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Biofuels offer significant potential for reducing carbon emissions and enhancing energy sustainability, but their efficient purification remains a significant challenge. In this study, the performance of a hydrophobic zeolitic imidazolate framework, ZIF-71(ClBr)-SE, in the adsorptive separation of butanol from single- and ternary-component systems (acetone, butanol, and ethanol) was investigated and compared with ZIF-8 and ZIF-71. Physicochemical characterization techniques, including XRD, SEM, BET, TGA, and DVS, confirmed that the modified ZIF-71 is hydrophobic, isostructural with ZIF-71, and has a higher surface area. Adsorption tests in aqueous solutions revealed that ZIF-71(ClBr)-SE unexpectedly showed a higher affinity for acetone over butanol. DFT molecular simulations provided insights into solute-ZIF interactions, highlighting preferential sites for ZIF interaction. [ABSTRACT FROM AUTHOR]

The bio‐based diols 1,3‐propanediol (1,3‐PDO) and 2,3‐butanediol (2,3‐BDO) can form strong hydrogen bonds with water, which increases the separation difficulty of diols in aqueous solutions. Herein, a series of mixed‐linker ZIF‐71‐clnImx samples with hydrogen bond–van der Waals (vdW) dual recognition sites have been constructed using 4‐chloro‐5‐nitroimidazole (clnIm) linkers to substitute partially for the original 4,5‐dichloroimidazole (dclIm) linkers of the ZIF‐71 framework. The experimental and calculated results show that ZIF‐71‐clnImx with appropriate clnIm substitution proportion (x = 7.6 and 12.8 mol%) can strengthen the interaction between ZIF‐71‐clnImx and 2,3‐BDO and enhance the adsorption and mass transfer of 2,3‐BDO, thus achieving the efficient separation of 2,3‐BDO/1,3‐PDO. Molecular simulation results further verify that 2,3‐BDO can simultaneously form strong H bonds with the –NO2 of the clnIm linker and weak vdW interactions with the –Cl of the dclIm linker, which are the mixed recognition sites for 2,3‐BDO adsorption intensification in aqueous solution for ZIF‐71‐clnImx. [ABSTRACT FROM AUTHOR]

The separation of Co(II) and Ni(II) from leaching solution is gaining interest because Co(II) and Ni(II) are increasingly used in emerging strategic areas, such as power batteries. Herein, the surface of silica gel is functionalized with 1,2-ethylenediamine and used for the separation of Co(II) and Ni(II). The Co(II) removal efficiency of the modified silica is 80.2%, with a 4-fold improvement in the separation factor. The geometry, frequency, and electrostatic potential of the ethylenediamine modified silica gel (en/SG) are calculated. The corresponding properties of M2+ (M-Co, Ni) adsorbed on en/SG in an aqueous solution are simulated and analyzed. The results show that ethylenediamine tends to form [Men(H2O)4]2+ after binding to M2+, and the binding ability of Co(II) to ethylenediamine is stronger. Besides, the thermodynamic calculations show that en/SG has a more negative Gibbs free energy when absorbing Co(II) in aqueous solution, so en/SG is more inclined to bind with Co(II) preferentially. It is the difference in complexation ability between Ni, Co, and ethylenediamine that enlarges the difference in the original physical adsorption, thus strengthening the separation performance. This work will provide guidance for a rational design of high-performance nickel-cobalt adsorption materials. [ABSTRACT FROM AUTHOR]

Acrylic acid (AA) and Acrylamide (AM) are copolymerised to produce copolymer of Poly-acrylic acid-co-acrylamide (PAA) in the aqueous solution of Polyvinyl alcohol (PVA). Both the polymers PVA and PAA were cross-linked in situ by glutaraldehyde and N, N O-methylene bis acrylamide (MBA) respectively using 2 mass% of polymer basis for both of them. Thus, three different full interpenetrating network (FIPN) hydrogels were synthesised varying the mass ratio of PVA to PAA. The hydrogel of PVA: PAA = 1:0.50 composition designated as PAA50 found competitive for separating Malachite green from its 50 ppm aqueous solution by adsorption compared to the other two. PAA50 was further modified by incorporating 2, 5, 8 and 10 mass% nano size sodium monomontellite filler and produced four filled FIPN hydrogels designated as PAA52, PAA55, PAA58 and PAA510, respectively. These four nano-filled FIPN hydrogels along with unfilled PAA50 and pure nano size sodium monomontellite were used for adsorption in same dye solution of 5, 10, 25, 50, 75 and 100 ppm concentrations and different pH of 4, 7, 9, 10 & 11. Highest 98.039% dye removal was done by PAA58 from 75 ppm feed at 9 pH. 93.7% recovery was observed at 3 pH in desorption study. [ABSTRACT FROM AUTHOR]

The present work aims to separate an amino acid (l‐phenylalanine) from a highly dilute aqueous solution by the 'adsorptive bubble separation method'. Separation is based on the principle of adsorption at the interphase of the gas bubble and aqueous phase and subsequent amino acid extraction in the top layered nonaqueous phase. The operation was carried out in a long glass column with a comprehensive solvent chamber at the top. Design‐Expert software optimizes the process parameters, and the process involves three variables: gas (nitrogen) flow rate, extractant, and solvent quantity, which control responses, recovery percentage, and the ratio of enrichment. The design models are found to be significant. The maximum recovery of amino acid observed was 75.545% and the value of the enrichment ratio was 3.87. In addition, two models were generated by the software, which was statistically significant (P < 0.05). Therefore, this process is adopted as it is of straightforward construction, eco‐friendly, and less costly than other methods previously known to recover l‐phenylalanine from a dilute solution. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

[Display omitted] • Using aromatic template and corresponding π–π interactions to direct one-pot synthesis of hybrid ZIFs. • ZIF-11–93 hybrids covering the entire dual-linker composition range have been synthesized. • ZIF-11–93 22.6 with the appropriate hydrophobic and hydrogen-bonding synergistic site composition can realize separation of 2,3-BDO/1,3-PDO in aqueous solutions. Problems arising from differences in size, shape, and type of two distinct linkers can hamper the direct synthesis of hybrid Zeolite imidazolate frameworks (ZIFs) spanning the full range of linker compositions. We report herein the use of toluene as a template, exploiting its π–π interactions with benzimidazole (bIm) and 4-methyl-5-imidazolecarboxaldehyde (almeIm) linkers, to directly synthesize ZIF-11–93 hybrids covering the entire dual-linker composition range, which show tunable and desirable properties. Experimental results show that ZIF-11–93 22.6 , with an appropriate balance of hydrophobic and hydrogen-bonding groups, demonstrates enhanced 2,3-BDO affinity and driving force in aqueous solution, leading to longer breakthrough time, shorter mass-transfer zone, and higher dynamic column adsorption capacity than those of ZIF-11 with a hydrophobic linker and ZIF-93 with a hydrogen-bonding linker. Calculations predict that the hydrophobic/hydrogen-bonding synergistic sites of ZIF-11-93 x hybrids should intensify its interaction with 2,3-BDO in aqueous solution, thereby permitting the effective separation of 2,3-BDO and 1,3-PDO. [ABSTRACT FROM AUTHOR]

