Pore Surface Properties Research Articles

Thermoresponsive membrane based on UCST-type organoboron polymer for smart gating and self-cleaning

Thermoresponsive polymers can endow membranes with tunable separation and self-cleaning performance. However, up to now, there have been only very limited choices of thermoresponsive polymers for the fabrication of smart membranes. Herein, thermoresponsive membranes based on UCST-type organoboron polymer (Poly(CPBA)) were fabricated for the first time. Poly(CPBA) synthesized via a nucleophilic ring-opening reaction with Poly(GMA) and 3-carboxyphenylboronic acid has shown typical thermoresponsive behavior in water and water/ethanol mixture. Under vacuum conditions, Poly(CPBA) formed the cross-linked boroxine network on the membrane surface via a dehydration-induced condensation reaction. The reversible conformational change of Poly(CPBA) near UCST acted as a smart “gating” to regulate both pore size and surface properties of the membrane. When the temperature exceeded UCST, the fully extended polymer chains provided a strong washing force to remove contaminants, resulting in effective self-cleaning performance (FRR up to 99.2 %). In particular, due to the presence of the boroxine network, the polymer chains were firmly “stuck” on the membrane surface, providing stable performance and superior repeatability of the composite membrane.

Synergistically regulating the separator pore structure and surface property toward dendrite-free and high-performance aqueous zinc-ion batteries

As an emerging electrochemical device, aqueous zinc-ion batteries (ZIBs) present promising potential in safe and large-scale energy storage. However, the large pores of commercial glass fiber (GF) separators result in uneven Zn2+ ion flux, leading to severe dendrite growth issues of Zn metal anodes. Herein, we integrated a multifunctional layer on the GF separator that can synergistically regulate the pore feature and surface property of commercial GF separators. Such modification layer, composed of nanocellulose and SiO2 nanoparticles, exhibited uniform nanoporous structure and abundant negatively charged polar functional groups. These features allow regulating the distribution of Zn2+ ions at the separator-anode interface, facilitating stable and uniform Zn nucleation and growth. Moreover, the electrostatic interaction between the negatively charged functional groups and Zn2+ ions enhanced the Zn2+ ion transport kinetics, preventing the Zn dendrites formation and adverse reactions. Consequently, the modified electrolyte-filled GF separator showed an increased Zn2+ ion transference number of 0.65. The symmetric Zn//Zn batteries utilizing such a separator achieved an impressive cycling life of 500 h at a high current density/capacity of 10 mA cm−2/4 mAh cm−2, nearly nine times longer than the battery using the unmodified GF separator (<55 h). The superior electrochemical performance was verified in both Zn//AC and Zn//LiMn2O4 full battery evaluations. This work presents a novel synergistic modification strategy for developing advanced separators for aqueous ZIBs.

Controllable Preparation of a N-Doped Hierarchical Porous Carbon Framework Derived from ZIF-8 for Highly Efficient Capacitive Deionization.

Capacitive deionization (CDI) is a promising desalination technology, and metal-organic framework (MOF)-derived carbon as an electrode material has received more and more attention due to its designable structure. However, MOF-derived carbon materials with single-pore structures have been difficult to meet the technical needs of related fields. In this work, the ordered hierarchical porous carbon framework (OMCF) was prepared by the template method using zeolitic imidazolate frameworks-8 (ZIF-8) as a precursor. The pore structures, surface properties, electrochemical properties, and CDI performances of the OMCF were investigated and compared with the microporous carbon framework (MCF), also derived from ZIF-8. The results show that the hierarchical porous carbon OMCF possessed a higher specific surface area, better hydrophilic surface (with a contact angle of 13.45°), and higher specific capacitance and ion diffusion rate than those of the MCF, which made the OMCF exhibit excellent CDI performances. The adsorption capacity and salt adsorption rate of the OMCF in a 500 mg·L-1 NaCl solution at 1.2 V and a 20 mL·min-1 flow rate were 12.17 mg·g-1 and 3.34 mg·g-1·min-1, respectively, higher than those of the MCF. The deionization processes of the OMCF and MCF closely follow the pseudo-first-order kinetics, indicating the double-layer capacitance control. This work serves as a valuable reference for the CDI application of N-doped hierarchical porous carbon derived from MOFs.

