High Kinetic Performance Research Articles

A multifunctional N-GO/PtCo nanocomposite bridged carbon fiber interface for the electrochemical aptasensing of CA15-3 oncomarker

The development of integrated analytical devices is crucial for advancing next-generation point-of-care platforms. Herein, we describe a facile synthesis of a strongly catalytic and durable Nitrogen-doped graphene oxide decorated platinum cobalt (NGO-PtCo) nanocomposite that is conjugated with target-specific DNA aptamer (i-e. MUC1) and grown on carbon fiber. Benefitting from the combined features of the high electrochemical surface area of N-doped GO, high capacitance and stabilization by Co, and high kinetic performance by Pt, a robust, multifunctional, and flexible nanotransducer surface was created. The designed platform was applied for the specific detection of a blood-based oncomarker, CA15-3. The electrochemical characterization proved that nanosurface provides a highly conductive and proficient immobilization support with a strong bio-affinity towards MUC1 aptamer. The specific interaction between CA15-3 and the aptamer alters the surface properties of the aptasensor and the electroactive signal probe generated a remarkable increase in signal intensity. The sensor exhibited a wide dynamic range of 5.0 × 10−2 -200 U mL−1, a low limit of detection (LOD) of 4.1 × 10−2 U mL−1, and good reproducibility. The analysis of spiked serum samples revealed outstanding recoveries of up to 100.03 %, by the proposed aptasensor. The aptasensor design opens new revelations in the reliable detection of tumor biomarkers for timely cancer diagnosis.

Efficient separation, adsorption, and recovery of Samarium(III) ions using novel ligand-based composite adsorbent

The novel organic compound of ammonium (4-chlro-2-mercaptophenyl)carbamodithioate (ACMPC) was prepared and then subsequently grafted onto the mesoporous silica by direct approach for the preparation of composite adsorbent (CPA). The lanthanide (Ln(III)) intra-series separation behavior was measured using CPA and then the samarium (Sm(III)) ion was selected according to the high adsorption ability by CPA for effective separation, adsorption, and recovery in the solid-liquid approach. The mesoporous silica and CPA were characterized systematically for the evaluation of affecting experimental criterion. The solution acidity played an important factor as the alkaline pH area was avoided due to the hydroxide precipitation probability and pH 5.0 was selected for selective and effective Sm(III) ion separation and recovery. The data clarified that CPA exhibited high kinetic performances with high adsorption ability. The Sm(III) adsorption was highly fitted with the Langmuir adsorption isotherm model with monolayer coverage and the maximum adsorption capacity was determined as 155.13 mg/g. In addition, the diverse foreign ions were not reduced the Sm(III) ion adsorption significantly, and the CPA has approximately no adsorption capacity for other ions at this pH. The Sm(III) ion was strongly coordinated with the ACMPC and the expected highly stable complexation mechanism with the soft donor of N- and S- atoms. The elution of Sm(III) ions from the saturated CPA was desorbed successfully with 0.30 M HNO3. The regenerated CPA that remained maintained the high selectivity to Sm(III) ions and exhibited almost the same adsorption capacity as that of the original CPA. Therefore, the proposed CPA offered a cost-effective material and may be considered a viable alternative for effectively Sm(III) ion separation and recovery from waste samples as potential materials.

The heavy lanthanide of Thulium(III) separation and recovery using specific ligand-based facial composite adsorbent