Adsorptive separation of Pb(II) from aqueous solution containing Pb(II) and other heavy metals (Cu(II), Zn(II) and Cd(II)) has been investigated, using three adsorbents, such as an iminodiacetic acid-chelating resin (CR11) and Fe-based adsorbents (goethite and magnetite). Batchwise adsorption of Pb(II) and other metal ions in single metal system and multi-components system was carried out with varying parameters, such as pH, time and initial concentrations of metals. CR11 possesses the highest adsorption ability for these metals, while the selectivity of individual metal is little. Goethite possesses selectivity for Pb(II) and Cu(II), and magnetite possesses selectivity for Pb(II), though the adsorption capacity for the metals is less than those with CR11. The kinetics of the adsorption of metals with all adsorbents is of pseudo-second-order, and the magnetite is revealed to have the fastest adsorption kinetics. The three adsorbents can be applied for chromatographic separation for these metals. The magnetite is feasible for selective separation of Pb(II), although complete elution cannot be achieved. [ABSTRACT FROM AUTHOR]

Recently, highly porous metal–organic frameworks (MOFs), with excellent porosity and abundant functional groups, have represented a new addition to the area of capturing uranium ion pollutants. To achieve high adsorption capacity and removal efficiency of uranium, it is significant to modify the morphology of MOF-based adsorbents. In this contribution, two hollow structured ZIF-8 adsorbents were used for the adsorptive separation of uranium from aqueous solution. Both of them showed faster adsorption rate and larger adsorption capacity than pristine ZIF-8, providing the prospect of hollow MOF materials to the application of uranium extraction. [ABSTRACT FROM AUTHOR]

Heavy metals in the environment are a problem due to their toxicity and bioaccumulation. Adsorptive removal of heavy metals by clay minerals has garnered increasing attention due to the abundance, low cost, and exceptional physicochemical properties of the clays. The purpose of the present study was to investigate the utilization of two Turkish sepiolite samples, nodular sepiolite (NS) and industrial sepiolite (IS), as adsorbents in removing Ni2+ ions from aqueous solutions. The specific surface areas of NS and IS are 182.19 m2 g–1 and 63.78 m2 g–1, respectively. The effects of adsorbent dosage, initial pH, contact time, initial concentration, and temperature on the adsorption of Ni2+ ions onto the sepiolite samples were investigated using a batch method. The optimum adsorbent dosage was determined as 0.6 g/50 mL of adsorbent and the optimum pH value was 6.0, for both sepiolite samples. The adsorption process obeyed the Freundlich isotherm model (KF: 4.89–9.73 mg1–1/n L1/n g–1 for NS and 4.27–6.42 mg1–1/n L1/n g–1 for IS) and the pseudo-second order kinetics model (k2: 0.0049–0.0397 g mg–1 min–1 for NS and 0.0688–0.1195 g mg–1 min–1 for IS). The adsorption process was spontaneous and endothermic, and the randomness increased. The samples exhibited large adsorption capacities through three cycles of adsorption-desorption tests. The results revealed that the sepiolite samples are promising as cost-effective adsorbents for the removal of Ni2+ ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

In terms of energy resource recovery and environmental protection, the separation of U(VI) from aqueous solutions is vital. Adsorption and solvent extraction are the most common separation technologies, which are also widely used for uranium recovery or removal from aqueous solution. The linear structure of uranyl ion and its multiple coordination feasibilities offer great opportunities for its extractive and adsorptive separation. This review briefly summarized and analyzed the recent advances in the separation of uranyl ions from aqueous solutions, mainly focusing on the selective extraction and adsorption using affinity ligands-based technology, which is promising method due to the high selectivity, capable of recovering uranium at low concentration and complicate aqueous environment. The affinity ligands for uranyl ions, including organophosphorus, calixarenes, amidoxime, imidazole and other derivatives were introduced. These donor ligands for design of extraction solvents or adsorbents for the separation of uranyl ions were summarized. The further research on the coordination chemistry towards uranyl ions and removal mechanisms would provide vital information for the development of more effective ligands with higher affinity, stability and compatibility in various systems, which is still challenging. [ABSTRACT FROM AUTHOR]

Highlights • The protocol for controllable and scalable synthesis of H-PAP was developed. • H-PAP shows an exclusive adsorption for HMF, without adsorption of fructose, LA and FA. • HMF with high purity from the reaction mixture of fructose dehydration was recovered. • The adsorption mechanism was revealed via combining experimental results and DFT calculation. Abstract The hollow-structured porous aromatic polymers (H-PAP) with cavity diameter from 228 ± 11 to 464 ± 15 nm were controllably prepared through surface coating and template-etching method under scalable synthesis conditions from standard scale to 20-fold scale-up. It is found that the fill factor ( f ) of reactor is an important parameter for determining the scalability of synthesis. Benefiting from the favorable textural properties, chemical and thermal stability, surface hydrophobicity and π electrons, the well-developed H-PAP as adsorbent was investigated in selective adsorption of 5-hydroxymethylfurfural (HMF) under static batch mode from the single-component and multi-component aqueous solutions. The H-PAP shows an exclusive adsorption for HMF, without adsorption of fructose, levulinic acid (LA) and formic acid (FA), and can be recycled three times without significant decrease in adsorption capacity. Structure-performance relationship points out that the apparent amount of HMF adsorbed on H-PAP is related to micropore surface area, micropore volume and cavity diameter, while HMF selectivity depends on surface hydrophobicity. In the case of HMF adsorption from the real reaction mixture of acid-catalyzed fructose dehydration, the HMF constituent with high purity (ca.94.4%) can be recovered. Combining the adsorption isotherms with DFT calculation reveals adsorption mechanism that HMF adsorption on H-PAP proceeds initially via π–π stacking interaction, and then assembles into regular array around spherical surface to form monolayer coverage following modified Langmuir model, and finally diffuses into interior cavity until adsorption saturation. [ABSTRACT FROM AUTHOR]

Adsorptive removal of phosphorus from wastewater effluents has attracted attention because of its reduced sludge production and potential P recovery. In this study, we investigated granular activated carbons (GACs) impregnated with amorphous ferrihydrite (FH@GAC) for the sorption of phosphorus from aqueous solutions. Preoxidation of intact GAC surfaces using an oxidant (e.g., hypochlorite) and strong acids (e.g., HNO 3 /H 2 SO 4 ) was performed to create active functional groups (e.g., carboxyl or phenolic) for enhanced iron binding, leading to greater phosphorus uptake. Both the rate and the capacity of phosphorus sorption onto FH@GAC had significant, positive relationships (Pearson correlation coefficient r > 0.9) with the product of surface area and Fe content. The pseudo-second-order reaction kinetics explained the P sorption rate better than the pseudo-first-order reaction kinetics, whereas the Langmuir model fit the P sorption isotherm better than the Freundlich model. The iron content in the FH@GAC increased significantly (>10 mg/g) when GAC (e.g., BMC1050) was preoxidized by a 1:1 (w/w) concentrated HNO 3 /H 2 SO 4 mixture. The Langmuir maximum P sorption capacity of a functionalized FH@BMC1050 adsorbent prepared with acid pretreatment was estimated to be substantial (5.73 mg P/g GAC corresponding to 526 mg P/g Fe). This sorption capacity was superior to that of a FH slurry, possibly because the nano-sized FH formed inside the GAC pores (<2.5 nm) can bind phosphate ions more effectively than FH aggregates. Fixed-bed column reactor operation with bicarbonate regeneration showed potential for efficient, continuous phosphorus removal by FH@GAC media. [ABSTRACT FROM AUTHOR]

