Biosorption of phenolic compounds by the brown alga Sargassum muticum

Phenol, 2‐chlorophenol (2‐CP), and 4‐chlorophenol (4‐CP) biosorption on Sargassum muticum, an invasive macroalga in Europe, has been investigated. The efficiency of this biosorbent was studied measuring the equilibrium uptake using the batch technique. A chemical pre‐treatment with CaCl₂ has been employed in this study in order to improve the stability as well as the sorption capacity of the algal biomass. The influence of pH on the equilibrium binding and the effect of the algal dose were evaluated. The experimental data at pH = 1 have been analysed using Langmuir and Freundlich isotherms. It was found that the maximum sorption capacity of chlorophenols, q_max = 251 mg g^?1 for 4‐CP and q_max = 79 mg g^?1 for 2‐CP, as well as that of a binary mixture of both chlorophenols, q_max = 108 mg g^?1, is much higher than that of phenol, q_max = 4.6 mg g^?1. Moreover, sorption kinetics have been performed and it was observed that the equilibrium was reached in less than 10 h. Kinetic data have been fitted to the first order Lagergren model, from which the rate constant and the sorption capacity were determined. Finally, biosorption of the phenolic compounds examined in the present study on Sargassum muticum biomass was observed to be correlated with the octanol‐water partitioning coefficients of the phenols. This result allows us to postulate that hydrophobic interactions are the main responsible for the sorption equilibrium binding. Copyright © 2006 Society of Chemical Industry     

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

The 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 (K_i) and effective diffusion coefficient (D_i) 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.     

Removal of nickel from aqueous solutions by citric acid modified Ceiba pentandra hulls: Equilibrium and kinetic studies

The removal of Ni(II) from aqueous solutions using biomass prepared from Ceiba pentandra hulls powder modified with citric acid treatment (CAMCPH) has been studied by batch method. The biosorbent was characterised before and after citric acid modification using SEM, FT‐IR and XRD. Experimental parameters that influence the biosorption of Ni(II), such as pH, biosorbent dose, contact time and initial concentration of metal ion have been investigated. The adsorption of Ni(II) increased with increase in contact time and reached equilibrium within 50 min. The maximum removal of Ni(II) was observed at pH 5.0. The kinetic data were analysed using three adsorption kinetic models: the pseudo‐first, second‐order kinetics and intra‐particle diffusion. The results showed that the pseudo‐second‐order model fits the experimental data very well. The equilibrium data were analysed using Langmuir, Freundlich and Dubinin–Radushkevich isotherm models. Langmuir model provided the best correlation for the adsorption of Ni(II) by CAMCPH and the monolayer biosorption capacity for Ni(II) removal was 34.34 mg/g. Desorption experiments were carried out using HCl solution and the recovery of the metal ion from CAMCPH was found 98%. Desorption experiments showed the feasibility of regeneration of the biosorbent for further use after treating with dilute HCl. © 2011 Canadian Society for Chemical Engineering     

Removal of lead ions from aqueous solutions using powdered corn cobs

This paper is a report on an investigation conducted on adsorption of lead ions (Pb²⁺) onto powdered corn cobs (PCC). Corn cobs were collected from a selected location in Nigeria. The corn cobs were crushed and pulverised into different particle sizes. Its compositions and adsorption properties of Pb²⁺ onto PCC were studied. The effects of pH, particle size of PCC, and initial concentration of Pb²⁺ on the adsorption properties were monitored. The adsorption capacities were analysed by using standard adsorption models. The models were evaluated statistically (total error, coefficient of determination (CD), model of selection criterion (MSC), and root mean square error). The study revealed that PCC contained 2.33%, 86.89%, 10.78%, 0.52%, and 4.56% ash, volatile, moisture, solubility in water, and solubility in 0.25 M of HCl by mass, respectively. Acid digestion of a gram of PCC indicated that PCC contained no chromium and lead, but contained 131 mg Fe, 54.79% carbon, 8.03% hydrogen, 0.41% nitrogen, 0.010 mg of Al, and 1.70 mg calcium. The isotherm models parameters were 28.509 L/mg and 0.141 mg/g; 0.138 mg/g and 11.494 L/mg; 0.142 L/mg and 0.013 mg/g; 0.129 mg/g and 25.641 L/mg, 28.509 L/mg, 3.795 mg/g and 2.336 for Langmuir, Freundlich, Temkin, activated sludge, and Redlich–Peterson. The PCC particle size, initial pH, and initial Pb²⁺ concentration had effects on the adsorption parameters. The statistical evaluations showed that the best model for adsorption of lead ions from raw water onto PCC based on lower errors, high CD (0.88), reliability (97.5%), and MSC (1.86) was Freundlich and followed by activated sludge model. It was concluded that PCC is a good adsorbent like powdered eggshell and other carbon‐based materials.     