The organic ligand of 3–(((5–ethoxybenzenethiol)imino)methyl)–salicylic acid (EBMS) was synthesized and then immobilized onto the mesoporous silica for the fabrication of facial composite adsorbent (FCA). The FCA was successfully utilized for the heavy lanthanide of Thulium(Tm(III)) separation, adsorption, and recovery in the solid-liquid approach. The FCA characterizations and affecting experimental parameters were assessed systematically. The Tm(III) ion was selected due to the high adsorption ability of the FCA according to the intra-series separation behaviors. The solution pH played a key role based on hydroxide formation in the basic pH region and a slightly acidic pH (3.50) was selected based on the high adsorption ability. The FCA was shown high kinetic performance and diverse competing metal ions did not interfere with Tm(III) adsorption. The Tm(III) adsorption was well-fitted with the Langmuir adsorption isotherm model with monolayer coverage and the maximum adsorption capacity was determined as 168.57 mg/g. The Tm(III) ion was strongly coordinated with the EBMS and the expected bond distance between Tm-N was shorter than the other bond length of Tm-S atoms in the complexation mechanism. The adsorbed Tm(III) ion was completely desorbed from the FCA with the suitable eluent of 0.25 M HNO3 and then simultaneously regenerated the FCA into the initial form without significant deterioration in the original functionality. The highest selectivity and maximum adsorption capacity of FCA to Tm(III) ions indicated that the proposed EBMS ligand-based composite adsorbent high potentiality to separate and recover the Tm(III) ions from waste samples effectively.

Efficient separation of butane isomers via ZIF-8 slurry on laboratory- and pilot-scale

n-butane and isobutane are important petrochemical raw materials. Their separation is challenging because of their similar properties, including boiling point. Here, we report a zeolitic imidazolate framework-8 (ZIF-8)/N,N-Dimethylpropyleneurea (DMPU)-water slurry as sorption material to separate butane mixtures. The isobutane/n-butane selectivity of ZIF-8/DMPU-water slurries is as high as 890 with high kinetic performance, which transcends the upper limit of various separation materials or membranes reported in the literature. More encouragingly, a continuous pilot separation device was established, and the test results show that the purity and recovery ratio of isobutane product are 99.46 mol% and 87%, respectively, which are superior to the corresponding performance (98.56 mol% and 54%) of the industrial distillation tower. To the best of our knowledge, the use of metal-organic frameworks (MOFs) for gas separation in pilot scale remains underexplored, and thus this work provides a step forward to the commercial application of MOFs in gas separation.

Simultaneous Electrospinning and Electrospraying for the Preparation of a Precursor Membrane Containing Hydrothermally Generated Biochar Particles to Produce the Value-Added Product of Carbon Nanofibrous Felt.

Biochar is a byproduct generated from the hydrothermal liquefaction of biomass, such as corn stover, in an anaerobic environment. This work aims to convert biochar into a value-added product of carbon nanofibrous felt. First, the biochar-containing precursor membrane was prepared from simultaneous electrospinning and electrospraying. After thermal stabilization in air and carbonization in argon, the obtained precursor membrane was converted into a mechanically flexible and robust carbon nanofibrous felt. Electrochemical results revealed that the biochar-derived carbon nanofibrous felt might be a good candidate as a supercapacitor electrode with a good rate capability and high kinetic performance.

Toward high-performance Li storage anodes: design and construction of spherical carbon-coated CoNiO2 materials

CoNiO2 nanosheets were prepared by a simple hydrothermal process, and then the spherical CoNiO2@C micro-nano structures composed of nanoparticles were designed by morphology reshaping for the first time. The results show that the carbon coating changes the morphology of CoNiO2, and the CoNiO2@C composite shows porous microsphere structure consisted of nanoparticles. The porous structure combined with highly conductive carbon shell indicates an improved electronic conductivity and charge transfer. The carbon shell decreases the charge-transfer resistance of CoNiO2, and thus enhances the kinetic performances. The pristine CoNiO2 and CoNiO2@C (3, 5, and 10 wt%) composites deliver charge/discharge capacities of 511.7/526.9, 811.3/826.3, 997.1/1013.1, and 1216.1/1241.8 mAh g−1 at 500 mA g−1 after 200 cycles, respectively. The carbon coating improves the reversible capacity, rate capability, and cycle performance of CoNiO2, especially at high rates. The improved rate performance, excellent cycle performance, and high kinetic performances are ascribed to the elaborate design of architecture and composition. Hence, such porous CoNiO2@C microsphere consisted of nanoparticles can be regarded as promising candidates as anode materials for lithium-ion battery.

