An Ultramicroporous Graphene-Based 3D Structure Derived from Cellulose-Based Biomass for High-Performance CO2 Capture.

The use of powered activated carbon is often limited by inconsistent particle sizes and porosities, leading to reduced adsorption efficiencies. In this study, we demonstrated a practical and environmentally friendly method for creating a 3D graphene nanostructure with highly uniform ultramicropores from wood-based biomass through a series of delignification, carbonization, and activation processes. In addition, we evaluated the capture characteristics of this structure for CO2, CH4, and N2 gases as well as its selectivity for binary-mixture gases. Based on textural and chemical analyses, the delignified monolith had a lamellar structure interconnected by cellulose-based fibers. Interestingly, applying the KOH vapor activation technique solely to the delignified samples led to the formation of a monolithic 3D network composed of interconnected graphene sheets with a high degree of crystallinity. Especially, the Act. 1000 sample exhibited a specific surface area of 1480 m2/g and a considerable pore volume of 0.581 cm3/g, featuring consistently uniform ultramicropores over 90% in the range of 3.5-11 Å. The monolithic graphene-based samples, predominantly composed of ultramicropores, demonstrated a notably heightened capture capacity of 6.934 mol/kg at 110 kPa for CO2, along with favorable selectivity within binary gas mixtures (CO2/N2, CO2/CH4, and CO2/CH4). Our findings suggest that this biomass-derived 3D structure has the potential to serve as a monolithic adsorbent in gas separation applications.

Sustained drug release behavior of captopril-incorporated chitosan/carboxymethyl cellulose biomaterials for antihypertensive therapy.

Captopril (CTP) is an oral drug widely used to treat high blood pressure and congestive heart failure. In this study, CTP-incorporated biomaterials for antihypertensive therapy were synthesized from chitosan, carboxymethyl cellulose, and plasticizers. The physicochemical properties of the prepared biomaterials were characterized using FE-SEM, FT-IR analysis, and physical properties. CTP release experiments were carried out in buffer solutions at various pH values and temperatures. Results indicated that above 99.0 % of CTP was released within 180 min. Optimization of the experimental conditions for CTP release was analyzed by using response surface methodology (RSM). Results of CTP release through artificial skin indicated that CTP was continuously released above 95.0 % from the prepared biomaterials for 36.0 h. The CTP release mechanisms into a buffer and through artificial skin followed pseudo-Fickian diffusion mechanism and non-Fickian diffusion mechanisms, respectively. Moreover, angiotensin-converting enzyme (ACE) inhibition (related to cardiovascular disease) via the released CTP clearly reveals that the prepared biomaterials have a high potential as a transdermal drug delivery agent in antihypertensive therapy.

Hierarchically Porous Carbon Networks Derived from Chitosan for High-Performance Electrochemical Double-Layer Capacitors.

Activated carbon (AC) compounds derived from biomass precursors have garnered significant attention as electrode materials in electric double-layer capacitors (EDLCs) due to their ready availability, cost-effectiveness, and potential for mass production. However, the accessibility of their active sites in electrochemistry has not been investigated in detail. In this study, we synthesized two novel macro/micro-porous carbon structures prepared from a chitosan precursor using an acid/potassium hydroxide activation process and then examined the relationship between their textural characteristics and capacitance as EDLCs. The material characterizations showed that the ACs, prepared through different activation processes, differed in porosity, with distinctive variations in particle shape. The sample activated at 800 °C (Act-chitosan) was characterized by plate-shaped particles, a specific surface area of 4128 m2/g, and a pore volume of 1.87 cm3/g. Assessment of the electrochemical characteristics of Act-chitosan showed its remarkable capacitance of 183.5 F/g at a scan rate of 5 mV/s, and it maintained exceptional cyclic stability even after 10,000 cycles. The improved electrochemical performance of both chitosan-derived carbon structures could thus be attributed to their large, well-developed active sites within pores < 2 nm, despite the fact that interconnected macro-porous particles can enhance ion accessibility on electrodes. Our findings provide a basis for the fabrication of biomass-based materials with promising applications in electrochemical energy storage systems.

Acetaldehyde Adsorption Characteristics of Ag/ACF Composite Prepared by Liquid Phase Plasma Method.

