Mineralization Efficiency Research Articles

Optimization of hollow fiber membrane contactor system for CO2 mineralization using seawater brine: Comparative analysis of performance and transport mechanisms

Carbon mineralization is a promising approach for carbon capture, utilization, and storage (CCUS) but still faces technical and economic challenges. This study reports on CO2 mineralization using various hollow fiber membrane contactors (HFMCs) to optimize the system and understand the mass transport mechanism. We conducted a quantitative comparative assessment through theoretical and experimental approaches to evaluate the performance of three HFMC types with different morphological and chemical characteristics at various gas and liquid velocities. Results showed that the in-house developed highly porous hollow fiber (HF) membrane exhibited superior CO2 capture efficiency compared to commercial membranes. In contrast to other HFMCs showing a sharp decline in CO2 flux due to internal fouling caused by pore wetting and external fouling, the highly porous HF membrane with surface modification maintained stable performance during continuous operation due to its superhydrophobicity and surface roughness. The HF membrane also achieved the highest overall mass transfer coefficients, closely matching the theoretical non-wetted mode due to negligible partial wetting. We expect that this study will provide insights into optimizing HFMCs for enhanced carbon mineralization efficiency.

Oxygen Vacancy Engineering and Constructing Built-In Electric Field in Fe-g-C3N4/Bi2MoO6 Z-Scheme Heterojunction for Boosting Photo-Fenton Catalytic Degradation Performance of Tetracycline.

A novel Fe-g-C3N4/Bi2MoO6 (FCNB) Z-scheme heterojunction enriched with oxygen vacancy is constructed and employed for the photo-Fenton degradation of tetracycline (TC). The 2% FCNB demonstrates prominent catalytic performance and mineralization efficiency for TC wastewater, showing activity of 8.20 times greater than that of pure photocatalytic technology. Density-functional theory (DFT) calculations and degradation experiments confirm that the formation of Fe-N4 sites induces spin-polarization in the material, and the difference in Fermi energy levels results in the formation of built-in electric field at the contact interface, which facilitates the continuous generation and migration of photogenerated carriers to address the issue of insufficient cycling power of Fe (III)/Fe (II).The reactive radicals persistently target the extremely reactive sites anticipated by the Fukui function, causing the mineralization of TC molecules into "non-toxic" compounds through processes of hydroxylation, demethylation, and deamidation. This work holds significant importance in the domain of eliminating organic pollutants from water.

Investigating the Potential of Microbially Induced Carbonate Precipitation Combined with Modified Biochar for Remediation of Lead-Contaminated Loess

Lead (Pb) contamination in loess poses a significant environmental challenge that impedes sustainable development. Microbially induced carbonate precipitation (MICP) is an innovative biomimetic mineralization technology that shows considerable promise in remediating soil contaminated with heavy metals. However, the toxicity of lead ions to Bacillus pasteurii reduces the efficiency of mineralization, subsequently diminishing the effectiveness of remediation. Although biochar can immobilize heavy metal ions, its adsorption instability presents a potential risk. In this study, we first compared the pH, electrical conductivity (EC), unconfined compressive strength (UCS), permeability coefficient, and toxicity leaching performance of lead-contaminated loess specimens remediated using biochar (BC), red mud (RM), red-mud-modified biochar (MBC), and MICP technology. Additionally, we evaluated the mechanism of MICP combined with varying amounts of MBC in remediating lead-contaminated loess combing Zeta potential, X-ray diffraction (XRD) analyses, and scanning electron microscopy (SEM) tests. The results showed that MICP technology outperforms traditional methods such as RM, BC, and MBC in the remediation of lead-contaminated loess. When MICP is combined with MBC, an increase in MBC content results in a higher pH (8.71) and a lower EC (232 us/cm). Toxic leaching tests reveal that increasing MBC content reduces the lead leaching concentration in loess, with optimal remediation being achieved at 5% MBC. Microscopic analysis indicates that the remediation mechanisms of MICP combined with MBC involve complexation, electrostatic adsorption, ion exchange, and precipitation reactions. The synergistic application of MICP and MBC effectively adsorbs and immobilizes lead ions in loess, enhancing its properties and demonstrating potential for pollution remediation and engineering applications.