Passive Detection of Phosphorus in Agricultural Tile Waters Using Reactive Hybrid Anion Exchange Resins

Tile drainage waters carry considerable loads of phosphorus (P) from agricultural fields to rivers and streams in the Midwestern U.S. An innovative and economical approach to monitor dissolved reactive P (DRP) flux in tile waters is needed to understand the extent of P loss in field-scale. In this study, a passive sampling technique was developed using iron oxide-coated polyacrylic/polystyrene anion exchange resins (hybrid resins) a P sink. Laboratory batch adsorption isotherm and kinetic experiments indicated that the hybrid resins had high P adsorption capacity (7.69–19.84 mg/g) and high kinetic performance. The passive sampling method with field-calibrated hybrid polyacrylic resin and hybrid polystyrene resins (sampling rate: 0.1351 and 0.0763 L/h, respectively) predicted the average DRP concentrations of 0.006–0.020 mg/L, which did not differ significantly (p > 0.05) from the auto-sampling data. A rapid increase in DRP concentration during storm events and subsequent flooding events was also predicted well. In conclusion, a passive detection method using iron oxide coated hybrid resins can be recommended for monitoring seasonally fluctuating DRP flux in agricultural waters as long as the hybrid resins are well-calibrated under specific field conditions (e.g., flow rate and concentration range).

Preparation and evaluation of composite hybrid nanomaterials for rare-earth elements separation and recovery

A new technology is necessary to representing an entire process of separation and recovery of rare-earth lanthanides (Ln(III)) elements to keep the eco-system for stable industrial growth. In this study, novel hard and soft donor organic ligand containing mesoporous composite hybrid nanomaterial (CHM) was fabricated for specific ytterbium (Yb(III)) ion separation and recovery in sustainable method. The Yb(III) ion was selected based on the Ln(III) intra-series separation behavior in the solid-liquid separation approach. The present approach was based on basic research of individual process steps with the stable complexation mechanism according to the O- and N-donor coordination. The usual bond distance between Yb-O and Yb-N was 2.206 and 2.847 Å, which was clarified that the O-atom was hardly donating than the N-atom of the synthesized organic ligand. However, both atoms were coordinating with Yb(III) ions to clarifying the stable complexation and coordination mechanism. The optimum pH solution was evaluated before selecting the separation and uptake operations and the pH was 5.0 to avoid the hydroxyl precipitation rather than adsorption based on the Ln(III) chemistry. The fabricated CHM was exhibited the high kinetic performances. The adsorption data were highly fitted with the Langmuir isotherms model and the maximum Yb(III) adsorption amount was found 139. 19 mg/g. The results were also affirmed that the effect of competing ions were not affected seriously in the Yb(III) adsorption. After successful adsorption, the Yb(III) ion was recovered with elution operation using 0.40 M HNO3 and the CHM was also regenerated at the same time for next adsorption process after washing with water. Moreover, the reuses of the CHM were possible in several cycles complying the cost-effective potential material in real waste sample treatment.

Carbon Nanofibrous Sponge Made from Hydrothermally Generated Biochar and Electrospun Polymer Nanofibers

The objective of this study was to convert biochar, a byproduct generated from the hydrothermal process (in oxygen-limited environment) of biomass (e.g., corn stover), into value-added product. In specific, three-dimensional (3D) biochar-containing precursor sponge, which was made by using electrospun polymer nanofibers as skeleton support, was fabricated via an innovative approach. The weight ratio of biochar to polymer (in the precursor sponge) was 2/1, and it appeared that the biochar weight ratio could be further increased. Upon heat treatments (i.e., stabilization in air and carbonization in argon), the precursor sponge was converted into carbon nanofibrous sponge that had the porosity of ~ 90 vol%, the BET surface area of ~ 51.7 m2 g− 1, and the carbon content of ~ 95 wt%; and it was mechanically elastic/resilient. The electrochemical study indicated that, the carbon nanofibrous sponge could be utilized for making supercapacitor electrode with excellent rate capability and high kinetic performance. This study would not only demonstrate a high-value application of hydrothermally generated biochar, but also provide a facile while novel approach for the fabrication of carbon nanofibrous sponge which could be potentially used for various applications (particularly the energy storage application).

