Surface Micropore Research Articles

Preparation and Characterization of Five Amino-Modified Hyper-Crosslinked Polymers and Performance Evaluation for Aged Transformer Oil Reclamation

Adsorption is intensively considered to be the most feasible and economical option for aged transformer oil treatment. In this work, five aminated hyper-crosslinked polymers were prepared from chloromethylated polystyrene–co-divinylbenzene (Cl-PS-DVB) through a two-stage modification of crosslinking and five different reagents aminating. After modification, the specific surface area (SBET) and nitrogen content (CN) of prepared resins were greatly improved. To evaluate the reclamation performance of resins for removing oxides and contaminants from aged transformer oils, the total acid number (TAN) and color of oils were mainly examined. The results shown that the prepared resins have superior oil reclamation capacity compared to commercial resin XAD-4 due to their higher microporous specific surface area (Smic) and surface polarity. Among them, the NHC-R3, which used dimethyltriamine (DETA) as an aminating agent, had the best deacidification and decolorization performance. A series of experiments were designed to investigate the optimal regeneration program conditions for NHC-R3, and the additional electrical characteristics of the reclaimed oil, including breakdown voltage, dielectric dissipation factor (DDF), and interfacial tension, were measured as evidence that aged oil was successfully reclaimed.

Pore evolution and reaction mechanism of coal under the combination of chemical activation and autothermal oxidation

Aiming at the limitation problems such as limited scope, high cost and energy consumption of coal bed penetration enhancement technology by traditional physical and chemical methods, a coal seam methane penetration enhancement method based on the combined action of chemical activation and auto thermal oxidation is proposed from the idea of utilizing the in-situ energy of the coal body. In this paper, N2 and CO2 adsorption, XPS and FTIR methods are used to study the pore structure evolution law and the change characteristics of the reactive structure of coal matrix under the effect of chemically activated autothermal oxidation. The synergistic microporous pore volume of chemical activation and auto thermal oxidation was 48.91 cm3/g−1 × 10-3, which was 28.96 % and 22.7 % higher than chemical activation and auto thermal oxidation respectively; The microporous specific surface area was 162.7 m2/g, which was 38 % and 26.6 % higher than chemical activation and auto thermal oxidation respectively. Activated coals expand and merge holes to a deeper degree after oxidative warming, and the complexity of the pore structure in the coal decreases; Highly reactive radicals in coal pores substantially promote the oxidation of coal structure, enhance the aromatic polymerization reaction of activated coal, and improve the maturity and aromaticity of activated coal, and the oxygen-containing functional groups in activated coal are negatively correlated with the oxidation temperature. The results of this study reveal the potential of the auto thermal oxidation-driven penetration enhancement method under chemical activation for coal seam gas penetration enhancement and extraction.

Surface phonon activation for broadband high emissivity via textured structure on TiO2 coating

In the pursuit of developing broadband high emissivity coatings for metallic radiation thermal protection, conventional approaches often involve complex photonic structures or the incorporation of transition metals and rare earth additives, which pose significant technological challenges and environmental concerns. Here, we present a straightforward and eco-friendly surface structuring strategy for creating a high emissivity TiO2 coating on titanium, eliminating the need for environmentally hazardous additives. By controlling surface micropore diameter to ∼6 um through soft-sparking discharge, we successfully engineered a textured surface that effectively mitigates the intrinsic emissivity dip of planar TiO2 at wavelengths with weak polarization extinction (3–8 µm) and strong polarization resonance (>12 µm). Finite-difference time-domain (FDTD) simulations highlighted the crucial role of micropores in confining the incident electric field, maximizing the absorption potential of surface phonon polaritons. This improvement yields an impressive emissivity of 0.83 across the thermal infrared spectrum. The coating also demonstrated robust resistance to oxidation and retained its high emissivity at elevated temperatures, presenting a promising solution for sustainability in spacecraft and electronic applications.

