Sb(III)-Imprinted Organic-Inorganic Hybrid Sorbent Prepared by Hydrothermal-Assisted Surface Imprinting Technique for Selective Adsorption of Sb(III)

Sb(III)-imprinted organic-inorganic hybrid sorbent was prepared by hydrothermal-assisted surface imprinting technique and was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy coupled to an energy dispersive spectrometer and N₂ adsorption/desorption isotherms. Hydrothermal-assisted process can improve the selectivity of the Sb(III)-imprinted hybrid sorbent for Sb(III) due to stable control of temperature and pressure. The Sb(III)-imprinted hybrid sorbent IIS indicated higher selectivity for Sb(III), had high static adsorption capacity of 37.3 mg g^–1 for Sb(III), displayed stable adsorption capacity in pH range from 4 to 8, reached an rapid adsorption equilibrium within 30 min. According to the correlation coefficient (r² > 0.99), the experimental data fitted better the pseudo-second-order kinetic model and Langmuir equilibrium isotherm.

     

Adsorption Kinetics,Equilibrium, and Thermodynamics of Copper From Aqueous Solutions using Silicon Carbide Derived from Rice Waste

Adsorption of Cu(II) from aqueous solution on a novel adsorbent, silicon carbide ash (SiC ash), was studied using batch technique. The adsorbent was prepared by pyrolysis of Egyptian rice waste (rice straw and rice husk) and was characterized by scanning electron microscopy (SEM), energy-dispersive x-ray (EDX), Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and surface area analysis by Brunauer-Emmett-Teller (BET) Theory. The influence of pH, contact time, initial Cu(II) concentration, adsorbent dose, agitation speed, and temperature was investigated. Adsorption kinetics was analyzed using the pseudo-first-order, the pseudo-second-order, and intraparticular diffusion model. The adsorption process was found to follow a pseudo-second-order rate mechanism. The adsorption isotherm data could be well described by the Langmuir and Freundlich than the Dubinin–Radushkevich adsorption model. The adsorption capacity of 22.06 mg g^?1for SiC ash was obtained at pH = 5 and temperature of 298 K. Thermodynamic parameters, change in the free energy (ΔG°), the enthalpy (ΔH°), and the entropy (ΔS°), were also calculated. The overall adsorption process was exothermic, spontaneous in nature, and proceeds with decreased randomness as the entropy is negative value. Adsorption process was successfully applied to remove Cu(II) from an industrial wastewater sample.     

Reactive blue 19 adsorption behaviors of magnesium hydroxide modified biochar derived from the traditional Chinese medical residual

This study examined the reactive blue 19 (RB-19) adsorption behaviors of magnesium hydroxide modified biochar (MBC) derived from the traditional Chinese medical residual. The obtained MBC was characterized using Scanning Electron Microscope (SEM), Fourier Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET). The static adsorption experiment was carried out to investigate the adsorption properties. The results indicated that pH 4 was best for the adsorption removal of RB-19 in the pH range of 4–9. Compared with the pseudo-first-order model and Elovich model, the pseudo-second-order equation was best to describe the adsorption process (R² > 0.995). The Langmuir model was better than the Freundlich model to fit the experimental data (R² > 0.990). The intra-particle diffusion model showed that film diffusion and intra-particle diffusion were involved in the adsorption process. Thermodynamic parameters showed that the RB-19 adsorption by MBC was spontaneous and endothermic. The adsorption mechanism might include electrostatic interaction, pore filling, and hydrogen bond, and the MBC was a promising adsorbent.     

Selective Solid‐phase Extraction of Cu2+ by a Novel Cu(II)‐imprinted Silica Gel

A new Cu(II)‐imprinted salen functionalized silica gel adsorbent was synthesized by surface imprinting technique and was employed as a selective solid phase extraction material for Cu²⁺ removal from aqueous solutions. The samples were characterized by FT‐IR, ¹HNMR, ¹³CNMR, CHNS and DTG techniques. The BET surface area of the silica gel was also determined. The adsorbent was then used for removal of Cu²⁺ from aqueous solutions under different experimental conditions. It was concluded that the synthesized imprinted silica gel had higher selectivity and capacity compared to the non‐imprinted silica gel and the maximal adsorption capacity of 67.3 and 56.5 mg.g^?1 was obtained respectively for ion‐imprinted and non‐imprinted adsorbents. The relative selectivity factor (β) of 50.32 and 31.94 was obtained respectively for Cu²⁺/Ni²⁺ and Cu²⁺/Zn²⁺ pairs. The dynamic adsorption capacity of the imprinted adsorbent was close to the static adsorption capacity due to the fast kinetic of adsorption. Furthermore, the ion‐imprinted adsorbent was recovered and repeatedly used and satisfactory adsorption capacity with acceptable precision was obtained. Each experiment was repeated at least for three times and the mean and the standard deviation for each measurement were calculated. The applicability of the method was examined for Zayandehrood water as real sample. Acceptabe standard deviation was obtained.     