Application of activated biomass waste as an adsorbent for the removal of lead (II) ion from wastewater

This work focuses on the application of activated biomass as an alternative to conventional adsorbents for the removal of Pb2+ from wastewater. The biomass was carbonized at 800 °C before chemical activation. Scanning Electron Microscope (SEM) and UV/VIS Spectrophotometer were used in characterizing the adsorbents. Batch adsorption studies were carried out to determine the effect of process conditions on the percentage removal. The kinetic studies were carried out using Pseudo-first order, Pseudo-second order, Elovich and Weber morris kinetic models while the thermodynamics studies were carried out using Gibbs free energy equation. SEM characterization revealed that micro porous space on the surface of the adsorbents (biomass wastes) increased significantly after activation. The composites maintained high surface area after chemical activation. pH of point zero charge revealed negative charge predominance on the surface of the adsorbents and adsorption was found to be very fast due to strong electrostatic force between Pb2+ and ion diffusion on the biomass surface. Cassava peel demonstrated highest potential for lead (II) ion removal from solution with 96.83% removal after 80 min with 50 mg/l lead concentration and adsorbent/liquid ratio of 0.3 g/30 ml at 60 °C and pH of 7.6. The highest adsorption capacities recorded with cassava peels, groundnut shell and yam peel at initial concentration of 50 mg/g were 50. 1 mg g, 46.6 mg/g and 38.5 mg/g ΔH, ΔS and R2 values for the adsorption with cassava peels are: 12762 J/mol, 67.2 J/kmol.K and 0.945; for groundnut shell adsorbent, the ΔH, ΔS and R2 values are; 36756 J/mol, 130 J/mol.K and 0.997; while for yam peels adsorbent, the ΔH, ΔS and R2 values are 12163 J/mol, 46 J/mol.K and 0.9278. Thus, the sorption process was feasible, spontaneous and endothermic. Adsorption of Pb2+was rapid and showed high kinetic performance. The experimental data were well fitted with pseudo second order kinetic model. However, the present approach has the advantage of simplicity, less time consuming and most importantly, low cost.

Novel conjugated hybrid material for efficient lead(II) capturing from contaminated wastewater

An efficient material is always welcoming for the water treatment due to the need of clean water to safe the human health. The conjugate adsorbent (CJA) was fabricated by functional ligand embedded onto the highly porous silica material for selective lead (Pb(II)) ion monitoring and removal from wastewater. The study was achieved not only investigating the beginning material but also the performing extrusion as novel conjugate material, this defining the material novelty of this study considers to the modern state-of-art. The fabricated material was characterized in all aspects and then the experimental works for Pb(II) ion assessing were carried in batch mode. The CJA was exposed the color and signal intensity upon addition of Pb(II) ion from low to high concentrations. The optimum pH was considered at 5.50 based on the sensitivity, the color formation ability and high adsorption of Pb(II) ion. The determined limit of low detection was 0.18 μg/L, which was the extraordinary performance for the Pb(II) ion monitoring ability by the CJA. The adsorption efficiency, specific attention was remunerated to the influence of solution pH, reaction time, foreign ion, initial Pb(II) amounts and regeneration. The CJA was exhibited high kinetic performances and showed high adsorption Pb(II) ion compared with the different forms of material. The adsorption was completely fitted with the Langmuir adsorption as defining the monolayer coverage as expected of the homogeneous porosity of the CJA. The maximum adsorption was determined as high as 175.16 mg/g. In addition, the foreign ions were not affected in the Pb(II) adsorption by the CJA, and the adsorbent was regenerated using 0.20 M HCl for several cycles used without significant loss of the initial performance. Considering these advantages, the CJA demonstrated the potential low-cost material for competitive use in wastewater remediation, especially in the developing countries.