Non‐Faraday Electrolyte Additives for Capacitance Boosting by Compression of Dielectric Layer Thickness: Organic Ferroelectric Salts

AbstractCarbon‐based supercapacitors are one of the most widely used commercial products. Organic electrolyte systems, such as tetraethylammonium tetrafluoroborate/acetonitrile (TEABF4/ACN), remain dominant after decades of development due to cost and performance advantages. However, improving the capacitance of existing carbon‐electrolyte systems not by altering the pore structure and surface properties of activated carbon is full of challenges. Herein, a non‐Faraday organic ferroelectric salt additive (diisopropylamine perchlorate, DIPAP) that can significantly increase capacitance from the standpoint of electrolyte dielectric modulation is proposed for the first time. Compared to counter ions, DIPA+ plays a vital role in capacity enhancement, in which electron‐rich N‐doped mesoporous carbon can greatly boost capacity by promoting local ion mobility. In situ Raman and theoretical studies show that small‐size DIPA+ can enter the pore and be enriched closer to electrode surfaces than TEA+ and ACN, allowing it to regulate the distribution of electric double‐layer species and dielectric properties (i.e., effective thickness of dielectric and/or relative dielectric constant), increasing capacity by up to 21.6–45.8% with only 1 wt% DIPAP while maintaining desired rate performances. The understanding of the mechanism of capacitance increase by such additives opens up new avenues for further extension of the commercialized carbon electrode‐organic electrolyte system's potential.

Plasma-Synthesis of MOF-Derived Nanoporous Copper Oxides for Solar Thermal Application

Nanoporous Metal oxides (P-MOx) have attracted great attention because of their enhanced performances in e.g., energy storage, catalysis, sensors, solar technology, and biomedicine due to large surface area coupled with good thermal and chemical stability. Existing synthesis techniques of P-MOx suffer from major drawbacks such as longer time and limitation in material choices. Plasma assisted synthesis of metal organic framework (MOF) derived P-MOx can be a rapid and sustainable one-step process and allow a higher degree of flexibility in controlling porosity, pore size distribution and surface properties. Herein, synthesis of nanoporous copper oxides (P-CuOx) was carried out by plasma treating copper-based MOF as a precursor. A systematic study of the transformation of MOF to derived P-CuOx has been carried out by varying the plasma treatment time also the formation of different phases of CuO and Cu2O was investigated. Additionally, a comparative study of properties was done between the plasma-synthesised P-CuOx and pyrolytically synthesised P-CuOx. Transformation process of MOF to P-CuOx was studied using x-ray diffraction (XRD) and Raman analysis. Moreover, morphological properties were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Finally detail optical characterization and solar thermal conversion properties of P-CuOx based nanofluid were studied to test its applicability in solar thermal energy harvesting.

Evolution of the porous structure for phosphoric acid etching carbon as cathodes in Li–O2 batteries: Pyrolysis temperature‐induced characteristics changes

AbstractAlthough biomass‐derived carbon (biochar) has been widely used in the energy field, the relation between the carbonization condition and the physical/chemical property of the product remains elusive. Here, we revealed the carbonization condition's effect on the morphology, surface property, and electrochemical performance of the obtained carbon. An open slit pore structure with shower‐puff‐like nanoparticles can be obtained by finely tuning the carbonization temperature, and its unique pore structure and surface properties enable the Li–O2 battery with cycling longevity (221 cycles with 99.8% Coulombic efficiency at 0.2 mA cm−2 and controlled discharge–charge depths of 500 mAh g−1) and high capacity (16,334 mAh g−1 at 0.02 mA cm−2). This work provides a greater understanding of the mechanism of the biochar carbonization procedure under various pyrolysis conditions, paving the way for future study of energy storage devices.

