Hybrid Sorbent Research Articles

Mesoporous silica functionalized with 1-furoyl thiourea urea for Hg(II) adsorption from aqueous media

New organic–inorganic hybrid materials were prepared by covalently anchoring 1-furoyl thiourea on mesoporous silica (SBA-15). By means of various characterization techniques (X-ray diffraction, nitrogen adsorption–desorption, thermogravimetric analysis, and FTIR spectroscopy) it has been established that the organic groups were successfully anchored on the SBA-15 surfaces and the ordering of the inorganic support was preserved during the chemical modifications. The hybrid sorbents exhibited good ability to remove Hg(II) from aqueous solution. Thus, at pH 6, the adsorption capacity of mercury ions reached 0.61 mmol g −1.

Evaluating the performance of iron nanoparticle resin in removing arsenate from water

This research was undertaken to evaluate the effectiveness of a hybrid sorbent resin (Lewatit FO36) with goethite structure for removing arsenate from water. Column experiments (with constant flow rate of 8 mL/min, corresponding to 2 min empty bed contact time (EBCT)) were conducted to evaluate the adsorption capacity of resin before and after regeneration and effects of chloride, sulfate, bicarbonate and combined competing ions for arsenate removal from water. The adsorption capacity was approximately 3.229 mg/g that was reduced to 2.826 mg/g after regeneration with 12.48% decrease, which indicates to a successful regeneration procedure. Chloride and sulfate ions had no significant effects on arsenate removal but arsenic removal decreased in the presence of bicarbonate and combined ions. This reduction may be due to the ability of bicarbonate ions in extracting and mobilizing the arsenate ions from iron oxyhydroxides. Results of this study showed that Lewatit FO36 could be developed as a suitable sorbent for arsenate removal.

Preparation of Fe oxide nanoparticles for environmental applications: arsenic removal

The objective of this study is to examine the adsorption-desorption behavior of a magnetically active hybrid sorbent (MAHS) material, prepared by dispersing colloid-like hydrated iron oxide particles in the outer periphery of a macroporous ion-exchange resin (Amberlite XAD-2). The experimental results show that the new sorbent material can simultaneously remove arsenic (V) and a chlorinated organic compound (2,6-dichlorophenol [2,6-DCP]) from aqueous solutions at around neutral pH. The recovery of arsenic and 2,6-DCP from MAHS was conducted using a regenerant containing 50% (v/v) CH3OH + 3% (w/v) NaOH. In less than 10 bed volumes of regenerant, more than 90% of As(V) and 2,6-DCP were recovered.

Ceramic-Supported Alginate Adsorbent for the Removal of Heavy Metal Ions

Hybrid alginate/ceramic support sorbents have been developed by the physical imbibing of an alginic acid solution into silica pores and γ-alumina microspheres. The metal ion-binding capacity of the prepared hybrids was examined by means of batch Cd2+ ion adsorption experiments. In addition, since the porous γ-alumina microspheres proved capable of retaining higher quantities of alginic acid than silica, they were chosen as a more appropriate substrate for the application of a chemical modification procedure. In this context, the aim was to develop hybrid sorbents with an enhanced stability and adsorption capacity obtained by grafting the bio-molecule onto the substrate. Such chemical modification included grafting two different types of silanes onto the external surface and pores of γ-alumina, followed by chemical bonding of the alginate with the characteristic groups of the silane molecules involved. Such chemically-prepared sorbents exhibited almost twice the Cd2+ ion adsorption capacity of sorbents pre...

Nanohybrid anionic surfactant-akaganéite: Preparation, structural analysis and cations sorption

The preparation of a nanocrystalline hybrid anionic surfactant-akaganeite (denoted as Akh) as an innovative sorbent, the investigation of its surface properties and the evaluation of its ability to remove cations from aqueous solutions were studied in the present paper. The nanocrystalline hybrid anionic surfactant-akaganeite was prepared in the laboratory using FeCl3 as precursor and an anionic surfactant (sodium dodecyl sulphate) as modifier. The new adsorbent was investigated with X-ray Diffraction (XRD), Fourier-Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HRTEM). The maximum loading capacity of the new hybrid sorbent was 64 mg Zn2+/g and 48 mg Cd2+/g compared with 28 Zn2+mg/g and 17 mg Cd2+/g for pure akaganeite.