Removal and recovery of cationic dyes from aqueous solutions using spherical sulfonic lignin adsorbent

A novel spherical sulfonic lignin adsorbent, denoted as SSLA, was adopted to removal and recover the cationic dyes from aqueous solutions, e.g., Cationic Red GTL, Cationic Turquoise GB, and Cationic Yellow X‐5GL, and various affecting factors were optimized. It was found that the adsorption of cationic dyes on the adsorbent was initially concentration‐ and temperature‐dependent, and followed both the Freundlich and Langmuir isothermal adsorption. The positives values for ΔH indicated that the process was endothermic. The breakthrough adsorption capacities for GTL, GB, and X‐5GL were 536.0, 550.0, and 582.0 mg/g, respectively, which prevailed over the commercial powdered activated carbon and strongly acidic cation‐exchange resin R732 evidently. Additionally, the maximum recovery percentage could reach 93.2, 97.1, and 96.5% separately for GTL, GB, and X‐5GL, when a mixture of 3.0 mol/L HCl and alcohol with the volume ratio of 1 : 4 was adopted as eluant. Moreover, the results of the mobile desorption and recovery tests indicated that the maximum concentrations of GTL, GB, and X‐5GL in the eluants could reach 13,108, 13,980, and 13,520 mg/L, respectively. Only 6.3, 5.0, and 4.6% of adsorption capacities for GTL, GB, and X‐5GL decreases individually after 20 replicates of adsorption and desorption. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2284–2291, 2006     

Removal of Rhodamine B from aqueous solutions and wastewater by walnut shells: kinetics,equilibrium and thermodynamics studies

An adsorption study of Rhodamine B (RB) dye from aqueous solutions was carried out using walnut shells pretreated by different methods. In addition to the effects of the pretreatment, the effects of various parameters like pH, adsorbent dose, contact time, initial dye concentration and temperature on the adsorption of RB was studied. The adsorption process was highly pH dependent and a maximum adsorption was achieved at pH 3.0. The best fit for the rates of dye adsorption was a pseudo-second-order kinetic model with good correlation coefficients (R²>0.99). Langmuir isotherms were used to determine that the maximum loading capacity of the different walnut shells and the RB capacities ranged from 1.451–2.292 mg·g^-1. The dye adsorption was also evaluated thermodynamically. Positive standard enthalpy (?H°) values were obtained indicating that the RB adsorption process is endothermic as well as ?G° and ?S° values showed that adsorption process is spontaneous with an increased randomness at the solid-liquid interface. Desorption studies were carried out to explore the feasibility of regenerating the used walnut shells and it was found that 97.71%–99.17% of the retained RB was recovered with 0.1 mol?L^-1 NaOH solution. The walnut shells were also successfully used to remove RB from industrial effluents.     

Removal of arsenic(III) from aqueous solution by concrete-based adsorbents

The present paper investigates the adsorption of arsenic(III) (As(III)) onto 2 concrete-based low-cost materials, i.e., Aerocrete and Vermiculite impregnated by ferric oxyhydroxide. Adsorption experiments were performed to study the effect of initial pH, initial concentration of As(III), contact time, and ions usually present in water. No significant effect of the initial pH on the adsorption of As(III) by Aerocrete and Vermiculite was observed at the pH range of 4–8. The As(III) removal efficiency decreased at a high initial pH (i.e., 10). The Langmuir isotherm showed that the maximum As(III) adsorption capacity of Aerocrete and Vermiculite is 15.15 and 13.51 mg/g, respectively, which is higher than that observed using titanium dioxide (i.e., 3.52 mg/g), at pH 7 and 24 ±1 °C. A pseudo-second order kinetic model fitted well the experimentally obtained kinetic data. This suggests that chemisorption most probably controls the adsorption of As(III) on Aeroctere and Vermiculite. Significantly, As(III) (1 mg/L) could be removed almost completely by both Aeroctere and Vermiculite (1 g/L) in 30 and 60 min, respectively at pH 7 and 24 ±1 °C. Importantly, Ca²⁺, Mg²⁺, Na⁺, HCO₃⁻, SO₄²⁻, and Cl⁻ ions had no significant effect on the adsorption of As(III) on Aeroctere and Vermiculite. The results showed that the proposed concrete-based adsorbents have the potential to remove As(III) from water.     

