Sorption-desorption Cycles Research Articles

New Anion-Exchange Solid-Phase Extraction Support Used for Preconcentration and Determination of Lead in Water Samples by Flame Atomic Absorption Spectrometry

A new chelating resin was prepared by coupling Amberlite XAD-2 with Brilliant Green through an azo spacer. The resulting resin has been characterized by FTIR spectrometry, elemental analysis, and thermogravimetric analysis and studied for the preconcentration and determination of trace Pb(II) ions from solution samples. The anionic complex of Pb(II) and iodide was retained on the resin by the formation of an ion associate with Brilliant Green on Amberlite XAD-2 in weak acidic medium. The optimum pH value for sorption of the metal ion was 5.5. The sorption capacity of the functionalized resin is 53.8 mg/g. The chelating resin can be reused for 20 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 103% was obtained for the metal ion with 0.1 M EDTA as the eluting agent. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The resin was subjected to evaluation through batch binding and column chromatography of Pb(II). The equilibrium adsorption data of Pb(II) on modified resin were analyzed by Langmuir, Freundlich, and Temkin models. Based on equilibrium adsorption data, the Langmuir, Freundlich, and Temkin constants were determined to be 0.192, 13.189, and 3.418 at pH 5.5 and 25 degrees C. The method was applied for lead ion determination in tap water samples.

Preparation, characterization of wheat residue based anion exchangers and its utilization for the phosphate removal from aqueous solution

Wheat residue based anion exchanger (WR-AE) was prepared by ETM (epichlorohydrin–triethylamine method), which is the reaction of wheat residue (WR) with epichlorohydrin and triethylamine in the presence of ethylenediamine and N,N-dimethylformamide. Characterization of WR-AE was measured, including BET surface area, SEM, zeta potential, nitrogen content and FTIR analysis. Batch experiments and statistical analysis were conducted to study its ion-exchange property for phosphate from aqueous solutions. Filter bed experiment was conducted for the regeneration test. The characteristic results validated the increased amine groups in WR-AE and its maximum sorption capacity ( Q max, mmol g −1) of phosphate was 1.80 ± 0.06 mmol g −1. More over, the WR-AE regenerated in both NaCl and HCl solutions can be repeatedly used in several sorption–desorption cycles without any significant loss of the sorption capacities.

Immobilized citric acid-treated bacterial biosorbents for the removal of cationic pollutants

Corynebacterium glutamicum, a full-scale fermentation process waste, showed good performance for the removal of a cationic dye, Basic Blue 3 (BB 3), after chemical modification using citric acid (CA) as an esterifying agent. This study investigated the potential use of immobilized biomass for dye biosorption in batch experiments. The powder form of CA-treated biomass (CAB) was immobilized in three polymer matrices: calcium alginate (CaA), polysulfone (PS) and polyurethane (PU). Three batch experiments were conducted: pH edge, isotherms and kinetics. As shown in the pH edge experiments, the BB 3 removal was favored at pH values greater than 7. The experimental equilibrium data were analyzed using two two-parameter (Langmuir and Freundlich models) and two three-parameter (Redlich–Peterson and Sips models) isotherm models. The experimental data were well described by the Redlich–Peterson isotherm model, followed by the Sips, Langmuir and Freundlich isotherm models. The kinetic data showed that immobilized CAB was slower than free CAB. Of the three diffusion models used to fit the kinetic data, pseudo-first order, pseudo-second order and intra-particle, the first fitted well for free CAB, and the second for immobilized CAB. Regeneration experiments of free and immobilized CAB were carried out for five sorption–desorption cycles, and immobilized CAB showed higher desorption efficiencies (>80%) than the powder form of free CAB, except for CaA-immobilized CAB which was dissolved in the second sorption cycle.