Ag particles were precipitated on an activated carbon fiber (ACF) surface using a liquid phase plasma (LPP) method to prepare a Ag/ACF composite. The efficiency was examined by applying it as an adsorbent in the acetaldehyde adsorption experiment. Field-emission scanning electron microscopy and energy-dispersive X-ray spectrometry confirmed that Ag particles were distributed uniformly on an ACF surface. X-ray diffraction and X-ray photoelectron spectroscopy confirmed that metallic silver (Ag0) and silver oxide (Ag2O) precipitated simultaneously on the ACF surface. Although the precipitated Ag particles blocked the pores of the ACF, the specific surface area of the Ag/ACF composite material decreased, but the adsorption capacity of acetaldehyde was improved. The AA adsorption of ACF and Ag/ACF composites performed in this study was suitable for the Dose-Response model.

Boosting Photovoltaic Performance in Organic Solar Cells by Manipulating the Size of MoS2 Quantum Dots as a Hole-Transport Material.

The design of photoactive materials and interface engineering between organic/inorganic layers play a critical role in achieving enhanced performance in energy-harvesting devices. Two-dimensional transitional dichalcogenides (TMDs) with excellent optical and electronic properties are promising candidates in this regard. In this study, we demonstrate the fabrication of size-controlled MoS2 quantum dots (QDs) and present fundamental studies of their optical properties and their application as a hole-transport layer (HTL) in organic solar cells (OSCs). Optical and structural analyses reveal that the as-prepared MoS2 QDs show a fluorescence mechanism with respect to the quantum confinement effect and intrinsic/extrinsic states. Moreover, when incorporated into a photovoltaic device, the MoS2 QDs exhibit a significantly enhanced performance (5/10-nanometer QDs: 8.30%/7.80% for PTB7 and 10.40%/10.17% for PTB7-Th, respectively) compared to those of the reference device (7.24% for PTB7 and 9.49% for PTB7-Th). We confirm that the MoS2 QDs clearly offer enhanced transport characteristics ascribed to higher hole-mobility and smoother root mean square (Rq) as a hole-extraction material. This approach can enable significant advances and facilitate a new avenue for realizing high-performance optoelectronic devices.

Ti3C2Tx MXene-Based Three-Dimensional Architecture for Carbon Dioxide Capture.

Dramatic increases in fossil fuel consumption inevitably led to the emission of huge amounts of CO2 gas, causing abnormalities in the climate system. Despite continuous efforts to resolve global atmospheric problems through CO2 capture and separation, success has been limited by poor CO2 selectivity in the CO2/N2 mixture. Herein, we demonstrate the fabrication of a three-dimensional (3D) nanostructure from two-dimensional transition metal carbides (Ti3C2Tx, MXene), and assess its utility as an adsorbent in a CO2 capture system. Through structural and textural analysis, we confirm that the as-prepared MXene possesses high size uniformity with a thickness of ~2.5 nm, and that an MXene aerogel interconnected by MXene nanosheets has a 3D porous architecture with micro/nano porosity (Barrett-Joyner-Halenda (BJH) pore size = 11.4 nm). Moreover, the MXene aerogel exhibits favorable adsorption behavior for CO2, due to the high-quality MXene nanosheets even with a low specific surface area. Our approach could lead to significant advances in CO2 capture by adsorbents and open up new opportunities for mass production.

Recovering Nutrients from Waste Black Water Through Multi-Functional Mesoporous Silica.

In order to prevent the harmful effects in water phase such as eutrophication, industrial and urban sewages must be treated before discharging into the aquatic environment. In this work, amine grafted magnetic nanoporous silica materials are synthesized and applied as an adsorbent for the recovery of nutrients from waste black water. The magnetic force could separate the surface func-tionalized nanoporous silica materials from aqueous medium after treatment, and showed the higher adsorption capacity of nutrients than that of the original mesoporous silica. The multi-functional nanoporous silica adsorbents were effectively removed phosphate and nitrate at 20 °C with the maximum adsorption capacities of 42.5 and 34.9 mg/g, respectively. The overall results indicated that the synthesized multi-functional nanoporous silica sorbents can be a candidate material for the nutrient recovery in wastewater treatment system.

