Adsorption of Lignosulfonate Compound from Aqueous Solution onto Chitosan-Silica Beads

The main objective of this study is to investigate the possibility of crosslinked chitosan-tetraethoxy orthosilane (TEOS) (chitosan-silica) beads to be used as an adsorbent material to adsorb the lignosulfonate compound in solution. Different parameters affecting the adsorption capacity such as contact time, adsorbent dosage, initial concentration, pH, ionic strength, and temperature have been investigated. Adsorption isotherms of lignosulfonates onto chitosan-silica beads were also studied. Batch adsorption experiments were carried out and the optimum lignosulfonate adsorption onto chitosan-silica beads occurred at contact time of 30 minutes, the adsorbent dosage of 40 g/L, initial concentration of 50 mg/L, pH 5, and a temperature of 45°C. Adsorption isotherms studied through the use of graphical methods revealed that the adsorption of lignosulfonates onto chitosan-silica beads follows the Langmuir model, with the maximum adsorption capacity being 238.3 mg/g at pH 7. Adsorption is dependent on the ionic strength. The adsorption of lignosulfonate on chitosan-silica beads was best described with the pseudo-second-order kinetic model with a rate constant of 0.32 g · mg^?1 · min^?1, while intra-particle-diffusion was the main rate-determining step in the lignosulfonate adsorption process. The chitosan-silica beads investigated in this study were thus exhibited as a high potential adsorbent for the removal of lignosulfonate from solution.     

Porous dye affinity beads for nickel adsorption from aqueous solutions: A kinetic study

We investigated a new adsorbent system, Reactive Red 120 attached poly(2‐hydroxyethyl methacrylate ethylene dimethacrylate) [poly(HEMA–EDMA)] beads, for the removal of Ni²⁺ ions from aqueous solutions. Poly(HEMA–EDMA) beads were prepared by the modified suspension copolymerization of 2‐hydroxyethyl methacrylate and ethylene dimethacrylate. Reactive Red 120 molecules were covalently attached to the beads. The beads (150–250 μm), having a swelling ratio of 55% and carrying 25.5 μmol of Reactive Red 120/g of polymer, were used in the removal of Ni²⁺ ions. The adsorption rate and capacity of the Reactive Red 120 attached poly(HEMA–EDMA) beads for Ni²⁺ ions was investigated in aqueous media containing different amounts of Ni²⁺ ions (5–35 mg/L) and having different pH values (2.0–7.0). Very high adsorption rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 60 min. The maximum adsorption of Ni²⁺ ions onto the Reactive Red 120 attached poly(HEMA–EDMA) beads was 2.83 mg/g at pH 6.0. The nonspecific adsorption of Ni²⁺ ions onto poly(HEMA–EDMA) beads was negligible (0.1 mg/g). The desorption of Ni²⁺ ions was studied with 0.1M HNO₃. High desorption ratios (>90%) were achieved. The intraparticle diffusion rate constants at various temperatures were calculated as k_20°C = 0.565 mg/g min^0.5, k_30°C = 0.560 mg/g min^0.5, and k_40°C = 0.385 mg/g min^0.5. Adsorption–desorption cycles showed the feasibility of repeated use of this novel adsorbent system. The equilibrium data fitted very well both Langmuir and Freundlich adsorption models. The pseudo‐first‐order kinetic model was used to describe the kinetic data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5056–5065, 2006     

Magnetic and K+-cross-linked kappa-carrageenan nanocomposite beads and adsorption of crystal violet

Biopolymer-based magnetic beads, composed of kappa-carrageenan (κ-Car) and Fe₃O₄ nanoparticles, were synthesized. The magnetic beads were prepared through in situ precipitation of Fe²⁺/Fe³⁺ ions in the presence of carrageenan and subsequently treating with K⁺ solution. The structure of magnetic kappa-carrageenan beads (mκ-Carb) was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer, and thermal gravimetric analysis techniques. According to SEM micrographs, an undulant and coarse structure with cubic-shaped sections was obtained when the magnetic nanoparticles were incorporated in composition of beads. The TEM image confirmed the formation of magnetic nanoparticles with an average size of 3–7 nm. The synthesized beads were examined as adsorbent to remove crystal violet dye from aqueous solutions. It was found that due to coarse surface, the rate of dye adsorption on magnetic beads can be improved slightly. The experimental adsorption kinetics was analyzed according to pseudo-first-order and pseudo-second-order kinetic models and the adsorption kinetics followed well the pseudo-second-order model. Isotherm adsorption data of dye on beads were modeled according to Langmuir and Freundlich isotherm models. The results revealed that the experimental data have the best fit to Langmuir isotherm model, and maximum adsorption capacity of beads for dye obtained was 84.7 mg/g. The influence of pH on the variation of adsorption capacity of beads for crystal violet was not considerable. The thermodynamic parameters indicated that the adsorption of CV dye on beads is spontaneous.     

