Adsorption Efficiency of Polyaspartate-Montmorillonite Composite Towards the Removal of Pb(II) and Cd(II) from Aqueous Solution

The selective modification of sodium montmorillonite (Na⁺-Mt) surface with polyionene followed by poly (succinimde-co-aspartate) has been considered. Na⁺-Mt was allowed to react with well characterized polyionene in two fold excess. The resulting polyionene/Mt (IC) was further modified with poly (succinimide-co-aspartate) through an ion exchange process. The obtained polyaspartate/Mt (IPS) composite was characterized by elemental analysis, X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and BET surface analyzer. The adsorption efficiency of IPS composite was investigated for the removal of Pb(II) and Cd(II) from aqueous solution under different experimental conditions including initial metal ions concentration, temperature and single and binary mixture systems of metal ions. The experimental data were analyzed by Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. Langmuir model reveals that the monolayer adsorption capacity of IPS was 92.59 and 67.57 mg/g for Pb(II) and Cd(II), respectively. The modification of parent Na⁺-Mt enhanced their adsorption capacity by about 87.91 and 29.84% for Pb(II) and Cd(II), respectively, due to inclusion of extra active sites of polyaspartate. The mean sorption energy, E calculated from Dubinin–Radushkevich isotherm were 2.75 and 1.98 kJ/mol for the adsorption of Pb(II) and Cd(II), respectively, indicating physical adsorption process. Also, The thermodynamic parameters were calculated and indicated that the adsorption was spontaneous and exothermic process. The mechanism of cation exchange and complexation of metal ions was suggested. IPS composite has a considerable potential for the removal of heavy metal ions from aqueous solution and wastewater stream.     

Insights into Effective Adsorption of Lead ions from Aqueous Solutions by Using Chitosan-Bentonite Composite Beads

Journal of Polymers and the Environment - The chitosan (Ch)—bentonite (B) composite was synthesized and its adsorption properties were investigated for lead ions. The characterization of the...     

Epichlorohydrin Crosslinked 2,4-Dihydroxybenzaldehyde Schiff Base Chitosan@SrFe12O19 (EP-DBSB-CS@SrFe12O19) Magnetic Nanocomposite for Efficient Removal of Pb(II) and Cd(II) from Aqueous Solution

Journal of Polymers and the Environment - In this paper, new epichlorohydrin crosslinked 2,4-dihydroxybenzaldehyde Schiff base chitosan@SrFe12O19 magnetic nanocomposite (EP-DBSB-CS@SrFe12O19) was...     

Synthesis of Ion-Imprinted Alginate Based Beads: Selective Adsorption Behavior of Nickel (II) Ions

Ni(II) imprinted and non-imprinted bioadsorbent alginate beads were prepared, and utilized in the selective adsorption of Ni(II) ions. The optimum adsorption capacity were 6.00 mmol g^?1 at 500 ppm initial metal ion concentration at pH 7 for Ni(II) imprinted alginate beads (IIP). The equilibrium data were applied to Langmuir and Freundlich adsorption isotherms, and it fitted both isotherm models. Thermodynamic parameters showed favorable and endothermic nature of adsorption. Ni(II) imprinted bead showed the strong ability to selective adsorption from Cu(II), Co(II) and Zn(II) ions. In conclusion, Ni(II) ion imprinted alginate beads could be used repeatedly without any significant reduce of adsorption capacity.     

Green Synthesis and Physical Properties of poly(Vinyl Alcohol) Maleated in an Aqueous Solutions

The objective of this work was to synthesize maleated poly(vinyl alcohol) (PVAM) in aqueous solution through esterification, and to seek near optimal degree of grafting and crosslinking. The effects of maleic anhydride (MA) content on the properties of PVAM were investigated. The experimental observations included characterizations by ATR–FTIR and thermo gravimetric analyses (TGA), and determinations of grafting ratio, dynamic viscosity, and swelling ratio. The percentage degree of grafting, dynamic viscosity, and particle size increased with MA content, while the swelling ratio decreased due to copolymerization of poly(vinyl alcohol) (PVA) and MA. The peaks at 945 and 918 cm^?1 in the spectrum of PVA indicated the presence of carboxylic groups, while in the spectrum of PVAM only one peak at 920 cm^?1 indicated presence of carboxylic groups, due to copolymerization of PVA and MA. Moreover, the thermal stability of PVA-g-MA was enhanced as observed from TGA. The results suggest 7:3 PVA/MA mass ratio as near optimal for PVA-g-MA.     