Synthesis, characterization and application of allyl phenol modified amberlite XAD-4 resin for preconcentration and determination of copper in water samples

A new chelating resin was prepared by coupling Amberlite XAD-4 with phenol through an azo spacer, then modified by allyl bromide and characterized (by elemental analysis and IR) and studied for preconcentration of Cu(II) using flame atomic absorption spectrometry (FAAS) for metal monitoring. The optimum pH value for sorption of the above mentioned metal ion was 4.5. The resin was subjected to chemical evaluation through batch binding and column chromatography of Cu(II). The chelating resin can be reused for 15 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 98% was obtained for the metal ion with 0.5 M HNO3 as eluting agent. The equilibrium adsorption data of Cu(II) on modified resin were analyzed by Langmuir, Freundlich and Temkin models. Based on equilibrium adsorption data the Langmuir, Freundlich and Temkin constants were determined to be 0.061, 0.193 and 0.045 at pH 4.5 and 25 o C. The method was applied for the copper determination from industrial waste water sample.

Development of high-temperature CO 2 sorbents made of CaO-based mesoporous silica

This study develops a modified CaO-based mesoporous CO 2 sorbent with high sorption capacity (about 10 mol/kg sorbent) and long-term durability. Highly ordered mesoporous SBA-15 molecular sieves used as carriers were successfully synthesized through direct-synthesis by using non-ionic surfactants as the structure-directing agent under strong acidic conditions. Calcium ions using calcium acetate as the precursor were finely dispersed onto prepared carriers using an impregnation method. Calcium oxide was obtained under calcination at high temperature. Analytical techniques, such as X-ray diffraction patterns, nitrogen physisorption isotherms, scanning electron microscopy/energy dispersive spectrometer, and transmission electron microscopy, were used to characterize the synthesized mesoporous materials. The thermo-gravimetric analysis was used to test the performance of CO 2 capture using prepared CaO-modified sorbents. The property and carbon dioxide sorption ability of the substrates and sorbents were examined and discussed. Carbon dioxide was effectively adsorbed, concentrated, and separated using the reasonable reaction paths. Durability tests showed that the CO 2 adsorption ratio remains at 80% after 40 cyclic runs under a carbonation temperature at 700 °C and calcination temperature at 910 °C, respectively. The results showed that the structural stability of the sorbents was improved sufficiently under high temperature and cyclic sorption–desorption operations.

Hydrogen production via sorption enhanced reforming of methane: Development of a novel hybrid material—reforming catalyst and CO 2 sorbent

This study presents the development and the evaluation of a new hybrid material, NiO–CaO–Ca 12Al 14O 33, which functions simultaneously as reforming catalyst and CO 2 sorbent for application in sorption enhanced reforming. CaO–Ca 12Al 14O 33 acts as an effective CO 2 sorbent and also as a support for the active metallic Ni particles. This idea aims to overcome the complex problems related with handling of the two different solids (catalyst and CO 2 sorbent) required for sorption enhanced reforming and also to increase the industrial potential of the process by decreasing the cost of the total solid material used. The CO 2 fixation ability of the new material (56% carbonation conversion) remains unchanged for 45 cycles of sorption-desorption. It is assumed that the presence of NiO acts synergetically with Ca 12Al 14O 33 to the excellent stability of the novel material compared with other CaO-based sorbents. The effect of NiO loading on the catalytic functionality of the material, under methane sorption enhanced reforming conditions was studied and the results showed that conversion goes through a maximum (80%) in the presence of the hybrid material with 16 wt% Ni loading. The hybrid material with the optimum metallic loading was tested at 650 °C and methane to steam ratio equal to 3.4. The presence of free CaO resulted in the capture of CO 2 formed, producing a stream rich in H 2 (90%) and poor in CO 2 (2.8%) and CO (2%).

