Removal of Cu(II) and Zn(II) Using Lignocellulosic Fiber Derived from Citrus reticulata (Kinnow) Waste Biomass

Abstract

The biosorption of Cu(II) and Zn(II) using dried untreated and pretreated Citrus reticulata waste biomass were evaluated. The Cu(II) and Zn(II) sorption were found to be dependent on the solution pH, the biosorbent dose, the biosorbent particle size, the shaking speed, the temperature, the initial metal ions (800 mg/L), and the contact time. Twenty-eight physical and chemical pretreatments of Citrus reticulata waste biomass were evaluated for the sorption of Cu(II) and Zn(II) from aqueous solutions. The results indicated that biomass pretreated with sulphuric acid and EDTA had maximum Cu(II) and Zn(II) uptake capacity of 87.14 mg/g and 86.4 mg/g respectively. Moreover, the Langmuir isotherm model fitted well than the Freundlich model with R ² > 0.95 for both metal ions. The sorption of Cu(II) and Zn(II) occurred rapidly in the first 120 min and the equilibrium was reached in 240 min. FTIR and SEM studies were also carried out to investigate functional groups present in the biomass and the surface morphological changes of biomass.     

Preparation and Application of a Novel Functionalized Coconut Coir Pith as a Recyclable Adsorbent for Phosphate Removal

Abstract

This study was to develop a new adsorbent, Iron(III) complex of an amino-functionalized polyacrylamide-grafted coconut coir pith (CP), a lignocellulosic residue, for the removal of phosphate from water and wastewater. The kinetics of adsorption follows a pseudo-second-order model. The equilibrium sorption capacity of 96.31 mg/g was determined at 30°C from the Langmuir isotherm equation. Complete removal of 16.4 mg/L phosphate in 1 L of fertilizer industry wastewater was achieved by 1.5 g/L AM-Fe-PGCP at pH 6.0. The acid treatment (0.1 M HCl) and re-introduction of Fe³⁺ lead to a reactivation of the spent adsorbent and can be reused through many cycles of water treatment and regeneration without any loss in the adsorption capacity.     

Sorption of Natural Uranium on Weakly Basic Anion Exchangers

The effects of the sorption of naturally occurring uranium on weakly basic anion exchangers (WBA) have been investigated. Systematic investigations on the effects of various parameters show in general three important factors influencing the adsorption equilibrium. First, the sorption depends on the presence of competing anions, with sulfates showing the greatest influence. Second, the speciation of uranium (VI), which in carbonate-containing waters in a pH range between 6.5 and 9 exists mainly as anionic complexes UO₂(CO₃)₂^2- and UO₂(CO₃)₃^4-, is changed by calcium and bicarbonates. Calcium forms neutral complexes with uranium and carbonate, and with these complexes no ion exchange occurs. On the other hand, increasing concentrations of carbonate species support the formation of anionic uranyl complexes of higher charge, and an increased uranium uptake arises. Third, the effective capacity of WBA depends on the pH. With increasing pH, the amount of protonated functional groups decreases and the sorption capacity decreases.

It has been demonstrated that WBA sorb uranium very selectively out of drinking water. WBA Amberlite IRA 67 reached the uranium loading of 10 mg/g at the uranium concentration of 10 µg/L by sorption out of tap water at pH 7.     

Biosorption of Chromium from Effluent Generated in Chrome‐Electroplating Unit using Saccharomyces cerevisiae

Abstract

Biosorption of chromium from effluent generated in chrome‐electroplating unit using waste yeast biomass Saccharomyces cerevisiae was carried out. Chromium concentration in the effluent was 204 mg/L. Chromium biosorption equilibration time was found to be 2 hours, with uptake of 6.607 mg/g. Biosorption increased with rise in pH and chromium concentration. Equilibrium biomass concentration and agitation speed were 2% and 150 rpm, respectively. The biosorption equilibrium data fit with Freundlich and Langmuir isotherm models revealed K_f and Q_max values of 0.3727 and 384.61 mg/g, respectively.     