The ZnO/ZnMn2O4 nanocomposite (ZnMn) was used as adsorbent for the removal of cationic dye Basic Yellow 28 (BY28) from aqueous solutions. The adsorbent was characterized by X-ray diffraction, scanning electron microscope, TEM, Fourier transform infrared ray, BET, particle size distribution and zeta potential measurements. The adsorption parameters, such as temperature, pH and initial dye concentration, were studied. Kinetic adsorption data were analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of BY28 was 48.8 mg g−1. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were calculated. [ABSTRACT FROM AUTHOR]

Amino-functionalized multi-walled carbon nanotubes (MWCNTs) were synthesized by a simple, cost-effective method using 3-aminopropyltriethoxysilane and were evaluated for cesium ion removal in aqueous solution. Experimental results showed that the maximum cesium adsorption capacity of amino-functionalized MWCNTs was 136.3 mg g−1, reaching 95% of the ultimate adsorption capacity within 30 min. The adsorption capacity of amino-functionalized MWCNTs was not significantly affected by the presence of competing ions. The Langmuir isotherm fitted the experimental data well and a thermodynamic study indicated the spontaneous and endothermic nature of cesium adsorption on the amino-functionalized MWCNTs. [ABSTRACT FROM AUTHOR]

Magnetite nanosorbents are known with high sorption capacity and ease of solid phase separation from surrounding liquid by the imposed external magnetic field. In this study, magnetite nanoparticles (MNPs) and silica‐coated magnetite nanoparticles (Si‐MNPs) were prepared and used for the removal of arsenic (III) from aqueous solutions. The nanosorbents were characterized by transmission electron microscope, X‐ray diffraction, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. The spherical Fe3O4 nanoparticles in diameter of about 100 nm and SiO2 shells of 12 nm were formed. The saturation magnetization was found to be 78 and 58 e mug–1 for MNPs and Si‐MNPs, respectively. Under optimal conditions, both nanosorbents were very efficient for arsenite uptake (removal efficiency ≥99%). The highest removal percentage was obtained near PZC of nanosorbents where the net surface charge was zero. The MNPs exhibited higher sorption capacities in comparison with Si‐MNPs although they tended to be agglomerated in higher applied doses. The kinetic of experiments indicated the best fit to the pseudo‐second order model. Furthermore, the experimental data were best described by the Langmuir model. This study demonstrated the effectiveness of bare and silica coated magnetic nanoparticles to remove trace concentrations of arsenic (III) in water environment. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 951–960, 2018 [ABSTRACT FROM AUTHOR]

A novel nanosorbent is designed via crosslinking of nanolayer carboxymethyl cellulose (CMC) onto the surface of nano‑zirconium oxide (Nano-ZrO 2 ) using glutaraldehyde for the formation of Nano-ZrO 2 -glu-CMC. The nanosorbents were characterized using TGA, SEM, HR-TEM, FT-IR and surface area analysis. The particle size of Nano-ZrO 2 -glu-CMC was 22–39 nm. The potential implementation of Nano-ZrO 2 -glu-CMC sorbent for selective speciation and extraction of chromium ions from real water samples and aqueous solutions was explored and compared versus Nano-ZrO 2 sorbent using the batch technique in presence of various values of pH, time, mass of sorbent, concentration and competing ions. The maximum metal capacity values of chromium (VI) by Nano-ZrO 2 -glu-CMC and Nano-ZrO 2 were identified as 680 and 120 μmol g − 1 , respectively in pH 1.0–2.0, while the identified maximum values of chromium (III) were 1120 and 500 μmol g − 1 , respectively in pH 7.0. Nano-ZrO 2 -glu-CMC and Nano-ZrO 2 sorbents were further successfully applied for speciation of Cr(VI) and Cr(III) as well as adsorptive removal from tap water, sea water and industrial wastewater samples adjusted to pH 2.0 and pH 7.0, respectively. The identified percentage values of chromium species by the multistage microcolumn technique confirmed the superiority of ZrO 2 -glu-CMC versus Nano-ZrO 2 based on the determined recovery range 97.9–100.0% and 89.6–100.0%, respectively. [ABSTRACT FROM AUTHOR]

Adsorptive removal of a toxic sulfonamide antibiotic, sulfachloropyradazine (SCP), from aqueous solution was studied on several metal organic frameworks, UiO-66 and ZIF-67, for the first time. UiO-66 exhibited a much higher adsorption capacity than ZIF-67, fast kinetics, and easy regeneration for reuse, demonstrating as a promising adsorbent in wastewater treatment processes. The batch adsorption shows an adsorption capacity of SCP at 417 mg/g on UiO-66. The kinetic adsorption of SCP on UiO-66 reached equilibrium just in 10 min and the kinetics fits accurately with a pseudo 2nd order model. A plausible mechanism was proposed based on pH effect, p K a value of the adsorbate and Zeta potential of UiO-66. The high adsorption is mainly contributed to hydrophobicity and π-π interactions along with electrostatic interactions. Thermodynamic studies show the spontaneous adsorption and exothermic process. The easy regeneration and high adsorption capacity confirms structural stability of the robust UiO-66 in wastewater treatment processes, making it suitable for a large scale application. [ABSTRACT FROM AUTHOR]

Single and multi-component adsorptive removal of 134 Cs + , 60 Co 2 + and 152 + 154 Eu 3 + from aqueous solutions onto sepiolite are studied in the present study. Removal of these radionuclides in single systems is found to be strongly dependent on the initial pH on the solution. Removals > 99% (for 60 Co 2 + and 152 + 154 Eu 3 + ) and of about 82% (for 134 Cs + ) are achieved at initial pH values higher than 4 and 5, respectively. The kinetic data and the equilibrium isotherms are modeled by two kinetic models, the pseudo-first-order and the pseudo-second-order, and two isotherm models, Langmuir and Freundlich, respectively. The effect of various coexisting cations, Na + , Ca 2 + and Al 3 + , at different concentrations on the adsorption processes of the concerned radionuclides in single systems was evaluated. Desorption studies of radionuclide-loaded sepiolite are studied using different concentrations of organic, EDTA and HA (strong complexing agents for radionuclides), and inorganic, HCl, NaCl, CaCl 2 , Mg(NO 3 ) 2 and AlCl 3 , desorbing agents. Adsorption mechanisms of radionuclides onto sepiolite are deeply discussed. Multi-component adsorptive removal of 134 Cs + , 60 Co 2 + and 152 + 154 Eu 3 + onto sepiolite as a function of adsorbent weight and time was also studied. The influence of the solution pH on co-removal efficiency of radionuclides was investigated in presence of EDTA. Furthermore, the present investigation evaluated the removal efficiency of radionuclides, in multi-systems, in presence of different concentrations either of NaCl or CaCl 2 . [ABSTRACT FROM AUTHOR]