Synthesis and characterization of azoxystrobin hydrophilic molecularly imprinted microspheres

Abstract

In this research, hydrophilic molecularly imprinted microspheres (HMIPs) for azoxystrobin were successfully synthesized through precipitation polymerization. The adsorption capacities of HMIPs for azoxystrobin in water medium were higher than ordinary molecularly imprinted microspheres (MIPs), and HMIPs exhibited good hydrophilic properties. HMIPs and non-imprinted microspheres (HNIPs) were characterized by FT-IR, SEM, laser particle size analyzer and TGA. Comparing with HNIPs, azoxystrobin had a significant influence on morphologys and sizes of HMIPs. The Langmuir adsorption isotherm illustrated each binding site of HMIPs had the same adsorption capacity. The Lagergran pseudo-second-order kinetic model indicated the adsorption process between azoxystrobin and HMIPs was chemical adsorption. BET test illustrated HMIPs had bigger specific surface areas than HNIPs. Selective adsorption indicated that HMIPs had highly specific recognition of azoxystrobin. HMIPs successfully exhibited high selectivity and high hydrophilicity in water medium.     

Enhanced Adsorption of Hexavalent Chromium onto Magnetic Calcium Ferrite Nanoparticles: Kinetic,Isotherm, and Neural Network Modeling

Calcium ferrite nanoparticles with super-paramagnetic behavior were synthesized via simple chemical precipitation method for effective removal of hexavalent chromium from aqueous media. The properties of synthesized nanoparticles were studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and vibrating sample magnetometer (VSM) measurements. The ferrite nanoparticles have shown polycrystalline nature and high BET specific surface area (229.83 m²/g) with active functional groups on the surface. The adsorption process follows second-order kinetics with the involvement of intra-particle diffusion and adsorption capacity as much as 124.11 mg/g was determined from the Langmuir isotherm. The thermodynamic analysis revealed that the adsorption process was feasible, spontaneous, and exothermic in nature. A three-layer feed-forward back-propagation artificial neural network (ANN) model was employed to predict the removal (%) of Cr(VI) ions as output. Optimal ANN network (4:8:1) shows the minimum mean squared error (MSE) of 0.00161 and maximum coefficient of determination (R²) of 0.984. The adsorption process is mostly influenced by solution pH and followed by adsorbent dosage, initial Cr(VI) concentration, and contact time as illustrated by sensitivity analysis. With small size and high surface area, biocompatibility, ecofriendly nature, easy magnetic separation, and enhanced adsorption capacity towards Cr(VI), calcium ferrite nanoparticles will find its potential application in wastewater remediation.     

Sol–gel derived ion imprinted thiocyanato-functionalized silica gel as selective adsorbent of cadmium(II)

A Cd(II)-imprinted thiocyanato-functionalized silica gel adsorbent with high adsorption capacity was prepared by surface imprinting technique combined with sol–gel process for the selective adsorption of Cd(II) ion in aqueous solution, and was characterized by Fourier-transform infrared spectroscopy, nitrogen gas sorption and thermogravimetric analysis. The influences of different conditions (such as the pH of solutions, the contact time and the initial concentrations of Cd(II) ions) on the adsorption capacity of Cd(II) were investigated. The optimum pH of adsorption was in the range of 4–8.5. The adsorption equilibrium could be reached in 20 min. The relatively selectivity coefficients of the imprinted silica were higher than those of the non-imprinted adsorbents. Ho’s pseudo-second-order model well described the kinetics of the adsorption reaction. The adsorption process of metals followed Redlich–Peterson isotherm model, and the experimental value of maximum adsorption capacity for Cd(II) was 72.8 mg·g^?1. The positive value of ΔH ^o suggested endothermic nature of Cd(II) adsorption on the imprinted silica adsorbent. Increase in entropy of adsorption reaction was shown by the positive value of ΔS ^o and the negative value of ΔG ^o indicating that the adsorption was spontaneous in nature.     