Preparation and Performance of a Novel Polyurethane Microporous Film on Polypropylene Medical Mesh Surface

This study aims to develop a medical patch surface material featuring a microporous polyurethane (PU) membrane and to assess the material's properties and biological performance. The goal is to enhance the clinical applicability of pelvic floor repair patch materials. PU films with a microporous surface were prepared using PU prepolymer foaming technology. The films were produced by optimizing the PU prepolymer isocyanate index (R value) and the relative humidity (RH) of the foaming environment. The surface morphology of the PU microporous films was observed by scanning electron microscopy, and the chemical properties of the PU microporous films, including hydrophilicity, were analyzed using infrared spectroscopy, Raman spectroscopy, and water contact angle measurements. In vitro evaluations included testing the effects of PU microporous film extracts on the proliferation of L929 mouse fibroblasts and observing the adhesion and morphology of these fibroblasts. Additionally, the effect of the PU microporous films on RAW264.7 mouse macrophages was studied. Immune response and tissue regeneration were assessed in vivo using Sprague Dawley (SD) rats. The PU films exhibited a well-defined and uniform microporous structure when the R value of PU prepolymer=1.5 and the foaming environment RH=70%. The chemical structure of the PU microporous films was not significantly altered compared to the PU films, with a significantly lower water contact angle ([55.7±1.5]° ) compared to PU films ([69.5±1.7]° ) and polypropylene (PP) ([ 104.3±2.5]°), indicating superior hydrophilicity. The extracts from PU microporous films demonstrated good in vitro biocompatibility, promoting the proliferation of L929 mouse fibroblasts. The surface morphology of the PU microporous films facilitated fibroblast adhesion and spreading. The films also inhibited the secretion of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β by RAW264.7 macrophages while enhancing IL-10 and IL-4 secretion. Compared to 24 hours, after 72 hours of culture, the expression levels of TNF-α and IL-1β were reduced in both the PU film and PU microporous film groups and were significantly lower than those in the PP film group (P<0.05), with the most notable decreases observed in the PU microporous film group. IL-10 and IL-4 levels increased significantly in the PU microporous film group, surpassing those in the PP film group (P<0.01), with the most pronounced increase in IL-4. The PU microporous film induced mild inflammation with no significant fibrous capsule formation in vivo. After 60 days of implantation, the film partially degraded, showing extensive collagen fiber growth and muscle formation in its central region. The PU microporous film exhibits good hydrophilicity and biocompatibility. Its surface morphology enhances cell adhesion, regulates the function of RAW264.7 macrophages, and promotes tissue repair, offering new insights for the design of pelvic floor repair and reconstruction patch materials.

Enhancing electrochemical properties of bacterial cellulose-derived carbon nanofibers through physical CO2 activation

Carbon nanofiber (CNF) derived from carbonization of bacterial cellulose (BC), with a unique three-dimensional porous nanostructure, has received significant interest in electrochemical applications. In this study, CNF samples were physically activated in CO2 at different temperatures and durations. Raman spectroscopy and FTIR analysis showed that CO2 activation caused hexagonal lattice defects, disorder, and oxygen-related functional groups in an amorphous carbon structure. CNF surface morphology changed after physical activation, reducing fiber diameter to 55 nm and introducing mesopores. Through activation temperature and time adjustments, surface area (870.1 m2/g) and micropore surface area (535.6 m2/g) and pore volume (0.2148 cm3/g) increased. EDX elemental analysis showed that activated CNF had a carbon concentration of > 90 %, while XPS analysis showed surface functional groups like C-C (sp2) and C-C (sp3) hybridization, which could improve electrolyte ion adsorption and accessibility. Electrochemical properties improved owing to CO2 activation. The optimal activation condition of 800 ℃ for 60 min resulted in the highest specific area capacitance of 552 mF cm−2 at 1 mA cm−2. This activated CNF electrode retained capacitance nearly unchanged up to 3,000 cycles. It also achieved the highest energy density of 76.7 mWh cm−2 at 500 mW cm−2. This study demonstrates the efficacy of CO2 physical activation for enhancing the electrochemical properties of CNF electrodes. The findings also highlight the importance of tailoring activation conditions, providing valuable insights for the design of advanced energy storage materials.