Metal oxide-combined sol-gel synthesized ceria nanoparticles: An operative photocatalyst for visible-light-driven mineralization of ciprofloxacin antibiotic in water

The superb spreading of antibiotic waste represents a vital issue related to water and soil contamination that distress the environment and humankind. Accordingly, various research projects for the eco-friendly degradation of such contaminants. Here, we envisioned the coupling of narrow bandgap (Eg) metal oxide with copolymeric-assisted sol-gel-prepared ceria nanoparticles (CeO2) for photoelimination of ciprofloxacin (CiP) as a model for antibiotic waste in water. The few tens nanometer-sized cubic CeO2 was receptive to the irradiated visible light by a combination of a few nanometer-sized AgVO3, Bi2O3, and CoTiO3 at 10.0 wt% by simple precipitation of their salt precursors. The designed nanostructures exposed mesoporous surfaces similar to the pristine CeO2 with a specific surface area range of 165–169 m2 g−1. The 1.25 mg mL−1 dose CoTiO3-composited CeO2 displayed the best-performed photomineralization of CiP (98 ± 1.2 %) within only 2 h of light illumination compared to added oxides with an outstanding reaction rate of 0.0297 min−1. In addition, the CoTiO3/CeO2 displayed a bearable recyclability of five times with 93 % of its mineralization efficiency. The boosted photoactivity of CoTiO3/CeO2 is referred to the momentous light captivation and a band alignment with Eg minimization to 2.48 eV. Also, the constructed heterojunction among n-type CoTiO3 and n-type CeO2 has improved the photoexcited charge separation and migration as resolved by high photocurrent and photoluminescence suppression. Such a comparative study proposes an efficient photocatalyst design for clean and sustainable antibiotic waste remediation.

Preparation and application of wood-supported piezocatalyst with high efficiency and stability via partial hydrolysis of wood cellulose and hemicellulose with Lewis acid

The conveniently recoverable piezocatalyst with self-floating and stable performance has drawn wide attention. Herein, MoS2 was anchored on 1-cm-square eucalyptus wood blocks via a facile hydrothermal/solvothermal process to fabricate two floating piezocatalysts, i.e., MoS2/unpretreated wood (MUW) and MoS2/pretreated wood (MPW). FeCl3 solution was used as a Lewis acid to pretreat the wood through partial hydrolyzing cellulose and hemicellulose for an purpose to creat rich micropores for MoS2 loading in the wood and to form MoFe heterojunction. The piezocatalytic properties and performance of the prepared wood were systematically studied. The scanning electron microscopy confirms MoS2 was anchored on wood surface. The macroscopic photos show that MoS2 penetrated through the MPW interior whereas it was only loaded on the wood surface layer. The X-ray photoelectron spectroscopy reveals the shift of Mo 3d and S 2p, verifying the heterojunction formation of MPW. The Fourier transform infrared spectra prove the partial hydrolysis of wood matrix. In comparison to MUW, MPW had excellent piezocatalytic property, wide pH adaptability, convenient recyclability and high stability. Sildenafil and Cr6+ ions could be completely removed in 20 and 15 min, respectively, by MPW. Contrastly, the removal efficiency of sildenafil and Cr6+ by MUW was 78.6 % and 68.3 % in 20 and 15 min, respectively. After five cycles of use, the removal ratio of sildenafil was 62.4 % by MUW and 90.5 % by MPW in 20 min. The mineralization efficiency of sildenafil reached 99.2 % in 30 min by MPW, and various types of N/S-containing intermediates were effectively degraded. The electron spin resonance characterization and active species scavenging experiments displayed that e− and •O2− were major active species responsible for Cr6+ piezoreduction by MUW and MPW, while •O2− and •OH were the dominant species accounting for sildenafil degradation by MUW and MPW, respectively. And •OH was not generated in the MUW piezocatalysis process. MPW had higher piezoelectric current and lower resistance at the electron transfer interface than MUW. Conclusively, this study paves a new pathway for preparing new floating piezocatalysts with easy recyclability and high stability from biomass for wastewater treatment.