A low-cost and environment friendly chitosan/aluminum hydroxide bead adsorbent for fluoride removal from aqueous solutions

A novel low-cost adsorbent named chitosan/Al(OH)₃·(CS/Al(OH)₃) bead was successfully prepared by employing AlCl₃·6H₂O aqueous solution as the solvent for CS. The CS/Al(OH)₃ beads were used for fluoride removal from water. The beads were synthesized using the chitosan and aluminum chloride with the mass ratio of 2:1 as the precursor and in situ generation of aluminum hydroxide sorbents in sodium hydroxide solution. Then, the beads were washed with distilled water to neutral and freeze dried. The sorbents were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), Fourier transform infrared spectrometry (FTIR), and X-ray diffractometry (XRD), respectively. Batch adsorption experiments were conducted to evaluate the parameters that affected the defluoridation capacity. The influencing parameters including pH, co-existing ions in water and initial temperature of the adsorption process were studied. The influence of temperature confirmed that the adsorption was spontaneous and endothermic. The adsorption isotherm of fluoride followed Langmuir isotherm model and the sorption kinetics was more suitable for pseudo-second-order kinetic model. The defluoridation capacity of chitosan/Al(OH)₃ calculated using Langmuir model was 23.06 mg/g (293 K, pH 4). The experimental results showed that the CS/Al(OH)₃ bead adsorbent is promising for the fluoride adsorption.     

Amino-functionalized magnetic zirconium alginate beads for phosphate removal and recovery from aqueous solutions

Amino-functionalized magnetic zirconium alginate beads with an interpenetrating network (Fe₃O₄/PAM/SA–Zr) were prepared, characterized, and then tested as a novel biomass adsorbent for phosphate removal and recovery. The hydrogel beads exhibited outstanding thermostability and possessed a magnetic response. The effects of the pH, dosage, initial phosphate concentration, interference ions, and temperature on the removal of phosphate were investigated. The kinetics, isotherms, and thermodynamics of the adsorption were studied. Notably, the adsorption of phosphate was endothermic, feasible, and spontaneous with a maximum uptake capacity of 42.23 mg-P/g at an optimized pH of 2.0. The phosphate could be desorbed effectively with a 0.2 mol/L NaOH solution, and the adsorbent exhibited a good reusability. The possible adsorption mechanisms were verified by zeta potential, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses. Continuous phosphate-adsorption tests were conducted in a fixed-bed columns packed with Fe₃O₄/PAM/SA–Zr, and the breakthrough curves were predicted by the Adams–Bohart, Thomas, and Yoon–Nelson models, respectively. The suitability of the hydrogel beads for the treatment of real wastewater was also tested. These hydrogel beads should be a promising adsorbent for phosphate removal and recovery from aqueous solutions, with the advantages of a high uptake capacity, good reusability, and easy magnetic separation. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46897.     

Adsorption characteristics of sericite for cesium ions from an aqueous solution

To efficiently remove cesium ions from aqueous solution, sericite was used as a novel adsorbent. The silanol (SiO₂) and aluminol (Al₂O₃) groups in sericite are likely to play an important role in adsorption process. The maximum adsorption capacity (q_m) and adsorption constant (K_L) for cesium ions obtained from the Langmuir isotherm model were 6.68 mg/g and 0.227 L/mg, respectively and regression curve fit well with the experimental data as the 0.965 of correlation coefficients (r²). However, when the Freundlich isotherm model was used correlation coefficient (r²) was 0.973. Therefore, it was concluded that Freundlich model fits equilibrium data better than Langmuir model. When the 6.0 g/L of sericie concentration was added to aqueous solution, cesium ions were removed by about 80% and the increase was not happened above 6.0 g/L of sericite concentration any more. The process was determined as exothermic reaction because the removal efficiency of cesium ions decreased as temperature increased. Furthermore, all adsorption was completed in 120 min and comparing the pseudo first and second-order kinetic models indicates that the adsorption of cesium ions using sericite follows well the pseudo-second-order kinetics.     