Effects of polyimide on corrosion and wear resistance of PEO composite coating on AZ91 Mg alloy

The accelerated deterioration resulting from microscopic defects in Mg alloy PEO coatings is a notable issue. This study introduced a PEO/PI composite coating on the surface of AZ91 Mg alloy PEO coating through coating method, aiming to enhance its corrosion resistance and wear resistance. The findings indicated that as the coating time increases, the surface micropores sealed and filled by the PI coating. This led to a positive shift in the corrosion potential of the composite coating, a significant decrease in corrosion current density by three orders of magnitude, and a marked improvement in corrosion resistance. The strong adhesion of the PI coating to the PEO surface acted as a lubricant, making the composite coating self-lubricating. Additionally, PI's excellent high temperature resistance ensured that surface wear was not induced by elevated temperatures resulting from localized friction.

Enhancing osteointegration and antibacterial properties of PEEK implants via AMP/HA dual-layer coatings

Polyetheretherketone (PEEK) is a widely used engineering plastic in orthopedic and dental implants, but its bioinertness leads to poor bone integration. To overcome this, a sulfonation treatment was applied to PEEK first to create a rough, microporous surface enhancing cellular adherence and integration. Subsequently, amorphous magnesium phosphate (AMP) nanosheets were produced through microwave-assisted synthesis, and hydroxyapatite (HA) was generated using a bionic solution hydrothermal method. A dual-layer coating system composed of an interlayer AMP and a top layer HA on the surface of PEEK was developed to enhance osteointegration. Surface analysis confirms the creation of increased surface area, improved hydrophilicity with introduced hydrophilic groups, and enhanced protein attraction. In vitro assessments on mouse embryonic osteoblasts (MC3T3-E1) demonstrate the non-toxicity of these coatings and their efficacy in promoting cell proliferation. Moreover, antimicrobial evaluations against E. coli and S. aureus highlight the potential of these composite coatings in preventing implant-related infections. The AMP/HA dual-layer coating on sulfonated PEEK emerges as a potent method for enhancing osteointegration and antibacterial properties, offering a promising approach to improve bone repair efficiency in clinical applications.

In Ukrainian

The CMs were obtained in argon in three stages: 1) heating (4 grad/min) to the specified temperature t in the range of 350–825 °С; 2) isothermal exposure 1 h; 3) cooling, washing from alkali and drying. Samples are denoted as CM(t). The CM yield (Y, %) and CMs elemental composition are determined. Based on low-temperature (77 K) nitrogen adsorption-desorption isotherms, integral and differential dependences of the specific surface area SDFT (m2/g) and pore volume V (cm3/g) on the average pore diameter (D, nm) were calculated by 2D-NLDFT-НS method (SAIEUS program). They were used to define volumes of ultramicropores (Vumi), supermicropores (Vsmi) and micropores (Vmi). The total pore volume V was calculated from the nitrogen amount adsorbed at a relative pressure p/p0 ~ 1.0. The S values of ultramicropores (Sumi), supermicropores (Ssmi) and micropores (Smi) were similarly determined. The CM yield was established to decrease linearly (R2 = 0.979) from 70.2 to 45.3 % with an increase in temperature from 350 to 825 °С. The carbon content decreases to a minimum value at 500 °С (72.6 %), and then increases to a maximum value (87.5 %) at 825 °С; the oxygen content changes antibatically. Two temperature regions were identified: region I (≤ 500 °С) of increasing the oxygen content due to reactions in which KOH acts as a donor of O atoms; region II (≥ 500 °C) of dominating the thermal destruction of functional groups (carboxyl, lactone, ester) with the release of CO and CO2, and condensation increasing the size of polyarenes of the CM secondary framework and formsng single Сar-Саr bonds between them. The CM(350) sample was found to contain only mesopores (D ≥ 10 nm) and macropores. An activation temperature increase to 400 °C initiates the additional formation of small-diameter micropores and mesopores. In samples CM(400) - CM(825), the main portion of newly formed pores falls on pores with D ≤ 5 nm. With increasing temperature, the micropores volume increases almost linearly (R2 = 0.992). The Vumi and Vsmi volumes increase up to 600 °C. At higher temperatures the ultramicropores volume decreases due to transforming ultramicropores (D ≤ 0.7 nm) into supermicropores (D = 0.7–2.0 nm). Portion of the ultramicropores volume changes with a maximum (23.9 %) in the CM(600) sample. The SBET specific surface area linearly (R2 = 0.992) increases with temperature up to 1729 m2/g. The SDFT values are close to SBET, but noticeably lower (1514–1530 m2/g) for CM(785)-CM(825). The micropores specific surface area increases to 1415 m2/g, and ultramicropore surface Sumi changes extremely with a maximum (526 m2/g) for the CM(600) sample, which should be expected based on the temperature dependence of the Vumi parameter. The decrease in Sumi values after the maximum is compensated by an increase in the supermicropore surface. Such an effect - the redistribution of pores by size in the microporous range (D ≤ 2 nm) with an increase in the alkaline activation temperature is not described in the literature. The portion of the micropores surface is dominant (92.6–97.0 %) in samples prepared at t ≥ 450 °C. The portion of the ultramicropore surface is maximum (56.3 %) in CM(500). Pores are revealed that do not form at all at 450–750 °C. These are supermicropores (D = 0.96–2.00 nm) and mesopores of small diameters (D = 2.0–2.82 nm). This effect was assumed to be due to the properties of the CM supramolecular framework, which is formed from polyarene fragments of the initial and activated coals having polyarenes with diameters of the same order (1.68–2.54 nm).