Experimental study on the effect of hydrothermal activation on the physicochemical properties and mineralization efficiency of fly ash-supercritical CO2

To address the challenge of low mineralization efficiency of fly ash-supercritical carbon dioxide (CO2), a hydrothermal activation method was proposed to enhance fly ash-supercritical CO2 mineralization. The study systematically investigated the mechanism through which hydrothermal activation parameters influenced the efficiency of fly ash-supercritical CO2 mineralization through a series of experimental reactions. The effects of hydrothermal activation temperature and time on mineralization efficiency were investigated macroscopically. The results indicated that the mineralization efficiency increased by 202.93 % when hydrothermally activated at 220 °C for 30 min. Furthermore, when the activation time was ≤10 min, 220 °C exhibited a significant effect on the mineralization efficiency. For activation time ≥20 min, mineralization efficiency exhibited high stability with increasing temperature. Subsequently, under 220 °C conditions, mineralization efficiency reached 18.79 % for 5 min and 21.69 % for 30 min, representing only a 15.43 % increase despite a six-fold increase in time. Microscopic analysis of the pore structure of hydrothermally activated fly ash indicated that pore parameters (volume, specific surface area, and volume change rate) exceeded those of original fly ash for pore diameters ≥9 nm, and the opposite was observed for pore diameters <9 nm. Additionally, compared with the pristine fly ash, the pore size and volume fraction of the mineralized fly ash macropores increased, while mesopores decreased, and small pores exhibited a slight decrease in volume fraction and size. This indicated that pores ≥9 nm were primarily affected by hydration expansion, while pores <9 nm were primarily affected by mineralization precipitation. The hydrothermal activation mineralization reaction predominantly affected medium and large pores ≥9 nm, exhibiting less effect on smaller pores.

Multi-field and multi-scale dynamic numerical modeling of supercritical CO2 and fly ash mineralization

Fly ash-CO2 mineralization technology can effectively control gas–solid waste emissions and improve the climate environment. However, rationally describing the evolution mechanism of the fly ash-supercritical CO2 mineralization reaction and accurately predicting the efficiency of the mineralization reaction are of great significance for improving and evaluating the supercritical CO2 mineralization sequestration capacity. Fly ash micro- and nanopore multi-scale effects are the key to influencing the supercritical CO2 seepage-mineralization reaction mechanism. None of the current theoretical models consider the pore multi-scale effects, thus the validity and accuracy of predicting and describing the evolutionary mechanism of supercritical CO2 mineralization rates and efficiencies are questionable. To address this scientific issue, a multi-scale continuous pore structure theoretical model was established based on the structural characteristics of fly ash micro- and nanopores. Additionally, a new model of supercritical CO2 multi-field and multi-scale dynamic mineralization theory was developed by considering parameters such as temperature, pressure, and humidity. The accuracy of the model was verified through the mineralization experiments. The new model effectively describes the dynamic evolution mechanism of supercritical CO2 mineralized fly ash. The effects of parameters such as temperature, pressure, water vapor diffusion coefficient, supercritical CO2 permeability, and pore multi-scale effect on the efficiency and mineralization rate were investigated through numerical simulation. The results showed the following: The mineralization efficiency exhibited a parabolic increase with temperature, with 72℃ being the turning point for the growth rate of mineralization efficiency, and 82℃ being the optimal effective temperature to promote the mineralization efficiency of supercritical CO2. A 3.5-fold increase in supercritical CO2 pressure changes the mineralization efficiency by a maximum of only 0.0493 %. Increasing the water vapor diffusion coefficient by 5 orders of magnitude changes the mineralization efficiency by only 8.3 %. The pore attenuation coefficient increases by 3 orders of magnitude, and the supercritical CO2 mineralization efficiency changes by a factor of 2.27. A model that does not account for pore multi-scale effects overestimates the fly ash- supercritical CO2 mineralization efficiency by a factor of 2.47 at a permeability of 3 × 10-10 m2. Therefore, neglecting the pore continuum multi-scale effect can lead to a serious overestimation of the mineralization efficiency of supercritical CO2.