Insight into the Adsorption Properties of Chitosan/Zeolite-A Hybrid Structure for Effective Decontamination of Toxic Cd (II) and As (V) Ions from the Aqueous Environments

Chitosan/zeolite-A hybrid structure (CS/Z.A) was synthesized and characterized as a multifunctional and environmental adsorbent for the Cd (II) and As (V) ions. The adsorption capacities of CS/ZA for Cd (II) and AS (V) are 170 mg/g and 125 mg/g, respectively which are higher values than several adsorbents in literature. The kinetic study demonstrates Pseudo-First-order behavior for the Cd (II) adsorption process and Pseudo-second order for the As (V) uptake reactions. The Cd (II) and As (V) uptake reactions follow the Freundlich equilibrium behavior with heterogeneous and multilayer adsorption properties. The kinetic and equilibrium studies in addition to the Gaussian energy {6.35 kJ/mol [Cd (II)] and 9.44 kJ/mol [As (V)]} demonstrate physical properties for the Cd (II) adsorption mechanism and more chemical behavior for the As (V) adsorption mechanism. The thermodynamic study declares exothermic, spontaneous, and favorable adsorption reactions for Cd (II) and As (V) by CS/Z.A composite. The CS/Z.A is of significant capacity for Cd (II) and As (V) ions in the existence of other competitive dissolved anions (PO₄^3?, NO₃^?, and SO₄^2?) and other metals [Zn (II), Co (II), and Pb (II)]. Finally, the CS/Z.A composite is a recyclable product and can be applied in effective Cd (II) and As (V) decontamination processes for five runs.

     

Biosorptive removal of Pb(II) and Cu(II) from wastewater using activated carbon from cassava peels

The ability of activated carbon from cassava peels to remove heavy metals like Cu(II) and Pb(II) from hospital wastewater was investigated. The study showed that a pH of 8 was the best for the sorption of both metal ions onto the biosorbent. The time-dependent experiments for the metal ions showed that the binding of the metal ions to the biomass was rapid and occurred within 20–120 min. Sorption efficiency increased with a rise in adsorbent dosage. It increased from 12 to 73 % for Pb(II) and 26 to 79 % for Cu(II) when the adsorbent dose increased from 2 to 12 g. An increase in temperature led to an increase in sorption for both metal ions. The Langmuir model showed that the biomass has a higher sorption capacity for Cu(II) than Pb(II), with q _m = 5.80 mg g^?1 for Pb(II) and 8.00 mg g^?1 for Cu(II). The Freundlich isotherm K _f was 1.4 for Pb(II) and 1.8 for Cu(II), indicating a preferential sorption of Cu(II) onto the biosorbent. Adsorption capacity was found to decrease with an increase in particle sizes. Sorption occurred by physical mechanisms and was mainly controlled by intraparticle diffusion.     

Preparation and Characterization of Hybrids of Cellulose Acetate Membranes Blended with Polysulfone and Embedded with Silica for Copper(II), Iron(II) and Zinc(II) Removal from Contaminated Solutions

Journal of Polymers and the Environment - With the objective to assess the suitability of cellulose acetate (CA), polysulfone (PSF) and silica (SiO2) for wastewater treatment, this work presents...     

Application of ameliorated wood pulp to recover Cd(II), Pb(II), and Ni(II) from e-waste

In this study, dl-malic acid and hydrogen peroxide were used as leaching agents to remove metals from e-waste (printed-circuit boards) and itaconic acid-grafted poly(vinyl alcohol)-encapsulated wood pulp (IA-g-PVA-en-WP) to uptake metals from leachate with high proficiency [11.63 mg g^?1; 93.03 % for Cd(II), 11.90 mg g^?1; 95.18 % for Pb(II), and 12.14 mg g^?1; 97.08 % for Ni(II)]. Metals were recovered from the loaded biosorbent by desorption studies. The standard analytical techniques, such as elemental analysis, Fourier-transform-infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and thermogravimetric analysis, were used to characterize the recovering agent (biosorbent). At equilibrium, the metal uptake data were fitted to Langmuir and D–R isotherms (R ² > 0.99) significantly, revealing, the homogeneous distribution of active sites on biosorbent’s backbone. The possible mechanism appeared to be ion exchanges of metal ions with H⁺ together with binding over functionalities (COO^?). Dimensionless equilibrium parameter (R _L) showed the favourability of metal uptake at lower concentration, while mean adsorption energy (E) certified the physical binding of metal on functionalities which was further confirmed by sticking probability and activation energy parameters. Reusability studies were also conducted to state the performance of biosorbent.     

