High Saturation Capacity Research Articles

3D Wood Microfilter for Fast and Efficient Removal of Heavy Metal Ions from Water.

Adsorption is an effective method for the treatment of heavy metal ions in water; however, the existing adsorbents are complicated to prepare, and costly and difficult to recover. In this work, a 3D wood microfilter was prepared by modifying wood for the removal of heavy metal contaminants from water. First, a green deep eutectic solvent was used to remove lignin from beech wood. Then citric acid and l-cysteine were sequentially used to graft carboxyl and sulfhydryl groups (-SHs) on the surface of cellulose. Finally, a three-dimensional wood microfilter with an abundant porous structure and adsorption sites was formed. The adsorption kinetics and adsorption isotherms of heavy metal ions on the 3D wood microfilter were systematically investigated using Cu2+ and Cd2+ as model species. The results showed that the 3D wood microfilter had a fast adsorption rate and high saturation capacity for both Cu2+ and Cd2+. Based on the advantages of easy processing and multilayer assembly and stacking, a three-layer wood microfilter was designed to achieve high flux rate (1.53 × 103 L m-2 h-1) and high efficiency (>98%) for the removal of heavy metal ions in water. The enhancement mechanism of the adsorption process of Cu2+ and Cd2+ by the 3D wood microfilter was investigated using SEM and EDS, FTIR, and XPS characterization. The simple synthesis method and high adsorption efficiency of this wood microfilter provide a new strategy for the preparation of cheap, efficient, and recyclable adsorbents for heavy metal ions in water.

Study Komparasi Penambahan Palm Oil Ash Dengan Bantuan Semen Berdasarkan Nilai California Bearing Ratio

High water content, water saturation, and low carrying capacity are characteristics of clay soils. The road body may have an uneven surface. On the other hand, in the dry season it will harden and have a high carrying capacity so that a lot of dust is scattered on the road and blocks the driver's view. As a result, the neighborhood can experience traffic jams and accidents. Check the CBR and PI values to see if there is an increase in clay after stabilization using a mixture of Palm Oil Fuel Ash and cement with variations (0% POFA + 2% Cement), (3% POFA + 2% Cement), (5% POFA + 2% Cement), and (7% POFA + 2% Cement). Test method Sieve Analysis, Atterberg Limit, Specific Gravity, Moisture Content, Compaction and CBR. Cement and palm oil bunch ash produced a CBR value of 7.4% compared to a natural soil CBR value of 1.59%. The CBR value of the soil will increase, the dry unit weight value will decrease, and the plasticity value will decrease with the higher proportion of Oil Palm Bunch Ash and cement

Rapid and Selective Uptake of Radioactive Cesium from Water by a Microporous Zeolitic-like Sulfide.

The fast and efficient removal of 137Cs+ ions from water is of great significance for the further treatment and disposal of highly active nuclear waste. Hitherto, although many layered metal sulfides have been proven to be very effective in capturing aqueous cesium, three-dimensional (3D) microporous examples have rarely been explored, especially compounds that are systematically used to study cesium ion exchange behaviors. In this paper, we present detailed Cs+ ion exchange properties of a 3D, microporous, zeolitic-like sulfide, namely K@GaSnS-1, in different conditions. Isotherm studies indicate that K@GaSnS-1 has a high cesium saturation capacity of 249.3 mg/g. In addition, it exhibits rapid sorption kinetics, with an equilibrium time of only 2 min. Further studies show that K@GaSnS-1 also displays a strong preference and good selectivity for cesium, with the highest distribution coefficient Kd value up to 3.53 × 104 mL/g. Also noteworthy is that the excellent cesium ion exchange properties are well-maintained despite acidic, basic, and competitive multiple-component environments. More importantly, the Cs+-exchanged products can be easily eluted and regenerated by a low-cost and eco-friendly method. These merits demonstrated by K@GaSnS-1 render it very promising in the effective and efficient separation of radioactive cesium from nuclear waste.