Removal of Fluoride from Contaminated Drinking Water using Unmodified and Aluminium Hydroxide Impregnated Blue Lime Stone Waste

Abstract

The adsorption of fluoride on lime stone (LS) and aluminium hydroxide impregnated lime stone (AlLS) was investigated using a batch adsorption technique. A series of experiments were under taken in an agitated batch adsorber to assess the effect of the system variables such as solution pH, dye concentration and temperature. Removal of fluoride was observed to be the most effective at pH 8. The langmuir and Freundlich isotherm models were applied to the equilibrium data. The results showed that the Freundlich equation fits better than the Langmuir equation. The maximum sorption capacities for the LS and AlLS adsorbents were found to be 43.10 mg/g and AlLS 84.03 mg/g respectively. The FTIR studies indicate that the adsorption of fluoride is physiorption. The adsorption of fluoride onto AlLS proceeds according to a pseudo-first-order model. The results reveal that the LS and AlLS can be economical for the removal of fluoride compared to many other expensive adsorbents.     

Biosorptive uranium uptake by a Pseudomonas strain: characterization and equilibrium studies

The biosorptive uranium(VI) uptake capacity of live and lyophilized Pseudomonas cells was characterized in terms of equilibrium metal loading, effect of solution pH and possible interference by selected co‐ions. Uranium binding by the test biomass was rapid, achieving >90% sorption efficiency within 10 min of contact and the equilibrium was attained after 1 h. pH‐dependent uranium sorption was observed for both biomass types with the maximum being at pH 5.0. Metal uptake by live cells was not affected by culture age and the presence of an energy source or metabolic inhibitor. Sorption isotherm studies at a solution pH of either 3.5 or 5.0 indicated efficient and exceptionally high uranium loading by the test biomass, particularly at the higher pH level. At equilibrium, the lyophilized Pseudomonas exhibited a metal loading of 541 ± 34.21 mg g^?1 compared with a lower value by the live organisms (410 ± 25.93 mg g^?1). Experimental sorption data showing conformity to both Freundlich and Langmuir isotherm models indicate monolayered uranium binding by the test biomass. In bimetallic combinations a significant interference in uranium loading was offered by cations such as thorium(IV), iron(II and III), aluminium(III) and copper(II), while the anions tested, except carbonate, were ineffective. Uranium sorption studies in the presence of a range of Fe³⁺ and SO₄^2? concentrations indicate a strong inhibition (80%) by the former at an equimolar ratio while more than 70% adsorption efficiency was retained even at a high sulfate level (30 000 mg dm^?3). Overall data indicate the suitability of the Pseudomonas sp biomass in developing a biosorbent for uranium removal from aqueous waste streams. © 2001 Society of Chemical Industry     

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

Abstract

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.     

Modification of Langmuir model for simulating initial pH and temperature effects on sorption process

ABSTRACT

The present study modifies the sorption isotherm for simulating the influences of initial pH and temperature variations on the cadmium sorption from contaminated water using waste foundry sand based on Langmuir, Freundlich, and Temkin models. Results proved that the Langmuir expression is able to adopt these effects by relating sorption capacity and affinity constants with pH and temperature of aqueous solution through exponential relationships (determination coefficient = 0.9375). The present model is assumed that the sorption process occurs through acidic functional groups and this is consistent with FTIR outputs. Interaction of cadmium/WFS is found to be exothermic by thermodynamic analysis.     

Separation and Recovery of Silver(I) Ions from Base Metal Ions by Melamine‐formaldehyde‐thiourea (MFT) Chelating Resin

Abstract

Melamine‐formaldehyde‐thiourea (MFT) chelating resin were prepared using melamine (2,4,6‐triamino‐1,3,5‐triazine), formaldehyde, and thiourea and this resin has been used for separation and recovery of silver(I) ions from copper(II) and zinc(II) base metals and calcium(II) alkaline‐earth metal in aqueous solution. The MFT chelating resin was characterized by elemental analysis and FT‐IR spectra. The effect of pH, adsorption capacity, and equilibrium time by batch method and adsorption, elution, flow rate, column capacity, and recovery by column method were studied. The maximum uptake values of MFT resin were found as 60.05 mg Ag⁺/g by batch method and 11.08 mg Ag⁺/g, 0.052 mg Zn²⁺/g, 0.083 mg Cu²⁺/g and 0.020 mg Ca²⁺/g by column method. It was seen that MFT resin showed higher uptake behavior for silver(I) ions than base and earth metals due to chelation.     

