Enhancing the Startup Rate of Microbial Methanogenic Systems through the Synergy of ß-lactam Antibiotics and Electrolytic Cells.

The slow startup and suboptimal efficiency of microbial carbon sequestration and methane-production systems have not been fully resolved despite their contribution to sustainable energy production and the reduction of greenhouse gas emissions. These systems often grapple with persistent hurdles, including interference from miscellaneous bacteria and the slow enrichment of methanogens. To address these issues, this paper examines the synergistic effect of coupling ß-lactam antibiotics with an electrolytic cell on the methanogenic process. The results indicated that ß-lactam antibiotics exhibited inhibitory effects on Campylobacteria and Alphaproteobacteria (two types of miscellaneous bacteria), reducing their relative abundance by 53.03% and 87.78%, respectively. Nevertheless, it also resulted in a decrease in hydrogenogens and hindered the CO2 reduction pathway. When coupled with an electrolytic cell, sufficient electrons were supplied for CO2 reduction to compensate for the hydrogen deficiency, effectively mitigating the side effects of antibiotics. Consequently, a substantial improvement in methane production was observed, reaching 0.57 mL·L-1·d-1, exemplifying a remarkable 6.3-fold increase over the control group. This discovery reinforces the efficiency of methanogen enrichment and enhances methane-production levels.

Leaching Vanadium from the Spent Denitration Catalyst in the Sulfuric Acid/Oxalic Acid Combined Solvent.

Huge amounts of spent denitration catalysts are produced annually as waste from the flue gas denitration process, which will cause resource waste and environmental pollution. It is important to develop an efficient method for the recovery of metals from spent denitration catalysts. In this work, the leaching of vanadium (V) from the spent denitration catalyst by the sulfuric acid/oxalic acid combined solvent was investigated. Factors that influence the leaching rate of V have been studied. Results showed that the optimal leaching rate was 95.65% by 20 wt % sulfuric acid and 0.3 mol·L-1 oxalic acid with a liquid-to-solid ratio of 20 mL·g-1 at 140 °C for 7 h. For further study of the leaching process, the leaching mechanism of V was explored subsequently. Results indicated that sulfuric acid provided a strongly acidic environment, which was beneficial to transformation, complexation, and redox reactions of V in the mixed acid leaching system. Meanwhile, oxalic acid with excellent complexation and reducing-dissolving properties promoted the formation of stable water-soluble VO2+. The "complex effect" generated from the combined acids was greatly favored for leaching V from the spent denitration catalyst.

Technical alternatives for coke oven gas utilization in China: A comparative analysis of environment-economic-strategic perspectives.

China is the largest coke producer and consumer. There is a pressing need to address the high emissions of air pollutants and carbon dioxide associated with traditional coking production. As the nation pursues a transition towards carbon neutrality, expanding supply chains for coking plants to produce hydrogen, methanol, and other green alternatives has garnered significant attention. However, the relative advantages of these strategies have remained uncertain. In this study, we integrate a life cycle assessment-economic analysis-scenario analysis model to evaluate various coke oven gas (COG) utilization routes (COGtM: COG-to-methanol, COGtLNG: COG-to-liquefied natural gas, COGtSA: COG-to-synthetic ammonia, and COGtH: COG-to-hydrogen). The results indicate that COGtSA emerges as the preferred option for balancing environmental and economic benefits. Meanwhile, COGtM demonstrates economic viability but is associated with higher environmental impacts. Despite being recognized as a significant strategic direction under carbon neutrality initiatives, COGtH faces economic feasibility and risk resilience limitations. COGtLNG encounters both financial and environmental challenges, necessitating strategic development from an energy security perspective. The projected coking capacity is anticipated to experience a slight increase in the mid-term yet a significant decline in the long term, influenced by steel production capacity. In potential future markets, COGtM is estimated to potentially capture a maximum market share of 16-34% in the methanol market. Furthermore, against the backdrop of continuously expanding potential demand for hydrogen, COGtH holds advantages as a transitional solution, but in the long run, it can only meet a small portion of the market. COGtSA can meet 7-14% of market demand and emerges as the most viable pathway from the viewpoint of balancing environmental and economic aspects and covering future markets.