Accelerated kinetics of Pd(II) solvent extraction using functionalized 1-methyl-2-(nonylthio)-1H-imidazole and its comparison with dialkylsulfide to separate Pd(II) and Pt(IV)

Dialkylsulfide is considered as the most promising extractant for separating Pd(II) and Pt(IV) in industrial processes. However, the slow kinetics for Pd(II) extraction limits its extensive application. The development of new extractants with faster kinetics, high extraction efficiency, and exceptional Pd(II) separation selectivity has been a persisting goal over the past few decades. In this study, a new functionalized extractant, 1-methyl-2-(nonylthio)-1H-imidazole (MNI) containing both N and S atoms, was synthesized and employed to separate Pd(II) from mixed hydrochloric acid solutions with different initial Pd(II)/Pt(IV) concentration ratios. Experimental results revealed that MNI not only has a high selectivity for Pd(II) over Pt(IV) but also has faster kinetics for Pd(II) extraction than diisopentylsulfide (S201) under similar extraction conditions. In contrast to traditional dialkylsulfide extractants, MNI coordinates with Pd(II) ions via the N(5) atom in its imidazole ring to form Pd(MNI)2Cl2 complexes, instead of using the S atom as with dialkylsulfide. The extraction mechanism involving the coordination between Pd(II) and MNI was demonstrated using the slope analysis method and ultraviolet (UV), Fourier-transform infrared (FT-IR), 1H NMR, and 13C NMR spectroscopic methods. The fast extraction kinetics between MNI and Pd(II) was possibly attributed to the high charge density of the N(5) atom in the imidazole ring, whereas the outstanding separation selectivity for Pd(II) was due to the strong affinity of the N(5) atom. The facile synthesis, high saturation capacity, excellent Pd(II) selectivity, and remarkable reusability endow MNI with potential applications in Pd(II) recovery from leach solutions of waste automotive catalysts and other secondary resources.

Removal of different vat dyes by Aspergillus niger: A comparative study focusing on the molecular structure

Vat dyes are the most commonly used dyes in the denim industry. Since the pollution of the textile industry is a worldwide problem, Aspergillus niger was used in this study, to treat vat dye wastewater by pre-culture and simultaneous-culture methods. A comparison between the two biosorption techniques used showed that pre-culture was about 30% more efficient than simultaneous culture. The adsorption capacity was determined using the Langmuir and Freundlich adsorption models, with Langmuir proving to be the most suitable model. The high saturation capacity of 121.35 mg/g for C.I. Vat Brown 1 calculated with the Langmuir adsorption model indicated that A.niger is a suitable sorbent for vat dye wastewater.To investigate the influence of dye structure on biosorption efficiency, eight vat dyes with different chemical characteristics were used. The results showed that the complete decolorization time was reduced by 200 and 150 min for planar and non-planar structures, respectively, due to the reduction of molecular mass, indicating that molecular mass is probably the dominant factor in vat dye removal. In addition, planar structures resulted in a 50-min reduction in biosorption time. The possible adsorption sites were analyzed by Fourier transfer infrared analysis. The results showed that the amino and carboxyl groups of the fungus could serve as sorption sites for vat dyes through hydrogen bonding.”

Facile synthesis and characterization of Chromium(III)/Zirconium(IV) impregnated Chitosan/β-Cyclodextrin Bio-composite and Application towards efficient removal of Copper(II) from aqueous systems