Extractant-impregnated organogel for capturing heavy metals from aqueous solutions

An organogel of dodecyl acrylate loaded with an metal extractant di-2-ethylhexyl phosphoric acid (D2EHPA) or ethylhexylphosphonic acid (EHPNA) was applied for sorption of Zn(II) and Cu(II) from their hydrochloric acid solutions. Equilibrium and kinetics of sorption have been studied using the organogel of various crosslink degrees. The mechanism of metal sorption for each metal–extractant system was similar to that of metal separation in liquid–liquid extraction. Mass transfer flux for the metal ion uptake was in the range of 1.0–4.0 × 10 −6 mol/(m 2 s), and was independent of the crosslink degree. Kinetics of metal sorption with the organogel was similar to liquid–liquid extraction and ion exchange resin under the condition of large excess amount of extractant in comparison with the metal ion in feed solution. The metal uptake process seems to be classified as film-diffusion controlled. More than 98% of the extractant was retained after repeating five times the sorption–desorption cycle. Substantially high percentage of metal ion sorption and desorption was achieved in the cyclic use of the organogel. The results suggested the feasibility of extractant-impregnated organogels for separating metal ions from their aqueous solutions.

Carbon dioxide capture using amine-impregnated HMS having textural mesoporosity

A series of HMS (hexagonal mesoporous silica) materials having different textural mesoporosities was synthesized using dodecylamine as a structure directing agent, which were employed as a host for supporting PEI (polyethylenimine) (PEI/HMS) as a CO 2 capturing agent. The textural properties of the prepared materials were examined by XRD, N 2 adsorption–desorption isotherms, and SEM. CO 2 sorption/desorption measurements were carried out using a TGA unit using high purity (99.999%) CO 2. The as-prepared HMS alone exhibited a moderate sorption capacity of 34 m g C O 2 /g sorbent at 25 °C. The PEI/HMS prepared using a HMS having complementary textural mesopores exhibited CO 2 sorption capacity of 128 m g C O 2 /g sorbent with a 45 wt% PEI loading at 75 °C, whereas a sorption capacity of 94 m g C O 2 /g sorbent only was obtained under the same loading level using a HMS host with negligible textural mesoporosity. In addition, we were able to increase the PEI loading to 60 wt% without losing the capturing efficiency of the former, and achieved a CO 2 sorption capacity of 184 m g C O 2 /g sorbent, one of the highest capturing capacities reported in the literature thus far under the given conditions. PEI/HMS exhibited only a minor drop in CO 2 capture capacity during a 4 repeated cyclic sorption–desorption run at 75 °C.

Water absorption pattern and dimensional stability of oil palm fiber–linear low density polyethylene composites

AbstractThe water absorption pattern and associated dimensional changes and solid loss of oil palm fiber–linear low density polyethylene composites was studied. The effects of fiber size (425–840, 177–425, and 75–177 μ), fiber loading (0, 10, 20, 30, 40, and 50%), and time of immersion (192 h at an interval of 24 h) on these parameters were also studied. Alkali treatment of fibers was done to reduce the hydrophilic nature of the composites and its effect was studied. It was found that the water absorption in most of the combinations followed typical Fickian behavior. The rate of water absorption and swelling increased with fiber loading. However, alkali treatment of the fibers resulted in a reduction of water absorption at higher fiber loadings only, and composites with higher fiber sizes exhibited higher water absorption. A sharp increase in the thickness swelling was observed in the initial days of immersion, which remained constant thereafter. The thickness swelling also increased with fiber size; however, a constant trend was not observed for the 75–177 μ fiber size. In addition to thickness swelling, composites also expanded linearly during water absorption; however, linear expansion was considerably less than thickness swelling. Higher fiber loading and alkali treatment caused more linear expansion. We observed that maximum solid loss on water immersion occurred with small‐sized and also alkali‐treated fiber composites. An increase in thickness and a decrease in linear dimension were observed after one sorption–desorption cycle. This irreversible change was also found to be proportional to fiber loading and alkali treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Sorptive Removal of Trinitroglycerin (TNG) from Water Using Nanostructured Silica‐based Materials