Adsorption and reduction of Cr(VI) by N, S co-doped porous carbon from sewage sludge and low-rank coal: Combining experiments and theoretical calculations.

Herein, a novel N, S co-doped porous carbon (S5C5-AC) for Cr(VI) removal was prepared by co-hydrothermal carbonization (HTC) of sewage sludge (SS) and low-rank coal (LC) combining with KOH modification. The results showed that S5C5-AC had excellent adsorption performance on Cr(VI), and lower pH value, higher initial concentration and longer contact time were beneficial for Cr(VI) adsorption. The adsorption kinetics and isotherms revealed that Cr(VI) adsorption by S5C5-AC was homogeneous and dominated by chemisorption. The adsorption isotherm showed that the maximum equilibrium adsorption capacity of S5C5-AC for Cr(VI) was 382.04 mg/g at 25 °C. Furthermore, the results showed that the main mechanisms for Cr(VI) removal were the pore filling, electrostatic interaction and reduction. Moreover, the electron transfer mechanism during the adsorption and reduction process was further explored at the molecular and electronic levels by density functional theory (DFT) and front orbital theory (FOT) simulations. The analysis of DFT and FOT indicated that the synergistic effect between S and N functional groups was exhibited during the Cr(VI) removal process. Considering the existence of synergistic effects between N and S functional groups during adsorption, the S and N content and form were modified collaboratively. Increasing the relative content of pyrrolic N may be the most effective pathway for improving removal performance. Besides that, S5C5-AC exhibited excellent adsorption capacity over a high coexisting ion concentration range and various actual water bodies and regeneration performance, which indicated that S5C5-AC had promising potential for the remediation of wastewater in industrial applications.

Formation and Phase Transformation of MgCO3·3H2O Whiskers in the Presence of Sodium Dodecyl Sulfate.

Huge amounts of MgCl2·6H2O are produced annually as a byproduct or waste from KCl production in the Qinghai province of China. An ecological and economic way to solve this problem is transforming the abandoned MgCl2·6H2O to valuable MgCO3·3H2O whiskers. The formation and phase transformation of MgCO3·3H2O whiskers were studied in the crystallization process, in which MgCl2 and NH4HCO3 were precipitated in the presence of sodium dodecyl sulfate (SDS) at 50 °C. Results showed that porous spherical MgCO3·3H2O, MgCO3·3H2O whiskers, and flocculent rod-like 4MgCO3·Mg(OH)2·4H2O were formed with decreasing concentration of SDS as the crystallization proceeded. When the concentration of SDS was lower than the critical micellar concentration (6.5 mmol·L-1) at 60 min, SDS was beneficial for the growth in the [010] direction to form one-dimensional MgCO3·3H2O whiskers with a high aspect ratio, good uniformity, and a smooth surface (length, 60-70 µm; aspect ratio, 110-140).

Catalytic CO2 Capture via Ultrasonically Activating Dually Functionalized Carbon Nanotubes.

High energy consumption and high cost have been the obstacles for large-scale deployment of all state-of-the-art CO2 capture technologies. Finding a transformational way to improve mass transfer and reaction kinetics of the CO2 capture process is timely for reducing carbon footprints. In this work, commercial single-walled carbon nanotubes (CNTs) were activated with nitric acid and urea under ultrasonication and hydrothermal methods, respectively, to prepare N-doped CNTs with the functional group of -COOH, which possesses both basic and acid functionalities. The chemically modified CNTs with a concentration of 300 ppm universally catalyze both CO2 sorption and desorption of the CO2 capture process. The increases in the desorption rate achieved with the chemically modified CNTs can reach as high as 503% compared to that of the sorbent without the catalyst. A chemical mechanism underlying the catalytic CO2 capture is proposed based on the experimental results and further confirmed by density functional theory computations.

An Activatable NIR Fluorescent Probe for NAD(P)H and Its Application to the Real-Time Monitoring of p53 Abnormalities In Vivo.