Efficient photocatalytic degradation of malachite green dye from wastewater using facilely synthesized ternary ZIF-8/Ag/Ag2S nanocomposite: Optimization by RSM (CCD)

The current study compares the photocatalytic potential of zeolitic imidazolate framework-8 (ZIF-8) with ZIF-8 nanocomposites doped with two forms of silver (referred to as AgNPs/ZIF-8 and AgNPs/Ag2S/ZIF-8). Their physicochemical characteristics were evaluated using Fourier-transform infrared, X-ray diffraction, energy-dispersive X-ray, Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL), photocurrent density, Mott-Schottky, and Brunauer Emmett Teller techniques. The photocatalytic activity of the composites was assessed for degradation of malachite green (MG) under visible light irradiation in a solar-based staircase photoreactor for the first time. The optimization of the photodegradation process was achieved by employing central composite design, 0.020 g of AgNPs/ZIF-8 and ZIF-8photocatalyst (in 20 ml of solution), MG Concentration of 7 mg/l, pH of 8, and the irradiation time of 50 min. The predicted model had R2 and R2adj correlation coefficients of 0.987 and 0.975 respectively, which showed experimental results were very close to the predicted values. The results indicated remarkable efficiency in both degradation and mineralization, achieving the degradation rate of up to 98.6 %, a high-rate constant value of 0.0701 min-¹, and an 80 % mineralization efficiency. AgNPs/Ag2S/ZIF-8 exhibited superior photocatalytic performance in comparison to both AgNPs/ZIF-8 and ZIF-8. Different scavengers were used in the experiment and demonstrated that O2− played a crucial role in the photodegradation of MG. Moreover, the nanocomposite AgNPs/Ag2S/ZIF-8 exhibited robust stability and could be repeatedly utilized up to five cycles without notable decline in efficacy, rendering it an environmentally sustainable photocatalyst with promising prospects for industrial utilization.

Enhanced removal of tetracycline in light-dark tandem by FeCu-doped carbon composites derived from waste cotton fabrics

It is of great significance to develop an energy-efficient and external oxidant-free strategy for antibiotics removal. In this study, the novel light-dark tandem strategy was established to enhance tetracycline (TC) removal by bifunctional FeCu-doped carbon composites (FeCu@BC) derived from waste cotton fabrics. Interestingly, over 95 % TC was removed by FeCu@BC under light alone and dark alone in 10 min, with the same preferred conditions of pH 7.50 and 0.04 g/L catalyst dosage. Surprisingly, the enhanced mineralization efficiency of TC was achieved by the light-dark tandem without adjusting the parameters as 86.65 %, which was 1.13, 1.46 and 2.12 times higher than those of the dark-light tandem, light alone and dark alone, respectively. The mechanisms were elucidated as that 83.28 % direct degradation and 4.37 % indirect degradation under light while 47.63 % direct degradation and 24.16 % indirect degradation under darkness contributed for TC removal. The synergetic effects of persistent free radicals (PFRs) and FeCu interactions enabled FeCu@BC to work efficiently under both light and darkness, and light enhanced electron transfer between PFRs and FeCu interactions. Furthermore, energetic electrons stored in these active sites under light could be extracted to enhance electron transfer under subsequent darkness and the strongly catalytically active species initiated under light remained in action after cessation of light. Finally, high molecular TC was easily decomposed by energetic photo-catalysis and low molecular intermediates were mineralized under subsequent enhanced dark-catalysis to increase the mineralization efficiency. In general, this study provided an eco-friendly organics removal strategy and mechanisms insights based on the natural day-night cycle.