Synthesis and Characteristic Properties of Crosslinked Chitosan with Epichlorohydrin for Nitrate Removal from Water.

In this study, we prepared chitosan beads cross-linked with epichlorohydrin (CB-ECH) to improve the removal of nitrate in groundwater. It was confirmed that CB-ECH exhibited higher thermal stability and well-developed nano-pores compared to the pure chitosan beads (CB) by the thermogravimetric analyzer, nitrogen gas adsorption and desorption isotherm, and field emission scanning microscopy analysis. The CB-ECH showed a higher nitrate adsorption amount than the pure CB. Nitrate adsorption behaviors of CB-ECH were further investigated using adsorption isotherm, adsorption kinetics, adsorption energy distribution, and Gibbs free energy distribution models. The adsorption equilibrium and kinetics of nitrate ion on CB-ECH were well explained by the Sips isotherm and homogeneous surface diffusion model, respectively. It was also found from the AED analysis that the CB-ECH represent the heterogeneous adsorption behaviors for nitrate.

Preparation and evaluation of functional allopurinol imprinted starch based biomaterials for transdermal drug delivery.

This study focuses on the synthesis of functional allopurinol (ALP) imprinted biomaterials for a transdermal drug delivery using mung bean starch (MBS), polyvinyl alcohol (PVA), sodium benzoate (SB) as a crosslinking agent, and poloxamer (PX) as a thermo-sensitive polymer. Prepared functional biomaterials were characterized and evaluated by SEM, FT-IR analysis, and physical properties. Results of ALP recognition properties indicated that adsorbed amounts (Q) of ALP on functional ALP imprinted biomaterials were 3.8 to 4.9-fold higher than that of non-ALP imprinted biomaterial. Results of ALP release revealed that the ALP release rate for PX added biomaterials was 1.10 (36.5 °C) or 1.30 (45 °C) times faster than that at 25 °C. These results indicate that functional ALP imprinted biomaterials have thermo-sensitive properties due to the addition of PX. Results of ALP release using artificial skin indicated that ALP release was increased at a relatively steady-state rate for 3 h and that the ALP release behavior followed the non-Fickian diffusion mechanism.

Preparation and release properties of arbutin imprinted inulin/polyvinyl alcohol biomaterials.

The main objective of this work was to prepare inulin (INL)/polyvinyl alcohol (PVA) biomaterials imprinted with arbutin (AR) as the target drug. INL from Jerusalem artichoke flour was extracted with hot water extraction method. INL/PVA biomaterials were synthesized with a casting method and a UV curing. The optimal UV curing time and sodium benzoate content were about 10 min and 0.1 wt%, respectively. The biomaterials were characterized by SEM and FT-IR analysis. Mechanical properties of prepared AR imprinted biomaterials were also investigated. AR release was examined with changes of pH at 36.5 °C. The AR release ratio was also investigated using artificial skin. It was found that AR was released constantly for 40 min. Results of drug release mechanism indicated that AR release followed the Fickian diffusion behavior, whereas drug release using artificial skin followed the non-Fickian diffusion behavior. Tyrosinase inhibitory (%) for AR imprinted biomaterials with/without the addition of GL were 58.8% and 79.2%, respectively.

Complete Oxidation of Volatile Organic Compounds Over Spent Vanadium-Based Catalyst.

The catalytic oxidation of benzene and toluene (VOCs) was carried out in order to assess the properties and catalytic activities of spent vanadium-based catalyst and that modified with copper and manganese. The properties of the prepared catalysts were characterized by the Brunauer Emmett Teller (BET) surface area method as well as X-ray diffraction (XRD), Attenuated total reflection-Fourier transform infrared (ATR-FTIR), and Scanning electron microscopy-Energy dispersive X-ray (SEM-EDX) analyses. The experimental results showed that oxalic acid treatment significantly affected the activity of the spent vanadium-based catalyst, ultimately attributing to the removal of catalyst poison such as sulfur and the even redistribution of catalyst components. Moreover, the addition of copper or manganese to the spent vanadium base catalyst treated with oxalic acid (SVO) enhanced its catalytic activity.

Preparation of Mesoporous Gamma Alumina Derived from Waste Can for Nutrient Recovery Process.