NAD(P)H is crucial for biosynthetic reactions and antioxidant functions. However, the current probes developed for detecting NAD(P)H in vivo require intratumoral injection, which limited their application for animal imaging. To address this issue, we have developed a liposoluble cationic probe, KC8, which exhibits excellent tumor-targeting ability and near-infrared (NIR) fluorescence after reaction with NAD(P)H. By using KC8, it was demonstrated for the first time that the level of NAD(P)H in the mitochondria of living colorectal cancer (CRC) cells was highly related to the abnormality of the p53. Furthermore, KC8 was successfully used to differentiate not only between tumor and normal tissue but also between tumors with p53 abnormality and normal tumors when administered intravenously. Finally, we evaluated tumor heterogeneity through two fluorescent channels after treating a tumor with 5-Fu. This study provides a new tool for real-time monitoring of the p53 abnormality of CRC cells.

Influence of the freeze-thaw process on coal gangue-based ecological restoration materials: performance and ecological risk assessment of heavy metals.

Materials made from coal gangue (CGEr) can be used for ecological restoration in mining areas. This paper comprehensively analyzed the influence of the freeze-thaw process on the performance of CGEr and the environmental risk of heavy metals. The safety of CGEr was assessed by sediment quality guidelines (SQGs), geological accumulation index (Igeo), potential ecological risk index (RI), and risk assessment code (RAC). The freeze-thaw process reduced the performance of CGEr, that the water retention of CGEr decreased from 1.07 (g water/g soil) to 0.78 (g water/g soil), and the loss rate of soil and water increased from 1.07 to 4.30%. The freeze-thaw process reduced the ecological risk of CGEr, the Igeo of Cd and Zn decreased from 1.14 to 0.13 and 0.53 to 0.3, respectively, and the RI of Cd decreased by 50% from 0.297 to 0.147. Reaction experiments and correlation analysis showed that the freeze-thaw process destroyed the pore structure of the material, resulting in the degradation of its properties. Water molecules undergo phase transformation during freeze-thaw, and particles were squeezed by ice crystals to form agglomerates. The formation of granular aggregates resulted in the enrichment of heavy metals in the aggregates. Influenced by the freeze-thaw process, specific functional groups such as -OH were more exposed on the surface of the material, which affected the occurrence form of heavy metals and thus reduced the potential ecological risk of the material. This study provides an important basis for the better application of ecological restoration materials of CGEr.

Freeing Fluoride Termination of Ti3C2Tx via Electrochemical Etching for High-Performance Capacitive Deionization.

Ti3C2Tx MXene is a promising Faradic capacitive deionization (CDI) electrode for high salt removal in future desalination, whereas the surface termination group of fluoride (-F) significantly impedes ion access to Ti3C2 and charge-transfer efficiency. Herein, we propose an electrochemically etched strategy to synthesize -F-free Ti3C2Tx through three-electrode cyclic voltammetry scanning within a narrowed potential window in an alkaline electrolyte. The resulting assembly of an asymmetric electrochemical-etched Ti3C2Tx//activated carbon CDI device can deliver an excellent salt removal capacity of 20.27 mg·g-1 with an adsorption rate of 1.01 mg g-1 min-1 owing to the enhanced hydrophilicity and ion transport. The tiny CDI device is demonstrated, which can generate an electric current during the electrosorption of salt ions, thus facilitating the powering of a red light-emitting diode. This study opens a new avenue for the surface chemistry of Ti3C2Tx and is expected to achieve future applications in desalination and renewable energy.

Adsorption and catalytic oxidation of residual NH3 on coal ash after selective non-catalytic reduction in coal-fired boilers.

Selective non-catalytic reduction (SNCR) with NH3 as the reducing agent is widely used for the denitrification of flue gas in coal-fired boilers, where fly ash significantly influences the conversion of the residual NH3 that does not participate in denitrification. However, there have been few studies on the exact nature of this influence, particularly the adsorption and reaction mechanisms of NH3 on fly ash. In this study, temperature-programmed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were used to study the mechanisms of NH3 adsorption and reactions over coal ash. In the absence of oxygen, in the temperature range of 50-450 °C, NH3 was adsorbed on the surface of the coal ash. The adsorption capacity of lignite ash was higher than that of anthracite ash. This difference was attributed to the large specific surface area and surface acidity of the lignite ash. However, between 450-850 °C, coal ash had a catalytic effect on NH3 decomposition and oxidation. Due to the high surface lattice oxygen content of lignite ash, its catalytic oxidative ability was superior to anthracite ash. Moreover, NH3 was first adsorbed over Lewis and Brønsted acid sites on the surface of coal ash and later underwent hydrogen abstraction to produce either the NH2 or the NH intermediate. The intermediates further reacted with the surface lattice oxygen of coal ash to produce NO and N2O. These results might be helpful for the management of NH3 residues from SNCR processes and the utilization of amino reducing agents in coal-fired boilers.