A new strategy to prepare ammonium aluminum carbonate hydroxide using plasma electrolytic oxidation in electrolyte containing carbon nanotubes

In this work, a plasma electrolytic oxidation (PEO) technique was used to prepare ammonium aluminum carbonate hydroxide (AACH) in an electrolyte containing carbon nanotubes (CNTs). CNTs were also involved in the composite coating on the surface of 6063 aluminum alloy. The formation mechanism of AACH and effects of CNTs on the microstructure and corrosion behavior of the PEO coatings were investigated. The surface morphology, pore distribution, phase composition, functional groups and electrochemical characteristics of the PEO composite coatings were examined using scanning electron microscopy (SEM), Image Pro software, X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR) and electrochemical workstations, respectively. Results showed that the rod-like AACH was generated around the discharge channel by reacting between ammonia, carbon dioxide and AlOOH under transient high temperature and high pressure environment with the presence of CNTs. The surface micropores of the composite coatings were enlarged due to the excellent electrical conductivity of CNTs. With the by addition of CNTs of 1.5 g/L, the self-corrosion current of the coating was the smallest, and the polarization resistance Rp was larger than that of 1.0 g/L and 2.0 g/L CNTs.

Correlation Study between Multi-Scale Structure and In Vitro Digestibility of Starch Modified by Temperature Difference.

Physical techniques are widely applied in the food industry due to their positive impact on food quality and the environment. Temperature differences can effectively modify starch, but the resulting changes in starch structure and quality remain unclear. In this study, the corn starch was processed with high temperature, low temperature, and temperature difference (TD), including high temperature before low temperature (H-L) and low temperature before high temperature (L-H). The results showed that high temperature induced the umbilicus to concave inward shape and sharply decreased the amylose content, while low temperature increased the surface micropores and reduced the A-chain. TD reduced the fluorescence intensity and increased the clearness of the growth ring. TD elevated the relative crystallinity (RC), short-range order, A/B1 chains, hydrolysis parameters, and resistant starch (RS), and reduced amylose content, B2/B3 chains, and viscosity. Moreover, the corn starches treated by H-L had lower amylose content and higher RC, 1047/1022, A-chain, and RS than those treated by L-H. Overall, high temperature degraded the amylose and low temperature destroyed the amylopectin. During the TD, H-L can accelerate the starch molecular rearrangement more than the opposite temperature treatment order. These results will help produce novel starches for better food applications.