Insight into the performance and mechanism of N,O,S-codoped porous carbon based CO single-atom catalysts in organic oxidation through peroxymonosulfate activation

Single-atom catalysts (SACs) are charming for heterogeneous Fenton-like processes due to their unique and adjustable electron structure. Developing novel SACs and elucidating their mechanisms are critical for the development of water purification techniques. Herein, we present an N,O,S-codoped carbon based Co SAC (CoSA-N-CO,S) synthesized by anchoring isolated Co atoms onto porous carbon derived from low-cost protic salt. This catalyst exhibits significant efficiency in activating peroxymonosulfate (PMS) for rapid ibuprofen (IBU) degradation, achieving approximately 98.2 % within 10 min at a concentration of 0.2 g/L catalyst and 2 mM PMS, under ambient pH and at 30 °C, and demonstrates excellent reusability. Intensive studies reveal that the highly active atomic Co sites are favorable for activating PMS to produce both radical (SO4− and OH) and nonradical 1O2, while the electron-rich O and S sites contribute to PMS reduction to generate SO4− and OH. The CoSA-N-CO,S/PMS system leverages the synergy between radical and nonradical oxidation across multiple active sites, resulting in exceptional resistance to interference and high efficiency in degradation and mineralization of diverse organic pollutants. This study develops a novel single-atom catalyst for wastewater treatment and elucidates the mechanism behind PMS activation by a carbon-based cobalt single atom catalyst.

Comparative study on solar photocatalytic degradation of naproxen using nitrogen doped ZnO and nitrogen doped TiO2: Kinetics and Intermediates analysis

Solar photocatalytic degradation of Naproxen (NPX) in a synthetic wastewater was evaluated with synthesized nitrogen doped TiO2 and nitrogen doped ZnO and compared with commercial TiO2 and ZnO. The effect of operating parameters such as initial NPX concentration (1–3.5 mg/l), catalyst dosage (0.15–0.5 g/l), pH (4.5–9.0), and contact time (0–330 min) on NPX degradation was investigated in detail. The batch study showed 93 %, 90 %, 71 % and 85 % NPX degradation on average solar intensities (1200–1420 W/m2) with ZnO, N-ZnO, TiO2 and N-TiO2 respectively for optimised conditions (initial NPX concentration-2 mg/l, (ZnO & N-ZnO)−0.35 g/l, (TiO2 & N-TiO2)−0.15 g/l, pH-4.5 and contact time-180 min). Kinetic investigations on photocatalytic degradation of NPX were carried out for the initial 1 h duration and it complied with pseudo-first order kinetics with the four catalysts, whereas ZnO showed the highest rate constant (k = 0.0331/minutes). Depth of reactor solution had no significant impact on NPX degradation. Continuous process was conducted along with TOC analysis for HRT of 60 min, which showed mineralization efficiencies of 36 %, 26 % and 16 % for N-TiO2, ZnO and N-ZnO respectively. The 90th percentile solar light intensity corresponding to the maximum NPX degradation was found to be 1100 W/m2. Quantum yield were calculated for NPX degradation with and without catalyst, it showed 35 % for ZnO and 3.5 % for photolysis. The intermediates and mineralization efficiency was analysed using LC-MS and TOC analyzer respectively. This study concluded that N-TiO2 had better NPX removal and mineralization efficiency along with formation of simpler compounds and organic acids as the end products.