Surface fluorine preservation dependence of Ti3C2Tx MXene for high electrochemical properties in ionic liquid electrolytes.

We identified the contribution of -CF3 terminations to the Ti3C2Tx surface structure when ethanol and water were used as solvents during delamination through experimental and computational studies. Ethanol-treated -CF3-terminated Ti3C2Tx achieves better prevention of nanoflake aggregation, hydrophobicity, and small size, enabling enhanced capacitive properties in ionic liquid compared to water-treated Ti3C2Tx in aqueous and ionic liquid electrolytes.

Effect of Different Initial CaO/SiO2 Molar Ratios and Curing Times on the Preparation and Formation Mechanism of Calcium Silicate Hydrate.

To better understand the pozzolanic activity in fly ash used as a supplementary cementitious material in cement or concrete, calcium silicate hydrate (C-S-H) has been synthesized by adding silica fume to a supersaturated calcium hydroxide solution prepared by mixing calcium oxide and ultrapure water. Thermogravimetric analysis results have revealed the variation in the weight loss due to C-S-H in the samples and the conversion ratio of calcium oxide (the µCaO value), which represents the proportion of calcium oxide in the initial reaction mixture used to produce C-S-H, with curing time. The weight loss due to C-S-H and the µCaO value were both maximized (13.5% and 90.4%, respectively) when the initial C/S molar ratio was 1.0 and the curing time was 90 d. X-ray diffraction (XRD) analysis has indicated that C-S-H in the samples after curing for 7 d had the composition Ca1.5SiO3.5·xH2O. 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) analysis has revealed that the degree of polymerization of C-S-H increased with an increase in curing time for samples with an initial C/S molar ratio of 1.0. The ratio of internal to terminal tetrahedra (Q2/Q1) increased from 2.29 to 4.28 with the increase in curing time from 7 d to 90 d. At curing times ≥ 28 d, a leaf-like C-S-H structure was observed by scanning electron microscopy (SEM). An ectopic nucleation-polymerization reaction process is proposed for the formation mechanism of C-S-H.

[EMmim][NTf2 ]-a Novel Ionic Liquid (IL) in Catalytic CO2 Capture and ILs' Applications.

Ionic liquids (ILs) have been used for carbon dioxide (CO2 ) capture, however, which have never been used as catalysts to accelerate CO2 capture. The record is broken by a uniquely designed IL, [EMmim][NTf2 ]. The IL can universally catalyze both CO2 sorption and desorption of all the chemisorption-based technologies. As demonstrated in monoethanolamine (MEA) based CO2 capture, even with the addition of only 2000 ppm IL catalyst, the rate of CO2 desorption-the key to reducing the overall CO2 capture energy consumption or breaking the bottleneck of the state-of-the-art technologies and Paris Agreement implementation-can be increased by 791% at 85 °C, which makes use of low-temperature waste heat and avoids secondary pollution during CO2 capture feasible. Furthermore, the catalytic CO2 capture mechanism is experimentally and theoretically revealed.

Co-hydrothermal carbonization of sewage sludge and coal slime for clean solid fuel production: a comprehensive assessment of hydrochar fuel characteristics and combustion behavior.

The fuel characteristics and combustion behavior of the hydrochar obtained from the co-hydrothermal carbonization (co-HTC) of sewage sludge (SS) and coal slime (CS) were investigated. The results showed that a synergistic effect existed during the co-HTC process of SS and CS, which could make the mass yield, high heating value, carbon retention rate, energy recovery efficiency, fuel ratio, and energy balance of the hydrochar increase by 1.87-6.52%, 4.04-17.54%, 7.52-16.80%, 4.20-19.59%, 7.58-25.45%, and 35.26-40.08%, respectively. Furthermore, thermogravimetric and derivative thermogravimetry analysis indicated that the weight loss of co-hydrochar was significantly increased with increasing of CS ratio, and it was 38.39%, 48.14%, and 58.08% when the CS ratio was 25%, 50%, and 75% respectively. Adding CS during HTC could significantly improve the combustion performance of the hydrochar. Moreover, SS and CS were efficiently converted into solid fuels with better combustion performance and reactivity.