A facile electrospinning strategy to prepare cost-effective carbon fibers as a self-supporting anode for lithium-ion batteries

Carbon materials with fibrous morphology and enhanced mechanical properties have shown to be promising materials as self-supporting anode materials for lithium-ion batteries (LIBs). In this study, coal-based carbon fibers (CFs) with favorable flexibility and superior tensile strength were prepared from lignite and coal derivatives such as coal-based humic acid and coal tar pitch via electrospinning in the assistance of polyacrylonitrile. All these coal-based CFs have an 1D dense fibrous microstructure with controllable diameter and appreciable specific surface area with enriched in O/N-containing groups by rationally choosing the precursor type. The organic macromolecules enriched aromatic ring in lignite and coal derivatives cross-link with linear polyacrylonitrile molecular chains to form a more solid three-dimensional (3D) network framework under the conditions of electrospinning and carbonization. Such 3D microstructure not only can significantly improve the flexibility and tensile strength of coal-based CFs, but also can increase the content of graphite-like microcrystalline carbon (sp2 carbon) in carbon fibers, thereby improving the electrical conductivity. Due to the smaller molecular structure, coal tar pitch can be more easily combined with polyacrylonitrile by electrostatic force. The CFs derived from coal tar pitch (CTP-CFs) exhibited the largest average diameter (156.2 nm), a higher microporous surface area (2.6 m2·g−1), higher pyrrole nitrogen and contained reasonable proportions of amorphous carbon (sp3 carbon) and sp2 carbon. As a consequence, among the various derived coal-based CFs applied as self-supporting anode materials for LIBs, CTP-CFs showed the highest first reversible capacity (770.8 mAh·g−1 at 20 mA·g−1) and excellent cycling performance with capacity retention rate of 89.1 % after 200 cycles. This work paves a new strategy to prepare CFs as flexible self-supporting anodes for LIBs from low-cost carbon precursors that can be rationally chosen to further tune the property of the CFs.

FeCl3-modified carbon as an electrode material for supercapacitors: preparation, analysis, and electrochemical properties

The necessity to combat the effects of global warming has made the use of renewable energy sources essential. Much attention has been focused on utilizing various types of biomass that can provide high energy productivity and serve as an alternative to traditional fossil fuels. This study specifically aims to investigate the electrochemical properties of carbon materials obtained from plant-based raw materials after biofuel production by the carbonization of melon and citrus peels at 300 °C and chemical activation using FeCl3. It is established that chemical activation with FeCl3 at 700 °C has led to dehydration, degradation of the carbon matrix, and the development of a microporous surface. For a two-electrode electrochemical cell, the specific capacitance values at a discharge current of 50 mA are 196 F/g in an aqueous KOH solution and 78 F/g in TEABF4. Based on the impedance spectroscopy results, an equivalent electrical circuit has been modeled, revealing the energy storage mechanism at the carbon electrode-electrolyte interface, with a physical interpretation of each circuit element provided. Most importantly, the device remains stable with no capacitance loss after 1000 cycles. The research findings may contribute to expanding the use of biomass as a cost-effective electrode component for supercapacitors.

Synthesis of microporous titanium surface with aligned pores through changes of currents during electrochemical process

This paper reports the synthesis of microporous Ti surfaces with aligned pores by applying a different current during electrochemical process for application in cell-surface interaction study and biomedical implants. As the microporous Ti surfaces were synthesized by current from (0.5–4)A, the microstructure of the Ti surfaces was shifted from a relative smooth to microporous one that was observed to have an aligned pore surface. Optical images showed that the micropore sizes in ∼(85.4–224.4)µm. The roughness of the microporous Ti was significantly higher than that of the Ti by a factor of approximately 5 to 7. Confocal laser scanning microscope showed excellent cell attachment and preferential growth on the microporous Ti with aligned channels after 72 h of culturing which could be important for cell-surface interactions study and biomedical implants.