Removal of Cr(VI) From Aqueous Solution by Turkish Vermiculite: Equilibrium,Thermodynamic and Kinetic Studies

Abstract

The adsorption of Cr(VI) from aqueous solution by Turkish vermiculite were investigated in terms of equilibrium, kinetics, and thermodynamics. Experimental parameters affecting the removal process such as pH of solution, adsorbent dosage, contact time, and temperature were studied. Equilibrium adsorption data were evaluated by Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. Langmuir model fitted the equilibrium data better than the Freundlich model. The monolayer adsorption capacity of Turkish vermiculite for Cr(VI) was found to be 87.7 mg/g at pH 1.5, 10 g/L adsorbent dosage and 20°C. The mean free energy of adsorption (5.9 kJ/mol) obtained from the D–R isotherm indicated that the type of sorption was essentially physical. The calculated thermodynamic parameters (ΔG ^o , ΔH ^o and ΔS ^o ) showed that the removal of Cr(VI) ions from aqueous solution by the vermiculite was feasible, spontaneous and exothermic at 20–50°C. Equilibrium data were also tested using the adsorption kinetic models and the results showed that the adsorption processes of Cr(VI) onto Turkish vermiculite followed well pseudo-second order kinetics.     

Biosorption of Strontium Ions by Magnetically Modified Yeast Cells

The sorption of Sr²⁺ ions from aqueous solutions on magnetically modified fodder yeast (Kluyveromyces fragilis) cells and their subsequent desorption were studied. The Sr²⁺ sorption increased with increasing pH and reached a plateau between pH 4.0 and 7.0. The changes of temperature slightly influenced the sorption process. The sorption values were 19.5 mg g^?1 and 53.5 mg g^?1 for 10 mg L^?1 and 40 mg L^?1 Sr²⁺ solutions respectively after 20 min incubation at a pH higher than 4. The Langmuir isotherm was successfully used to fit experimental data; the maximum adsorption capacity was 140.8 mg g^?1 under optimal conditions. The adsorbed Sr²⁺ ions can be desorbed with nitric acid (0.1 mol L^?1).     

Removal of divalent nickel from aqueous solution using blue-green marine algae: adsorption modeling and applicability of various isotherm models

Adsorption of Ni(II) onto blue-green marine algae (BGMA) is investigated under batch condition. Under optimum experimental conditions, the initial Ni(II) metal ion concentration is varied from 25 to 250 ppm and the maximum adsorption capacity of BGMA is found to be 42.056 mg/g. The optimum pH, biomass loading, and an agitation rate on maximum removal of Cu(II) ion are found to be 6, 2 g, and 120 rpm, respectively. 24 h of contact time is allowed to achieve equilibrium condition. All the experiments are carried out at room temperature. The equilibrium experimental data infer that the isotherm is L-shaped. It is the indication of no strong competition between solvent and Ni(II) to occupy the active sites of BGMA. Also, it indicates that the BGMA has a limited sorption capacity for adsorption of Ni(II). The experimental data are tested with various isotherm models; subsequently, the mechanism of adsorption is identified and the characteristic parameters for process design are established. Fritz–Schlunder-V isotherm model is highly significant in establishing the mechanism of adsorption of Ni(II) under the conditions employed in this investigation followed by Freundlich. The q_max of 41.89 mg/g obtained by this model indicates its relevance more precisely with experimental data.     

Weak Base Anion Exchanger Amberlite FPA51 as Effective Adsorbent for Acid Blue 74 Removal from Aqueous Medium – Kinetic and Equilibrium Studies

In this work, the macroporous anion exchange resin – Amberlite FPA51, is proposed as the effective adsorbent for the removal of Acid Blue 74 from aqueous solutions. The sorption mechanism was investigated under static conditions taking into account the phase contact time, solution pH, initial dye concentration, and temperature. The equilibrium data were fitted to the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. The maximum monolayer capacity Q ₀ was 123.8 mg/g. The adsorption kinetics was found to follow the pseudo-second order model. The sorption energy was equal to 14.5 kJ/mol and indicated that the adsorption process of the dye may be described via a chemical anion-exchange mechanism.     