Removal of cesium ion in aqueous solution using immobilized sericite beads

To apply sericite effectively in the adsorption process, it was immobilized by entrapment method using sodium alginate. Since the immobilized sericite beads have excellent mechanical strength and swelling characteristics, channeling of flow and the increase of pressure drop were not observed through column operations. In addition, it was also stable under pH 10 and 45 °C of cesium solution. The maximum adsorption capacity and Langmuir adsorption constant was 1.430mg/g and 2.329 L/mg, respectively, at initial pH 5 of cesium solution in batch type and the Langmuir model with higher correlation coefficient of 0.997 fits experimental data better than Freundlich model. The breakthrough point emerged around 15 (1.0 mL/min) and 20 bed volumes (0.5 mL/min), and the cesium ions bound to the immobilized sericite beads were readily released and quantitatively recovered by a few bed volumes of 1.0M of HNO₃ solution. Furthermore, bed volumes of cesium ions for firstly reused sericite beads can be still maintained as 18, which shows good regeneration ability.     

Sorption Potential of Styrene‐Divinylbenzene Copolymer Beads for the Decontamination of Lead from Aqueous Media

Abstract

The decontamination of lead ions from aqueous media has been investigated using styrene‐divinylbenzene copolymer beads (St‐DVB) as an adsorbent. Various physico‐chemical parameters such as selection of appropriate electrolyte, contact time, amount of adsorbent, concentration of adsorbate, effect of foreign ions, and temperature were optimized to simulate the best conditions which can be used to decontaminate lead from aqueous media using St‐DVB beads as an adsorbent. The atomic absorption spectrometric technique was used to determine the distribution of lead. Maximum adsorption was observed at 0.001 mol L^?1 acid solutions (HNO₃, HCl, H₂SO₄ and HClO₄) using 0.2 g of adsorbent for 4.83×10^?5 mol L^?1 lead concentration in two minutes equilibration time. The adsorption data followed the Freundlich, Langmuir, and Dubinin‐Radushkevich (D‐R) isotherms over the lead concentration range of 1.207×10^?3 to 2.413×10^?2 mol L^?1. The characteristic Freundlich constants i.e. 1/n=0.164±0.012 and A=2.345×10^?3±4.480×10^?5 mol g^?1 have been computed for the sorption system. Langmuir isotherm gave a saturated capacity of 0.971±0.011 mmol g^?1, which suggests monolayer coverage of the surface. The sorption mean free energy from D‐R isotherm was found to be 18.26±0.75 kJ mol^?1 indicating chemisorption involving chemical bonding for the adsorption process. The uptake of lead increases with the rise in temperature. Thermodynamic parameters i.e. ΔG, ΔH, and ΔS have also been calculated for the system. The sorption process was found to be exothermic. The developed procedure was successfully applied for the removal of lead ions from real battery wastewater samples.     

Effect of Preparation Conditions on the Property Cu/AC Adsorbents for Phosphine Adsorption

Copper-based activated carbon adsorbents (Cu/AC) were prepared and used to investigate the effects of various copper precursors, impregnation solution concentration, and calcination temperature on phosphine (PH₃) adsorption removal from yellow phosphorus tail gas. N₂ adsorption isotherm and X-ray Diffraction (XRD) were used for characterizing the Cu/AC adsorbents. It can be seen that the Cu(N)/AC adsorbent prepared from the Cu(NO₃)₂ precursor has higher PH₃ breakthrough adsorption capacity than other three adsorbent because the surface copper status of it is mainly CuO. Fresh activated carbon requires an optimal impregnation solution concentration (0.05 mol/L) to reach this optimal PH₃ breakthrough adsorption capacity (78.62 mg/g). The result shows that the surface chemical characteristics (Cu content) of activated carbon is more important than the physical ones (specific surface or pore volume) for the PH₃ adsorption performance. When the calcination temperature is 350°C, the Cu(N)/AC adsorbent has the biggest PH₃ breakthrough adsorbed amount of 112.38 mg/g. The present study confirmed that the Cu/AC adsorbents would be one of the candidates for PH₃ adsorption removal from yellow phosphorus tail gas.     