A Comprehensive Study on Methane Adsorption Capacities and Pore Characteristics of Coal Seams: Implications for Efficient Coalbed Methane Development in the Soma Basin, Türkiye

This study represents a comprehensive assessment of methane adsorption capacity and pore characteristics for the coal seams of the Soma Basin in Western Türkiye, with a focus on their implications for coalbed methane potential. Twenty-one exploration wells were utilized to obtain coal samples from the kP1 and kM2 coal seams in the Kınık coalfield of the Soma Basin. High-pressure methane adsorption experiments using the indirect gravimetric method were conducted to quantify the storage capacities of these coal seams. Results revealed a wide range of methane adsorption capacities, ranging from 10.5 to 28.3 m3/t (air-dry basis), indicating significant methane storage potential for the kP1 and kM2 coal seams. The gas contents, ranging from 1.1 to 4.3 m3/t (as-received basis), suggested that the coal seams were undersaturated. Low-pressure N2/CO2 adsorption tests, along with standard proximate and gross calorific value analyses, were performed to investigate the influence of coal quality and pore characteristics on methane adsorption capacities. The findings demonstrated correlations between coal quality parameters and adsorption capacity, with ash yield showing a moderately negative correlation and fixed carbon content and gross calorific values exhibiting moderately positive correlations. Microporosity was identified as the critical factor governing methane adsorption, with a strong positive correlation observed between micropore surface areas and volumes and adsorption capacity. These results highlight the significant methane storage capacities of the coal seams in the Soma Basin and underscore the importance of micropores in determining methane adsorption capacity. The findings provide valuable insights for optimizing methane extraction and utilization in the region and offer important considerations for reservoir characterization and development strategies in similar low-rank coal deposits.HighlightsExtensive evaluation of methane adsorption and pore characteristics in Soma Basin coals, uncovering substantial potential for coalbed methane.The study reveals a diverse range of methane adsorption capacities, indicating highly promising methane storage capabilities.Correlation between coal quality parameters and methane adsorption, offering valuable insights into gas storage influenced by coal composition.Emphasis on the crucial role of micropores in methane storage, underscoring their significance as primary adsorption sites.Practical implications for optimizing methane extraction and utilization, guiding reservoir development in low-rank coal deposits like Soma Basin.

The effect of Ce promotor on catalytic performance of Zn/ZSM-5 in coaromatization of methanol and n-hexane

Ce modified Zn/ZSM-5 catalyst was prepared and the effect of Ce promotor on coaromatization of methanol and n-hexane was studied. The physical and chemical properties of Zn–Ce/HZ were tested by XRD, XPS, TEM, N2 adsorption-desorption and Py-FTIR. The loading of Ce tuned the acidity distribution and increased the LAS/BAS ratio, and mainly reduced the microporous specific surface area. Most of Zn and Ce elements entered the zeolite channels. The loading of Ce enhanced the interactions between Zn species and support and significantly increased the numbers of active centers of ZnOH+ species. Under the optimized conditions, the yield of aromatics was greatly improved from 25.2 % of HZ to 62.6 %. The reasons of deactivation were also analyzed. The higher the aromatization activity, the more the formed carbon deposit. The blockage of micropores and the greatly coverage of acid sites by carbon deposit thus resulted in poor catalytic performance.

Double-walled Al-based MOF with large microporous specific surface area for trace benzene adsorption.

Double-walled metal-organic frameworks (MOFs), synthesized using Zn and Co, are potential porous materials for trace benzene adsorption. Aluminum is with low-toxicity and abundance in nature, in comparison with Zn and Co. Therefore, a double-walled Al-based MOF, named as ZJU-520(Al), with large microporous specific surface area of 2235 m2 g-1, pore size distribution in the range of 9.26-12.99 Å and excellent chemical stability, was synthesized. ZJU-520(Al) is consisted by helical chain of AlO6 clusters and 4,6-Di(4-carboxyphenyl)pyrimidine ligands. Trace benzene adsorption of ZJU-520(Al) is up to 5.98 mmol g-1 at 298 K and P/P0 = 0.01. Adsorbed benzene molecules are trapped on two types of sites. One (site I) is near the AlO6 clusters, another (site II) is near the N atom of ligands, using Grand Canonical Monte Carlo simulations. ZJU-520(Al) can effectively separate trace benzene from mixed vapor flow of benzene and cyclohexane, due to the adsorption affinity of benzene higher than that of cyclohexane. Therefore, ZJU-520(Al) is a potential adsorbent for trace benzene adsorption and benzene/cyclohexane separation.