Adsorption of phenols from contaminated water through titania-silica mixed imidazolium based ionic liquid: Equilibrium,kinetic and thermodynamic modeling studies

The present study describes the synthesis and characterization of titania-silica mixed imidazolium based ionic liquid (Ti-Si-IL) as well as evaluation of its adsorption behavior towards the 2,4-dinitrophenol (2,4-DNP) and 2,4,6-trichlorophenol (2,4,6-TCP). Synthesized Ti-Si-IL adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), BET surface area Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA) and elemental analysis (CHN). The adsorption of 2,4-DNP and 2,4,6-TCP on Ti-Si-IL was investigated systematically by evaluating the effects of adsorbent dosage, initial pH, contact time and temperature. Satisfactory adsorption 95% and 65% for 2,4-DNP and 2,4,6-TCP was observed at pH 4 and 6, respectively. The kinetic results for 2,4-DNP and 2,4,6-TCP on Ti-Si-IL indicated that the kinetic data follows pseudo-second-order model (R² = 0.9985 and 0.9750, respectively). Adsorption isotherms were fitted well by the Langmuir model for 2,4-DNP (q_m = 44.64 mg g^?1 at 318 K) and Freundlich model for 2,4,6-TCP (K_F = 0.63 mg g^?1 at 318 K). The +ΔH° and -ΔG° values demonstrated that the adsorption of 2,4-DNP was endothermic and spontaneous in nature. While the -ΔH° and +ΔG° values for 2,4,6-TCP adsorption demonstrated exothermic and comparatively nonspontaneous. During the removal process, the role of different functional groups, cyclic structure was monitored and found that the ionic property as well as π-π interactions of host molecules played important role in the extent of adsorption.     

Synthesis and Properties of Surface Molecular Imprinting Adsorbent for Removal of Pb<Superscript>2+</Superscript>

A new chitosan imprinting adsorbent using diatomite as core material was prepared by using the surface molecular imprinting technology with the Pb²⁺ as imprinted ion. The preparation process conditions of the surface molecular imprinting adsorbent were studied. The adsorbent was characterized by using Fourier transform infrared (FTIR) spectrum. FTIR spectrum indicated that it was cross-linked by epichlorohydrin. The new imprinting adsorbent could provide a higher adsorption capacity for Pb²⁺, which reached 139.6 mg/g increasing 32.3% compared with cross-linking chitosan adsorbent (the initial Pb²⁺ concentration of 600 mg/L). The adsorption velocity was quick and the equilibration time of the imprinting adsorbent for Pb²⁺ was 3 h that shortened about 40% compared with cross-linking chitosan adsorbent. It had a more wide pH range of 5–7 than that of cross-linking chitosan adsorbent. The new imprinting adsorbent can be reused for up to ten cycles without loss of adsorption capacity. In the kinetics and isotherm study, the pseudosecond order model and Langmuir model could represent the adsorption process.     

Novel surface molecularly imprinted material modified multi-walled carbon nanotubes as solid-phase extraction sorbent for selective extraction gallium ion from fly ash

A new gallium (Ga(III)) ion-imprinted multi-walled carbon nanotubes (CNTs) composite sorbent was synthesized by a surface imprinting technique. The Ga(III) ion-imprinted/multi-walled carbon nanotubes (Ga(III)-imprinted/CNTs) sorbent was characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), nitrogen adsorption experiment, static adsorption experiment, and solid-phase extraction (SPE) experiment. The effects of sample volume, sample pH, washing and elution conditions on the extraction of Ga(III) ion from real sample were studied in detail. The imprinted sorbent offered a fast kinetics for the adsorption of Ga(III). The maximum static adsorption capacity of the imprinted sorbent towards was 58.8 μmol g⁻¹. The largest selectivity coefficient for Ga(III) in the presence of Al(III) was over 57.3. Compared with non-imprinted sorbent, the imprinted sorbent showed good imprinting effect for Ga(III) ion, the imprinting factor (α) was 2.6, the selectivity factor (β) was 2.4 and 2.9 for Al(III) and Zn(II), respectively. The developed imprinted SPE method was applied successfully to the detection of trace Ga(III) ion in fly ash samples with satisfactory results.     