Enhancing carbon mineralization of slag leachate using amine-functionalized magnetic nanoparticle clusters

Carbon mineralization—converting carbon dioxide (CO2) into stable carbonate minerals, such as calcium carbonate (CaCO3)—has attracted much attention as a permanent way to sequester CO2. In this study, we developed a novel method for improving the efficiency of carbon mineralization using amine-functionalized magnetic nanoparticle clusters (A-MNCs). To prepare them, magnetic nanoparticle clusters composed of tens of small Fe3O4 nanoparticles were treated with 3-aminopropyltriethoxysilane to functionalize amine groups on their surfaces. When CO2 was bubbled into a NaOH solution, the rate of CO2 dissolution was enhanced in the presence of A-MNCs, mostly due to physical effects such as grazing and hydrodynamic effects that improved mass transfer between the solution and CO2 bubbles. In addition, A-MNCs promoted carbon mineralization in a NaOH solution containing Ca2+ by providing an additional mineralization route via carbamate formation, resulting in a threefold increase in efficiency to 81 %. We demonstrated that A-MNCs could be applied to leachate from slag, a byproduct of commercial steelmaking, increasing the efficiency by 2.6 times compared to the absence of A-MNCs. The resulting CaCO3 precipitate was confirmed to be calcite using X-ray diffraction and scanning electron microscopy. Furthermore, after the mineralization, A-MNCs were easily separated from the solution using a permanent magnet, while retaining their performance.

Efficient degradation of organics via sodium p-styrene sulfonate modified PbO2 electrode: The role of boosting electrocatalytic performance

In this work, Sodium p-styrene sulfonate (SSS)/PbO2 electrode was successfully prepared and further applied for the electrocatalytic degradation of methyl blue (MB). 95.8 % of methylene blue degradation via PbO2 electrodes was observed at the optimized conditions (100 mg/L of MB solution, current density of 30 mA·cm−2, pH=5, 180 min). When compared with PbO2 electrodes, SSS/PbO2 electrode was found to possess most effective electrocatalytic activity due to its higher oxygen evolution potential, lower charge transfer resistance, and longer service lifetime. When the concentration of SSS increases to 2vt.%, the grain size of PbO2 decreases from 21.79 nm to 19.42 nm, and the degradation rate of MB was enhanced for 5 %. Besides, the degradation rate of SSS/PbO2 electrode remained 86 % after 10 cycles, indicating that the stability and catalytic activity of the electrode were improved when the PbO2 was decorated by SSS. Moreover, the law of degradation of MB catalyzed by SSS/PbO2 electrode follows the first order kinetics. Furthermore, the energy consumption and mineralization efficiency of the SSS/PbO2 electrode were 68.73 kWh· L-1 and 4.39 %, respectively. Finally, a possible mechanism was proposed, which was further uncovered by DFT calculations.

Functional biochar accelerates peroxymonosulfate activation for organic contaminant degradation via the specific B–C–N configuration

Functional biochar designed with heteroatom doping facilitates the activation of peroxymonosulfate (PMS), triggering both radical and non-radical systems and thus augmenting pollutant degradation efficiency. A sequence of functional biochar, derived from hyperaccumulator (Sedum alfredii) residues, was synthesized via sequential doping with boron and nitrogen. The SABC-B@N-2 exhibited outstanding catalytic effectiveness in activating PMS to degrade the model pollutant, acid orange 7 (Kobs = 0.0655 min−1), which was 6.75 times more active than the pristine biochar and achieved notable mineralization efficiency (71.98%) at reduced PMS concentration (0.1 mM). Relative contribution evaluations, using steady-state concentrations combined with electrochemical and in situ Raman analyses, reveal that co-doping with boron and nitrogen alters the reaction pathway, transitioning from PMS activation through multiple reactive oxygen species (ROSs) to a predominantly non-radical process facilitated by electron transfer. Moreover, the previously misunderstood concept that singlet oxygen (1O2) plays a central role in the degradation of AO7 has been clarified. Correlation analysis and density functional theory calculations indicate that the distinct BCN configuration, featuring the BC2O group and pyridinic-N, is fundamental to the active site. This research substantially advances the sustainability of phytoremediation by offering a viable methodology to synthesize highly catalytic functional biochar utilizing hyperaccumulator residues.