Mesoporous gamma alumina (MGA) was synthesized using aluminum trash containers by a low temperature hydrothermal method for effectively removing phosphate from wastewater. The effects of precursor concentrations in gel precipitation process over the pore size and surface area of MGA were investigated in detail. The phosphate removal by prepared MGAs were rigorously investigated through adsorption isotherms and kinetics of phosphate.

Synthesis of Walnut Shaped V2O3 Particles and Its Photocatalytic Activity for Methylene Blue Degradation Under Visible Light Irradiation.

In this study, walnut-shaped V2O3 particles with high photocatalytic activity in the visible light were synthesized by hydrothermal process. The V2O3 samples synthesized with the various temperature conditions of the hydrothermal process were characterized using XRD, SEM, TEM, UV-Visible spectrometer and N2gas adsorption/desorption analysis. For investigating the photocatalytic performance of synthesized V2O3 particles in the visible light condition, photodegradation experiments of methylene blue (MB) solution under artificial sunlight irradiation was conducted. As a result, the V2O3 hydrothermal-synthesized at 280 °C was composed of pure V2O3 crystal structure and showed high photocatalytic activity for the degradation of MB dye in visible light.

Radio-Frequency Thermal Plasma Treated Activated Carbon Impregnated with Mn and Ag for Volatile Organic Compounds Adsorption.

In this study, we have prepared a composite adsorbent with highly dispersed Mn and Ag nanocatalyst on the surface of activated carbon (AC) by applying the Radio-Frequency (RF) thermal plasma technique for the efficient removal of VOCs. The ACs before and after metal impregnation with RF plasma treatment were characterized by SEM, TEM, EDS, and nitrogen adsorption analysis. Adsorption behaviors of toluene, acetaldehyde, and formaldehyde on ACs before and after modification were also investigated in fixed-bed systems. The experimental adsorption results for VOCs on parent ACs and metal impregnated ACs (Mn-AC and Mn/Ag-AC) were well explained by modified continuous sigmoidal (MCS) model.

Enhanced Adsorptive Desulfurization Using Mongolian Anthracite-Based Activated Carbon.

This study reports usage of Mongolian anthracite-based porous activated carbons (PMACs), namely, PMAC 1/3 and PMAC 1/4 for model diesel fuel desulfurization, having 500 ppmw of dibenzothiophene (DBT) in n-heptane. Further, the effects of contact time, adsorbent dosage, and temperature on the adsorption capacity were studied systematically. The experimental adsorption isotherm results were well represented by the Sips isotherm for PMAC 1/3 and the dual site Langmuir isotherm for PMAC 1/4. The maximum DBT adsorption by PMAC 1/3 and PMAC 1/4 were 99.7 and 95.7%, respectively. The kinetics for the adsorption of DBT on PMACs follows the pseudo second order behavior. The Weber-Morris plot shows the multilinearity over the entire time range, suggesting that both the surface and pore diffusions control the adsorption. The values of boundary layer thickness for PMAC 1/4 and PMAC 1/3 were found to be 3.183 and 1.643, respectively. Thus, PMAC 1/4 possesses more surface diffusion control than PMAC 1/3. The changes in Gibbs free energy (ΔG°), entropy (ΔS°), and enthalpy (ΔH°) are negative, which confirms that the studied process is spontaneous and exothermic and possesses less randomness at the interface. Based on the Sips isotherm, single-stage batch-adsorber design was prepared for the adsorption of DBT onto PMAC 1/3.

Adsorption of Nitrate and Phosphate on Basalt Based Nanostructured Zeolite 13X.

In this work, we prepared basalt based nanostructured zeolite 13X by alkali fusion and hydrothermal synthesis process. The sample prepared was characterized using XRD, SEM, and low-temperature nitrogen analysis. The adsorption equilibrium and kinetic characteristics of ammonia nitrogen (NH+4-N) and phosphate phosphorus (PO3-4-P) were investigated. It was found that the basalt based nanostructured zeolite 13X showed high adsorption capacities for NH+4-N (75 mg/g) and PO3-4-P (25 mg/g) under the experimental conditions used. Our results demonstrate that basalt based zeolite 13X can be a good alternative adsorbent for the simultaneously removal of NH+4-N and PO3-4-P from aqueous solution.