• Synthesis of Cr(III)/Zr(IV) impregnated chitosan-β-cyclodextrin bio-composite (CB@CZ) and characterization. • At pH 5, CB@CZ compound efficiently adsorbs Cu(II) from an aqueous solution. • At optimum conditions, CB@CZ has a high monolayer saturation capacity of 76.47 mg g -1 for Cu(II). • kinetic data agree well with the pseudo-second-order equation, implying the chemisorption mechanism. • Ion-exchange cum electrostatic attraction mechanisms have been hypothesized for Cu(II) adsorption onto the adsorbent. Chromium(III)/zirconium(IV) impregnated chitosan-β-cyclodextrin bio-composite (CB@CZ) was fabricated successfully by a simple chemical method. The synthesized NC is characterized by analytical tools such as FT-IR, PXRD, FESEM, TEM, EDS, BET, TGA, etc. Application of as-prepared material selectively adsorb Cu(II) over other metal ions from water has been investigated in varying different parameters. The pH is optimized between 5.0 and 6.0 and kinetic data agree well with the pseudo-second-order equation. The isotherm data agree better with the Freundlich, Redlich-Peterson and Dubinin-Radhuskevich models than the Langmuir. Thermodynamics studies indicate that the adsorption process is endothermic but spontaneous and Cu(II) adsorption occurs with increasing entropy. The spontaneity of this surface adsorption is more favorable at higher temperatures. The adsorption mechanisms suggest that Ion-exchange as well as electrostatic attraction process occurred. The Cu(II) adsorption is dominated by the hydroxyl and amino functional groups of β–cyclodextrin and chitosan. Overall, the CB@CZ has tremendous potential in removing Cu(II) for practical applications from contaminated wastewater due to its green synthesis technique, selectivity, and strong adsorption capability.

Surface Modification of Biomass with Di-(2-Ethylhexyl)phosphoric Acid and Its Use for Vanadium Adsorption.

The method of carbonizing biomass using di-(2-Ethylhexyl) phosphoric acid and tributyl phosphate impregnation (SICB) was studied in this research. SICB combines the benefits of an extractant and an ion exchange resin. The adsorption and desorption properties of vanadium were investigated, and the adsorption mechanism was analyzed. The results showed that the carrier was first prepared at a temperature of 1073.15 K using sawdust as a biomass substitute and then cooled to room temperature. The best adsorption performance was obtained by impregnating the carriers with di-(2-Ethylhexyl) phosphoric acid and tributyl phosphate for 60 min. The vanadium adsorption rate of 98.12% was achieved using the biomass at an initial V(IV) solution concentration of 1.1 g/L, a pH value of 1.6, and a solid-to-liquid ratio of 1:20 g·mL for 24 h. Using 25 wt.% sulfuric acid solution as desorbent, the desorption rate of vanadium was as high as 98.36%. The analysis showed that the adsorption of vanadium by SICB was chemisorption, and the adsorption process was more consistent with the proposed second-order kinetic equation. Therefore, SICB has high selectivity and high saturation capacity because of the mesopores and micropores produced by carbonization.

Exposed carboxyl functionalized MIL-101 derivatives for rapid and efficient extraction of heavy metals from aqueous solution

Exploring efficient adsorbent for heavy metals remediation from wastewater and contaminated soil is a pursuing issue. Robust functionalized metal-organic frameworks (MOFs) represent one of burgeoning scavengers because of their tunable structural topology, designable functionalities and extraordinary affinity for heavy metal ions. In this present work, we report a facile and versatile strategy to synthesize a series of carboxyl-functionalized MIL-101(Fe) derivatives by microwaving a solution of organic ligands with varying carboxyl number and Fe3+ ions. The resulting MIL-101(Fe) derivatives were characterized using various techniques including scanning electron microscope (SEM), powder X-ray diffraction, Fourier transformed infrared, Brunauer–Emmett–Teller specific surface area and X-ray photoelectron spectroscopy. The intrinsically carboxyl-rich characteristic and large surface area of MIL-101-(COOH)2 afford fast adsorption kinetics (< 15 min) and high saturation capacity (467.6 mg/g) for Pb(II). Strikingly, it can efficiently capture Pb(II) possessing impressive adsorption efficiencies (> 90%) over a wide pH range of 4.5–11.0. Moreover, the resulting MIL-101-(COOH)2 simultaneously exhibited high affinity toward different types of heavy metal ions, including borderline Lewis acid (Pb(II), Cu(II) and Ni(II)), soft Lewis acid (Cd(II) and Hg(II)) and hard Lewis acid (Eu(III) and Cr(III)). Such impressive treatment for Pb(II)-contaminated lead-acid battery industrial wastewater (more than 96.7%) can be attributed to the coordination arising from abundant carboxyl groups in the pores of MIL architecture with target heavy metal ions. Significantly, these findings validate the exceptional potential of carboxyl-functionalized MIL-101(Fe) derivatives in the application of heavy metal ions remediation.