Trinitroglycerin (TNG), a nitrate ester, is widely used in the pharmaceutical industry for the treatment of angina pectoris (chest pain) and by the military for the manufacturing of dynamite and propellants. Currently, TNG is considered as a key environmental contaminant due to the discharge of wastewater tainted with the chemical from various military and pharmaceutical industries. The present study describes the use of a nanostructured silica material (Mobil Composite Material no. 48 [MCM-48]) prepared by mixing tetraethylorthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) to remove TNG from water. The sorption of TNG onto MCM-48 rapidly reached equilibrium within 1 h. Sorption kinetics were best described using a pseudo-second order model, whereas sorption isotherms were best interpreted using the Langmuir model. The latter gave a maximum sorption capacity of 55.2 mg g(-1) at 40 degrees C. The enthalpy and entropy of TNG sorption onto MCM-48 were 1.89 kJ mol(-1) and 79.0 J mol(-1).K(-1), indicating the endothermic nature of the TNG sorption onto MCM-48. When MCM-48 was heated at 540 degrees C for 5 h, the resulting calcined material (absence of the surfactant) did not sorb TNG, suggesting that the surfactant component of the nanomaterial was responsible for TNG sorption. Finally, we found that MCM-48 lost approximately 30% of its original sorption capacity after five sorption-desorption cycles. In conclusion, the nanostructured silica based sorbent, with high sorption capacity and remarkable reusability, should constitute the basis for the development of an effective technology for the removal of TNG from contaminated water.

Biosorption of As(III) and As(V) from Aqueous Solution by Lichen (Xanthoria parietina) Biomass

The biosorption of As(III) and As(V) from aqueous solution on lichen (Xanthoria parietina) biomass were investigated using different experimental parameters such as solution pH, biomass concentration, contact time, and temperature. The equilibrium data were evaluated by Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherm models. The biosorption capacity of X. parietina for As(III) and As(V) was found to be 63.8 mg/g and 60.3 mg/g. The mean sorption energy values calculated from D–R model indicated that the biosorption of As(III) and As(V) onto X. parietina biomass took place by chemical ion-exchange. The thermodynamic parameters showed that the biosorption of As(III) and As(V) ions onto X. parietina biomass was feasible, spontaneous, and exothermic in nature. Kinetic examination of the sorption data revealed that the biosorption processes of both As(III) and As(V) followed well the pseudo-second-order kinetics. The arsenic ions were desorbed from X. parietina using both 1 M HCl and 1 M HNO3. The recovery yield of arsenic ions was found to be 80-90% and the biosorbent had good reusability after consecutive seven sorption-desorption cycles.

Cadmium sorption characteristics of phosphorylated sago starch-extraction residue

The residue produced by the extraction of sago starch is usually discarded as a waste material. In this study, we phosphorylated the sago starch-extraction residue with phosphoryl chloride and used the phosphorylated residue to remove cadmium from wastewater. The phosphoric ester functionality in the phosphorylated residue was evaluated by means of infrared microspectrometry and solid-state NMR. The dependence of the cadmium sorption behavior on pH, contact time, and electrolyte concentration and the maximum sorption capacity of the phosphorylated residue were also studied. The cadmium sorption varied with pH and electrolyte concentration, and the maximum sorption capacity was 25.2 mg g(-1), which is almost half the capacity of commercially available weakly acidic cation exchange resins. The phosphorylated residue could be reused several times, although cadmium sorption gradually decreased as the number of sorption-desorption cycles increased. The phosphorylated residue sorbed cadmium rapidly, which is expected to be favorable for the continuous operation in a column.

Studies on sorption, desorption, regeneration and reuse of sugar-beet pectin gels for heavy metal removal

This work reports the effectiveness of sugar-beet pectin xerogels for the removal of heavy metals (cadmium, lead and copper) after multiple batch sorption-desorption cycles, with and without a gels regeneration step. Metals were recovered from xerogel beads without destroying their sorption capability and the beads were successfully reused (nine cycles) without significant loss in both biosorption capacity and biosorbent mass. Metals uptake levelled off or increased after using a 1M CaCl(2) regeneration step after each desorption. Calcium, as a regenerating agent, increased the stability and reusability of the gels repairing the damage caused by the acid and removing the excess protons after each elution providing new binding sites. Because of their excellent reusability, pectin xerogels are suitable for metal remediation technologies.