Insight into the key factors for the tetracycline removal in biochar-mediated oxidative system

This study prepared pomelo peel biochar (PBC) under different pyrolysis temperatures (T) (300–800 °C) and investigated the removal efficiency of tetracycline (TC) under the oxidative systems established by PBC and oxidants (hydrogen peroxide (H2O2), peroxymonosulfate (PMS), and peroxydisulfate (PDS)). The correlation between the properties of PBC and the removal efficiencies of TC was studied by Pearson analysis to clarify the critical properties of biochar in catalytic processes. The inorganic carbon (IC), ash, pH, basic functional groups (BFG), specific surface area (SSA), microporous surface area (Smicro), pore volume (PV), and graphitization degree (ID/IG) of PBC were positively correlated with the increase of T (p < 0.05). Notably, the SSA and PV of PBC increased from 4.294 m2/g and 0.002 cm3/g to 496.864 m2/g and 0.261 cm3/g as the pyrolysis temperature increased from 300 to 800 °C. In contrast, the yield, organic carbon (OC), and acidic functional groups (AFG) of PBC displayed negatively correlated with the increase of T (p < 0.05). Rad, RPBC/H2O2, RPBC/PMS, and RPBC/PDS represented the removal efficiencies of TC by PBC adsorption, PBC/H2O2, PBC/PMS, and PBC/PDS system. RPBC/H2O2, RPBC/PMS, and RPBC/PDS showed a highly positive correlation to the Rad (r = 0.965, 0.952, 0.946, p < 0.01). Rad, RPBC/H2O2, RPBC/PMS, and RPBC/PDS were positively correlated with K, Mg, ash, pH, BFG, and ID/IG (p < 0.01). There was no statistically significant correlation between persistent free radicals (PFRs) and the removal efficiencies of TC. Furthermore, SSA and PV showed positive relationships with the removal efficiencies of TC in the PBC/PMS and PBC/PDS systems, but no significant correlation with the removal efficiencies of TC in the PBC/H2O2 systems. Moreover, the catalytic behaviors and mechanisms were studied in the PBC-800 based oxidative systems. The quenching experiments and EPR spectra indicated that singlet oxygen (1O2) was the main active species. Except for 1O2, superoxide radical (O2•−) also contributed to TC removal in the oxidative systems. From the changes in used PBC-800, the disordered sp2 hybrid carbon, sp3 C–C, and pyridinic-N were the main active sites in activation.

Utilization of cotton gin waste biochars for agronomic benefits in soils

AbstractCotton gin waste (CGW) is produced in large quantities (1–1.5 × 106 metric ton/year) in the Texas High Plains (THP), one of the largest cotton-producing regions in the USA. We examined locally supplied CGW for soil amendment as biochar (CGW-BC) with a view toward rainfed cropping systems, which will likely become increasingly necessary due to declines in groundwater availability for irrigation. Sixteen unique biochar samples were produced under varying conditions of time, temperature, and post-processing wash in a muffle furnace. We performed material characterization on the biochar. We then incubated CGW-BC samples that seemed favorable for increasing the water holding capacity increase for 10 days with local, rainfed, clay loam soil. We found that increasing the pyrolysis time and temperature decreased the biochar yield but only up to 40 min. Beyond 40 min, the yield did not decrease further. Additionally, the majority of mass loss occurred during pyrolysis and not during crush-sieving or postproduction washes. CGW-BC produced at higher temperatures and for longer times had greater thermal stability. This interesting aspect of thermal stability, which did not always follow strict time‒temperature trends, may be because cotton gin waste is a heterogeneous material. We found that the addition of acid decreases the mineral content while lowering the thermal stability of lower temperature (450 °C) biochars. Regarding the CGW-BC surface area, we found that higher temperatures generally increase the micropore surface area. Using a GAB isotherm, water vapor surface area did not correlate with the highest WHC when water was added to the soil. In fact, biochar, which was pyrolyzed in less time at a lower temperature and with the use of acid washing, better held the water in soil-biochar mixtures. The measurements suggested that CGW-BC could be a valuable soil amendment that could increase the WHC without adversely increasing the pH. Our initial investigation revealed how scaled-up production of CGW-BC for soils might be economically and sustainably pursued for use in rainfed cropping, deficit irrigation, or ranchlands.