Biosorption potentials of activated carbons from pentaclethra Macrophylla (PMAC) seed shells for the removal of Pb(II) from aqueous solution were investigated. The physicochemical properties of pentaclethra Macrophylla (PMAC) seed shells were characterized through ASTM standards for adsorbents tests. The functional groups of the pentaclethra Macrophylla (PMAC) were investigated using Fourier transform infrared (FTIR) spectroscopy, morphology measured with scanning electron microscopy (SEM),oxides investigated by X-ray fluorescence (XRF) and diffraction pattern observed by x-ray diffraction (XRD). Influence of key parameters such as contact time, pH of Pb(II) solution, temperature of Pb(II) solution, adsorbent dosage, adsorbent particle size and initial concentration of Pb(II)solution were studied by batch mode. These process parameters were optimized using response surface methodology (RSM) and analysis of variance (ANOVA). The significance of the different process parameters and their combined effects on the adsorption efficiency were established through a full factorial central composite design. The results obtained are in good agreement with published data for other activated carbons as well as various international standards for water treatment. An optimal yield of 94.83% was obtained with optimal conditions of solution temperature, 30°C; contact time, 120minutes; adsorbent dosage, 1.50 g; and pH, 7. The optimization was performed using the numerical method of the Design Expert version 8.7.1.0 by State Ease U.S.A. This investigation has shown that Pentaclethra Macrophylla (PMAC) seed shells from Nigeria can be used for industries as activated carbon for waste water treatment. [ABSTRACT FROM AUTHOR]

In the present work ability of the two novel adsorbents, sulphonyl and carboxyl functionalized stearyl alcohol-grafted epichlorohydrin, SA-g-E-SOH, SA-g-E-COOH; to remove lysozyme (LYZ) from aqueous solution was assessed. The adsorbent characterization was done using FTIR, XRD, SEM and TGA analyses. The adsorption efficiency was influenced by solution pH and the optimum operating pH was found to be 4.0 for SA-g-E-SOH and 5.0 for SA-g-E-COOH and their adsorption efficiency was evaluated using the various isotherm and kinetics models. The Sips isotherm model and pseudo-second-order kinetic model were found to be the best for describing the equilibrium and kinetic behaviors of the adsorption process. Batch adsorption/desorption studies in acidic medium, for over six cycles showed excellent regeneration capability of the adsorbents and could lead to the development of viable and promising technology for the adsorptive recovery of LYZ from aqueous solutions. The efficiency of the adsorbents for the LYZ adsorption was verified using egg white. The result obtained from this study revealed that adsorption ability of 25 mg of SA-g-E-COOH is 98.4 % which is more than that of SA-g-E-SOH (96.2 %). The efficiency of SA-g-E-SOH to remove LYZ from aqueous solution was found to be higher compared to SA-g-E-COOH. [ABSTRACT FROM AUTHOR]

A metal-organic framework (MOF) (here, zeolitic-imidazolate framework-8) was pyrolyzed at different temperatures (800, 1000, and 1200 °C) in order to prepare porous carbons derived from MOF (PCDMs). Adsorption of ibuprofen (IBP) and diclofenac sodium (DCF) from aqueous solutions was carried out over the produced PCDMs and compared with that over pristine MOF and commercial activated carbon (AC). Among the tested adsorbents, the PCDM prepared at 1000 °C (PCDM-1000) was found to be the best candidate for both IBP and DCF. The maximum adsorption capacities of IBP (320 mg/g) and DCF (400 mg/g) over PCDM-1000 were ∼3 and ∼5 times, respectively, of that of AC. Interaction mechanisms such as H-bonding (H-donation from PCDM, H-acceptance from IBP or DCF) were suggested based on the effect of solution pH on the zeta potential of PCDM and the adsorbed quantity of IBP and DCF along with functional groups created on the surface of PCDM-1000. Finally, PCDM-1000 was confirmed to be as a highly efficient and recyclable adsorbent having potential applications in water purification. [ABSTRACT FROM AUTHOR]

Cr(VI) is a toxic water pollutant, which causes cancer and mutation in living organisms. Adsorption has become the most preferred method for removal of Cr(VI) due to its high efficiency and low cost. Peanut and almond shells were used as adsorbents in downflow fixed bed continuous column operation for Cr(VI) removal. The experiments were carried out to scrutinise the adsorptive capacity of the peanut shells and almond shells, as well as to find out the effect of various operating parameters such as column bed depth (5-10 cm), influent flow rate (10-22 ml min) and influent Cr(VI) concentration (10-20 mg L) on the Cr(VI) removal. The fixed bed column operation for Cr(VI) adsorption the equilibrium was illustrated by Langmuir isotherm. Different well-known mathematical models were applied to the experimental data to identify the best-fitted model to explain the bed dynamics. Prediction of the bed dynamics by Yan et al. model was found to be satisfactory. Applicability of artificial neural network (ANN) modelling is also reported. An ANN modelling of multilayer perceptron with gradient descent and Levenberg-Marquardt algorithms have also been tried to predict the percentage removal of Cr(VI). This study indicates that these adsorbents have an excellent potential and are useful for water treatment particularly small- and medium-sized industries of third world countries. Almond shell represents better adsorptive capacity as breakthrough time and exhaustion time are longer in comparison to peanut shell. [ABSTRACT FROM AUTHOR]

Trace metal ions in aqueous samples may be separated and preconcentrated by solid phase extraction (SPE) prior to their determination by flame atomic absorption spectrometry (FAAS). The trace amounts of heavy metals can form complex with D2EHPA – MWCNTs. The quantitative adsorption was at pH 5.0 with a flow rate of 2 mL−1. The adsorbed metal ions can be eluted with 2.0 mol L−1HNO3. The highest enrichment factor was 25. The thermodynamic parameter (ΔG) revealed that the adsorption was spontaneous. The procedure was applied to the determination of copper, nickel, lead, zinc and cadmium in laboratory water, well water and electroplating wastewater samples. [ABSTRACT FROM AUTHOR]

Arsenate (As(V)) removal ability by nanoscale zero-valent iron (nZVI) is compromised by aggregation of nZVI particles. In this work, pine derived biochar (PB) was used as a supporting material to stabilize nZVI for As(V) removal. The biochar supported nZVI (nZVI/BC) was synthesized by precipitating the nanoparticles on carbon surfaces. Experiments using batch and continuous flow, completely mixed reactors (CMRs) were carried out to investigate the removal of As(V) by the nZVI/BC from aqueous solutions. Batch experiments showed that nZVI/BC had high As(V) removal capacity in a wide range of pH (3–8). Kinetic data revealed that equilibrium was reached within 1 h and the isotherm data showed that the Langmuir maximum adsorption capacity of the nZVI/BC for As(V) at pH 4.1 was 124.5 g kg −1 . As(V) (100 mg L −1 ) adsorption in anoxic condition was about 8% more than in oxic conditions, where As(V) reduction was observed in anoxic condition. The performance of the nZVI/BC in flowing condition was evaluated in CMRs at influent As(V) concentrations of 2.1 and 5.5 mg L −1 and the adsorbent removed 100% and 90% of the As(V), respectively. Furthermore, the nZVI/BC composite is magnetic which facilitates collection from aqueous solutions. [ABSTRACT FROM AUTHOR]