Statistical evaluation of liquid phase sequestration of acridine orange and Cr6+ by novel mesoporous glutamic acid-g-polyacrylamide/plaster of paris/riboflavin hydrogel nanocomposite

The adsorption of acridine orange and Cr6+ ion onto plaster of paris reinforced glutamic acid-grafted-polyacrylamide hydrogel nanocomposite modified with riboflavin, Glu-g-PAM/POP/Rb HNC was studied. The Glu-g-PAM/POP/Rb HNC was physico-chemically characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, transmission electron microscopy and Brunauer-Emmett-Teller analysis. The specific surface area, pore volume and pore diameter were 15.48 m2/g, 0.015 cm3/g and 4.23 nm, respectively. Adsorption process was strategized by response surface methodology (RSM) based on a 3-level 5-factor (initial solution pH, contact time, adsorbent dose, initial adsorbate concentration and temperature) central composite design (CCD), and validity of the estimated parameters was statistically evaluated using analysis of variance (ANOVA). The optimized operating variables were: pH (AO = 10; Cr6+ = 4.15), contact time (AO = 60 min; Cr6+ = 59 min), adsorbent dose (0.8 g/L), initial adsorbate concentration (60 mg/L) and temperature (298 K). Isotherm results were coincident with Langmuir isotherm model. The experimental kinetic adsorption data was congruous with pseudo-second order model, with the uptake rate controlled by both intraparticle and liquid film diffusions. The relatively high Langmuir saturation capacity of 202.63 mg AO/g and 143.68 mg Cr6+/g, supported by the decent recyclability up to four times affirmed the promising performance of the adsorbent. The efficacy of the adsorbent for simultaneous removal of AO and Cr6+ from bi-component system was assessed. The possible adsorption mechanism mainly involved hydrogen bonding, van der Waals forces, electrostatic and π-π interactions. Adsorption of AO and Cr6+ onto Glu-g-PAM/POP/Rb HNC was feasible and exothermic as revealed by the thermodynamic parameters. The findings demonstrated superior adsorbent efficacy for the seizure of pollutants, particularly AO and Cr6+ from aqueous solution.

Evaluation of adsorptive and photocatalytic degradation properties ofFeWO4/polypyrrole nanocomposite for rose bengal and alizarin red S from liquid phase: Modeling of adsorption isotherms and kinetics data

AbstractThe FeWO4/polypyrrole nanocomposite (FeWO4/PPy NC), prepared by oxidative polymerization of pyrrole monomer with FeWO4NPs, is used for adsorption and photocatalytic degradation of rose bengal and alizarin red S. The characterization of the nanocomposite (NC) is performed by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectroscopy, and transmission electron microscopy. The performance of FeWO4/PPy NC is appraised under varying conditions of agitation time/solar irradiation time, initial dyes concentration, adsorbent/photocatalyst dose, and initial solution pH. The Langmuir isotherm and pseudo‐second‐order kinetic models best express the equilibrium data. The FeWO4/PPy NC exhibits a maximum saturation capacity of 202.63 mg/g for rose bengal (RB) and 142.80 mg/g for alizarin red S (ARS). The adsorption of both dyes follows liquid film and intraparticle diffusion. Thermodynamic studies demonstrate feasibility, spontaneity, and exothermic essence of the removal process. The NC shows remarkable visible‐light photocatalytic activity at 100–120 min irradiation time, 40 mg/L dyes solution concentration, 0.5 g/L of photocatalyst, and pH 6. Photodegradation reaction obeys first‐order kinetics. The mechanism of adsorption of RB and ARS is governed by electrostatic attraction, hydrogen bonding, van der Waals, and π–π interactions. A good regeneration capacity up to four sorption–desorption cycles, high saturation capacity, and remarkable photodegradation efficiency depicts that FeWO4/PPy NC can be used efficiently for decolorization of RB and ARS in aqueous medium.

