuir isotherm model and pseudo second order kinetic model fitted well to the data of Pb(II) biosorption. Highly negative magnitude of Gibbs free energy (Δ G°) indicated that the process was spontaneous in nature. In addition to this surface coverage and distribution coefficient values of Pb(II) biosorption process were also determined. At optimized conditions Pb(II) uptake was more rapid in case of industrial effluents in comparison to synthetic solutions. FTIR spectroscopic analysis revealed that the main functional groups involved in the uptake of Pb(II) on the surface of G. hirsutum biomass were carboxyl, carbonyl, amino and alcoholic.

Biosorption characteristics of uranium(VI) from aqueous medium onto Catenella repens, a red alga

The biosorption characteristics of uranium(VI) onto Catenella repens (a red alga), were evaluated as a function of pH, biosorbent size, time, biomass dosage, initial uranium concentration and temperature. Within the pH range studied (1.5–7.5), 4.5 was the optimum pH for the uptake of uranium(VI) by C. repens. Reduction in particle size did not increase the biosorption capacity. The metal removal was rapid, with more than 90% of total biosorption taking place in 30 min, and equilibrium was attained in 45 min. The maximum metal loading capacity of the alga was 303 mg/g. Within the temperature range studied (15–55 °C), there was no significant change in biosorption, under optimal conditions. Adsorption process could be well defined by both the Langmuir and Freundlich isotherms with r 2 of 0.94 and 0.96, respectively. The kinetic data fitted the pseudo-second-order kinetic model with the r 2 value of 0.99. At a low pH of 2.5, where most of the biomasses show either no or less metal uptake, a good (>15%) metal loading capacity of 25% was achieved. Therefore biosorption characteristics were also evaluated at pH 2.5.

Biosorption of acid dye on Pueraria lobata ohwi. Equilibrium and kinetic modelling

The applicability of the biomaterial kudzu (Pueraria lobata ohwi) for the removal of the acid dye Erionil Marine Blau (EMB) from aqueous medium was investigated. The equilibrium results were described by the Langmuir and Freundlich models and the isotherms parameters were calculated. The experimental data were correlated better by the Freundlich model (R² = 0.9029). The effect of the system variables, initial sorbate concentration, mass of biosorbent, agitation rate and particle size, were examined. It was established that the biosorption of EMB on kudzu followed pseudo second order kinetics. The intraparticle diffusion model was also applied to explain the mechanism of dye molecules diffusion through the non-living biomass. The comparative estimation of the results proved the feasibility of using kudzu as an effective biosorbent for the removal of the acid dye EMB from aqueous phase. The highest obtained percent uptake of dye was 93%.

Kinetic and Equilibrium Modeling of Pb(II) and Co(II) Sorption onto Rose Waste Biomass

An attempt was made to assess the biosorption potential of rose waste biomass for the removal of Pb(II) and Co(II) ions from synthetic effluents. Biosorption of heavy metal ions (>90%) reached equilibrium in 30 min. Maximum removal of Pb(II) and Co(II) occurred at pH 5 and 6 respectively. The biosorbent dose for efficient uptake of Pb(II) and Co(II) was 0.5 g/L for both metals. The biosorbent size affected the Pb(II) and Co(II) biosorption rate and capacity. Rose waste biomass was found effective for Pb(II) and Co(II) removal from synthetic effluents in the concentration range 10–640 mg/L. Equilibrium sorption studies showed that the extent of Pb(II) and Co(II) uptake by the rose waste biomass was better described by the Langmuir isotherm in comparison to the Freundlich model. The uptake capacities of the two metal ions were 156 and 27.15 mg/g for Pb(II) and Co(II) respectively.

Biosorption of zinc from aqueous solution using Azadirachta indica bark: Equilibrium and kinetic studies

The removal of zinc ions from aqueous solutions on the biomass of Azadirachta indica bark has been studied by using batch adsorption technique. The biosorption studies were determined as a function of contact time, pH, initial metal ion concentration, average biosorbent size and biosorbent dosage. The equilibrium metal uptake was increased and percentage biosorption was decreased with an increase in the initial concentration and particle size of biosorbent. The maximum zinc biosorption occurred at pH 6 and percentage biosorption increases with increase in the biosorbent dosage. Experimental data obtained were tested with the adsorption models like Langmuir, Freundlich and Redlich–Peterson isotherms. Biosorption isothermal data were well interpreted by Langmuir model with maximum biosorption capacity of 33.49 mg/g of zinc ions on A. indica bark biomass and kinetic data were properly fitted with the pseudo-second-order kinetic model.