A sol-gel derived pH-responsive bovine serum albumin molecularly imprinted poly(ionic liquids) on the surface of multiwall carbon nanotubes

A pH-responsive surface molecularly imprinted poly(ionic liquids) (MIPILs) was prepared on the surface of multiwall carbon nanotubes (MWCNTs) by a sol-gel technique. The material was synthesized using a 3-aminopropyl triethoxysilane modified multiwall carbon nanotube (MWCNT-APTES) as the substrate, bovine serum albumin (BSA) as the template molecule, an alkoxy-functionalized IL 1-(3-trimethoxysilyl propyl)-3-methyl imidazolium chloride ([TMSPMIM]Cl) as both the functional monomer and the sol-gel catalyst, and tetraethoxysilane (TEOS) as the crosslinking agent. The molecular interaction between BSA and [TMSPMIM]Cl was quantitatively evaluated by UV–vis spectroscopy prior to polymerization so as to identify an optimal template/monomer ratio and the most suitable pH value for the preparation of the MWCNTs@BSA-MIPILs. This strategy was found to be effective to overcome the problems of trial-and-error protocol in molecular imprinting. The optimum synthesis conditions were as follows: template/monomer ratio 7:20, crosslinking agent content 2.0–2.5 mL, temperature 4 °C and pH 8.9 Tris–HCl buffer. The influence of incubation pH on adsorption was also studied. The result showed that the imprinting effect and selectivity improved significantly with increasing incubation pH from 7.7 to 9.9. This is mainly because the non-specific binding from electrostatic and hydrogen bonding interactions decreased greatly with the increase of pH value, which made the specific binding affinity from shape selectivity strengthened instead. The polymers synthesized under the optimal conditions were then characterized by BET surface area measurement, FTIR, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The adsorption capacity, imprinting effect, selective recognition and reusability were also evaluated. The as-prepared MWCNTs@BSA-MIPILs were also found to have a number of advantages including high surface area (134.2 m² g⁻¹), high adsorption capacity (55.52 mg g⁻¹), excellent imprinting effect (imprinting factor of up to 5.84), strong selectivity (selectivity factor of 2.61 and 5.63 for human serum albumin and bovine hemoglobin, respectively), and good reusability.     

Efficient removal of heavy metal ions using hydrophilic thiacalix[4]arene doped polyaniline prepared by emulsion polymerization: conductivity,isotherm and kinetic study

The adsorption capacity of conductive polyaniline doped by thiacalix[4]arene tetrasulfonate (PANI–TCAS) towards Cu(II), Cd(II), Co(II) and Cr(III) was investigated through batch adsorption techniques, and the extent of adsorption was measured as a function of pH, initial metal ion concentration and contact time. It was found that the metal ion removal reached maximum at pH 8.0 and remained constant after 60 min. Experimental data was fitted to Langmuir, Freundlich, Redlich–Peterson and Temkin equation models with the maximum adsorption capacity calculated to be 833.3, 555.5, 526.3 and 500 for Cr³⁺, Cu²⁺, Co²⁺ and Cd²⁺, respectively, from the Langmuir isotherm model. The kinetic study was carried out through pseudo‐first‐order, pseudo‐second‐order, Elovich kinetic and intraparticle diffusion models in which the related correlation coefficient for each kinetic model showed that the pseudo‐second‐order rate equation was better described by the adsorption process. XRD spectra, SEM and TEM images of the adsorbent revealed a homogeneous distribution of nano‐sized particle structure with a porous surface, the morphology of which brings about high adsorption capacity for the PANI–TCAS molecular nanocomposite which in turn was observed by the AFM micrograph. The conductivity of thiacalix[4]arene tetrasulfonate doped polyaniline after metal ion adsorption was also assessed, and the four‐probe measurement technique revealed conductivity increment as high as 102.4 S cm^?1 with a 100 order of magnitude enhancement. Copyright © 2015 John Wiley & Sons, Ltd.     

A novel green biosorbent from chitosan modified by sodium phytate for copper (II) ion removal

A novel kind of adsorbent bead was prepared from chitosan (CS) by ionic‐linked with sodium phytate (SP) and then covalent cross‐linked with epichlorohydrin (ECH) by nonsolvent‐induced phase separation. The structure of the beads was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. The adsorption properties of the beads for Cu(II) ions under different adsorption conditions were investigated. The maximum adsorption capacity of Cu(II) ions was 177.1 mg g⁻¹ at the conditions of pH of 5.2, temperature of 50°C, and initial Cu(II) ion concentration of 728.3 mg L⁻¹. The adsorption isotherm of Cu(II) ions on the CS/SP/ECH beads was well correlated with the Langmuir isotherm model, and the whole adsorption process could be better followed the pseudo‐second‐order kinetic model. Moreover, the CS/SP/ECH beads still exhibited good adsorption capacity even after the 15th regeneration cycles.     