Utilization of polyampholyte hydrogels for simultaneous removal of textile dyes from aqueous solutions

The study aimed to create hydrogel structures with greater functionality, otherwise known as polyampholytes (PAHs), and to use these in simultaneous removal studies for remazol-type dyes found in environmental waste waters. Adsorption studies were accomplished at 20°C and 35°C, indicated that adsorption process was exothermic in nature. The Q_m values for the PAH-dye systems were in the interval 111–122 mg dye/g PAH with Ads% from 94% to 98%. The ability of PAH hydrogels to adsorb two different species of dye molecules at the same time is an advantage of PAH adsorbents compared to other hydrogel adsorbents prepared in this area.     

Removal of Cu(II) from aqueous solutions by recycled tire rubber

A batch adsorption system was applied to study the adsorption of Cu(II) ions from aqueous solutions by crumb rubber. The effects of pH ranging from 1.5 to 7.0, contact time ranging from 6 to 96 h and initial metal concentration ranging from 1 mg L^− 1 to 50 mg L^− 1 on the removal of Cu(II) were studied. Results show that adsorption of Cu(II) is pH-dependent and the best results are obtained at pH = 6.0. Results also show that copper uptake is accompanied by displacement of zinc and therefore probably involves an ion exchange type mechanism. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Equilibrium data agreed very well with the Langmuir model. Results clearly show that crumb rubber is an effective adsorbent for the removal of Cu(II) from aqueous solutions.     

Biosorption of a Basic Dye from Aqueous Solutions by Euphorbia rigida

Abstract

In this study, the biosorption of Basic Blue 9 (BB9) dye from aqueous solutions onto a biomass of Euphorbia rigida was examined by means of the initial biosorbate concentration, biosorbent amount, particle size, and pH. Biosorption of BB9 onto E. rigida increases with both the initial biosorbate concentration and biosorbent amount, whereas decreases with the increasing particle size. The experimental data indicated that the biosorption isotherms are well‐described by the Langmuir equilibrium isotherm equation at 20, 30, and 40°C. Maximum biosorption capacity was 3.28×10^?4 mol g^?1 at 40°C. The biosorption kinetics of BB9 obeys the pseudo‐second‐order kinetic model. The thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated to estimate the nature of biosorption. These experimental results have indicated that E. rigida has the potential to act as a biosorbent for the removal of Basic Blue 9 from aqueous solutions.     

Removal of congo red from aqueous solutions by biogas waste slurry

Removal of Congo Red was carried out using biogas waste slurry as adsorbent at different concentrations of dye, adsorbent dosage, agitation time and pH. The process follows the first-order rate expression. The equilibrium data fit well in the Freundlich model of adsorption. Maximum removal of dye, 95%, was observed in the pH range 2.3–9.4. Desorption of Congo Red showed that it is solubilised in 50% acetic acid to the extent of 6% and the remainder appears to be chemically complexed irreversibly to the adsorbent. Low desorption of dye from the adsorbent surface in water indicates that the process may not be, essentially, a reversible one.     

Investigation of adsorption of lead,mercury and nickel from aqueous solutions onto carbon aerogel

Recently a new form of activated carbon has appeared: carbon aerogel (CA). Its use for the removal of inorganic (and especially metal ions) has not been studied. In the present study, the adsorption of three metal ions, Hg(II), Pb(II) and Ni(II), onto carbon aerogel has been investigated. Batch experiments were carried out to assess adsorption equilibria and kinetic behaviour of heavy metal ions by varying parameters such as agitation time, metal ions' concentration, adsorbent dose and pH. They facilitated the computation of kinetic parameters and maximum metal ion adsorption capacities. Increasing the initial solution pH (2–10) and carbon concentration (50–500 mg per 50 cm³) increases the removal of all three metal ions. A decrease of equilibrium pH with an increase of metal ion concentration led us to propose an adsorption mechanism by ion exchange between metal cations and H⁺ at the carbon aerogel surface. Carboxylic groups are especially involved in this adsorption mechanism. Langmuir and Freundlich isotherm models were used to analyse the experimental data of carbon aerogel. The thermodynamics of the metal adsorption was also investigated for the practical implementation of the adsorbent. The sorption showed significant increase with increase of temperature. Kinetics models describing the adsorption of Hg(II), Pb(II) and Ni(II) ions onto carbon aerogel have been compared. Kinetics models evaluated include the pseudo‐first order and second order model. The parameters of the adsorption rate constants have been determined and the effectiveness of each model assessed. The result obtained showed that the pseudo‐second order kinetic model correlated well with the experimental data and better than the pseudo‐first order model examined in the study. Mass transfer coefficients obtained can be useful in designing wastewater treatment systems or in the development of environmental technologies. Copyright © 2005 Society of Chemical Industry     