Biosorption of lead by the immobilised fungus Phanerochaete chrysosporium in a packed bed column

Biosorption of lead by immobilised Phanerochaete chrysosporium over two successive cycles of sorption-desorption was investigated in a continuously operated packed bed column. The breakthrough curves in each sorption cycle were measured as a function of different bed depths in the column at an inlet lead concentration of 40 mg/L. The values of various breakthrough parameters obtained in the study indicated good potential of the system in removing lead from constituent wastewaters. Kinetic and mass transfer aspects of lead biosorption in the study were also evaluated by fitting the experimental data to several breakthrough models found in the literature. And, compared to the other models, Clark model showed good predictability of the entire breakthrough data.

Column studies on the evaluation of novel spacer granules for the removal of arsenite and arsenate from contaminated water

Decontamination of arsenic ions from aqueous media has been investigated using iron chitosan spacer granules (ICS) as an adsorbent. Drying of beads saturated with a spacer sucrose was considered as simple treatment, to prevent the restriction of polymer network and enhance sorption capacity. The novel sorbent was studied in up flow column experiments conducted at different flow rates, pH and bed depth to quantify the treatment performance. It was found that silicate was more inhibitory than phosphate, and the silicate in groundwater controlled the arsenic removal efficiency. The column regeneration studies were carried out for two sorption–desorption cycles using 0.1 N NaOH as the eluant. TCLP leaching tests were conducted on the arsenic loaded adsorbent which revealed the containment of arsenic-laden sludge can be managed without adverse environmental impact. The developed procedure was successfully applied for the removal of both As(III) and As(V) from arsenic contaminated drinking water samples.

Bed depth service time model for the biosorption of reactive red dye using the Portunus sanguinolentus shell

AbstractBiosorption is an efficient and regenerative technique that often uses low‐cost adsorbent materials, particularly for the treatment of wastewaters containing dyes and heavy metals. This study investigates the ability of crab shell (Portunus sanguinolentus) to remove reactive red dye in a packed bed up‐flow column (internal diameter 2 cm; height 35 cm). Crab shell has high surface area (after proper size reduction) and high regenerative capacity. The experiments were performed with different bed heights (20 and 30 cm) and using different flow rates (12 and 17 ml/min) in order to obtain experimental breakthrough curves. The bed depth service time (BDST) model was used to analyze the experimental data and the model parameters were evaluated. The column regeneration studies were carried out for five different sorption–desorption cycles. The elutant used for the regeneration of the sorbent was 0.01 M EDTA (disodium) solution at pH 9.8 adjusted using NH4OH. This solution was found to have the best bed regeneration capacity and could be reused for several sorption–desorption cycles. The elution efficiency was greater than 99.1% in all seven cycles. Continuous use of the crab shell leads to a decrease in the adsorptive performance, as observed by the breakthrough curves becoming flatter and also because of a broader mass transfer zone. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

Preconcentration and determination of chromium in water with flame atomic absorption spectrometry by thiourea-formaldehyde as chelating resin

Thiourea-formaldehyde chelating resin is synthesized simply and rapidly from thiourea and formaldehyde by condensation polymerization and characterized by IR spectra and studied for the preconcentration and determination of trace Cr(III) ion from solution samples. The optimum pH value for sorption of the metal ion was 6.5. The sorption capacity of resin for Cr(III) was determined. The chelating resin can be reused for 20 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 96% was obtained for the metal ion with 0.5M HNO3 as eluting agent. The equilibrium adsorption data of Cr(III) on modified resin were analyzed by Langmuir, Freundlich and Temkin models. Based on equilibrium adsorption data the Langmuir, Freundlich and Temkin constants were determined as 0.016, 0.040 and 0.074 at pH 6.5 and 20°C. The method was applied for chromium ion determination from river water sample.