Catalytic Performance of Supported Pd Catalyst Prepared with Different Palladium Precursors for Catalytic Combustion of BTH.

Catalytic combustion of benzene, toluene, and hexane (BTH) was carried out to investigate in this study the effect of palladium precursor on the property and performance of 1 wt.% Pd/γ-Al2O3. Properties were characterized by X-ray diffraction (XRD), Brunauer Emmett Teller (BET) surface area, temperature programmed reduction (TPR), Transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. When palladium precursor was used to prepare the catalyst, it had a great effect on the property and performance of the supported palladium catalyst. Total acidity, size of palladium particle, and oxidation state of palladium were associated with catalytic activity of the catalyst. Higher total acidity of the catalyst and larger particle size of palladium favorably affected the catalytic activity. In addition, palladium species with high oxidation state might be useful to increase catalytic activity in BTH combustion.

Modelling equilibrium adsorption of single, binary, and ternary combinations of Cu, Pb, and Zn onto granular activated carbon.

Elevated concentrations of heavy metals in water can be toxic to humans, animals, and aquatic organisms. A study was conducted on the removal of Cu, Pb, and Zn by a commonly used water treatment adsorbent, granular activated carbon (GAC), from three single, three binary (Cu-Pb, Cu-Zn, Pb-Zn), and one ternary (Cu-Pb-Zn) combination of metals. It also investigated seven mathematical models on their suitability to predict the metals adsorption capacities. Adsorption of Cu, Pb, and Zn increased with pH with an abrupt increase in adsorption at around pH 5.5, 4.5, and 6.0, respectively. At all pHs tested (2.5-7.0), the adsorption capacity followed the order Pb > Cu > Zn. The Langmuir and Sips models fitted better than the Freundlich model to the data in the single-metal system at pH 5. The Langmuir maximum adsorption capacities of Pb, Cu, and Zn (mmol/g) obtained from the model's fits were 0.142, 0.094, and 0.058, respectively. The adsorption capacities (mmol/g) for these metals at 0.01 mmol/L equilibrium liquid concentration were 0.130, 0.085, and 0.040, respectively. Ideal Adsorbed Solution (IAS)-Langmuir and IAS-Sips models fitted well to the binary and ternary metals adsorption data, whereas the Extended Langmuir and Extended Sips models' fits to the data were poor. The selectivity of adsorption followed the same order as the metals' capacities and affinities of adsorption in the single-metal systems.

Characterization of Pt-Based Catalyst by Consecutive Experiments of Toluene Oxidation.

Catalytic oxidation of toluene was carried out to investigate the effect of consecutive run on the catalytic property and performance of 1 wt.% Pt/γ-Al2O3 and the reduced 1 wt.% Pt/γ-Al2O3. The properties were characterized by X-ray diffraction (XRD), the Brunauer Emmett Teller (BET) surface area, temperature programmed reduction (TPR), and transmission electron microscopy (TEM) analyses. In consecutive experiments the second catalytic run resulted in a significant increase of the toluene conversion compared to the first catalytic run, but the toluene conversion in the third catalytic run was similar to that of the second catalytic run. In addition, the reducing treatment of the catalyst led to an increase in the catalytic activity. The increasing catalytic activity in consecutive runs was dependent on the platinum particle size and the oxidation state of the platinum. The increase in platinum particle size during reaction and the reduction in the oxidation state of platinum by hydrogen pretreatment were responsible for the increase in the catalytic activity.

Nanostructured Biomass Based Carbon Materials from Beer Lees for Hydrogen Storage.

The present work describes the preparation of carbon materials from beer lees and their hydrogen adsorption abilities. Activated carbons (ACs) from beer lees were prepared through chemical activation using potassium hydroxide as an activating agent. The low temperature nitrogen adsorption isotherm studies on prepared ACs were conducted at 77 K to determine their physical properties and adsorption energy distribution. The beer lees based carbons have energetically heterogeneous surfaces and high surface area ranging from 1927-2408 m2/g. ACs prepared in this study show the gravimetric hydrogen adsorption capacity of 2.43-2.92 wt% depending on their physical properties.