Characterizing water vapor adsorption on coal by nuclear magnetic resonance: Influence of coal pore structure and surface properties

Steam injection is a novel and promising technology for enhancing coalbed methane (CBM) recovery. Accurate descriptions of the migration and adsorption of water vapor on coal is crucial for determining the occurrence state of the CBM and improving CBM production. This study quantitatively characterized the dynamic transport and adsorption processes of water vapor in coal pores and fractures using nuclear magnetic resonance (NMR). The results demonstrated that water vapor was preferentially adsorbed in the coal micropores, which was mainly related to capillary condensation, whereas liquid water filled a wide range of pores and fractures. Due to the differences in the microstructure and surface properties among different coals, the water vapor adsorption behaviors varied significantly. Among the coals used in this study, water vapor was most easily adsorbed on the bitumite with the biggest specific surface area, pore volume, pore area, the highest content of oxygen-containing functional groups, and the strongest wettability. Additionally, the coal pore structure had a greater impact on the water vapor adsorption capacity than the oxygen functional groups and the wettability. This research is of great significance for understanding the flow behaviors of water vapor in porous media and the interactions between coal and water.

A new strategy to achieve the recycling of plastic waste by catalysis under mild conditions

It is extremely difficult to break cross-linked structures of plastic, causing that conditions of recycling wastes plastic usually were rigorous by traditional chemical methods. The high temperature and high pressure conditions lead to waste of energy, pollution of environment, and costly. A novel plastics conversion into the adsorbent or catalyst precursor at ambient temperature and pressure is surveyed. Polyester plastics' low-temperature-driven HCl catalysis conversion achieves effective control of the pore structure and surface properties, and the specific surface area increased by 563%. In addition, the well-optimized polyester using H2SO4 catalytic optimization increased the NH3 adsorption capacity by 105 times, which was higher than that of most reported activated carbon NH3 adsorbents due to the formation of porous structure and numerous interaction sites (e.g., −SO3H), and confinement effects in the polyester. These results provide a new route of plastic recycling as an adsorbent or catalyst precursor.

Effect of co-pyrolysis of sewage sludge with different plastics on the nitrogen, sulfur, and chlorine releasing characteristics and the heavy metals ecological risk of biochar

The high calorific value, low ash content and high volatility of the plastic can compensate for the deficiencies of the single pyrolysis of sewage sludge (SS), and these properties can improve the quality of the pyrolysis product. However, secondary contaminants may be generated during the co-pyrolysis of sludge and plastics. Plastics contain polluting elements that may also enter sludge, so different plastics may affect the release of N, S, and Cl as well as the ecological risk of heavy metals. In this study, polypropylene (PP), polyamide 6 (PA6) and polyvinyl chloride (PVC) were added to sludge to analyze the release of N, S and Cl from sludge pyrolysis products by different plastics. An environmental risk assessment was also conducted to evaluate the various forms of heavy metals. The results showed that PP, PA6, and PVC increased the total mass losses of sludge by 16.88%, 6.82% and 9.46%, respectively, inhibiting the release of NH3, CH3Cl, H2S and SO2 harmful gases from sludge. PP and PA6 increased the calorific value of pyrolysis oil and released more aliphatic hydrocarbons and alcohols. However, PA6 and PVC will increase the release of HCN and HCl, respectively. The presence of plastics enhanced the carbon structure of biochar, with PP and PA6 particularly enriching the pore structure and surface properties of biochar. PA6 and PVC reduced the potential ecological risk of biochar. These results will provide new insights into the co-pyrolysis of sludge and plastics.

Tuning the Trade-Off between Ethane/Ethylene Selectivity and Adsorption Capacity within Isoreticular Microporous Metal-Organic Frameworks by Linker Fine-Fluorination.