Application of Ordered Nanoporous Silica for Removal of Uranium Ions from Aqueous Solutions

Ordered nanoporous silica (MSU-H) with high surface area has been utilized as a solid substrate of a surface-modified hybrid sorbent for the application to the removal of U(VI). Carboxymethylated polyethyleneimine (CMPEI) with a strong complexing property has been introduced to the pore surface of MSU-H substrate. CMPEI-modified MSU-H (CMPEI/MSU-H) has been characterized by scanning electron microscopy and nitrogen sorption. In a kinetic experiment for 12.5 ppm U(VI) solution at pH 4.0, 99% U(VI) was removed from solution by the hybrid sorbent within less than 10 min, indicating that the sorption of U(VI) on the CMPEI/MSU-H proceeds very rapidly. It was evident that a U(VI) sorption capacity increased with pH in the range of 2.0 to 4.0. The CMPEI/MSU-H showed a high sorption capacity of 153 mg/g-sorbent at pH 4.0. In particular, the CMPEI/MSU-H showed a significantly high uranium loading stability. Only about 1% U(VI) was released out of CMPEI/MSU-H during 4 months, when the CMPEI/MSU-H was treated with polyacrylic acid.

Nanohybrid anionic surfactant-akaganeite: preparation, structural analysis and cations sorption

The preparation of a nanocrystalline hybrid anionic surfactant-akaganeite (denoted as Akh) as an innovative sorbent, the investigation of its surface properties and the evaluation of its ability to remove cations from aqueous solutions were studied in the present paper. The nanocrystalline hybrid anionic surfactant-akaganeite was prepared in the laboratory using FeCl3 as precursor and an anionic surfactant (sodium dodecyl sulphate) as modifier. The new adsorbent was investigated with X-ray Diffraction (XRD), Fourier-Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and High-Resolution Transmission Electron Microscopy (HRTEM). The maximum loading capacity of the new hybrid sorbent was 64 mg Zn2+/g and 48 mg Cd2+/g compared with 28 Zn2+mg/g and 17 mg Cd2+/g for pure akaganeite.

Al-centered functionalized inorganic–organic hybrid sorbent containing N and S donor atoms for effective removal of cadmium

A new aluminium-incorporated layered inorganic–organic hybrid material (Al-GPTS-TU) has been successfully synthesized by using sol–gel based precursor under mild temperature condition and silylaing agent (GPTS-TU) derived from the reaction of 3-glycidoxypropyltrimethoxysilane (GPTS) and thiourea (TU). The hybrid material was characterized by using various instrumentation techniques and the result confirmed the attachment of organic functionality to the inorganic silicon network. The inter-lamellar distance for the hybrid material was found to be 41.33 Å. The synthesized hybrid was used for the removal of cadmium from dilute aqueous solution with variation of solution parameters. Thermodynamic parameters Δ H and Δ S, evaluated for the adsorption of cadmium from water solution, were found to be 73.68 kJ mol −1 and 282.9 J mol −1 K −1, respectively, indicating adsorption process to be endothermic in nature. The negative value of Δ G indicated the feasibility and spontaneity of ongoing adsorption process. The hybrid material containing multiple coordination sites such as S and N in the attached organic functionality can find potential applications for the removal of various metal toxicants from water bodies to prevent the eco-system.

Highly efficient removal of heavy metals by polymer-supported nanosized hydrated Fe(III) oxides: Behavior and XPS study

The present study developed a polymer-based hybrid sorbent (HFO-001) for highly efficient removal of heavy metals [e.g., Pb(II), Cd(II), and Cu(II)] by irreversibly impregnating hydrated Fe(III) oxide (HFO) nanoparticles within a cation-exchange resin D-001 (R-SO 3Na), and revealed the underlying mechanism based on X-ray photoelectron spectroscopy (XPS) study. HFO-001 combines the excellent handling, flow characteristics, and attrition resistance of conventional cation-exchange resins with the specific affinity of HFOs toward heavy metal cations. As compared to D-001, sorption selectivity of HFO-001 toward Pb(II), Cu(II), and Cd(II) was greatly improved from the Ca(II) competition at greater concentration. Column sorption results indicated that the working capacity of HFO-001 was about 4–6 times more than D-001 with respect to removal of three heavy metals from simulated electroplating water (pH ∼4.0). Also, HFO-001 is particularly effective in removing trace Pb(II) and Cd(II) from simulated natural waters to meet the drinking water standard, with treatment volume orders of magnitude higher than D-001. The superior performance of HFO-001 was attributed to the Donnan membrane effect exerted by the host D-001 as well as to the impregnated HFO nanoparticles of specific interaction toward heavy metal cations, as further confirmed by XPS study on lead sorption. More attractively, the exhausted HFO-001 beads can be effectively regenerated by HCl–NaCl solution (pH 3) for repeated use without any significant capacity loss.