Tailored construction of β-cyclodextrin covalently-supported tannic acid polymer nanosponge towards highly selective lead recovery

Low-cost and high-selective adsorbents is desirable but challenging for recovering heavy metal ions from actual wastewater. In this work, we developed a novel β-cyclodextrin covalently-crosslinked tannic acid (TA@CD) polymer nanosponge via a simple condensation reaction, and then realized the selective capture of Pb2+ from complex wastewater. TA@CD demonstrated a strong affinity for Pb2+ compared to other coexisting metal ions with a high selective coefficient of 1143 (approximately 188 times higher than that of other polymer, metal-based and bio-based adsorption materials), which can be attributed to the phenolic hydroxyl groups of TA that can effectively bind with Pb2+ to form a relatively stable structure. In the typical adsorption experiments, a high adsorption saturation capacity of 136.8 mg g−1 on Pb2+ at an initial concentration of 200 mg/L (maximum capacity was 116.5 mg/g) and an ultrafast removal efficiency of 81% Pb2+ within 3 min were achieved by TA@CD (adsorption finished within 50 min), due to the abundant exposed TA adsorption sites and the efficient mass transfer rate supported by CD. With the favorable adsorption and regeneration performance, in the dynamic treatment process with a fixed-bed reactor pack of TA@CD nanosponge, the treatment volume of Pb2+-containing simulated wastewater can up to 9860 bed volume (BV) with only 176.5 mL eluent production. This work provides a feasible approach to design economic and directional adsorbents with the potential to selectively recover heavy metal ions from actual wastewater.

Magnetic Carbon Nanotubes‐Silica Binary Composite for Effective Pb(II) Sequestration from Industrial Effluents: Multivariate Process Optimization

AbstractIn this work, magnetic multiwalled carbon nanotubes‐silica binary composite (mCNT@APS) is synthesized via amide bond and utilized for the Pb(II) adsorption from aqueous solutions in batch mode. The composite is characterized using Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and point of zero charge (pHpzc) studies. Three levels and three factorial Box–Behnken design in response surface methodology is employed to assess and optimize the effects of influential parameters: pH, initial concentration, and contact time. Using the desirability function, the obtained optimum conditions are pH 5.4, feed concentration 757 µg mL−1 and contact time 4 min. The electrostatic attraction between the active binding sites of adsorbent and Pb(II) at pHpzc &lt; pH results in higher saturation capacity (79.69 mg g−1) in accordance with the best fitted non‐linearized Langmuir isotherm model. The pseudo‐second‐order model fits well to the kinetic data implying chemisorption of Pb(II) onto mCNT@APS. The material can be regenerated up to 15 sorption–desorption cycles using 5 mL of 1.5 M HNO3. The adsorbent exhibits excellent Pb(II) removal efficiency (&gt;98%) from industrial effluents and tap water samples.

INCREASING THE PERFORMANCE OF STEEL PARTS BY COMPLEX SATURATION OF THE SURFACE WITH ALLOYING ELEMENTS

The change in the microstructure, hardness and thickness of diffusion coatings with varying content of boron carbide salts in the melt is studied. For samples made of U10 steel, the highest saturation capacity with the formation of a carbide layer is characteristic of a composition containing 2% BC, 5-6% alloying elements (Cr, V, Ti), 10% NaCl, the rest is borax NaBO. The addition of 3-5% aluminum oxide significantly increases the stability of the melt and contributes to the preservation of the saturating capacity. The technology of complex saturation of steel with alloying elements can be used to harden parts of stamping equipment and a wide range of tractor parts.

Low-Cost Activated Grape Seed-Derived Hydrochar through Hydrothermal Carbonization and Chemical Activation for Sulfamethoxazole Adsorption