Divalent lead present in the water stream was removed by using adsorption techniques with montmorillonite clay (Mt) modified with tri-n-octylamine (Mt-TOA). Batch adsorption data at equilibrium were determined with different initial Pb2+ ions concentration (8, 10, 12, 14, and 16 mg·L-1) in the aqueous solution at 298 K, and these results were correlated by using three different isotherm models, for instance, the Langmuir, the Freundlich, and the Temkin. The two-parameter Langmuir model was the best fit to the equilibrium data with a coefficient (R ²) greater than 0.99. The maximum capacities for monolayer adsorption of Mt and Mt-TOA were determined to be 3.37 mg·g-1 and 33.1 mg·g-1, respectively, as estimated from Langmuir. Also, experimental values were generated to evaluate the influence of adsorbent amount (w, 0.05-0.3 g for Mt, 0.01-0.06 g for Mt-TOA), starting Pb2+ ion concentration (C 0, 8 mg·L-1 to 16 mg·L-1), pH (between 1 and 9), and contact period (t, from 10 to 110 min) on the removal effectiveness and adsorption capability of Mt and Mt-TOA adsorbents. In respect to kinetic studies, the removal efficiency of Pb2+ ion reached to a fixed value of 81.42% with Mt (0.1 g) and 80.67% by Mt-TOA (0.01 g) next 100 and 80 min, respectively. Pseudo-first order, pseudo-second order, and intraparticle diffusion models were studied to obtain the kinetic parameters of the adsorption practice. It is observed that the rate of mass transfer of Pb2+ ions was mainly governed by the intraparticle diffusion mechanism. [ABSTRACT FROM AUTHOR]

In this study, Extran (biodegradable surfactant) was used for the preparation of FeO nanoparticles by microemulsion process to improve removal efficiency of As(III) from aqueous solution. FeO nanoparticles were characterized by XRD, FTIR, FESEM, TEM, HRTEM, and VSM instrumental techniques. The effect of different parameters such as adsorbent dose, initial As(III) concentration, and solution pH were studied by response surface methodology (RSM) based on Box-Behnken design (BBD). The optimized condition for adsorption of As(III) from aqueous solution was obtained as adsorbent dose of 0.70 mg/g, solution pH of 7.7, and initial As(III) concentration of 33.32 mg/L. In this optimum condition, about 90.5% of As(III) was removed from the aqueous solution. Isotherm studies have been done at optimal condition, and it was observed that the Langmuir isotherm models were fitted well with experimental data having a high correlation coefficient of 0.993. From the Langmuir isotherm data, the maximum adsorption capacity of FeO nanoparticles was found to be 7.18 mg/g at pH 7.7 in room temperature. This study revealed that FeO nanoparticles can be used as an efficient, eco-friendly, and effective material for the adsorptive removal of As(III) from aqueous system. [ABSTRACT FROM AUTHOR]

The goal of this paper is to investigate the removal of iron and copper from aqueous solutions using adsorption. Zeolitic tuff and kaolin were used as adsorbents and were collected from different areas in Jordan. Batch adsorption experiments using synthetic Fe3+and Cu2+solutions were employed to study the effects of adsorbent dose, initial concentration, particle size, pH, and temperature on metal uptake. Zeolitic tuff had higher Fe3+and Cu2+adsorption capacities (20.70 and 20.83 mg/g, respectively) compared with kaolin (14.68 and 9.81 mg/g, respectively). The optimum pH values for Fe3+and Cu2+removal on kaolin were found to be 4 and 6, respectively. For the initial metal concentration of 100 ppm, 100% of Fe3+and 62% of Cu2+were adsorbed. As the temperature increased from 25 to 55°C, the adsorption capacity of Fe3+on kaolin increased, thereby indicating the endothermic nature of the process. At the highest investigated temperature of 55°C, the Fe3+removal using kaolin was 95.5%. The kinetic data obtained for Cu2+removal confirmed the pseudo-second-order model. Fe3+removal using zeolitic tuff was not affected by the particle size, while Cu2+removal increased as the particle size decreased. This study suggests that zeolitic tuff and kaolin can be used as low-cost adsorbents for Fe3+and Cu2+removal with high efficiency. Kaolin was modified by pillaring with Al13polyoxycation and acid activation. The mineralogy of the kaolin, analyzed using X-ray diffraction, confirmed that its structure was not changed significantly due to Al-pillared activation. Both pillaring and acid activation decreased the adsorption capacity. [ABSTRACT FROM AUTHOR]

In this study, the peat samples from two different sites of Brunei Darussalam (Mumong and Panaga) were investigated. The peats were found to be acidic in nature containing 66–75% organic matter. Thermogravimetric analysis revealed their thermal stability up to 500°C, while scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray fluorescence provided information on the modes of interaction of Cu(II) ions with peat through complexation and ion-exchange mechanisms. Further, the extent of removal of Cu(II) ions from aqueous solution investigated under different experimental conditions revealed that the optimum values for shaking time and medium pH were 3.0 h and 5.5, respectively. Equilibrium adsorption data fitted to the Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (D–R), Redlich–Peterson (R–P), and Sips isotherm models indicated that adsorption of Cu(II) ions on peat obeyed the Sips model with an average adsorption capacity of 16.5 and 14.6 mg g−1for the Mumong and Panaga peat, respectively. Application of the pseudo-first-order, pseudo-second-order, Elovich, Boyd, and intraparticle diffusion models to evaluate the kinetics of the adsorption process led to the validity of the pseudo-second-order and intraparticle diffusion models to explain the adsorption of Cu(II) ions on the selected peat samples. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of the anionic dye Acidol Red 2BE-NW (AR42) on chitosan/montmorillonite (CTS/MMT) is investigated. A series of CTS/MMT beads were prepared by varying the chitosan to montmorillonite ratio and characterized by means of Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction (XRD) techniques. Batch experiments were carried out to assess the adsorption of AR42 from its aqueous solution using CTS/MMT as the adsorbent surface. Factors influencing control of the adsorption capacity of CTS/MMT such as initial pH value (pH0), adsorption time, initial dye concentration, chitosan contents, and temperature were investigated. The adsorption curves showed that the adsorption kinetics and isotherms were in good agreement with a pseudo-second-order and Langmuir patterns, respectively, with an observed maximum dye adsorption of 905 mg/g on CTS/MMT (CTS wt% = 25%). These results demonstrated the potential and the outstanding ability of CTS/MMT material for use in the anionic dye adsorption. [ABSTRACT FROM AUTHOR]

This article reports the efficient removal of Direct Red 80 (DR80) dye from aqueous phase using a semi-interpenetrating network (IPN) superabsorbent chitosan-starch (ChS) hydrogel. In the present investigation, the influence of initial pH, ChS dose, initial dye concentration, temperature and effect of salts on the sorption of DR80 dye was evaluated. A maximum swelling capacity of 15 g/g was determined for ChS hydrogel. The sorption equilibrium data demonstrated good agreement with Freundlich isotherm. The sorption process best fitted the pseudo-second order kinetic model. Maximum uptake capacity of the hydrogel was determined as 312.77 mg/g. The mean sorption energy ( E = 11.34–14.9 kJ/mol) demonstrated that DR80 sorption was mainly chemisorption. The temperature dependence data revealed the sorption process was spontaneous, endothermic and favourable at higher temperature based on the enthalpy (Δ H ° = +83.68 kJ/mol) value obtained. Boyd model confirmed intraparticle diffusion was the limiting step for DR80 uptake. In addition, sorption/desorption studies were performed to investigate the reusability of ChS hydrogel which demonstrated significant sorption for four consecutive cycles. [ABSTRACT FROM AUTHOR]