Study Progress on Inorganic Fibers from Industry Solid Wastes and the Key Factors Determining Their Characteristics.

Compared to basalt and glass fibers, the production of inorganic fiber from industry solid wastes is an effective method to not only save natural resources but also recycle waste resources. Because the preparation of the fibers requires high temperature treatment, the production process is associated with high energy consumption and high carbon emissions. How to resolve these problems is a current research challenge in this field. Herein, we reviewed the study progress on these fibers and further discussed the key factors determining their characteristics, including chemical composition, melt structure, and viscosity of melt. In production, the matching of solid waste blends containing enough total content of SiO2 and Al2O3, and a suitable amount of MgO and CaO, is beneficial to the structure control of the melt. The study found that the melt consisted of Q2 and Q3; and that Q3 content more than Q2 was more suitable for fiber production and its performance improvement. Such a melt structure can be achieved by controlling the degree of depolymerization and the temperature. New ultrasonic technology can shorten the homogenization time; its application is hoped to save energy and reduce carbon emissions. These conclusions will offer important guidance for the development of inorganic fibers from industry solid wastes in the future.

Novel heterostructured metal doped MgFe2O4@g-C3N4 nanocomposites with superior photo-Fenton preformance for antibiotics removal: One-step synthesis and synergistic mechanism.

A novel metal doped MgFe2O4@g-C3N4 (m-MF@CN) nanocomposite was synthesized by one-pot method using saprolite laterite nickel ore and urea as raw materials. The heterostructure was verified as an effective heterogeneous Fenton-like catalyst for degrading antibiotics including tetracycline, oxytetracycline and chlortetracycline hydrochloride, and the related catalytic mechanism was elaborated in detail. Under the optimum conditions, the m-MF@CN/H2O2/vis system exhibited superior photo-Fenton property (degradation efficiency of 93.15% within 30 min, TOC removal efficiency was as high as 60.54% within 120 min) and cycle stability for tetracycline removal. The combination of MgFe2O4 and g-C3N4 enhanced the absorption of visible light, and the energy level matched heterojunction promoted the separation of photogenerated electron-holes to accelerate the redox cycle of ≡Fe3+/≡Fe2+. Free radical quenching and electron spin resonance (ESR) analysis confirmed that O2- was the main active species, h+ and OH also played a synergistic role in the degrading reactions. Notably, a possible degradation pathway of tetracycline was proposed according to the intermediates produced in the reaction process. The one-step synthesized m-MF@CN nanocomposite catalysts possessed high catalytic performance, good stability and recoverability, which not only realized the high-value utilization of ore raw materials, but also provided a potential practical way for efficient treatment of antibiotic wastewater.

Enzyme-activated prodrugs and their release mechanisms for the treatment of cancer.

Enzyme-activated prodrugs have received a lot of attention in recent years. These prodrugs have low toxicity to cells before they are activated; when they interact with specific enzymes, they can effectively release anticancer drugs, thereby achieving the effect of treating cancer. At the same time, compared with other thiol-activated prodrugs, reactive oxygen species-activated prodrugs, and acid-activated prodrugs, the specificity of enzyme-activated prodrugs is stronger; therefore, these prodrugs have greater development potential. In this review, we summarize the different release mechanisms of prodrugs on the basis of enzyme-activated prodrugs, such as enzyme reduction, enzymatic hydrolysis, enzyme-activated and light-radiation-assisted release, and enzymatic-activated and nanoparticle-assisted release mechanisms. A profound understanding of these release mechanisms will contribute to the design of enzyme-activated prodrugs.

Insights into Coproduction of Silica Gel via Desulfurization of Steel Slag and Silica Gel Adsorption Performance.