Physical and chemical modification of distillery sludge for Pb(II) biosorption

The waste distillery sludge from sugar-cane industry was pretreated physically (boiled, heated and autoclaved) as well as chemically (HCl, H 2SO 4, H 3PO 4, NaOH, Ca(OH) 2, Al(OH) 3, C 6H 6, HCHO, CH 3OH and C1 2H 25OSO 3Na (sodium dodecyl sulphate (SDS)) for assessing the comparative sorption capacity of untreated and modified distillery sludge for Pb(II) biosorption from aqueous solutions. Experiments were conducted in shake flasks on a batch basis to access the effect of different experimental parameters such as pH, biosorbent dosage, biosorbent size, initial Pb(II) concentration and contact time. The uptake capacity ‘ q’ (mg/g) of untreated and pretreated distillery sludge was in following order: NaOH (51.29 ± 1.21) > HCl (49.82 ± 1.22) > HCHO (49.56 ± 1.14) > H 2SO 4 (47.71 ± 1.20) > HgCl 2 (45.32 ± 1.06) > Ca(OH) 2 (44.01 ± 1.18) > MeOH (43.73 ± 1.23) > C 6H 6 (42.72 ± 1.19) > H 3PO 4 (42.01 ± 1.17) > SDS (40.87 ± 1.27) > autoclaved (40.23 ± 1.24) > Boiled (39.95 ± 1.19) > heated (38.87 ± 1.32) > Al (OH) 3 (38.30 ± 1.14) > untreated (37.76 ± 1.21). In further parameter studies, the optimized biosorbent size was 0.250 mm at pH 5 and best dose was 0.05 g of biosorbent. The applicability of the Langmuir and Freundlich models for sorption process was tested and best fitted model was Langmuir with the coefficient of determination ( R 2) value, 0.97, the process followed second order kinetic mechanism.

Biosorption of nickel from protonated rice bran

In the present study biosorption technique, the accumulation of metals by biomass was used for the removal of nickel from aqueous medium. The rice bran in its acid treated (H 3PO 4) form was used as a low cost sorbent. The adsorption characteristics of nickel on protonated rice bran were evaluated as a function of pH, biosorbent size, biosorbent dosage, initial concentration of nickel and time. Within the tested pH range (pH 1–7), the protonated rice bran displayed more resistance to pH variation, retaining up to 102 mg/g of the nickel binding capacity at pH 6. Meanwhile, at lower pH values the uptake capacity decreased. The % age removal of nickel was maximum at 0.25 g of biosorbent dose and 0.25 mm biosorbent size. At the optimal conditions, metal ion uptake was increased as the initial metal ion concentration increased up to 100 mg/L. Kinetic and isotherm experiments were carried out at the optimal pH 6.0 for nickel. The metal removal rate was rapid, with 57% of the total adsorption taking place within 15–30 min. The Freundlich and Langmuir models were used to describe the uptake of nickel on protonated rice bran. The Langmuir and Freundlich model parameters were evaluated. The equilibrium adsorption data was better fitted to Langmuir adsorption isotherm model. The adsorption followed pseudo second-order kinetic model. The thermodynamic assessment of the metal ion-rice bran biomass system indicated the feasibility and spontaneous nature of the process and Δ G° values were evaluated as ranging from −22.82 to −24.04 kJ/mol for nickel sorption. The order of magnitude of the Δ G° values indicated an ion-exchange physiochemical sorption process.

Biosorption of Zinc from Aqueous Solutions by Rice Bran: Kinetics and Equilibrium Studies

Rice bran, an agricultural by‐product, was used for the removal of zinc ions from aqueous solution. The work considered the determination of zinc‐biomass equilibrium data in batch system. These studies were carried out in order to determine some operational parameters of zinc sorption such as the time required for the Zinc‐biosorbent equilibrium, the effects of biomass particle size, pH, and temperature. The results showed that pH has an importance effect on zinc biosorption capacity. The biosorbent size also affects the zinc biosorption capacity. The sorption process follows pseudo‐second‐order kinetics. The intraparticle diffusion may be the rate‐controlling step involved in the adsorption zinc ions onto the rice bran up to 30 min. The equilibrium data could be best fitted by the Langmuir sorption isotherm equation over the entire concentration range (40–160 mg/dm3). Thermodynamic parameters, such as ΔG°, ΔH°, ΔS°, have been calculated. The thermodynamics of zinc ion/rice bran system indicate spontaneous and endothermic nature of the process.

Biosorption of chromium(III) by Sargassum sp. biomass

Chromium is present in different types of industrial effluents, being responsible for environmental pollution. Traditionally, the chromium removal is made by chemical precipitation. However, this method is not completely feasible to reduce the chromium concentration to levels as low as required by environmental legislation. Biosorption is a process in which solids of natural origin are employed for binding heavy metals. It is a promising alternative method to treat industrial effluents, mainly because of its low cost and high metal binding capacity. In this work the chromium biosorption process by Sargassum sp. seaweed biomass is studied. Sargassum sp. seaweed, which is abundant in the Brazilian coast, has been utilized with and without milling. The work considered the determination of chromium-biomass equilibrium data in batch system. These studies were carried out in order to determine some operational parameters of chromium sorption such as the time required for the metal-biosorbent equilibrium, the effects of biomass size, pH and temperature. The results showed that pH has an important effect on chromium biosorption capacity. The biosorbent size did not affect chromium biosorption rate and capacity.