Batch experiments were executed to investigate the removal of Congo red (CR) from aqueous solutions using the crosslinked chitosan (CCS) and crosslinked chitosan immobilized bentonite (CCS/BT composite). The CCS and CCS/BT composite were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The removal of CR was examined as a function of pH value of CR solution, contact time, and inorganic sodium salt and ionic strength. The equilibrium data of CCS and CCS/BT composite agreed well with the Langmuir model. The adsorption capacities of CCS and CCS/BT composite at 298 K and natural pH value were 405 and 500 mg/g, respectively. The kinetic data correlated well with the pseudo-second-order model. The adsorption of CR onto the CCS was mainly controlled by chemisorption while the adsorption of CR onto the CCS/BT composite was controlled by chemisorption and the electrostatic attraction. [ABSTRACT FROM AUTHOR]

Anaerobic fermentation can transform carbohydrates to yield a multicomponent mixture comprising mainly of acetone, 1-butanol, and ethanol (ABE) in a typical weight ratio of 3:6:1. Compared to ethanol, 1-butanol, the main product of ABE fermentation, offers significant advantages as a biofuel or a fuel additive. However, the toxicity of 1-butanol for cell cultures requires broth concentrations to be low in 1-butanol (≈1-2 wt %). An energy-efficient recovery method that performs well even at low 1-butanol concentrations is therefore necessary to ensure economic feasibility of the ABE fermentation process. In this work, configurational-bias Monte Carlo simulations in the Gibbs ensemble are performed to probe the adsorption of 1-butanol/water solutions onto all-siliceous zeolites with the framework types MFI and FER. At low solution concentration, the selectivity and capacity for 1-butanol in MFI are larger than those in FER, while the opposite is true for concentrations at or above those of ABE broths. Structural analysis at various loadings sheds light on the different sorbate-sorbate and sorbate-sorbent interactions that govern trends in adsorption in each zeolite. [ABSTRACT FROM AUTHOR]

The metal organic framework UiO-66-NH 2 has been post-synthetically modified to introduce thiourea, isothiocyanate and isocyanate functionalities without compromising the structural and thermal stability of the parent framework. 1 H NMR and IR spectroscopies have been used to monitor the extent of framework functionalization. UiO-66, UiO-66-NH 2 and the new functionalized frameworks UiO-66-NHC(S)NHMe, UiO-66-NHC(S)NHPh, UiO-66-NCS and UiO-66-NCO have been studied as adsorbents for the capture of a range of heavy metals from homoionic aqueous solution, with a view towards applications in environmental remediation. Functionalization markedly improved metal removal efficiency up to 99% with calculated maximum adsorption capacities of 49, 117, 232 and 769 mg/g for Cd 2+ , Cr 3+ , Pb 2+ and Hg 2+ respectively for UiO-66-NHC(S)NHMe. [ABSTRACT FROM AUTHOR]

ZSM-5 (Zeolite Scony Moblie-5) (SiO2/Al2O3 = 360, 470), NaY, 13X (pellet, powder) and coconut shell activated carbon (YK-AC) are employed for acetic acid separation from dilute aqueous solutions via adsorption. Zeolite 13X exhibits a much higher adsorption capacity than other zeolites and activated carbon. The effects of adsorption time and different initial acetic acid concentrations were studied. At 71.77 g•kg-1, the initial acetic acid concentration, 13X in pellet exhibited the highest uptake capacity of 354.03 mg•g-1 at 318 K. Meanwhile, adsorption equilibrium, kinetics, and thermodynamics of an acetic acid aqueous solution on zeolite 13X in pellet were studied in batch experiments. Kinetic models such as pseudo-first-order, pseudo-second-order, and Elovich have been used to describe the adsorption behavior of zeolite 13X in pellet. Pseudo-second-order was found the most suitable for this system. Langmuir and Freundlich isotherm models were applied to experimental data depending on temperature. The Freundlich isotherm fitted the experimental data better than the Langmuir isotherm for adsorption of acetic acid. Using the thermodynamic equilibrium coefficients obtained at different temperatures, the thermodynamic constants (ΔG, ΔH, and ΔS) of adsorption were also calculated, and the results indicated that the adsorption process of acetic acid on zeolite 13X in pellet was spontaneously endothermic. [ABSTRACT FROM AUTHOR]

The removal of Basic Yellow 2 (BY2), a cationic dye, from aqueous solution by using montmorillonite as adsorbent was studied in batch experiments. The effect of pH, agitation speed, adsorbent dosage, initial dye concentration ionic strength, and temperature on the removal of BY2 was also investigated. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms were applied to fit the adsorption data of BY2 dye. Equilibrium data were well described by the typical Langmuir adsorption isotherm. The maximum monolayer adsorption capacity was calculated as 434.196 mg g−1from the Langmuir isotherm model. The adsorption data was fitted to both the pseudo-first-order, pseudo-second-order, Elovich, and intraparticle kinetic models, and the calculated values of the amount adsorbed at equilibrium (qe) by pseudo-second-order equations were found to be in good agreement with the experimental values. The thermodynamic factors were also evaluated. The entropy change (ΔS*) was negative, suggesting that the adsorption process decreases in entropy and enthalpy change (ΔH*) was positive which indicates endothermic nature. The positive ΔG* value confirms the un-spontaneity of the process. In addition, a semiempirical model was calculated from kinetic data. [ABSTRACT FROM PUBLISHER]

Converting the waste biomasses with high-carbon content into value-added materials is an environmental-friendly way for their utilization. In this study, a leaf-derived biochar is modified with graphitic C 3 N 4 to fulfill an affordable composite material capable of removing organic pollutants via adsorptive and photocatalytic processes simultaneously. The preparation process includes a carbonization process of chestnut leaf biomass and a followed condensation reaction of melamine at 520 °C. The characterization shows that biochar and C 3 N 4 existed in the composites in their pristine status, and the effective connection of C 3 N 4 and biochar was established. The adsorptive performance of the composites is governed by the biochar content in the composite, thus showing favorable performance for the removal of cationic dye methylene blue (MB). The condensation reaction of the melamine precursor has a coalescing effect on the dispersed biochar, resulting in the growth of particle size of composite. The composites prepared at different biochar/melamine ratios all show a photocatalytic activity on decolorization of MB. In terms of the specific photocatalytic activity of C 3 N 4 in the composite, biochar/melamine ratio of 0.5:1 is the best. Unlike the conventional adsorptive carbon materials which have saturated adsorption capacity, the composite in this study retain a sustaining decontamination capability due to the photocatalytic degradation of adsorbed organic pollutants under irradiation. [ABSTRACT FROM AUTHOR]