Modified Sugarcane Bagasse with Tartaric Acid for Removal of Diazonium Blue from Aqueous Solutions

The present study concerns with exploring the possibility of using of tartaric acid pretreated sugarcane bagasse (SCB) for removing diazonium blue (DB) from aqueous solutions. The effect of different factors on the efficiency of the adsorbent for the DB dye removal was investigated, including initial dye concentration, contact time, SCB dosage and SCB particle size. Langmuir, Freundlich, Tempkin and D–R isothermal models have been employed to analyze the adsorption equilibrium data. It was found that the adsorption of the dye fits well with the D–R model. The adsorption kinetics was also done applying four kinetic models. The regression equation coefficients refer to fitting the data to the second-order kinetic equation for removal of the DB dye. It is probable that the rate limiting step is a chemical adsorption between the adsorbent and the dye. This chemisorption process is further confirmed from the energy value of 15.1 kJ mol^?1 deduced from the D–R isotherm.     

Adsorptive Removal of Malachite Green Chloride and Reactive Red-198 from Aqueous Solutions by Using Multiwall Carbon Nanotubes-Graft-Poly (2-acrylamido-2-methyl-1-propanesulfonic acid)

The multiwall carbon nanotubes (MWCNTs) were modified by 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) via grafting reaction and γ-rays of ⁶⁰Co source was used as initiator. The outcome product was called hydroxyethylated (HOEt-MWCNTs) graft poly(AMPS) and abbreviated as HOEt-MWCNTs-g-PAMPS. The parameters that affected the grafting yield were optimized. The maximum grafting obtained was ~20 %. HOEt-MWCNTs-g-PAMPS were characterized by Fourier transform infra red, scanning electron microscopy, high resolution transmission electron microscopy, thermal gravimetric analysis. The adsorptive removals of malachite green chloride (MGC) and reactive red 198 (RR-198) onto HOEt-MWCNTs-g-PAMPS were studied at variable conditions. The adsorption isotherms were analyzed using Langmuir, Redlich–Peterson, Freundlich, Khan and Sips models. The results referred that Sips model is the best fitting to adsorption of MGC and Freundlich model is the best fitting to RR-198 adsorption. The monolayer coverage capacities of HOEt-MWCNTs-g-PAMPS for MGC and RR-198 dyes were found 172 and 323 mg g^?1, respectively. The rate of kinetic adsorption processes of MGC and RR-198 onto HOEt-MWCNTs-g-PAMPS were described by using pseudo-first order, pseudo-second order and intraparticle diffusion models. The pseudo-first order and pseudo-second order models were the best choice among the kinetic models to depict the adsorption behaviors of MGC and RR-198 dyes onto HOEt-MWCNTs-g-PAMPS, respectively. Further, the effect of temperature on the adsorption isotherms was investigated and the thermodynamic parameters were obtained. The results indicated that the adsorption process is spontaneous and endothermic. The values of ΔG° varied in range with the mean values showing a gradual increase from ?3.17 to ?3.64 kJ mol^?1 for MGC and ?3.36 to ?3.73 kJ mol^?1 for RR-198. The reusability and regeneration of adsorbent were investigated. The outcome data referred to that the efficiency of adsorbent >98 %. The outline results declared that there is a good potentiality for the HOEt-MWCNTs-g-PAMPS to be used as an adsorbent for the removal of MGC and RR-198 from aqueous solutions.     