Use of three types of magnetic biochar in the removal of copper(II) ions from wastewaters

Three types of magnetic biochars (MBC1, MBC2, and MBC3) were synthesized from biochar using NaBH₄ as a reducing agent of Fe(II) to Fe(0) to remove copper(II) ions from different wastewaters. Based on the research it was found that removal of copper(II) ions by MBC1 occurs with a yield of 99.8% for the concentration 50 mg/dm³ and decreases to 71.7% at 200 mg/dm³. The maximum pH sorption was found at pH 5. The highest correlation coefficient values (65.55 mg/g) were obtained for the Langmuir isotherm model. Application of 0.5 mol/dm³ HNO₃ as a desorbing agent gives the highest desorption percentage 98.92%.     

Study of uranium adsorption using amidoximated polyacrylonitrile‐encapsulated macroporous beads

Polyacrylonitrile beads, containing the amidoximated polyacrylonitrile, were prepared for adsorption of uranium. The synthesized amidoximated polyacrylonitrile chelating beads were evaluated, for their ability to adsorb uranium from aqueous solution, at different temperatures and pH values. The kinetic measurement showed that about 120 min of equilibration time was enough, to remove saturation amount of uranium from the solution. The pseudo first‐order and pseudo second‐order equations were used to analyze the kinetic data, and the rate constants were determined. The equilibrium adsorption data were examined by the Langmuir, Freundlich, and Temkin isotherms. The data showed a better fit to the Langmuir isotherm. The loaded uranium could also be leached out from the beads, by treating with dilute acids. The uranium uptake capacity of the polymeric beads was found to be 3.5 mg/g of the swollen beads. Reusability of the beads was also established by multiple adsorption–desorption experiments. The pore volume and the surface area of the dried beads, measured by BET method, were found to be 1.93 cc/g and 320 m²/g, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

BIOSORPTION STUDIES ON NACL-MODIFIED CERATOPHYLLUM DEMERSUM: REMOVAL OF TOXIC CHROMIUM FROM AQUEOUS SOLUTION

The present research provides information on the Cr(VI) removal potential of NaCl-modified Ceratophyllum demersum, an aquatic plant biomass. The effects of various parameters including pH, biomass dosage, contact time, and initial concentration on Cr(VI) biosorption were investigated. The best conditions for Cr(VI) biosorption in the present study were: pH of 2, biosorbent dose of 8 g/L, and contact time of 60 min. Under these conditions, maximum adsorption capacity of modified C. demersum for Cr(VI) was 10.20 mg/g. The experimental biosorption data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The biosorption process followed the Langmuir isotherm model with a high coefficient of determination (R² > 0.99). The biosorption process followed pseudo-second-order kinetics. Further, the biosorbent was characterized by Fourier transform-infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The results showed that biosorption of Cr(VI) on NaCl-modified C. demersum occurred through chemical sorption.     

Removal of Fluoride from Aqueous Solution by CaO Nanoparticles

Abstract

Colloidal particles of CaO were synthesized by the sol-gel method. The particle morphology was characterized by FT-IR, TGA, DTA, and TEM analysis. The ability of the CaO nanoparticles for removal of fluoride from aqueous solution through adsorption has been investigated. All the experiments were carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH 2–10), adsorbent dose (0.01–0.1 g/100 ml), initial fluoride concentration (10–100 mg/l) and competitive ions has been investigated to determine the adsorption capacity of CaO nanoparticles. Almost complete removal (98%) of fluoride was obtained within 30 minutes at an optimum adsorbent dose of 0.6 g/L for initial fluoride concentration of 100 mg/L. The adsorption isotherm was also studied to find the nature of adsorbate-adsorbent interaction.     