Optimizing the fluoride removal from drinking water through adsorption with mesoporous magnetic calcite nanocomposites

Fluoride (F−) contamination in groundwater is a global concern arising from natural processes and human activities. This study investigates the adsorption of F− using surface-activated magnetic calcite nanocomposites (NCs) synthesized via co-precipitation assisted wet-impregnation (CP-WI). Various Fe3O4 loadings and calcination temperatures (300 °C and 500 °C) were explored to optimize synthesis parameters. Batch adsorption experiments were conducted to assess the performance of synthesized nanoparticles (NPs) and nanocomposites (NCs). BET, FTIR spectroscopy, X-ray diffraction, and SEM characterization techniques were employed to analyze the physicochemical properties, including surface functional groups, crystallite size, and morphology. The adsorption process was investigated using RSM statistical design with adsorbent dose (A) and F− concentration (B) as independent variables. 0.5Fe-C-NC-5, calcined at 500 °C, exhibited superior adsorption capacity (7.81 mg/g) compared to Fe3O4 and calcite NPs (6.57 mg/g and 6.81 mg/g, respectively). Maximum F− adsorption occurred within 10 min of contact time. NPs and NCs that were exposed to higher calcination temperatures, reaching up to 500 °C, showed an increase in crystallite development while experiencing a reduction in surface area and an enlargement of pore size compared to those treated at lower temperatures. The BET analysis revealed a narrow, slit-like mix of microporous and mesoporous surface with a type IV isotherm and H3 hysteresis loop, indicating multilayer adsorption followed by capillary condensation. The SEM images displayed columnar shapes of CaCO3 polymorph in the prepared Fe3O4-calcite NP and Fe–C NP, which can be attributed to lower calcination or synthesis temperatures.

Pre‐Oxidating and Pre‐Carbonizing to Regulate the Composition and Structure of Coal Tar Pitch: The Fabrication of Porous Carbon for Supercapacitor Applications

AbstractThe capacitive properties of supercapacitors highly rely on the reasonable design of high‐performance electrode materials. Herein, a synergetic strategy of pre‐oxidation and pre‐carbonization is proposed to prepare coal tar pitch (CTP) based porous carbon. The formation mechanism of porous carbon is revealed. Pre‐oxidation increases the heteroatom content and promotes the decomposition of polycyclic aromatic hydrocarbons into small molecules, which is more conducive to improving the subsequent activation and enhancing the microporous specific surface area. Also, the autoclave pre‐carbonization promotes the polymerization of the precursors and increases the carbon yield. Benefiting from the synergistic effect of pre‐oxidation and pre‐carbonation, the obtained carbon exhibits a superior specific capacitance of 365 F g−1. Meanwhile, ZnCl2 is used as a hydrogen‐bonding acceptor to synthesize ZnCl2‐EG/PVA deep eutectic solvent (DES) gel, and it is applicable to acidic, neutral, and alkaline electrolytes. The capacitor assembled with the prepared porous carbon and DES gel electrolyte achieves a high energy density of 41.3 Wh kg−1 and works well in unconventional temperatures (−40–75 °C). This work confirms the effect of pre‐oxidation and pre‐carbonization on the fabrication of CTP‐based carbon material and expects to prepare porous carbon using other pre‐oxidation/carbonization agents.