花生壳活性炭吸附溶液中的铀

以农林废弃物花生壳为原料、氢氧化钾为活化剂、微波为热源,制备了花生壳活性炭。以花生壳活性炭为吸附剂吸附溶液中的U(VI),考察了初始U(VI)质量浓度、活性炭加入量、溶液pH、吸附时间对U(VI)去除效果的影响。实验结果表明,在溶液中初始U(VI)质量浓度为30mg/L、活性炭加入量为0.5g/L、溶液pH为5.5、吸附时间为150min的较佳条件下,活性炭对U(VI)的吸附量为56.37mg/g,U(VI)去除率为93.94％。     

Hydrolysis of Polylactic Acid (PLA) and Polycaprolactone (PCL) in Aqueous Acetonitrile Solutions: Autocatalysis

Polylactic acid (PLA) is a hydrolytically degradable aliphatic polyester. The rate of polymer hydrolysis increases with time, and that has been attributed to the high reactivity of the terminal ester and the kinetics of autocatalysis. Hydrolysis is carried out in an acetonitrile/water solution to eliminate any solid-state contributions such as diffusion and crystallinity to the degradation process. A kinetic equation is derived to describe the autocatalytic effect of the increasing carboxylic acid end-group concentration. The results of solution hydrolysis are examined and found to fit the derived equation. Hydrolysis was also carried out with polycaprolactone (PCL) in acetonitrile, where reaction kinetics were found to differ from those of PLA. The PCL polymer required external acid catalysis by the addition of HCl, whereas hydrolysis of PLA was selfcatalyzed by the carboxylic acid end-groups.     

Diethylenetriaminepentaacetic Acid (DPTA)-modified Magnetic Cellulose Nanocrystals can Efficiently Remove Pb(II) from Aqueous Solution

Journal of Polymers and the Environment - Surface modification of cellulose nanocrystals (CNC) is essential for improving their reactivity and adsorption capacity. Oxidation, as a conventional...     

Removal of Cr(VI) Ions from Aqueous Solutions Using Poly 3-Methyl Thiophene Conducting Electroactive Polymers

This paper deals with a new application of poly 3-methyl thiophene synthesized chemically onto sawdust (termed as P3MTh/SD) as an effective adsorbent for removal of Cr(VI) ions from aqueous solutions using column system. Chemical synthesis of poly 3-methyl thiophene was performed by addition of ferric chloride (in chloroform) as oxidant to sawdust which had previously been soaked in monomer solution. All the sorption experiments were conducted using dynamic or column system at room temperature. The effect of important parameters such as pH and initial concentration on uptake of Cr(VI) was investigated. In order to find out the possibility of the regeneration and reuse of the exhausted adsorbent, desorption studies were also performed. The currently introduced adsorbent was found to be an efficient adsorbent for removal of highly toxic and hazardous Cr(VI) ions from aqueous solutions. As our breakthrough analysis has indicated, each gram of P3MTh/SD is able to remove more than 95% of Cr(VI)ions from 300 mL of Cr(VI) polluted solution with the initial concentration of 25 mg L⁻¹ in column system. Sorption/desorption of Cr(VI) ions was found to be a highly pH dependent processes.     

Anionic Methyl Orange Removal from Aqueous Solutions by Activated Carbon Reinforced Conducting Polyaniline as Adsorbent: Synthesis,Characterization, Adsorption Behavior,Regeneration and Kinetics Study

This work investigated the elimination of Methyl Orange (MO) using a new adsorbent prepared from Activated Carbon (AC) with polyaniline reinforced by a simple oxidation chemical method. The prepared materials were characterized using XRD, TGA, FTIR and nitrogen adsorption isotherms. Furthermore, PANI@CA highest specific surface area values (near 332 m² g^?1) and total mesoporous volume (near 0.038 cm³ g^?1) displayed the better MO removal capacity (192.52 mg g^?1 at 298 K and pH 6.0), which is outstandingly higher than that of PANI (46.82 mg g^?1). Besides, the process’s adsorption, kinetics, and isothermal analysis were examined using various variables such as pH, MO concentration and contact time. To pretend the adsorption kinetics, various kinetics models, the pseudo first- and pseudo second- orders, were exercised to the experimental results. The kinetic analysis revealed that the pseudo second order rate law performed better than the pseudo first order rate law in promoting the formation of the chemisorption phase. In the case of isothermal studies, an analysis of measured correlation coefficient (R²) values showed that the Langmuir model was a better match to experimental results than the Freundlich model. By regeneration experiments after five cycles, acceptable results were observed.