The pore dimension and surface property directly dictate the transport of guests, endowing diverse gas selective adsorptions to porous materials. It is highly relevant to construct metal-organic frameworks (MOFs) with designable functional groups that can achieve feasible pore regulation to improve their separation performances. However, the role of functionalization in different positions or degrees within framework on the separation of light hydrocarbon has rarely been emphasized. In this context, four isoreticular MOFs (TKL-104-107) bearing dissimilar fluorination are rationally screened out and afforded intriguing differences in the adsorption behavior of C2 H6 and C2 H4 . Ortho-fluoridation of carboxyl allows TKL-105-107 to exhibit enhanced structural stabilities, impressive C2 H6 adsorption capacities (>125 cm3 g-1 ) and desirable inverse selectivities (C2 H6 over C2 H4 ). The more modified ortho-fluorine group and meta-fluorine group of carboxyl have improved the C2 H6 /C2 H4 selectivity and adsorption capacity, respectively, and the C2 H6 /C2 H4 separation potential can be well optimized via linker fine-fluorination. Meanwhile, dynamic breakthrough experiments proved that TKL-105-107 can be used as highly efficient C2 H6 -selective adsorbents for C2 H4 purification. This work highlights that the purposeful functionalization of pore surfaces facilitates the assembly of highly efficient MOF adsorbents for specific gas separation.

Porous Cu-based metal organic framework (Cu-MOF) for highly selective adsorption of organic pollutants

In this study, copper based metal organic frame work (Cu-MOF) was synthesized by using different solvents i. e. H2O, Dimethylformamide (DMF) and DMF ​+ ​C2H5OH ​+ ​H2O solutions at various temperatures. Cu-MOF synthesized in different solvents exhibited a large number of properties and advantages including easy synthesis procedure, high porosity, good crystallinity, high surface area, massive pore volume, controllable pore surface properties (zeta potential), rigid and chemical stability. The as-synthesized Cu- MOF was analysed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area, zeta potential, electrostatic attraction and Thermal gravimetric analysis (TGA). A higher BET surface area of 121.1 ​m2 ​g−1 was obtained for Cu-MOF synthesized in DMF ​+ ​C2H5OH ​+ ​H2O compared with H2O (109.3 ​m2 ​g−1) and DMF (115.1 ​m2 ​g−1) solvents. The as-obtained Cu-MOF was used to investigate adsorption kinetic performances of methylene blue (MB) and methyl orange (MO) dye molecules. Compared with other samples, Cu-MOF synthesized in (DMF ​+ ​C2H5OH ​+ ​H2O) has a significantly enhanced adsorption ability for MB but a lower for MO dyes. After 4 ​min, the adsorption co-efficient (k) values were calculated to be 0.506, 0.846 and 1.1915 min−1 for MB and 0.029, 0.024 and 0.005 min−1 for MO dyes for Cu-MOF (H2O), Cu-MOF (DMF) and Cu-MOF (DMF ​+ ​C2H5OH ​+ ​H2O), respectively. It was found that Cu-MOF has a higher adsorption for MB dye but a poor adsorption capacity for MO, which was attributed to the electrostatic attraction/repulsion phenomena. Moreover, compared with Cu-MOF (DMF) and Cu-MOF (H2O), Cu-MOF (DMF ​+ ​C2H5OH ​+ ​H2O) shows an improved stability at 370, 417 and 423 ​°C temperatures. The result obtained through experiment suggested that porous Cu-MOF microstructures synthesized in DMF ​+ ​C2H5OH ​+ ​H2O have potential application for the treatment wastewaters having MB and MO dyes.