Enhanced photocatalytic degradation of toluene on surface C- and CN-modified TiO2 microspheres

Surface modified TiO2 materials are widely used in photocatalytic environmental purification processes. The employment of solution might exert a discernible influence on the catalyst. In this study, we incorporated tetrahydrofuran (THF) and pyrrolidine (PY) during the hydrolysis of titanium butoxide (TBOT) to modify the surface of TiO2, successfully synthesizing surface C-modified TiO2 (THF-TiO2) and surface CN-modified TiO2 (PY-TiO2) catalysts. The assistance of THF and PY not only reduced agglomeration, but also increased the specific surface area of both catalysts, leading to the exposure of more active sites in TiO2 during the photocatalytic degradation of toluene. When compared to the unsatisfactory degradation of toluene (80%) and CO2 mineralization efficiencies (40–45 %) observed using unmodified TiO2, the synthesized THF-50-TiO2 and PY-1-TiO2 microspheres demonstrated enhanced toluene degradation efficiency to 100 % and 99.8 %, respectively, and improved mineralization efficiencies to 76 % and 80 % after 120 min of ultraviolet irradiation. The experimental data and characterization results indicate that the surface-modified carbon species in THF-50-TiO2 facilitate the acceleration of electron-hole pair separation and suppress recombination. In contrast, partial nitrogen species introduced into the surface lattice of PY-1-TiO2 narrow its band gap and induce a visible light response. Overall, this study provides two methods to modify the surface of TiO2, which can be applied to prepare outstanding photocatalysts for possible application in the degradation of volatile organic compounds (VOCs) present in the air. Furthermore, it has been confirmed that solution have a significant impact on the catalyst.

CO2-brine interactions in anhydrite-rich rock: Implications for carbon mineralization and geo-storage

The utilization of subsurface geologic media for carbon capture and storage through mineralization has been recognized as a reliable approach. However, less attention has been given to anhydrite rock type for CO2 mineralization and storage. Anhydrite-rich rock formations, commonly found in various geological settings, have the potential to serve as natural carbon sinks through the mineralization of CO2. Therefore, this study aims to investigate the mechanisms and potential of anhydrite-CO2-brine interactions for carbon storage. The experimental approach involved exposing anhydrite-rich rock to supercritical CO2-brine environments under varying conditions of fluid composition. Mineral transformation of an outcrop anhydrite-rich rock sample in static reactor under subsurface conditions of elevated temperature (60 °C) and pressure (104 bar), in the absence and the presence of SrCl2 was conduct for a one-month period. Mineralogical and geochemical analyses, including, solution analyses, X-ray fluorescence, X-ray diffraction, micro-computed tomography, and mechanical properties were conducted to examine the changes in the composition and rock structure resulting from the interactions. The experimental reactions revealed that anhydrite undergoes mineral transformation upon exposure to supercritical CO2-saturated brine to form stable minerals including calcite, dolomite, magnesite, and strontianite, which contributes to the potential for long-term storage of CO2 in the subsurface geologic media. The efficiency and extent of carbon mineralization were found to be influenced by brine composition. These findings contribute to the understanding of the potential of these formations for carbon storage, opening avenues for further research and the development of effective carbon capture and storage strategies.

Magnetic-supported catalyst derived from red mud-based Fe-Co PBA for efficient degradation of organic pollutants by activating peroxymonosulfate under visible light