     

Peanut hull pellets as a single use sorbent for the capture of Cu(II) from wastewater

This paper investigates the ability of peanut hulls and peanut hull pellets to adsorb copper from dilute aqueous metal ion solutions in batch and fixed bed systems. The kinetics of copper uptake onto the media have been investigated in batch systems and the influence of pH and particle size on the rate and extent of copper capture determined. The Langmuir and Freundlich isotherm theories were determined; the Langmuir model was found to best represent the equilibrium isotherm data. In normalized kinetic tests at least 75% of copper removal occurred within the first 20 min; 92% removal was effected within the first 50 min. The rate of uptake was optimum within the pH range 5-7.5, and media capacities remained relatively constant at a pH above 4.0. Bench-scale column studies were performed using peanut hull pellets. The overall capacity of pelletized peanut hulls was higher than for unmodified peanut hulls. Due to their demonstrated ability for Cu(II) uptake and favorable structural characteristics, pelletized peanut hulls could gain use as a low-cost, once-through biomass filter medium for copper-bearing waste streams.     

Experimental and Modeling Studies for the Removal of Crystal Violet Dye from Aqueous Solutions using Eco-friendly <Emphasis Type="Italic">Gracilaria corticata</Emphasis> Seaweed Activated Carbon/Zn/Alginate Polymeric Composite Beads

This research article describes, an eco-friendly activated carbon prepared from the Gracilaria corticata seaweeds which was employed for the preparation of biodegradable polymeric beads for the efficient removal of crystal violet dye in an aqueous solution. The presence of chemical functional groups in the adsorbent material was detected using FTIR spectroscopy. The morphology and physical phases of the adsorbent materials were analyzed using SEM and XRD studies respectively. Batch mode dye adsorption behavior of the activated carbon/Zn/alginate polymeric beads was investigated as a function of dosage, solution pH, contact time, initial dye concentration and temperature. Maximum dye removal was observed at a pH of 5.0, 1 g of adsorbent dosage with 60 mg/L dye concentration, 50 min of contact time and at 30 °C. The equilibrium modeling studies were analyzed with Freundlich and Langmuir adsorption isotherms and the adsorption dynamics was predicted with Lagergren’s pseudo-first order, pseudo-second order equations and intra particle diffusion models. The process of dye removal followed a pseudo second-order kinetics rather than pseudo first order. The thermodynamic parameters like standard Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were determined and the results imply that the adsorption process was spontaneous, endothermic and increases the randomness between the adsorbent and adsorbate. The results from the experimental and correlation data reveal that the Gracilaria corticata activated carbon/Zn/alginate polymeric beads have proved to be an excellent adsorbent material for the removal of CV dye.     

Removal of Linear and Branched p-Alkylphenols from Aqueous Solution by Combined Use of melB Tyrosinase and Chitosan Beads

In this study, melB tyrosinase was applied for enzymatic removal of linear and branched p-alkylphenols from aqueous solutions. First, systematic studies were carried out to estimate the effects of the process parameters such as the temperature, pH value, and enzyme dose on quinone conversion of p-cresol as a model phenol compound. A variety of p-alkylphenols were removed from aqueous solutions through the tyrosinase-catalyzed quinone conversion and subsequent nonenzymatic adsorption of quinone derivatives on chitosan beads at pH 6.0 and 30 °C under the optimum conditions determined for p-cresol. The % removal values of 98–100 were obtained for p-n-alkylphenols. Branched p-alkylphenols with a weak estrogenic activity containing 4-tert-butylphenol and 4-tert-pentylphenol, which underwent no quinone conversion by commercially available mushroom tyrosinase in the absence of H₂O₂, were also effectively removed by further increasing either the melB tyrosinase concentration or the amount of added chitosan beads. The present technique is much effective in the fact that a series of reactions rapidly progress under mild conditions and the chitosan beads can be readily separated from the reaction medium after the enzymatic treatment.     

Fe(III) Complexed Polydopamine Modified Mg/Al Layered Double Hydroxide Enhances the Removal of Cr(VI) from Aqueous Solutions

Journal of Polymers and the Environment - Herein, we report the preparation of Fe(III) complexed polydopamine modified Mg/Al layered double hydroxides composite material (LDHs@PDA-Fe(III)) and its...