A semi-conducting polypyrrole/coffee grounds waste composite for rhodamine B dye adsorption

A composite based on coffee grounds waste (CGW) coated with the semi-conducting polypyrrole (PPy) was prepared by pyrrole polymerization using potassium persulfate as oxidant. The composite was characterized by FTIR spectroscopy, cyclic voltammetry, UV/vis spectroscopy, scanning electron microscopy (SEM) and TGA analysis. SEM analysis showed homogeneous coating of coffee fibers with spherical nanoparticles of PPy with diameters in the range of 200–300 nm. Aqueous adsorption experiments of rhodamine B dye (RhB) onto the as-prepared composite were performed. The effect of pH and initial dye concentration (C₀) on the adsorption behavior was studied. The results showed that this material was an efficient adsorbent of RhB dye at alkaline pH. The adsorption experiments were set at C₀ = 200 mg/L and initial pH values of 2.0, 3.25 and 9.0, the adsorption capacities were 7.22, 13.8, and 19.0 mg of dye/g of the composite, respectively. Nonetheless, when pH was maintained at 9.0 throughout adsorption time, the adsorption capacity increased to 32 mg of dye/g of the composite. When performing adsorption tests using pure CGW, dye adsorption was insignificant at any pH level. Adsorption isotherm for RhB at controlled pH of 9.0 was well described by the Redlich–Peterson model and by the typical Langmuir adsorption model with a theoretical maximum adsorption capacity (q_max) of 50.59 mg of dye/g of composite.     

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.     

Binary biopolymeric beads of alginate and gelatin as potential adsorbent for removal of toxic Ni2+ ions: A dynamic and equilibrium study

Binary biopolymeric beads of alginate and gelatin were prepared and characterized by IR spectral and scanning electron micrograph techniques. On to the surfaces of the prepared beads were performed static and dynamic adsorption studies of Ni²⁺ ions at fixed pH and ionic strength of the aqueous metal ion solutions. The adsorption data were applied to Langmuir and Freundlich isotherm equations and various static parameters were calculated. The dynamic nature of adsorption was quantified in terms of several kinetic constants such as rate constants for adsorption (k₁), Lagergreen rate constant (k_ad), interparticle diffusion rate constant (k_p), and pore diffusion coefficient (D ). The influence of various experimental parameters such as solid to liquid ratio, pH, temperature, presence of salts, and chemical composition of biopolymeric beads on the adsorption of nickel ions was investigated. Various thermodynamic parameters were also calculated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2581–2590, 2007     

Adsorption of Cr (VI) Oxyanions onto Modified Wood Pulp

A new adsorbent was prepared from wood pulp (WP) after reaction with epichlorohydrin and dimethylamine in the presence of pyridine and N,N-dimethylformamide (DMF). The adsorption of Cr (VI) from aqueous solutions by the so-prepared wood pulp adsorbent (WP-A) was investigated. Various factors affecting adsorption, such as pH, adsorbent concentration (1–5 g/L), agitation time (5–60 min), and Cr (VI) concentration (50–700), were taken into consideration. The adsorption of Cr (VI) onto (WP-A) was found to be pH-dependent and maximum adsorption was obtained at pH 3. The adsorption data obeyed Langmuir and Freundlich adsorption isotherms. The Langmuir adsorption capacity (Q_max) was found to be 588.24 mg/g. Freundlich constants, K_F and n, were found to be 55.03 and 2.835, respectively.     

Adsorption of Congo Red from Aqueous Solutions Using Chitosan Hydrogel Beads Formed by Various Anionic Surfactants

The structural organization of chitosan hydrogel beads (CSBs) formed by various anionic surfactants, sodium dodecyl sulfate (SDS), sodium decyl sulfate (DS), dodecyl benzenesulfonic acid sodium salt (SDBS), and dioctyl sulfosuccinate sodium salt (DSS), and their applications as adsorbents for environmental purifications were investigated using Congo red (CR) as a model dye. The adsorption capacities of CSB as a function of surfactant concentration revealed that CSBs formed by 5 g/L anionic surfactant were the most effective for CR adsorption. The structure of CSBs and their adsorption capacities for CR depend on the nature of anionic surfactants. The maximum adsorption capacities of CSB_SDS, CSB_DS, CSB_SDBS, and CSB_DSS obtained from the Langmuir isotherm model were 186.02, 209.28, 207.25, and 113.83 mg/g, respectively, indicating that CSB_DS was the best adsorbent for CR.     

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.     