Preparation of dye waste-barium sulfate hybrid adsorbent and application in organic wastewater treatment

A new hybrid material was developed by the template-free hybridization of weak acidic pink red B (APRB, C.I. 18073) with BaSO(4). The composition and structure of the material were determined and characterized. In contrast to conventional sorbents, the hybrid material has a specific surface area of 0.89 m(2)/g, but it contains lots of negative charges and lipophilic groups as the basis of specific adsorption. The efficient removal of cationic dyes and persistent organic pollutants (POPs) indicates that it has an improved adsorption capacity and selectivity with a short removal time less than 2 min; while the hybrid sorbents fit the Langmuir isotherm model, and follow the octanol-water partition law. Instead of using APRB reagent, an APRB-producing wastewater was reused to prepare the cost-effective sorbent, and the equilibrium adsorption capacities of which reached 222 and 160 mg/g for EV and BPR, respectively. The sorbents was then used to treat three wastewater samples with satisfactory results of over 97% decolonization and 88% COD-decreasing. In addition, the hybrid sorbent was regenerated from sludge over five cycles, and its adsorption capacity was not appreciably changed. This work has developed a simple and eco-friendly method for synthesizing a practical and efficient sorbent.

Evaluating the effectiveness of a hybrid sorbent resin in removing fluoride from water

In some regions of the world, the concentration of fluoride in groundwater is high. To reduce the amount of fluoride to acceptable drinking water standard, it is highly recommended to treat the water. Fluoride adsorption in aqueous solution by a hybrid resin was studied in this research because of its functional groups likeness with goethite. Kinetic data showed that F adsorption was rapid in the beginning and maximum uptake occurred in within 10 min and equilibrium reached within 100 min. The experimental results showed that fluoride adsorption was influenced by pH of solution and optimum operating pH was in the range of 3 to 5.5. Langmuir model was applicable to the present study and F ions were exchanged with hydroxide ions in nano-scaled structure on the surface of sorbent. This adsorbent with 61 % efficiency is suitable for the regions where F concentration is less than 4 mg/L.

Sensing of toxic metals through pH changes using a hybrid sorbent material: Concept and experimental validation

AbstractThis article reports a new hybrid sorbent material that is capable of detecting trace concentration of toxic metals, such as zinc, lead, copper, nickel, etc., through pH changes only. The material is essentially a composite granular material synthesized through rapid fusion of a mixture of amorphous hydrated ferric oxide (HFO) and akermanite or calcium magnesium silicate (Ca2MgSi2O7). When a water sample is rapidly passed through a mini‐column containing this hybrid material, effluent pH at the exit always remains alkaline (≈9.0) because of slow hydrolysis of akermanite and steady release of hydroxyl (OH−) ions. This exit solution turns pink through the addition of a phenolphthalein indicator. Commonly encountered electrolytes containing sodium, calcium, chloride, and sulfate have no impact on the exit pH from the mini‐column. However, when trace concentration of a heavy metal (say lead) is present in the sample water, a considerable drop in pH (>2 units) is observed for the exiting solution. At this point, the solution turns colorless through the addition of a phenolphthalein indicator. Moreover, the change in the slope of pH, i.e., −dpH/dBV, provides a sharp, noticeable peak for each toxic metal where BV is the bed volumes of solution fed. The technique allowed detection of zinc and lead through pH swings in synthesized samples, spiked Bethlehem City water, and also in Lehigh River water in the presence of phosphate and natural organic matter (NOM). Using a simple preconcentration technique, lower than 10 μg/l of lead was detected with a significant peak. From a mechanistic viewpoint, high sorption affinity of HFO surface sites toward toxic metal cations, ability of akermanite to maintain near‐constant alkaline pH for a prolonged period through slow hydrolysis and labile metal‐hydroxy complex formation causing dissipation of OH− ions from the aqueous phase provide a synergy that allows detection of toxic metals at concentrations well below 100 μg/l through pH changes. Nearly all previous investigations pertaining to toxic metals sensing use metal‐selective enzymes or organic chromophores. This simple‐to‐operate technique using an inexpensive hybrid material may find widespread applications in the developing world for rapid detection of toxic metals through pH changes. © 2009 American Institute of Chemical Engineers AIChE J, 2009

Reversible sorption of hydrogen on the novel hybrid material based on mesoporous chromium(iii) terephthalate with included rhenium clusters

The interaction of mesoporous chromium(iii) terephthalate [Cr3O(C8H4O4)3F(H2O)2] (MIL-101) with an aqueous solution of the anionic cluster [Re4S4F12]4− ({Re4}) afforded a novel hybrid material {Re4}@MIL-101. According to the elemental analysis data, one cavity of the nanoporous framework contains up to two-three tetranuclear rhenium clusters. The hybrid sorbent obtained reversibly absorbs up to 3.7 wt.% hydrogen at 77 K and 30 atm.