Steel slag is a calcium-containing alkaline industrial solid waste that can replace limestone for flue gas desulfurization. It can remove SO2 and coproduce silica gel while avoiding CO2 emission from limestone in the desulfurization process. In this study, steel slag with a D 50 of 3.15 µm was used to remove SO2. At room temperature, with a solid-liquid ratio of 1:10, a stirring speed of 800 rpm, and the mixed gas introduced at a flow rate of 0.8 mL/min, 1 ton of steel slag could remove 406.7 kg of SO2, a SO2 removal efficiency typical of existing calcium-rich desulfurizers. As limestone desulfurization can release CO2, when limestone desulfurization was replaced with steel slag of equal desulfurization ratio, CO2 emissions could be reduced by 279.6 kg and limestone could be reduced by 635.5 kg. The yield of silica gel was 5.1%. Silica gel pore structure parameters were close to those of commercially available B silica gel. Products after desulfurization were mainly CaSO4 ·2H2O, CaSO4 ·0.5H2O, CaSO3 ·0.5H2O, and silica gel. With a silica gel dosage of 30 mg, a temperature of 20 °C, a pH value of 6.00, a stirring time of 0.5 h, and a methylene blue concentration of 0.020 mg/mL, the removal ratio of methylene blue adsorbed by silica gel was 98.4%.

Spinel Ferrite Transformation for an Efficient Fe Removal from Circulating Fluidized Bed Fly Ash by Carbothermal Reduction at a Low Temperature.

Alumina (Al2O3) extraction from circulating fluidized bed (CFB) fly ash (CFBFA) is one of the most important pathways for value-added utilization. However, in CFBFA, impurity iron (Fe) normally coexists, resulting in complicated separation processes, low Al2O3 extraction efficiency, and substandard Al2O3-based products. How to remove Fe impurity effectively from CFBFA has become an important issue. For an effective Fe removal from CFBFA, spinel ferrite transformation by carbothermal reduction at a low temperature was discussed in the paper. The effects of the reduction temperature and reduction time on the removal efficiency of Fe and the recovery of aluminum (Al) as well as the removal of other metals were systematically investigated, and the transformation mechanisms of Fe-containing phases were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and a scanning electron microscope-energy dispersive spectrometer. The results showed that Fe in CFBFA was present in the form of weakly magnetic α-Fe2O3, leading to a Fe removal of about 17.1% after magnetic separation; however, the recovery efficiency of Al reached 97.4%. Weakly magnetic hematite (α-Fe2O3) could be converted to strongly magnetic spinel-type ferrite (MFe2O4) after carbothermal reduction at 700 °C for 60 min, and the Fe removal efficiency could reach 62.8% after magnetic separation; however, the recovery of Al was 81.2%, which was decreased compared to the recovery of Al under the condition without carbothermal reduction treatment. However, the carbothermal reduction-magnetic separation process did not have a major effect on the existing form and leaching behavior of Al, Li, and Ga. Simultaneously, it could be observed that some transition metal elements such as Mn, Cr, and so forth could be enriched in spinel-type MFe2O4 and removed after magnetic separation, which also provided a way for transition metal enrichment and extraction of transition metals from other tailings.

Research on the mechanism of sodium separation in bauxite residue synergy preparation of potassium-containing compound fertilizer raw materials by the hydrothermal method.

Bauxite residue poses an increasingly serious ecological safety problem in the alumina industry. A novel process for removing sodium in bauxite residue synergistic preparation of potassium-containing compound fertilizer raw materials was proposed to relieve pressure on the fertilizer industry. In this paper, synthetic sodalite and katoite were used to simulate the main mineral phases of bauxite residue to determine the suitable conditions for the method, and the transformation mechanism of the process was researched by analyzing the phase structure and microscopic morphology of the samples using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and specific surface area detection. The results show that the ideal reaction condition is 320 g/L K2O with solid reactants at 200 °C for 1 h. The separation rate of Na in the sodalite-katoite mixture reached 93.60%, with potassium aluminum silicate and katoite being the primary phases of the product, with a mesoporous structure and easy to be absorbed by crops. The bauxite residue transformation residue consisted of katoite and kaliophilite. With a total effective K2O, CaO, and SiO2 content of 38.22%, the Na2O content was 0.54%, meeting the requirements of compound fertilizer content on the market. The transformation mechanism is a dissolution-precipitation controlled sodium-potassium ion replacement reaction. This study provides theoretical guidance for the preparation of mineral fertilizer from bauxite residue and has practical production potential, opening up a new perspective for bauxite residue resource usage in the agricultural field.