Fabrication of Nanoparticle‐Doped Polyvinyl Alcohol‐Cellulose Acetate Membrane and Characterization of the Surface Enhancement

AbstractIn the present study, nanocomposite polymeric membranes are fabricated using polyvinyl alcohol (PVA), cellulose acetate (CA) as polymers, and dimethyl sulfoxide (DMSO) as the solvent. To enhance the performance of the membrane, nanoparticles like TiO2, CaO, CdO, and ZrO are added to the polymeric solution and the doped polymeric solution is cast on a glass plate. Nine combinations of membranes are fabricated with two different concentrations (0.1% and 0.2%) of nanoparticles. The basic properties of the membranes such as density, porosity, viscosity, permeability, pure water flux, and water content are studied for the samples. Membrane pore structure and surface properties are identified and it is found that doping nanoparticles on the surface of membranes improve mechanical strength, stability, pore size, etc., allowing the membranes to perform better in extreme industrial‐level effluent treatment applications. High‐resolution scanning electron microscopy (SEM) shows the homogeneous dispersion of ZrO, TiO2, CaO, and CdO nanoparticles on the surface of the PVA‐CA membrane. The doping of nanoparticles on the PVA‐CA membrane results in improved mechanical strength and good chemical oxidation stability. In comparison, the PCD‐TiO2 sample shows high thermal stability and oxidation stability at high temperatures until 200°C, which has a high potential for treating industrial effluents.

Bottom-Up Synthesis of De-Functionalized and Dispersible Carbon Spheres as Colloidal Adsorbent

Recent innovative adsorption technologies for water purification rely on micrometer-sized activated carbon (AC) for ultrafast adsorption or in situ remediation. In this study, the bottom-up synthesis of tailored activated carbon spheres (aCS) from sucrose as renewable feedstock is demonstrated. The synthesis is based on a hydrothermal carbonization step followed by a targeted thermal activation of the raw material. This preserves its excellent colloid properties, i.e., narrow particle size distribution around 1 µm, ideal spherical shape and excellent aqueous dispersibility. We investigated the ageing of the freshly synthesized, highly de-functionalized AC surface in air and aqueous media under conditions relevant to the practice. A slow but significant ageing due to hydrolysis and oxidation reactions was observed for all carbon samples, leading to an increase of the oxygen contents with storage time. In this study, a tailored aCS product was generated within a single pyrolysis step with 3 vol.-% H2O in N2 in order to obtain the desired pore diameters and surface properties. Adsorption characteristics, including sorption isotherms and kinetics, were investigated with monochlorobenzene (MCB) and perfluorooctanoic acid (PFOA) as adsorbates. The product showed high sorption affinities up to log (KD/[L/kg]) of 7.3 ± 0.1 for MCB and 6.2 ± 0.1 for PFOA, respectively.

Carbonaceous electrode materials for supercapacitor: Preparation and surface functionalization

Supercapacitors became more and more important recently in the area of energy storage and conversion. Their large power deliveries abilities, high stability and environmental friendliness characteristics draw tremendous attention in high-power applications such as public transit networks. Carbonaceous materials with unique surface and electrochemical properties were widely used in supercapacitors as electrode materials. This review focuses on the developments in supercapacitor electrodes made from carbonaceous materials recently, their working principle and evaluation parameters were summarized briefly. The preparation methods and electrochemical properties of different carbonaceous materials were compared and classified. It was found that the surface situation (e.g., porous structure, hydrophilic) of carbonaceous materials strongly affect the electrochemical performances of supercapacitor. So far, active carbons would be the most applicable carbonaceous electrode materials owing to their good chemical stability and conductivity, extensive accessibility inexpensiveness. But their energy densities still fall behind practical demands. Both theoretical calculations and experimental studies show that surface modification and doping of carbonaceous materials can not only optimize their pore size, structure, conductivity and surface properties, but also can introduce extra pseudocapacitance into these materials. Considering global environmental pollution and energy shortage problems nowadays, we sincerely suggested that future work should focus on domestic, medical and industrial wastes residues derived carbonaceous materials and scaled production process such as reactors and exhaust gas treatment.