Novel optical composite material for efficient vanadium(III) capturing from wastewater

The high-efficient detection and recovery of vanadium (V(III)) using organic ligand embedded inorganic-organic mesoporous composite material (MeCM) was studied in this work. After 2‑methyl‑8‑quinolinol immobilization onto the porous silica, the MeCM was confirmed the high surface area, large pore diameters and ordered morphological homogeneity. The MeCM was exhibited fast and specific signal response to V(III) ion, and the color was observed by naked-eye based on the charge-transfer stable complexation mechanism. The MeCM was influenced by the solution pH and pH 3.50 was selected for the highest detection and adsorption ability. The limit of detection was 0.27 μg/L, which was remarkably low as defined. The MeCM was also exhibited comparatively high kinetic performances as the equilibrium adsorption was observer within short contact time. The adsorption data were fitted with the Langmuir isotherm model as expected from the MeCM morphology. The maximum capacity was found to be 192.16 mg/g with the monolayer adsorption coverage. The presence of diverse metal ion was not affected significantly during the detection and adsorption operations. The V(III) ion desorbed from the MeCM using 0.15 M HCl and then simultaneously regenerated into the initial functionality for next operation as revealed from the several cycles reuses study. Therefore, the proposed MeCM is allowed to the sensitive, selective, easy to use, cost-effective, high efficiency, fast kinetics and stable capturing of V(III) ion even in the presence of diverse competing ion. In addition, there was no more secondary sludge production due to the reusability and makes it a potential candidate in better replacement technology for capturing V(III) ion in a wide range of practical purposes.

Composite nanofibers membranes of poly(vinyl alcohol)/chitosan for selective lead(II) and cadmium(II) ions removal from wastewater

The nanofibers membranes were fabricated by poly(vinyl alcohol)/chitosan (PVA/Chi) using an electro-spun technique for selective and high adsorption of lead (Pb(II)) and cadmium (Cd(II)) ions based on the solution acidity. The PVA/Chi NFs membranes were characterized systematically using several instrumentations. In addition, several experimental parameters such as initial metal ions concentration, interaction time, adsorbent dosage, solution pH and the effects of competing ions on Pb(II) and Cd(II) adsorption were evaluated. The adsorption data were also clarified that the PVA/Chi NFs membranes were exhibited high kinetic performances towards the both toxic ions at the optimum conditions. The adsorption data were manipulated using different kinetics models, and it was confirmed that only pseudo-second-order model obeyed the adsorption kinetics for Pb(II) and Cd(II) ions. Similarly, the equilibrium data were well fitted with the Langmuir adsorption isotherms model, and the maximum adsorption capacity was 266.12 and 148.79 mg/g for Pb(II) and Cd(II) ions, respectively. The Pb(II) and Cd(II) ions adsorptions were also measured to know the selectivity with simulated environmental solution, and the data were confirmed the high selectivity to Pb(II) and Cd(II) ions at the optimum condition and the nanofibers membrane shown the potentiality for possible use in efficient removal of the selected toxic ions from waste samples. Thus, the PVA/Chi NFs are considered to be effective and promising materials for Pb(II) and Cd(II) ions from wastewaters with high efficiency.

Improving the Performance of MoSx/r-GO Cathode Materials for Lithium-Ion Battery Via an in-Situ Electrochemical Method