Biosorption from aqueous solutions by eggshell membranes and Rhizopus oryzae: equilibrium and kinetic studies

This study assesses the use of eggshell membranes and Rhizopus oryzae as media for the biosorption of p‐chlorophenol (p‐CP), 2,4‐dichlorophenol (2,4‐DCP), 3,5‐dichlorophenol (3,5‐DCP), reactive dye and cadmium from aqueous solutions. The performance of the adsorbents was quantified by measuring the equilibrium uptake and the batch rate kinetics from solutions. The constants in the Freundlich, Langmuir and Redlich–Peterson isotherm models were calculated through the linearization of the equations and linear regression. The kinetics of the adsorption systems for cadmium and a reactive dye have been assessed in a batch stirred adsorber. The effect of the process parameters such as pH, adsorbate concentration, adsorbent dosage, adsorbent particle size, temperature and agitation speed are reported. The external mass transfer coefficients are reported for some different system conditions. Both materials are determined to be effective adsorbents and could find application in the treatment of contaminated wastestreams. © 2002 Society of Chemical Industry     

Biosorption Potential of Coco-Peat in the Removal of Methylene Blue from Aqueous Solutions

An agro-waste, coco-peat was investigated as a biosorbent for methylene blue from aqueous solutions. The practicability of biosorption process was examined by varying the experimental parameters such as pH (2-9), initial concentration (50-200 mg/L), contact time (2-240 min), and temperature (298-318 K). Maximum uptake of 212.8 mg/g was observed at pH 8 based on the Langmuir model. Among different isotherm models examined (Langmuir, Freundlich, Redlich-Peterson, and Sips), the Redlich-Peterson model described the experimental isotherms well. Coco-peat was characterized using the Fourier Transform Infrared Spectroscopy and their morphology was analyzed using scanning electron microscopy.     

Easy Preparation of Liposome@PDA Microspheres for Fast and Highly Efficient Removal of Methylene Blue from Water

Mussel-inspired chemistry was usefully exploited here with the aim of developing a high-efficiency, environmentally friendly material for water remediation. A micro-structured material based on polydopamine (PDA) was obtained by using liposomes as templating agents and was used for the first time as an adsorbent material for the removal of methylene blue (MB) dye from aqueous solutions. Phospholipid liposomes were made by extrusion and coated with PDA by self-polymerization of dopamine under simple and mild conditions. The obtained Liposome@PDA microspheres were characterized by DLS and Zeta potential analysis, TEM microscopy, and FTIR spectroscopy. The effects of pH, temperature, MB concentration, amount of Liposome@PDA, and contact time on the adsorption process were investigated. Results showed that the highest adsorption capacity was obtained in weakly alkaline conditions (pH = 8.0) and that it could reach up to 395.4 mg g⁻¹ at 298 K. In addition, adsorption kinetics showed that the adsorption behavior fits a pseudo-second-order kinetic model well. The equilibrium adsorption data, instead, were well described by Langmuir isotherm. Thermodynamic analysis demonstrated that the adsorption process was endothermic and spontaneous (ΔG⁰ = −12.55 kJ mol⁻¹, ΔH⁰ = 13.37 kJ mol⁻¹) in the investigated experimental conditions. Finally, the applicability of Liposome@PDA microspheres to model wastewater and the excellent reusability after regeneration by removing MB were demonstrated.     

Adsorption of Cu(II) ions from aqueous solutions using ion exchange resins with different functional groups

The extraction of heavy metals from industrial effluents using efficient adsorbents is crucial for wastewater treatment and beneficial for metal recycling. In this study, the removal of Cu(II) from an acidic solution by commercial resins Dowex G-26 and Puromet™ MTS9570 was investigated. The influences of contact time, solution concentration, pH, temperature, and a resin dosage on the adsorption process were studied with batch technique. The optimum adsorption conditions were obtained at a concentration of 1100 mg/L Cu, contact time of 30 min, pH 3.5, and resin dosage of 0.025 g/ml for the removal of 99.9% and 90% of copper ions by G-26 and MTS9570, respectively. The experimental data of copper adsorption were analyzed using the Langmuir, Freundlich, and Temkin isotherm models. The highest metal uptakes of 41.67 and 37.70 mg/g were observed for Dowex G-26 and MTS9570, respectively. It was found that both resins had higher adsorption capacities than the substances reported in the literature. The adsorption kinetic studies showed that the copper adsorption process could be better described by the pseudo-second order model. Adsorption occurs spontaneously under endothermic conditions, which indicates the endothermic nature of the process.     