Montmorillonite(Mt) was used to remove copper (Cu2+) ion from wastewaterstream generated from industrial effluents.This clay was modified (Mt-TOA) by using an amine-based solvent, trioctylamine(TOA). Equilibrium and kinetic experiments were carried out to determinethe effect of adsorbent amount (w, 0.05 g to 0.3g for Mt, 0.001 to 0.006 g for Mt-TOA), initial Cu2+ionconcentration (C0, 8 mg·L–1to 16 mg·L–1), pH (2 to 10), and contacttime (t, 10 to 90 min) on the capacity of both adsorbents.With an increase in the adsorbent amount, the uptake capacity of Mtand Mt-TOA for Cu2+ion was found to decrease but withan enhancement in the removal efficiency. The optimum amount of Mtand Mt-TOA was found to be 0.1 and 0.001 g, respectively. A betteradsorption of Cu2+ion was observed at low pH value ofaqueous solution, and was found to decrease with an increase in thevalue of pH. In the kinetic experiments, the amount removal of Cu2+ion reached to a constant value of 75.62 % with Mt (0.1g) and 80.12 % with Mt-TOA (0.001 g) after 70 min. Equilibrium andkinetic data were analyzed by using eight different isotherm (Langmuir,Freundlich, Elovich, Temkin, Dubinin–Radushkevich, Redlich–Peterson,Toth, and Sips) and two different kinetic (pseudo-first-order andpseudo-second-order) models, respectively. [ABSTRACT FROM AUTHOR]

The present investigation addresses the feasibility study of H3PO4-modified berry leaves (HMBL) towards the abatement of Eriochrome Black T (EBT) from aqueous solutions. The adsorbent is characterized by functional groups like hydroxyl, primary amine NH bending, aromatic phosphate (P–O–C stretch) and CH bending of alkyne group; BET surface area of 824.98 m2 g−1and homogenous surface morphology. Retention of EBT in batch system was executed to optimize the influencing variables for better adsorptive performance. The dye uptake reached equilibrium at 1 h with an optimum adsorbent load of 2 g L−1under optimum temperature of 303 K. Equilibrium adsorption isotherm data were in good agreement (R2 = 0.996) to Langmuir isotherm with monolayer adsorption capacity of 133.33 mg g−1at 303 K. The adsorption process followed pseudo-second-order kinetics with higherR2(0.9999) and lesser Δq% (0.439). Thermodynamic investigation revealed the adsorption process to be exothermic (ΔH = −37.149 kJmol−1) and spontaneous in nature (ΔG = −5.937 kJmol−1at 303 K) with a decrease in the randomness (ΔS = −103.01 J K−1 mol−1) at the solid/liquid interface. The exhausted HMBL can be regenerated by 0.1 M NaOH and utilized for three adsorption–desorption cycles. The estimated cost of HMBL (USD 10.684/kg) is less as compared to commercial activated carbon (CAC) (USD 172.96/kg). The results implied the promising candidature of HMBL as a non-conventional low-cost alternative to CAC for dye removal. [ABSTRACT FROM AUTHOR]

To remove strontium (Sr) efficiently from aqueous solutions is important as Sr-90 is a radionuclide and could be a serious threat to the environment. This study examines the feasibility of Sr-90 removal using BT9, generated from a FBR-Fenton facility that was utilized in treating tannery wastewater. A rapid increased of Sr adsorption was detected when the solution pH increased from 7.11 to 11.22. A maxima adsorption capacity was estimated to be 29.85 mg Sr/g BT9 at 323 K and pH 11.22. Additionally, Sr adsorption decreases with the increase of the M/Sr from 0 to 100, indicating that the outer-sphere mechanism was importantly involved in the Sr adsorption. This Sr adsorption is spontaneous and endothermic, supported by the negative changed standard free energy with temperatures (Δ G ° = −5.75, −6.26, −6.72 kJ/mol at 288, 303, and 323 K, respectively) and the positive Δ H ° values (2.14 kJ/mol). The positive Δ S ° (27.49 J/mol K) further indicates that the randomness increased at solid-solution interface during Sr adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • A polyimide with 18C6 was synthesized by the polycondensation of DAB18C6 and 6FDA. • The porous PI-18C6 membrane showed a high Cs± adsorption capacity (54.08 mg g−1) • The membrane exhibited high separation factor for Cs± (α Cs / K = 4.1) and good repeatability. • Cs+ adsorption on the membrane followed a monolayer chemical adsorption mechanism. • PI-18C6 showed a higher adsorption energy for Cs+ (-395.72 kJ mol−1) than K+ & Rb+. To develop recyclable adsorptive materials for high-efficient separation of cesium (Cs+) from aqueous salt lake brine is of great significance. Herein, a novel polyimide (PI-18C6) with high molecular weight (M n = 93 kDa) and high thermal stability (T d > 380 °C) was synthesized by the condensation and polymerization of di(aminobenzo)-18-crown-6 (DAB18C6) and 4,4′- (hexafluoro-isopropylidene) diphthalic anhydride. Simultaneously, porous membranes for Cs+ selective adsorption were prepared by non-solvent induced phase separation (NIPs) method. Results suggested that the adsorption of Cs+ on PI-18C6 membrane is the monolayer chemical adsorption as confirmed by fitting its adsorption data using pseudo-second-order adsorption model and Langmuir isotherm model, respectively. PI-18C6 membranes displayed a high adsorption capacity up to 54.08 mg g−1 combined with a higher selectivity of coexisting ions such as K+, Na+, Mg2+ and Rb+. Theoretical calculation results showed that the PI-18C6 has a higher adsorption energy for Cs+ (-395.72 kJ mol−1) than K+ and Rb+. The significant higher adsorption energy at the crown-ether sites is largely attributed to the fact that the cavity diameter cavity of DB18C6 (2.6–3.2 Å) is a closer to Cs+ (3.34 Å). The membrane also exhibited excellent repeatability. In summary, our study paves a facile way to develop functional membrane materials for the selective adsorption separation of Cs+ from aqueous solution. [ABSTRACT FROM AUTHOR]

Graphene-like layered hexagonal boron nitride (g-BN) was prepared and characterized. The performance of using g-BN as an adsorbent for removal of fluoroquinolone antibiotic gatifloxacin (GTF) from aqueous solution was evaluated. g-BN showed an excellent adsorption capability with notable GTF adsorption ratio of more than 90%. Data of equilibrium adsorption of GTF onto g-BN at different temperatures were represented by Langmuir, Freundlich and Tempkin isotherm models, and Langmuir exhibited the best fitting with the maximum adsorption capacity of 88.5 mg·g−1 at 288 K. GTF adsorption was insignificantly affected by solution pH. Competitive role of Na+ and Ca2+ in the solution inhibited the adsorption of GTF and decreased the adsorption capacity a bit. The adsorption process was spontaneous and exothermic. The adsorption was probably governed by π–π interaction between GTF and g-BN, and electrostatic interaction may also exist in the adsorption process. [ABSTRACT FROM AUTHOR]

Ordered nanoporous silica SBA-15 was successfully synthesized and functionalized by tris(2-aminoethyl)amine (Tren), a multi-amine ligand, to develop efficient cationic dye adsorbent. The prepared materials were characterized by XRD, N2 adsorption-desorption, TGA, and FT-IR analysis. Tren-SBA-15 was used for the removal of malachite green (MG) from both aqueous solution and real textile effluent. The effects of various operational parameters including solution pH, adsorbent dosage, contact time, initial concentration and temperature on removal of MG using Tren-SBA-15 were investigated in batch adsorption mode. Within the optimum conditions, Tren-SBA-15 exhibited an excellent adsorptive capability of 2330 m g−1 (6.38 mmol g−1) with removal of 89.8%. Equilibrium data was best described by the Freundlich and Sips isotherm models indicated a favorable adsorption process ( nF > 1) and heterogeneous system for dye adsorption ( nS > 1). The adsorption kinetic behavior was influenced by intraparticle diffusion and pseudo-second-order kinetic model provided well-fitted to the experimental data. The kinetic rate constant increased with temperature. Qualitative estimates of the thermodynamic parameters showed that the overall adsorption process is spontaneous (Δ G < 0) and a bit endothermic (Δ H > 0), and adsorption mechanism was assumed to be a physisorption. Experiment with real textile wastewater showed 48.7% MG removal by the use of 0.01 g Tren-SBA-15. The reusability of the adsorbent in real wastewater was shown to be successful along with its regeneration possibility. Desorption experiments were performed by two deferent eluents to desorbs both cationic ions and dye molecules from Tren-SBA-15. The results showed that dye is removed completely from real effluent after two continues adsorption/desorption cycles. © 2014 American Institute of Chemical Engineers Environ Prog, 33: 1242-1250, 2014 [ABSTRACT FROM AUTHOR]