Aminating modification of viscose fibers and their CO2 adsorption properties

An adsorbent for CO₂ capture was prepared by the grafting of acrylonitrile (AN) onto viscose fibers (VFs); this was followed by amination with triethylene tetramine (TETA). The effects of the reaction conditions, such as the concentrations of the monomer, initiator, and nitric acid, on the grafting degree and grafting efficiency were studied. The adsorption performance of the adsorbent for CO₂ was evaluated by fixed‐bed adsorption. The highest dynamic adsorption capacity of the adsorbent for CO₂ was 4.35 mmol/g when the amine content of the adsorbent VF–AN–TETA reached 13.21 mmol/g. Compared with the polypropylene (PP)‐fiber‐based adsorbent (PP–AN–TETA), VF–AN–TETA with hydroxyl groups on the fibers facilitated the diffusion of CO₂ and water and led to a higher CO₂ adsorption capacity than that of PP–AN–TETA. The VF–AN–TETA adsorbent also showed good regeneration performance: its CO₂ adsorption capacity could still retain almost the same capacity as the fresh adsorbent after 10 adsorption–desorption cycles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42840.     

Three-dimensional g-C3N4/MgO composites as a high-performance adsorbent for removal of Pb(II) from aqueous solution

ABSTRACT

A novel, three-dimensional material of g-C₃N₄/MgO was prepared by pyrolysis method. The adsorption behavior for Pb(II) onto g-C₃N₄/MgO was systematically investigated. The adsorption experiments confirmed that the g-C₃N₄/MgO exhibited remarkable adsorption performance owing to its rough morphology and abundant active sites on the surface. The maximum adsorption capacities for Pb(II) reached to 220.3, 226.2 and 235.1 mg/g at 308 K, 318 K and 328 K, respectively. The optimum adsorbent dosage was 1.0 g/L. The adsorption kinetics and isotherm could be well described by the pseudo-second-order model and Langmuir isotherm model, respectively. The adsorption process was spontaneous and endothermic.     

Rubidium and Cesium Ion Adsorption by a Potassium Titanium Silicate-Calcium Alginate Composite Adsorbent

In this work, a composite spherical adsorbent, which employs potassium titanium silicate as an adsorption active component, and calcium alginate as a carrier, was successfully prepared. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterize the adsorbent. The kinetics and thermodynamics of rubidium and cesium ions adsorption were investigated comprehensively, by considering the effects of initial concentration, temperature, solution pH, and coexisting NaCl. According to the determination coefficients, the pseudo second-order kinetic model provided an impressive and comparable correlation, and the second-order rate constant and the initial adsorption rate increase with increasing temperature. In general, the equilibrium adsorption amount increases with the increasing initial metal ion concentration, but decreases with increasing coexisting NaCl. The adsorption capacity keeps constant in the pH value range 3-12 and slightly fades when the temperature increases from 25 to 55°C. Under similar conditions, rubidium and cesium show the similar adsorption amount. The adsorbent has a fast adsorption rate and an adsorption capacity of about 1.55 mmol g^?1 for rubidium and 1.47 mmol g^?1 for cesium when the initial metal ion concentration is 0.10 mol L^?1. The composite adsorbent is effective for the adsorption of rubidium or cesium ions from simulated brines.     

Adsorption of Cu2+ Cations from Aqueous Solution by S-doped TiO2

S-doped TiO₂ as a novel adsorbent for Cu²⁺ cations removal from aqueous solutions was synthesized by simple sol-gel process. Removal of Cu²⁺ cations from aqueous solutions was investigated with particular reference to the effects of initial Cu²⁺ cations concentration, pH-value, adsorbent dosage, and temperature on adsorption. It was found that the maximum adsorption capacity was 96.35 mg g^?1 at 328 K. The adsorption equilibrium isotherms and the kinetic data were well described by the Langmuir and pseudo-second-order kinetic models, respectively. The high uptake capability of S-doped TiO₂ makes it a potentially attractive adsorbent for the removal of heavy metal pollutants from aqueous solution.     

Modification of Sodium Alginate for the Removal of Cd(II) from Aqueous Solutions

Sodium alginate was protonated using HCl in ethanol: H₂O mixture (30:70). The modified sodium alginate (MSA) was characterized by determination of carboxyl content and solubility percent. The modified sample acquires of 450 meq-COOH/100 g sample and exhibits the complete insolubility in water. The MSA was utilized as adsorbent material to remove Cd(II) ions from aqueous solutions. Factors affecting adsorption process, such as agitation time and adsorbent concentration and pH of the adsorbate, were examined. The adsorption data show that the maximum adsorption capacity, Q_max, of Cd(II) onto MSA is 769.23 mg/g. The adsorption data also showed that the adsorption of Cd(II) onto MSA obeys Langmuir and Freundlich isotherms.