A Ce3+-imprinted functionalized potassium tetratitanate whisker sorbent prepared by surface molecularly imprinting technique for selective separation and determination of Ce3+

A surface molecular imprinting technology was developed to adsorb Ce(III) ions that showed much higher adsorption affinity and selectivity for than for other metal ions. The batch adsorption process was studied with respect to effects of pH value, residence time, temperature, and initial concentration of Ce(III) ion. The maximum adsorption capacity is 43 mg g^?1 at an initial Ce(III) concentration of 300 mg L^?1 and at a sorbent dosage of 1.0 g L^?1. A Langmuir isotherm fits the experimental data. The imprinted sorbent exhibits a much higher separation and selectivity for the target imprinted ion than the non-imprinted polymer. Cerium ion can be desorbed with 1M hydrochloric acid solution which is also proven by scanning electron microoscopy and X-ray diffraction experiments. The limit of detection is 37 ng mL^?1. The sorbent has been applied to the determination of trace cerium in different environmental samples with satisfactory results.     

On‐Line Selective Solid‐Phase Extraction of Copper with a Surface Ion Imprinted Silica Gel Sorbent

Copper(II)‐ion imprinted silica gel (Cu‐IISG) sorbent was synthesized by surface imprinting technique and was employed as a selective solid‐phase extraction material for on‐line preconcentration and separation, then coupled with atomic absorption spectrometry (AAS) determination of Cu(II). The higher selectivity coefficient of Cu‐IISG for Cu(II) in the presence of competitive ions such as Fe(III), Ni(II) and Zn(II) was above 411, which was 35 times of NISG. The static adsorption capacity and dynamic adsorption capacity were 41.11 mg g^?1 and 16.20 mg g^?1, respectively. The Cu‐IISG offered a fast kinetics for the adsorption and desorption of Cu(II), which can be used for on‐line preconcentration and detection. Two certified reference materials of GBW07301a sediment and GBW07401 soil were analyzed and the determined values were in a good agreement with the certified values. The developed method was also successfully applied to the determination of trace copper in tea leaf with satisfactory results (recovery between 96.3% and 102.3%).     

Interaction between congo red and copper in a binary adsorption system: Spectroscopic and kinetic studies

This study focused on the competitive adsorption of congo red (CR) and copper by chitosan hydrogel beads in a binary adsorption system. Spectroscopic analysis, including Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were integrated with kinetic studies to elucidate the interaction. It was determined that chitosan hydrogel beads show better adsorption performance towards congo red and copper in single adsorption systems. The addition of copper caused a 25% reduction in congo red adsorption capacity, while copper adsorption was enhanced slightly by the presence of congo red. The adsorption results for binary adsorption systems seem due to competition for the present amine and hydroxyl groups that may occur between congo red and copper. A congo red–copper complex was formed in binary adsorption systems. Copper attached to chitosan hydrogel beads individually or was bound by the congo red–copper complex, which resulted in an increase in adsorption capacity. Chitosan exhibited higher adsorption selectivity to the free Cu²⁺ ion than the congo red–copper complex in the binary adsorption system. Adsorption of the congo red–copper complex indicated an inhibition in the attachment of the free Cu²⁺ ion in the form of Cu(II).     

Deep adsorptive desulfurization over Cu,Ce bimetal ion-exchanged Y-typed molecule sieve