Removal of Humic Acid Using PEI‐Modified Fungal Biomass

Abstract

A modified fungal biomass was prepared through the adsorption of polyethylenimine (PEI) and subsequent crosslinking with glutaraldehyde on the biomass surface. FTIR result verified that the amine groups were introduced on the biomass surface. As a large number of amine groups are present on the biomass surface and can be protonated in solution, the modified biomass was positively charged at pH<10.3. The modified biomass was used as an adsorbent to remove humic acid in a series of batch adsorption experiments. The amount of humic acid adsorbed on the biosorbent decreased with increasing solution pH, and the electrostatic interaction between the positive protonated amine groups on the biomass surface and the negative carboxyl groups in the humic acid molecules played an important role in humic acid adsorption. The time‐dependent sorption of humic acid on the biomass can be described well by the Fickian diffusion model at the initial stage and the pseudo‐second‐order equation over 10 h. Using the Langmuir adsorption isotherm, the maximum sorption capacity of the modified biomass for humic acid at pH 5 was 96.5 mg/g. The desorption experiments showed that the humic acid loaded biomass could be easily regenerated in a 0.1 M NaOH solution, and the regenerated biomass possessed good adsorption capacity up to the fifth cycle. The PEI‐modified biomass with polyamine chains shows the potential for application in water treatment for the removal of humic substances.     

Removal of lead ions from wastewater using novel Schiff-base functionalized solid-phase adsorbent

ABSTRACT

This article discusses the synthesis, characterization and lead ions sorption capability of a novel recyclable Schiff-base anchored cross-linked polyacrylamide. The synthesized polymeric adsorbent was characterized by FT-IR technique, XRD and SEM analysis. Sorption parameters, such as solution’s pH, contact time, polymer dose, lead ions initial concentration, etc., were studied and optimized. Experimentally, the optimum sorption pH was around 5.0 and the sorption equilibrium was attained after 30 min. Under the optimal conditions, the maximum sorption capacity was found to be 355 mg/g, which is considered high when compared with different adsorbents. Effect of interfering ions on the sorption capacity was explored. Sorption isotherms, kinetic and thermodynamic studies were considered to identify the sorption behavior of the new polymeric adsorbent. Sorption isotherm studies showed that the maximum sorption capacity was attended as a result of homogeneous monolayer sorption of lead ions on the surface of the synthesized polymeric adsorbent. The mechanism of lead ions sorption by the synthesized polymeric adsorbent was found to be chemisorption complexation mechanism. Moreover, kinetic studies revealed that the sorption process followed a pseudo second order kinetic model. Thermodynamic data depicted that the sorption process is spontaneous, reversible and exothermic in nature. Experiments on elution and reusability of the synthesized polymeric adsorbent were executed and the results showed its validity for reuse for at least four cycles with 11% loss in its original capacity. Finally, the applicability of the synthesized Schiff-base anchored solid phase adsorbent for the removal of lead ions from industrial wastewater was explored and the results indicated its good removal efficiency.     

Sorption of Cu(II) Ions from Aqueous Solution with Synthesized B-Doped Heptazine-Based g-C/N/H Polymers

In this study, boron doped heptazine-based g-C/N/H polymers (B-doped heptazine-based g-C/N/H polymers) were synthesized by the pyrolysis process of the mixture of low cost H₃BO₃ and melamine. X-ray power diffractometer (XRD) and Fourier transform infrared spectroscopy (FT-IR) were applied to characterize the successful doping of B atoms into the nanostructure of the graphic-C₃N₄ (heptazine-based g-C/N/H polymers). The synthesized material was conducted to investigate the sorption capacity for Cu(II) ions from aqueous solution and the sorption conditions including the doped amount, the solution pH, the contact time, and initial concentration were optimized. The results indicated that the sorption process was dependent on solution pH and the optimum pH was from 3.0 to 6.0. The kinetics was well evaluated by pseudo-second-order which indicated that the main rate-determining step was controlled by the chemical sorption process. The maximum sorption capacity calculated from Langmuir model amounted to 149.3 mg g^?1 with the initial concentration range from 80 ～ 800 mg L^?1. So, B-doped heptazine-based g-C/N/H polymers have the potential application as a low cost adsorbent for high concentration Cu(II) ions in aqueous solution.