Preparation and evaluation of iron–chitosan composites for removal of As(III) and As(V) from arsenic contaminated real life groundwater

A study on the removal of arsenic from real life groundwater using iron–chitosan composites is presented. Removal of arsenic(III) and arsenic(V) was studied through adsorption at pH 7.0 under equilibrium and dynamic conditions. The equilibrium data were fitted to Langmuir adsorption models and the various model parameters were evaluated. The monolayer adsorption capacity from the Langmuir model for iron chitosan flakes (ICF) (22.47 ± 0.56 mg/g for As(V) and 16.15 ± 0.32 mg/g for As(III)) was found to be considerably higher than that obtained for iron chitosan granules (ICB) (2.24 ± 0.04 mg/g for As(V); 2.32 ± 0.05 mg/g for As(III)). Anions including sulfate, phosphate and silicate at the levels present in groundwater did not cause serious interference in the adsorption behavior of arsenate/arsenite. The column regeneration studies were carried out for two sorption–desorption cycles for both As(III) and As(V) using ICF and ICB as sorbents. One hundred and forty-seven bed volumes of As(III) and 112 bed volumes of As(V) spiked groundwater were treated in column experiments using ICB, reducing arsenic concentration from 500 to <10 μg/l. The eluent used for the regeneration of the spent sorbent was 0.1 M NaOH. The adsorbent was also successfully applied for the removal of total inorganic arsenic down to <10 μg/l from real life arsenic contaminated groundwater samples.

Batch and continuous biosorption of Cu 2+ by immobilized biomass of Arthrobacter sp.

The ability of free and polysulphone immobilized biomass of Arthrobacter sp. to remove Cu 2+ ions from aqueous solution was studied in batch and continuous systems. The Langmuir and Freundlich isotherm models were applied to the data. The Langmuir isotherm model was found to fit the sorption data indicating that sorption was monolayer and uptake capacity ( Q o ) was 175.87 and 158.7 mg/g for free and immobilized biomass respectively at pH 5.0 and 30 °C temperature, which was also confirmed by a high correlation coefficient, a low RMSE and a low Chi-square value. A kinetic study was carried out with pseudo-first-order reaction and pseudo-second-order reaction equations and it was found that the Cu 2+ uptake process followed the pseudo-second-order rate expression. The diffusivity of Cu 2+ on immobilized beads increased (0.402 × 10 −4 to 0.435 × 10 −4 cm 2/s) with increasing concentration from 50 to 150 mg/L. The maximum percentage Cu 2+ removal (89.56%) and uptake (32.64 mg/g) were found at 3.5 mL/min and 20 cm bed height. In addition to this the Bed Depth Service Time (BDST) model was in good agreement with the experimental data with a high correlation coefficient (>0.995). Furthermore, sorption and desorption studies were also carried out which showed that polysulphone immobilized biomass could be reused for up to six sorption–desorption cycles.

Removal and recovery of uranium from aqueous solutions by Ca-alginate immobilized Trichoderma harzianum

The ability of Ca-alginate immobilized Trichoderma harzianum has been explored for removal and recovery of uranium from aqueous streams. Ca-alginate as polymeric support was selected after screening different matrices. Immobilization of Trichoderma harzianum to Ca-alginate improved the stability as well as uranium biosorption capacity of biosorbent at 28 ± 2 °C and 200 rpm. The suitability of packed bed column operations was illustrated by obtaining break through curves at different bed heights, flow rates and inlet uranium concentrations. The adsorption column containing 1.5 g dry weight of immobilized material has purified 8.5 L of bacterial leach liquor (58 mg/L U) before break through occurred and the biosorbent became saturated after 25 L of influent. Sorbed uranium was recovered in 200 ml of 0.1 N HCl resulting in 98.1–99.3% elution by 0.1 N HCl, which regenerated the biosorbent facilitating the sorption–desorption cycles for better economic feasibility without any significant alteration in sorption capacity/elution efficiency.