An imprinted organic–inorganic hybrid sorbent for selective separation of copper ion from aqueous solution

A new organic–inorganic hybrid sorbent was prepared by a double-imprinting approach for the selective separation of Cu(II) from aqueous solution. In the prepared hierarchically imprinted sorbent, both Cu(II) and surfactant micelles (cetyltrimethylammonium bromide) were used as templates. The sorbent was prepared through self-hydrolysis, self-condensation, and co-condensation of the crosslinking agent (tetraethoxysilane) and the functional precursor (3-aminopropyltrimethoxysilane) in an alkaline media followed by gelation. The adsorption property and selective recognition ability of the sorbents were studied by equilibrium-adsorption method. Results showed that in the presence of Zn(II) the biggest selectivity coefficient of the imprinted sorbents for Cu(II) was over 500, which is much higher than those of non-imprinted sorbents. The largest relative selectivity coefficient (k′) of the ion-imprinted functionalized sorbent between Cu(II) and Zn(II) was over 500. The uptake capacities and the selectivity coefficients of the hierarchically imprinted sorbent were much higher than those of the sorbent prepared without CTAB template. Furthermore, the new imprinted sorbent possessed a fast kinetics for the removal of Cu(II) from aqueous solution with the saturation time less than 10 min, and could be used repeatedly. This sorbent has been successfully applied to the separation and determination of the trace Cu(II) in real water samples and those spiked with standards. This new sorbent can be used as an effective solid-phase extraction material for the highly selective preconcentration and separation of Cu(II) in environmental samples.

Impregnating Zirconium Phosphate onto Porous Polymers for Lead Removal from Waters: Effect of Nanosized Particles and Polymer Chemistry

The subject study revealed several unique properties of polymer-based zirconium phosphate (ZrP) for lead removal from waters. ZrP particles were impregnated within two porous polymers, namely, a chloromethylated polystyrene (CP) and a polystyrene cation exchange resin (D-001). Both as-prepared hybrid sorbents (designated ZrP−CP and ZrP−001, respectively) were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and a N2 adsorption−desorption test at 77 K. As compared to the fresh particles, ZrP impregnated onto CP exhibits a slight increase in sorption capacity, which may result from their nanosized particles after impregnation. More attractively, ZrP−001 displays much higher sorption preference toward lead ions over calcium ions than ZrP, D-001, and ZrP−CP. Such significant phenomena is mainly attributed to the Donnan membrane effect exerted by the immobilized sulfonate groups on D-001 and further validates its potential application for enhanced removal of the toxic metal from contaminated waters.

Design of siliceous lignins – Novel organic/inorganic hybrid sorbent materials

Novel nanoporous lignin(lignocellulose)/SiO2 hybrid materials were designed using the sol–gel process. X-ray photoelectronic spectroscopy, Fourier transform infrared spectroscopy and 29Si and 13C nuclear magnetic resonance spectroscopy were applied to characterize the hybrids’ surface and bulk structure. Nitrogen and water vapor sorption were used for assessment of porous structure parameters and hydrophobization of matrices, respectively. The efficiency of the hybrid materials obtained was proved by adsorption tests with potential inorganic (Cu2+) and organic (2,4-dichlorophenoxyacetic acid) pollutants.