Oxygen-enriched hierarchical porous carbons derived from lignite for high-performance supercapacitors

Functional coal-based carbon materials with reasonable pore structure and surface properties have attracted extensive attention for use in high-performance supercapacitors. Herein, a ball milling-assisted bimetallic salt catalytic pyrolysis strategy was developed to prepare oxygen-doped hierarchical porous carbon (OHPC) derived from lignite. The optimized OHPC-1 shows a large specific surface area (1638 m2/g), rational pore structure distribution (mesopores account for 71.3%), and suitable oxygen doping, which ensure sufficient charge storage, rapid electrolyte ions diffusion, as well as the contributed pseudocapacitance. The obtained OHPC-1 exhibits a high specific capacitance of 283 F/g at 0.5 A/g in 6.0 M KOH electrolyte (operating voltage 1.2 V). The assembled OHPC-1//OHPC-1 symmetrical capacitor delivers a high energy density of 16.5 Wh/kg at the power density of 300 W/kg with long cycling stability. In sum, the proposed facile route for high-value utilization of lignite looks promising for the preparation of cost-effective porous carbons for high-performance supercapacitors.

Advanced stimuli-responsive membranes for smart separation.

Membranes have been extensively studied and applied in various fields owing to their high energy efficiency and small environmental impact. Further conferring membranes with stimuli responsiveness can allow them to dynamically tune their pore structure and/or surface properties for efficient separation performance. This review summarizes and discusses important developments and achievements in stimuli-responsive membranes. The most commonly utilized stimuli, including light, pH, temperature, ions, and electric and magnetic fields, are discussed in detail. Special attention is given to stimuli-responsive control of membrane pore structure (pore size and porosity/connectivity) and surface properties (wettability, surface topology, and surface charge), from the perspective of determining the appropriate membrane properties and microstructures. This review also focuses on strategies to prepare stimuli-responsive membranes, including blending, casting, polymerization, self-assembly, and electrospinning. Smart applications for separations are also reviewed as well as a discussion of remaining challenges and future prospects in this exciting field. This review offers critical insights for the membrane and broader materials science communities regarding the on-demand and dynamic control of membrane structures and properties. We hope that this review will inspire the design of novel stimuli-responsive membranes to promote sustainable development and make progress toward commercialization.

Shale Formation Damage during Fracturing Fluid Imbibition and Flowback Process Considering Adsorbed Methane

Hydraulic fracturing of shale gas reservoirs is characterized by large fracturing fluid consumption, long working cycle and low flowback efficiency. Huge amounts of fracturing fluid retained in shale reservoirs for a long time would definitely cause formation damage and reduce the gas production efficiency. In this work, a pressure decay method was conducted in order to measure the amount of fracturing fluid imbibition and sample permeability under the conditions of formation temperature, pressure and adsorbed methane in real time. Experimental results show that (1) the mass of imbibed fracturing fluid per unit mass of shale sample is 0.00021–0.00439 g/g considering the in-situ pressure, temperature and adsorbed methane. (2) The imbibition and flowback behavior of fracturing fluid are affected by the imbibition or flowback pressure difference, pore structure, pore surface properties, mechanical properties of shale and mineral contents. (3) 0.01 mD and 0.001 mD are the critical initial permeability of shales, which could be used to determine the relationship between the formation damage degree and the flowback pressure difference. This work is beneficial for a real experimental evaluation of shale formation damage induced by fracturing fluid.