The surfactants cetyltrimethylammonium bromide (CTAB) and sodium lauryl sulfate (NaLS) were utilized for modifying the activated carbon's surface. The materials were characterized using BET-N2, scanning electron microscope, and Fourier transform infrared (FT-IR) spectroscopy. Adsorption of Ce(IV) radionuclides from aqueous solutions by activated carbon (AC) and surfactant-impregnated AC was studied. The obtained data showed that adsorption of Ce(IV) is strongly dependent on the solution pH and AC-NaLS exhibits the widest pH-range of maximum removal. The experimental adsorption capacity of AC-NaLS (0.069 mmol/g) for Ce(IV) is found to be nearly twice greater than that of AC (0.036 mmol/g). The adsorption kinetics of Ce(IV) onto AC and AC-NaLS were analyzed by linear and non-linear fittings to the pseudo-first-order, pseudo-second-order and Elovich kinetic models. Of these models, the pseudo-second-order is the best kinetic expression for describing the experimental data. The diffusion studies indicated that adsorption of Ce(IV) radionuclides on AC and AC-NaLS is controlled by film diffusion. Linear and non-linear fittings of the adsorption equilibrium data for Ce(IV) onto AC and AC-NaLS revealed that the Dubinin-Radushkevich (D-R) isotherm model fits the experimental data better than Freundlich and Langmuir models. The values of adsorption free energy, E, calculated from both linear and non-linear methods suggested that Ce(IV) radionuclides are physically adsorbed onto AC and AC-NaLS. [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel adsorption study of Pb(II) using aqueous guar gum. [•] Nearly 60% adsorption efficiency with 100ppm original Pb(II) ion concentration. [•] Follows Langmuir model. [•] Efficiency supremely higher than conventional adsorbents. [Copyright &y& Elsevier]

Abstract: Hollow fiber mixed matrix membrane (MMM) of polyacrylonitrile and alumina nanoparticle was prepared. Incorporation of alumina in membrane matrix was confirmed by elemental analysis. The membrane was characterized by scanning electron microscopy, contact angle, permeability, neutral polymer rejection, pore size, mechanical strength and zeta potential. Hydrophilicity, mechanical strength and zeta potential of MMM increased with alumina concentration. Langmuir isotherm fitted the best for adsorption of nitrate by the membrane and it was confirmed by FTIR. The breakthrough performance of MMM was studied conducting continuous cross-flow experiments. Effects of operating conditions, like feed concentration, cross flow rate and transmembrane pressure on filtration performance, were investigated. The membrane was regenerated by passing 0.1M sodium hydroxide solution for 15min. Increasing cross-flow rate had an adverse effect and transmembrane pressure had a marginal effect on the removal of nitrate. The presence of other co-ions like chloride, sulfate and carbonate has a negative effect on nitrate removal. [Copyright &y& Elsevier]

While much attention of the MOF community has been devoted to adsorption and purification of gases, there is now also a vast body of data on the capability of MOFs to separate and purify liquid mixtures. Initial studies focused on separation of petrochemicals in apolar backgrounds, but the attention has moved now to the separation of complex, e.g. chiral compounds, and to the isolation of biobased compounds from aqueous media. We here give an overview of most of the existing literature, with an accent on separation mechanisms and structure-selectivity relationships. [ABSTRACT FROM AUTHOR]

Chemically prepared activated carbon derived from durian seed (DSAC) was used as adsorbent to adsorb Malachite green (MG) dye. The prepared DSAC was characterized using Brunauer-Emmet-Teller (BET), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and proximate analysis, respectively. Batch adsorption studies were carried out for the removal of MG dye from aqueous solutions by varying operational parameters like contact time, initial MG dye concentration, solution temperature, and initial solution pH. Maximum dye removal of 97 % was obtained at pH 8. Experimental data were analyzed by eight model equations-Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Radke-Prausnitz, Sips, Vieth-Sladek, and Brouers-Sotolongo isotherms-and it was found that the Freundlich isotherm model fitted the adsorption data the most. Adsorption rate constants were determined using pseudo-first-order and pseudo-second-order rate equations, Elovich, intraparticle diffusion, and Avrami kinetic model. The results clearly showed that the adsorption of MG dye onto DSAC followed the pseudo-second-order model, and the mechanism of adsorption was controlled both by film diffusion and intraparticle diffusion. Thermodynamic parameters such as ∆ G, ∆ H, and ∆ S were also calculated for the adsorption process. The process was found to be spontaneous and endothermic in nature. This work provided an attractive adsorbent for the removal of MG dye from wastewaters. [ABSTRACT FROM AUTHOR]

Peanut hull powders were chemically modified using mercaptoacetic acid to develop a convenient, lowcost, and highly efficient adsorbent for the removal of Hg(II) from aqueous solutions. A pseudo-second-order rate equation fitted the kinetic data better than a pseudo-first-order rate equation did for both the raw and the mercapto-modified peanut hull powder. The equilibrium data for both the raw and the mercapto-modified peanut hull powder fitted well with the Langmuir, Freundlich, and Temkin isotherm models. Mercapto-modification improved the adsorption capacity of Hg(II) onto peanut hull powder. Fourier-transform infrared spectra revealed that mercapto groups, together with hydroxyl and carboxyl groups, were the main function groups of Hg(II) biosorption onto chemical-modified peanut hull powder. [ABSTRACT FROM AUTHOR]

In this study, an amidoximated chelating ion exchange resin was prepared by poly-acrylonitrile (PAN) grafted potato starch. The adsorbent characterizations such as specific surface area, pore volume, average pore radius, and Fourier transform infrared (FTIR) spectrum of the resin were measured. The effects of pH, adsorbent dosage, contact time, initial concentration of thorium ion, and temperature on adsorption of thorium ion from aqueous solutions were investigated. Four isotherm models including Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin were applied to analyze the equilibrium isotherm data. The results showed that Langmuir and Temkin models had a good agreement with experimental data. The maximum capacity of the adsorbent using the Langmuir isotherm model was 227.27 mg · g−1. The kinetic models like pseudo-first-order, pseudo-second-order, Elovich, and intraparticle were examined to describe the adsorption process. The kinetics of the adsorption process was found to follow the pseudo-second-order kinetic model. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were also calculated using equilibrium constant values at various temperatures (25, 35, 45, 55°C) and the positive value for ΔH° showed an endothermic adsorption process. The study suggests that the prepared adsorbent has promising potential for the removal of thorium from wastewaters. [ABSTRACT FROM PUBLISHER]