While lithium-ion batteries (LIBs) with high energy density, long lifetime, and high operating voltage are widely used not only for portable devices but also for large scale devices and facilities, present LIBs have an insufficient energy density due to the use of large and heavy lithium metal oxide cathodes (100 ~ 200 Wh kg-1). Hence, sulfur is being proposed as a new cathode material due to about 5 times higher energy density (500 Wh kg-1) as well as lower cost than the commercial cathode materials. However, lithium-sulfur (Li-S) batteries have rapid initial capacity fading induced by dissolution of highly ordered polysulfide (Li2Sx, 8≥x>6) and large volume expansion (~80 %). Metal sulfides, such as MoS2, can directly form Li2S without the formation of intermediate products in a Li-S battery. In particular, the reversible reaction between Li2S and S at a voltage of over 2.2 V is notable for the use as new cathode material. Herein, we hypothesized that an increase of S content in the metal sulfide compound can expand the operating voltage window over 2 V such as S cathode. Therefore, we prepared molybdenum-sulfide compound with a higher content of S (MoSx, x>2) than MoS2 for use as a cathode instead of S. Moreover, we attached the MoSx on the oxygen functional group of graphene oxide (GO) to strongly anchor the MoSx and GO was partially changed to reduced GO (r-GO) in this process. In this study, we introduce an improved MoSx/r-GO cathode using an in-situ electrochemical method (named as “in-situ electrochemical pulverization”). The nano-sized material shows high kinetic performance and low volume expansion due to a short ion diffusion path and a large surface to volume ratio. Therefore, to improve the performance and stability of the prepared electrode, we pulverize bulk MoSx into nano-sheets by repetitive full lithiation/delithiation cycles. Moreover, the pulverized nano sheets are securely anchored by the oxygen functional group in partially reduced GO, so that they are not separated from the electrode. In addition, to enhance the stability more, a nano-scaled SEI layer is formed on the in-situ pulverized nano sheets by controlling the initial potential. As shown in Fig. 1a, the capacity rapidly decreased from 2680 to 561 mAh g-1 over the 20th cycle (step 1) presumably due to S dissolution. Then, the performance was recovered to 1627 mAh g-1 over the following 110th cycle (step 2) and it was maintained at that level for subsequent cycles (1606 mAh g-1 for the 250th cycle at 0.5 A g-1). To elucidate the behavior underlying this observed gradual increase in capacity during step 2, we studied the morphology of the electrode by HR-TEM at the uncycled state, 60th, and 100th cycles. As shown in Fig 1b, the uncycled electrode shows a micro-sized layer structure along the r-GO surface. However, the repetitive electrochemical reaction (step 2 of Fig. 1a) induced a continuous pulverization of the bulk sheets into nano sheets with a size of 5.0 nm for the 100th cycle (Fig. 1c-d). This TEM behavior is in good agreement with the cyclic performance of Fig. 1a. Moreover, in Fig. 2a thin film with a thickness of 0.9 – 1.0 nm, formed by controlling the potential, covered the pulverized sheets. Additionally, in XPS surface analysis of the electrode after the 100th cycle, peaks of 285, 286.5, and 290 – 291.5 eV associated with carbonate compounds were identified. (Fig. 2b). These compounds correspond to the SEI layer. Although the SEI layer is an insulator, it can protect the active material from side reaction with the electrolyte and dissolution in the solution itself. Thus, the formation of a thin SEI on the pulverized sheets led to maintenance of capacity of above 1500 mAh g-1 after the 110th cycle. Based on the above results, it is concluded that the in-situ electrochemical pulverization of the MoSx/r-GO can improve electrochemical performances by forming nano-sized sheets which are securely anchored on r-GO. Also, the formation of a thin SEI layer can support the stability of the pulverized nano sheets. Figure 1

Capillary methacrylate-based monoliths by grafting from/to γ-ray polymerization on a tentacle-type reactive surface for the liquid chromatographic separations of small molecules and intact proteins

Capillary methacrylate-based monoliths were prepared for the high performance liquid chromatography (HPLC) separation of both small molecules and large biomolecules. An efficient grafting from/to synthetic approach was adopted introducing a network of activated sites in the inner wall surface using the new silanization agent (N-trimethoxysilylpropyl)-polyethylenimine. Copolymerization of lauryl methacrylate monomer and 1,6-hexanediol dimethacrylate cross-linker in the presence of porogenic solvents was obtained under continuous γ-ray exposure with high conversion yield.The morphology and porous structure of the resulting monoliths have been investigated by Scanning Electron Microscopy (SEM) and 1H NMR cryoporosimetry. By chromatographic investigation, the new capillary columns attested high kinetic performance (with efficiency larger than 100,000 theoretical plate/m for small molecules at optimum mobile phase linear velocity of about 0.5mm/s) and also excellent mechanical stability and repeatability.The new methacrylate-based monolithic capillary columns have been successfully employed for efficient reversed-phase separation of intact proteins and peptides.

Binder/surfactant-free biocathode with bilirubin oxidase for gas-diffusion-type system

Direct electron transfer (DET)-type bioelectrocatalysis of dioxygen (O2) reduction is an essential process for constructing a biocathode for use in an enzymatic biofuel cell. In this study, a gas-diffusion-type electrode without any binders or surfactants, which are both known to interfere with DET-type bioelectrocatalysis, was constructed. Bilirubin oxidase (BOD), a promising catalyst for DET-type O2 reduction, and water-dispersed multiwalled carbon nanotubes compatible with BOD were used. The electrode displayed high kinetic performance in the DET reaction and large steady-state current density under quiescent conditions. In addition, the electrode provided a platform that was eight times more suitable for BOD than a traditional electrode.