Differential effects of pore structure of mineral and maceral components on the methane adsorption capacity evolution of the lower jurassic Da'anzhai member of the Ziliujing Formation lacustrine shale, Sichuan Basin, China

Adsorbed gas makes a great contribution to shale gas reserves. During the geological evolution process, it is of prominent significance to clarify the dynamic evolution mechanism of methane adsorption capacity (MAC) of shale to enhance exploration. Variations of the pore structure and surface properties of shales lead to their different MAC. However, the pore structure characteristics and the evolution mechanism of different maceral and mineral components is different. The co-evolution modes and influence mechanism on the MAC of shale remains poorly understood. Therefore, in order to investigate the influential relationship between pore structure evolution and MAC of shales, methane adsorption experiments were conducted on a series of shale samples with the same composition at different thermal maturities. In addition, the original components of the shale sample were analyzed by measuring total organic carbon (TOC) content and mineral composition. Pore structures of the four shale samples were characterized by N2 adsorption, high-pressure mercury intrusion porosimetry (HPMIP), and digital analyses of field-emission scanning electron microscopy (FE-SEM). The results showed a good correlation between the APpore (apparent porosity of pore) of organic pores with the size ranging from 10 to 30 nm and MAC (R2 = 0.943), confirming the prominent influence of organic pores on the MAC of shale. In addition, the APpore of pores within 10–30 nm and aspect ratio of secondary organic matter with spongy pores are highly correlated with MAC (R2 are 0.833 and 0.811, respectively), which suggests that secondary organic matter with spongy pores have a crucial influence on MAC. Clay mineral pores with a pore size of 10–30 nm also effect the MAC of shale. A large number of clay mineral microfractures, with a scale of less than 200 nm, appear to effectively connect organic pores, providing a viable mechanism for hydrocarbon migration and enhancing the MAC of shale. Siliceous mineral dissolution pores and microfractures are not conducive to hydrocarbon migration due to their inability to form effective connections with organic pores and fractures and showing a weak correlation with MAC. The outcome of this study elucidates the main controlling mechanism affecting methane adsorption behavior of continental shale reservoirs and provides a path for the efficient exploration and evaluation of shale gas under actual geological conditions.

A new method for tailoring the surface pore size and internal pore structure of ultrafiltration membranes without using additives—Atomization-assisted nonsolvent induced phase separation method

It is highly desired to improve the safety and stability of ultrafiltration (UF) membranes for biotechnology, medicine and food processing by eliminating the use of chemical additives during the membrane preparation process. In this work, a series of high-performance polyacrylonitrile (PAN) UF membranes were prepared continuously by the atomization-assisted nonsolvent induced phase separation (AA-NIPS) method. The pore structure and surface properties of the membranes can be precisely tailored, requiring no chemical additives. The prepared UF membranes are composed of a sublayer of highly interconnected three-dimensional (3D) network structure and a smooth surface layer of uniform small pore structure with a narrow pore size distribution. Compared to UF membranes prepared by the NIPS method, the PAN UF membranes exhibit enhanced water flux and antifouling properties as well as a well-preserved high rejection to bovine serum albumin (BSA). With different atomization pretreatment times, the pure water fluxes of the UF membranes increased by 41 %∼100 %. The AA-NIPS method employed in the present work can effectively modify the porous structure of the membranes without introducing pore-forming additives. The good separation performance, structural controllability, and easy functionalization of the UF membranes make them a promising candidate to be applied in many fields, especially in biotechnology, medicine, and food processing.

Adsorption of brilliant green dye by used-tea-powder: equilibrium, kinetics and thermodynamics studies

Abstract The present research is based on the removal of Brilliant Green (BG) dye from its aqueous solution. Used-tea-powder (UTP) was used as a potential adsorbent to remove BG from aqueous solution. Pore morphology, surface properties, crystalline nature and thermal stability of UTP were assessed by using SEM, FTIR, XRD and TGA analysis. The optimized working conditions were found to be pH 6, UTP dose 100 mg, adsorption time 60 min and BG concentration 100 mg L−1. The qmax obtained from the Langmuir model was 101.01 mg g−1 showing the utility of UTP in dye removal. The breakthrough volume and efficiency of the column were evaluated through column adsorption studies in fixed-bed mode. It was found that the pseudo-second-order kinetics model was followed as evaluated by the correlation studies. The calculated thermodynamic parameters showed that the adsorption process was feasible, exothermic and spontaneous.