Removal of basic dyes from aqueous solutions using natural clay

Adsorption properties of natural clay (from Eski?ehir of Turkey) were investigated by depending on different adsorption conditions such as different initial dye concentrations and contact times. The chemical composition of the natural clay was analyzed by X-ray fluorescence spectrometry (XRF). The removal of basic dyes such as Nile Blue (NB) and Brilliant Cresyl Blue (BCB) from aqueous solutions using natural clay in this study was described. After the equilibrium adsorption time of 8 h, the adsorption capacities for NB and BCB reach about 25 mg/g and 42 mg/g, respectively. Lagergren kinetic equation was used to test the experimental data to examine the controlling mechanism of adsorption processes. Adsorption data of the BCB and NB onto natural clay were fitted well by the pseudo-first-order model. The adsorption isotherms data were correlated with the Freundlich equation and the Freundlich constants K_f (mg/g) and n (intensity of adsorption) were calculated. The r² (regression coefficients) values were 0.9835 and 0.9849 for NB and BCB, respectively. The adsorption capacities of natural clay for NB and BCB have the following order: BCB > NB.     

Biosorptive Removal of Ni(II) from Aqueous Solution by Caesalpinia bonducella Seed Powder

The present work deals with the use of Caesalpinia bonducella seed powder (CBSP) as a biosorbent for Ni(II) removal from aqueous solution. The nature and morphology of the sorbent were determined using FTIR spectral, SEM, and EDX analysis. The biosorption characteristics of Ni(II) onto CBSP was investigated as a function of pH, biosorbent dosage, contact time, initial metal ion concentration, and temperature. Langmuir and Freundlich isotherms were used to fit the experimental data. The best interpretation for the equilibrium data was given by the Langmuir isotherm. The maximum biosorption capacity was found to be 188.7 mg/g for Ni(II) at pH 5.0 and at 323 K. The equilibrium biosorption data were well fitted with the pseudo-second-order kinetic equation. The values of thermodynamic parameters (ΔG^o, ΔH^o, and ΔS^o) indicated that the biosorption of Ni(II) onto CBSP was feasible, spontaneous and exothermic in nature. The FTIR results revealed that hydroxyl, amine, carboxyl, and carbonyl functional groups are responsible for Ni(II) biosorption onto CBSP.     

Removal of DDT from aqueous solutions using mesoporous silica materials

BACKGROUND: There are few reports about adsorbents for the effective removal of large‐molecule pesticides such as DDT (1,1,1‐trichloro‐2,2′ bis(p‐chlorophenyl)ethane). Some mesoporous silica materials and their modified derivatives might serve as good adsorbents for these large organic molecules because of their large pore diameter and special pore structures. In this work, the adsorption processes of DDT in aqueous solutions were investigated using different mesoporous silica materials, including HMS, MCM‐41, SBA‐15 and MCM‐48. RESULTS: All these materials exhibit efficient DDT removal, and the adsorption is a rapid process with over 50% of DDT removed within approximately 2 h. The efficiency of DDT removal is influenced by the adsorbent characteristics, such as pore volume, pore diameter, connectivity between pore channels and surface OH groups. The influences of water/acetone ratio and initial DDT concentration in solution were also explored. It was found that with enhancing DDT solubility, the addition of acetone in the reaction solution had no evident impact on DDT adsorption efficiency. Increasing the initial concentration of DDT resulted in a decrease of DDT adsorption efficiency. The adsorption kinetics of DDT on mesoporous silica material is shown to be pseudo‐second‐order. After thermal treatment at a relatively low temperature of 450 °C, the adsorbed DDT was completely decomposed and the adsorbents, except MCM‐41, were regenerated well. CONCLUSION: The results demonstrate the potential of a simple and efficient new approach for the removal of OCPs (organochlorine pesticides), especially large OCP molecules from surface water or groundwater. Copyright © 2008 Society of Chemical Industry