Assessing of phosphorus removal by polymeric anion exchangers

Assessing of phosphorous removal by the polymeric anion exchange resins was studied in this paper, aiming at the determination of effects of pH, competing ions, concentration and flow rates. Batch study was carried out of both weak-base and strong-base resins to determine the selectivity to phosphorus in presence of Cl–, NO3– and SO42–. Batch studies clarified that weak-base resin preferred phosphorus to competing anions and equilibrium adsorption capacity was from 4.95 to 1.39mmol/g. Strong-base resin was strongly affected by competing anions and equilibrium adsorption capacity as low as 0.39mmol/g. Column studies also performed of fixed-bed experiments using both resins packed column. The breakthrough capacities of weak-base resins were not so strongly affected by flow rates from 50 to 150h−1 and the breakthrough capacities were from 0.41 to 0.20mmol/g indicating high kinetic performances. Trace level of phosphorus was removed by weak-base resins from feed containing of 0.026mM phosphorus at high flow rate of 350h−1. Adsorbed phosphorus was quantitatively desorbed with 1M HCl acid and regenerated into hydrochloride form simultaneously for next adsorption operation. Therefore, weak-base resin is to be an effective means to treat wastewater to prevent eutrophication in the receiving water bodies.

High performance activated carbon for benzene/toluene adsorption from industrial wastewater

A coal-tar-derived mesophase was chemically activated to produce a high surface area (∼3200 m 2/g) carbon with a porosity made up of both micropores and mesopores. Its adsorption capacities were found to be among the highest ever reported in literature, reaching values of 860 mg/g and 1200 mg/g for the adsorption of benzene and toluene, respectively, and 1200 mg/g for the combined adsorption of benzene and toluene from an industrial wastewater. Such high values imply that the entire pore system, including the mesopore fraction, is involved in the adsorption process. The almost complete pore filling is thought to be due to the high relative concentrations of the tested solutions, resulting from the low saturation concentration values for benzene and toluene, which were obtained by fitting the adsorption data to the BET equation in liquid phase. The kinetics of adsorption in the batch experiments which were conducted in a syringe-like adsorption chamber was observed to proceed in accordance with the pseudo-second order kinetic model. The combined presence of micropores and mesopores in the material is thought to be the key to the high kinetic performance, which was outstanding in a comparison with other porous materials reported in the literature.

A weak-base fibrous anion exchanger effective for rapid phosphate removal from water

This work investigated that weak-base anion exchange fibers named FVA-c and FVA-f were selectively and rapidly taken up phosphate from water. The chemical structure of both FVA-c and FVA-f was the same; i.e., poly(vinylamine) chains grafted onto polyethylene coated polypropylene fibers. Batch study using FVA-c clarified that this preferred phosphate to chloride, nitrate and sulfate in neutral pH region and an equilibrium capacity of FVA-c for phosphate was from 2.45 to 6.87 mmol/g. Column study using FVA-f made it clear that breakthrough capacities of FVA-f were not strongly affected by flow rates from 150 to 2000 h −1 as well as phosphate feed concentration from 0.072 to 1.6 mM. Under these conditions, breakthrough capacities were from 0.84 to 1.43 mmol/g indicating high kinetic performances. Trace concentration of phosphate was also removed from feeds containing 0.021 and 0.035 mM of phosphate at high feed flow rate of 2500 h −1, breakthrough capacities were 0.676 and 0.741 mmol/g, respectively. The column study also clarified that chloride and sulfate did not strongly interfere with phosphate uptake even in their presence of equimolar and fivefold molar levels. Adsorbed phosphate on FVA-f was quantitatively eluted with 1 M HCl acid and regenerated into hydrochloride form simultaneously for next phosphate adsorption operation. Therefore, FVA-f is able to use long time even under rigorous chemical treatment of multiple regeneration/reuse cycles without any noticeable deterioration.