Impregnating titanium phosphate nanoparticles onto a porous cation exchanger for enhanced lead removal from waters

Titanium phosphate (TiP) exhibits preferable sorption toward lead ion in the presence of competing calcium ions at high levels, however, it is present as fine or ultrafine particles and cannot be directly employed in fixed-bed or any flow-through systems due to the excessive pressure drop and poor mechanical strength. In the present study a new hybrid sorbent TiP-001 was fabricated by impregnating titanium phosphate (TiP) nanoparticles onto a strongly acidic cation exchanger D-001 for enhanced lead removal from waters. D-001 was selected as a host material mainly because of the Donnan membrane effect resulting from the immobilized sulfonic acid groups bound on the exchanger matrix, which would enhance permeation of the target metal cation prior to effective sequestration. TiP-001 was characterized by transmission electron micrograph (TEM), X-ray diffraction (XRD), and pH-titration. Batch and column sorption onto TiP-001 was assayed to evaluate its performance as compared to the host exchanger D-001. Lead sorption onto TiP-001 is a pH-dependent process due to the ion-exchange nature, and its sorption kinetics follows the pseudo-second-order model well. Compared to D-001, TiP-001 displays highly selective lead sorption in the presence of competing calcium cations at concentration of several orders higher than the target metal. Fixed-bed sorption of a synthetic feeding solution indicates that lead retention by TiP-001 results in a conspicuous decrease of this toxic metal from 0.50 to below 0.010 mg/L (drinking water standard recommended by WHO). Moreover, its feasible regeneration by dilute HCl solution also favors TiP-001 to be a feasible sorbent for enhanced lead removal from water.

Arsenate Removal from Aqueous Media by Nanosized Hydrated Ferric Oxide (HFO)-Loaded Polymeric Sorbents: Effect of HFO Loadings

Hydrated ferric oxide-loaded hybrid sorbents are of considerable concern for arsenic removal from waters. In the current study, several nanosized hydrated ferric oxide (HFO)-loaded polymer sorbents were prepared and assayed to examine the effect of HFO loadings on arsenate sorption from aqueous solution. Batch and column sorption studies showed that the sorption capacity of arsenate increased with the increase of HFO loadings from 3 to 15% (in Fe mass); however, a further increase in the HFO loadings resulted in a dramatic decrease of the sorption capacity. At relatively low arsenate levels (e.g., <1 mg/L), sorbents with lower HFO loadings exhibited higher distribution coefficients (Kd) than others, implying that HFO loaded at a relatively lower level exhibits stronger sorption affinity toward arsenate than the larger one. However, at relatively high arsenate levels, the sorbent with HFO loading of 15% displayed the highest sorption capacity. Additionally, all the exhausted sorbents are amenable to an eff...

Selective Sorption of Lead, Cadmium and Zinc Ions by a Polymeric Cation Exchanger Containing Nano-Zr(HPO3S)2

A novel polymeric hybrid sorbent, namely ZrPS-001, was fabricated for enhanced sorption of heavy metal ions by impregnating Zr(HPO3S)2 (i.e., ZrPS) nanoparticles within a porous polymeric cation exchanger D-001. The immobilized negatively charged groups bound to the polymeric matrix D-001 would result in preconcentration and permeation enhancement of target metal ions prior to sequestration, and ZrPS nanoparticles are expected to sequester heavy metals selectively through an ion-exchange process. Highly effective sequestration of lead, cadmium, and zinc ions from aqueous solution can be achieved by ZrPS-001 even in the presence of competing calcium ion at concentration several orders of magnitude greater than the target species. The exhausted ZrPS-001 beads are amenable to regeneration with 6 M HCI solution for repeated use without any significant capacity loss. Fixed-bed column treatment of simulated waters containing heavy metals at high or trace levels was also performed. The content of heavy metals in treated effluent approached or met the WHO drinking water standard.

A comparative study on Pb 2+, Zn 2+ and Cd 2+ sorption onto zirconium phosphate supported by a cation exchanger

In the present study, a novel hybrid sorbent ZrP-001 was prepared by loading zirconium phosphate (ZrP) onto a strongly acidic cation exchanger D-001. Sorption behavior of Pb 2+, Zn 2+, and Cd 2+ onto ZrP-001 was experimentally examined by comparing with the host exchanger D-001. ZrP-001 was characterized by scanning electron micrograph (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), pH-titration and pore size distribution analysis. Sorption of the heavy metals onto ZrP-001 was found to be pH-dependent due to the ion exchange mechanism. Compared to D-001, a smaller pore size of ZrP-001 due to the ZrP dispersion consequently resulted in a lower sorption rate. Competitive effect of Ca 2+ on sorption of heavy metals onto ZrP-001 and D-001 was compared to elucidate sorption preference of the hybrid sorbent towards heavy metals. More favorable sorption of ZrP-001 than D-001 was observed for all the three metals and their sorption preference onto ZrP-001 followed the order Pb 2+ > > Zn 2+ ≈ Cd 2+. Fixed-bed sorption results and its efficient regeneration property further demonstrated that ZrP-001 is a potential candidate for removing heavy metals from contaminated water.