Activated carbons were prepared by chemical activation with KOH, FeCl3 and H3PO4 of the chars obtained via hydrothermal carbonization of grape seeds. The hydrochars prepared at temperatures higher than 200 °C yielded quite similar proximate and ultimate analyses. However, heating value (24.5–31.4 MJ·kg−1) and energy density (1.04–1.33) significantly increased with carbonization temperatures between 180 and 300 °C. All the hydrochars showed negligible BET surface areas, while values between 100 and 845 m2·g−1 were measured by CO2 adsorption at 273 K. Activation of the hydrochars with KOH (activating agent to hydrochar ratio of 3:1 and 750 °C) led to highly porous carbons with around 2200 m2·g−1 BET surface area. Significantly lower values were obtained with FeCl3 (321–417 m2·g−1) and H3PO4 (590–654 m2·g−1), showing these last activated carbons important contributors to mesopores. The resulting materials were tested in the adsorption of sulfamethoxazole from aqueous solution. The adsorption capacity was determined by the porous texture rather than by the surface composition, and analyzed by FTIR and TPD. The adsorption equilibrium data (20 °C) fitted the Langmuir equation well. The KOH-activated carbons yielded fairly high saturation capacity reaching up to 650 mg·g−1.

Highly Selective, High-Capacity Separation of o-Xylene from C8 Aromatics by a Switching Adsorbent Layered Material.

Purification of the C8 aromatics (xylenes and ethylbenzene) is particularly challenging because of their similar physical properties. It is also relevant because of their industrial utility. Physisorptive separation of C8 aromatics has long been suggested as an energy efficient solution but no physisorbent has yet combined high selectivity (>5) with high adsorption capacity (>50 wt %). Now a counterintuitive approach to the adsorptive separation of o-xylene from other C8 aromatics involves the study of a known nonporous layered material, [Co(bipy)2 (NCS)2 ]n (sql-1-Co-NCS), which can reversibly switch to C8 aromatics loaded phases with different switching pressures and kinetics, manifesting benchmark o-xylene selectivity (SOX/EB ≈60) and high saturation capacity (>80 wt %). Structural insight into the observed selectivity and capacity is gained by analysis of the crystal structures of C8 aromatics loaded phases.

Highly Selective, High‐Capacity Separation of o‐Xylene from C8 Aromatics by a Switching Adsorbent Layered Material

AbstractPurification of the C8 aromatics (xylenes and ethylbenzene) is particularly challenging because of their similar physical properties. It is also relevant because of their industrial utility. Physisorptive separation of C8 aromatics has long been suggested as an energy efficient solution but no physisorbent has yet combined high selectivity (&gt;5) with high adsorption capacity (&gt;50 wt %). Now a counterintuitive approach to the adsorptive separation of o‐xylene from other C8 aromatics involves the study of a known nonporous layered material, [Co(bipy)2(NCS)2]n (sql‐1‐Co‐NCS), which can reversibly switch to C8 aromatics loaded phases with different switching pressures and kinetics, manifesting benchmark o‐xylene selectivity (SOX/EB≈60) and high saturation capacity (&gt;80 wt %). Structural insight into the observed selectivity and capacity is gained by analysis of the crystal structures of C8 aromatics loaded phases.

Elucidation and characterization of entropy effects in mixture separations with micro-porous crystalline adsorbents

Separations of mixtures of xylene isomers, alkane isomers, linear alkanes, and linear alcohols using micro-porous crystalline adsorbents such as zeolites and MOFs are often carried out under conditions in which the pores are nearly saturated with guest molecules. Such separations are often dominated by factors other than the relative binding strengths of the constituents; the component that is preferentially adsorbed under pore saturation conditions is the guest molecule that has the higher saturation capacity, and packs more efficiently within the microporous channels. Higher saturation capacities, and packing efficiencies, arise from a wide variety of factors such as (a) smaller size, (b) shorter length, (c) smaller footprint, (d) commensurateness of molecular configuration with channel geometry. A common characteristic of all these separations is that at low pore occupancies, θmix<0.5, the separations are dominated by differences in binding strengths, and at pore occupancies θmix>0.5, the separations become increasing influenced by differences in saturation capacities. Remarkably, at pore saturation, i.e. θmix≈1, the component that packs more poorly is virtually excluded. Statistical thermodynamics, and the Boltzmann expression S=kBlnW, applied to lattice models, are used to quantify and rationalize the influence of packing efficiencies, and the phenomena of selectivity reversals.