In this paper, Ce(IV)–Y, Cu(II)–Y and Cu(II)–Ce(IV)–Y adsorbents were prepared by the liquid-phase ion-exchange Y zeolites with combined Cu and Ce ions at low temperature and room pressure. The adsorbents were characterized by means of X-ray diffraction, N₂-adsorption specific surface area measurements (BET), X-ray photoelectron spectroscopy, Pyridine adsorption infrared spectroscopy and Fourier transform infrared. The adsorptive desulfurization properties of these three adsorbents were studied in a fixed-bed unit through a model gasoline which made up of 1-octane solution of the refractory sulfur compounds (Such as thiophene and benzothiophene) and a certain amount of toluene or cyclohexene. The results indicate that Cu(II)–Ce(IV)–Y bind the organic sulfur compounds through two types of adsorption modes: π-complexation and direct sulfur–adsorbent interaction. The adsorption selectivity of sulfur compounds onto Cu(II)–Ce(IV)–Y decreased in the order: benzothiophene > 2,5-dimethylthiophene > 3-methylthiophene > thiophene. The effect of competition components on the metal ion-exchanged Y zeolites for sulfur removal in the order: cyclohexene > toluene. The Cu(II)–Ce(IV)–Y possesses the high sulfur adsorption capacity similar to Cu(II)–Y and high selectivity for sulfur compounds similar to Ce(IV)–Y, which can be attributed to the synergistic interaction between Cu²⁺ and Ce⁴⁺.     

One-pot synthesis of a novel magnetic activated carbon/clay composite for removal of heavy metals from aqueous solution

Abstract

In the present work, a novel composite consisting of magnetite, activated carbon from spent coffee grounds and natural clay (MACCC) was prepared by a one-pot synthesis method via a simultaneous activation and magnetization processes. Various techniques (XRD, FTIR, SEM, TEM, EDX, BET) were utilized to characterize the synthesized composite before utilizing it as an adsorbent for removal of Cu(II), Ni(II) and Pb(II) ions from aqueous solutions. Conditions for removal of heavy metals were thoroughly optimized as 25?°C, pH of 5.5, adsorbent dosage of 2?g L^?1, and a contact time of 60?min. Three models of pseudo first-, second-order and intraparticle diffusion as well as three models of Langmuir, Freundlich, and Temkin were used to analyze kinetics and isotherms of the adsorption process. Thermodynamics was discussed completely. Regeneration and recyclability of the adsorbent were also evaluated. Based on the analysis of experimental results, a possible adsorption mechanism of heavy metals onto the synthesized composite was proposed. The maximum capacities caculated from Langmuir model followed the order of Pb(II) > Cu(II) > Ni(II) as 143.56, 96.16 and 84.86?mg·g^?1, respectively. The overall results indicated that MACCC is a potential adsorbent for removal of toxic Pb(II), Cu(II) and Ni(II) ions from wastewater due to simple preparation, high removal efficiency and good recyclability.     

Design and syntheses of functionalized copper-based MOFs and its adsorption behavior for Pb(Ⅱ)

A novel copper-based MOFs adsorbent(Cu-BTC-Th) was prepared using an one-step method by introducing a new organic ligand of 4-thioureidobenzoicacid(Th) with active groups for selectively adsorbing Pb(Ⅱ) from aqueous solutions. The chemical composition and structure of the prepared MOFs materials were characterized by scanning electron microscope(SEM), X-ray diffraction(XRD), fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), Brunner-Emmet-Teller(BET) analysis, ...     

Development of hybrid adsorbent for effective aqueous phase sorptive removal of copper

Alginate beads (ABs) immobilized with hydrous zirconium oxide (ZO) were used as a hybrid adsorbent (ZO@AB) for the effective removal of copper ions [Cu(II)] from aqueous phase. ZO@AB was characterized using X‐ray photoelectron spectroscopy to confirm the impregnation of ABs with ZO and the adsorption of Cu(II) onto ZO@AB. The maximum equilibrium sorption capacity of ZO@AB for Cu(II) was 63.1 mg·g⁻¹ at pH 5. The Cu(II) removal rate was high at the beginning of reaction, with >90% adsorption within 24 hours, and equilibrium was achieved within 48 hours. The adsorption of Cu(II) onto ZO@AB was well described by pseudo‐second‐order kinetic model (R² > 0.99), and the monolayer nature of sorption was supported by the Langmuir model (R² > 0.99). The sorption process was endothermic, favorable, and spontaneous in nature. Regarding the reusability of the adsorbent, its sorption capacity remained satisfactory (>90%) throughout the 5 consecutive cycles (regeneration in 0.1 mol·L⁻¹ HCl). The stoichiometric ratio of released calcium ions [Ca(II)] to adsorbed copper ions [Cu(II)] was approximately 1:1, confirming that ion exchange was the main mechanism for removal of Cu(II) from aqueous phase. The developed adsorbent (ZO@AB) shows promise as a candidate for the effective and selective removal of Cu(II) from aqueous phase.