Preparation and characterization of modified rice husks by biological delignification and acetylation for oil spill cleanup

ABSTRACTCellulose is widely used as an effective sorbent to treat wastewater. Cellulosic sorbents have the advantage of biodegradability, as they are natural plant-based materials, compared with the synthetic materials such as polypropylene (PP) or polyurethane (PU). Among the raw biomass materials used for cellulose production, rice husk is one of the most cost competitive and widely available. In this work, biological treatments are compared to find the most effective treatment method for cellulose fibre production from rice husk. Using biological delignification, cellulose was extracted from raw rice husk and acetylated to acquire hydrophobicity. Delignification was performed using both bacteria and fungi and their results were compared. The white-rot fungi strain using ‘Aspergillus flavus CICC 40258’ was found to be the most effective treatment method, achieving a modified product with up to 55% w/w cellulose concentration. Acetylation further facilitated the sorption process and the maximum oil uptake capacity using delignification and acetylation treatment was found to be 20 g/g. The as-prepared sorbents exhibited high oil uptake rates and saturation capacity was reached after 5 min of contact with oil. The kinetic study presents a good correlation with the pseudo-second order model. The isothermal studies demonstrated that the oil sorption capacity of rice husk follows the Langmuir model as compared with the Freundlich model.

Superhydrophobic/Superoleophilic Polycarbonate/Carbon Nanotubes Porous Monolith for Selective Oil Adsorption from Water

A superhydrophobic/superoleophilic porous polycarbonate/carboxyl-functionalized multiwalled carbon nanotubes (PC/cMWCNTs) monolith with novel hierarchical micronanostructure was facilely fabricated via a thermally impacted nonsolvent induced phase separation method. A novel porous microstructure endowed PC/cMWCNTs monolith had a high porosity of 90.1%. Based on excellent superhydrophobicity (water contact angle of 159°) and superoleophilicity (oil contact angle of 0°), this porous monolith could selectively adsorb various types of oils/organic solvents from the oil–water mixture. Additionally, the monolith exhibited outstanding oil/water separation performance including fast adsorption speed, high saturation capacity, and superior recycling ability. The equilibrium adsorption time and saturated adsorption capacity of soybean oil were 20 s and 12.62 g g–1, respectively. By simple centrifugation or evaporation, the recovered PC/cMWCNTs monolith could be reused for at least 10 cycles. Thus, porous PC/cMWCNTs...

ZnO and Cu-based adsorbents for biogas desulfurization at room temperature

Synthesis and structural characterization of ZnO and Cu based materials were done in order to compare chemical, morphological and microstructural effects in sorbent materials for gas-phase desulfurization reaction at room temperatures as a potential application in biogas cleaning. The materials were synthesized through two wet chemical routes, firstly using zinc nitrate, hexamethylenetetramine and NaOH reagents at 70 and 90 °C for ZnO flower-like and rod-like structures, respectively; and secondly a typical calcination of metallic copper to obtain CuO. Powder X-ray diffraction, X-ray fluorescent spectroscopy analysis were realized. Results showed a unique zincite phase for ZnO and three phases in copper samples: Cu0, Cu2O and CuO (76.3, 18.3 and 5.4 wt%). The size of crystal domains varied from 180 to 1600 nm, while the particle size varied from 660 to 1020 nm. These materials were tested in desulfurization reactions at room temperature using a fixed-bed glass reactor. In order to avoid poisoning and asphyxiation risks a non-desulfurized biogas influent was simulated by a gas mixture of N2 and H2S (100 ppm). The reactor was fed with the gas mixture at rate of 450 ml/min (GHSV 9120 h−1). The composition of effluent gas was determined using a biogas detector, coupled with an electrochemical H2S sensor. Results show that CuO and ZnO could be feasible adsorbents for the removal of hydrogen sulfide; however, they became saturated after 300 s while high surface area materials, evidenced by SEM, showed higher saturation capacity. Characterization of wasted adsorbents using electron microscopy techniques and fluorescence X-ray spectroscopy evidenced the presence of metallic sulfides at amounts less than 0.05 wt%, although no crystalline phases were detected in further analysis.