To alleviate the environmental pressure caused by the continuous accumulation of solid waste red mud (RM) and organic pollutants, we developed a magnetic-supported catalyst derived from RM-based Fe-Co Prussian blue analogues (RM-Co PBA-D) using RM as the iron source and carrier. Then, the catalyst was used to activate peroxymonosulfate (PMS) under visible light for the degradation of tetracycline (TC) and rhodamine B (RhB). Due to the superior dispersion, strong visible light response, and high photo-generated carrier separation efficiency of the RM-Co PBA-D, the RM-Co PBA-D/PMS/Vis system could completely degrade both TC (10 mg/L) and RhB (20 mg/L) in 30 min, with mineralization efficiencies as high as 70.12 % and 60.59 %, respectively. Several reactive oxygen species (ROS) such as SO4⋅−, ⋅OH−, ⋅O2−, 1O2, and h+ were involved in the degradation process, with SO4⋅− and 1O2 playing a dominant role. More importantly, except for the production of ROS, the regeneration of active sites (Co2+/Fe2+) mediated by photo-generated carriers was also a critical factor in enhancing the removal of organic pollutants. In addition, the constructed system demonstrated significant potential for practical applications, which was attributed to the stable structure and catalytic performance of the catalyst as well as the strong ability of the system to resist interference by impurity anions and detoxify organic pollutants.

Oxygen vacancy mediated photocatalysis of Ti3C2 MXene quantum dots/W18O49 hybrid membrane for peroxymonosulfate-enhanced oxidation degradation

Photocatalytic membrane technology shows great prospects in water decontamination. Coupling photocatalysis with peroxymonosulfate (PMS) can boost oxidation capacity by combining their superiorities sufficiently. Herein, 0D Ti3C2 MXene quantum dots (TMQDs) embedded oxygen vacancy-rich 3D sea urchin-like W18O49 microspheres (OTW) were synthesized via facile interface engineering combined with green plasma etching strategy. The visible-light driving flow-through membrane reactor was capable of degrading cyclophosphamide, a typical anticancer drug, and other common pollutants (5-fluorouracil, carbamazepine, bisphenol A, rhodamine B), with the removal and mineralization efficiencies of 10 μM pollutants reaching over 99 % and 63 %−79 % in 60 min with 0.5 mM PMS. Moreover, the long-term reliability of OTW membrane was validated through continuous treatment of 20 L sewage. Significantly, the newly designed photocatalytic membrane exhibited good tolerance to wide pH ranges, common coexisting substances in water, and various actual water matrix. The results of experimental and DFT theoretical calculations revealed that Schottky junction formed on the TMQDs/W18O49 interfaces and tunable O-defects could optimize electronic configuration, improve solar energy utilization, prevent photogenerated carriers’ recombination, promote H2O and PMS dissociation, making it possible that more •OH and SO4•− radicals participated in the oxidation degradation reaction. This study offers a design idea for preparing efficient and robust photocatalytic membrane via interface engineering and defect engineering strategies, which might contribute to bridging the translational gap between emerging photocatalytic techniques and practical environmental applications in near future.

Redefining water purification: gC3N4-CLDH's electrochemical SMX eradication

The contamination of water sources by pharmaceutical compounds presents global environmental and health risks, necessitating the development of efficient water treatment technologies. In this study, the synthesis, characterization, and evaluation of a novel graphitic carbon nitride-calcined (Fe–Ca) layered double hydroxide (gC3N4-CLDH) composite for electrochemical degradation of sulfamethoxazole (SMX) in water yielded significant outcomes are reported. SEM, XRD, FTIR, and XPS analyses confirmed well-defined composite structures with unique morphology and crystalline properties. Electrochemical degradation experiments demonstrated >98% SMX removal and >75% TOC removal under optimized conditions, highlighting its effectiveness. The composite exhibited excellent mineralization efficiency across various pH levels, with superoxide radicals (O2●–) and hydroxyl radicals (●OH) identified as primary reactive oxygen species. With remarkable regeneration capability for up to 7 cycles, the gC3N4-CLDH composite emerges as a highly promising solution for sustainable water treatment. Humic acid (HA) in water significantly slows SMX degradation, suggests complicating SMX degradation with natural organic matter. Despite this, the gC3N4-CLDH composite effectively degrades SMX in groundwater and industrial wastewater, with slight efficiency reduction in the latter due to higher impurity levels. These findings highlight the complexities of treating pharmaceutical pollutants in various water types. Overall, gC3N4-CLDH's high removal efficiency, broad pH applicability, sustainability, and mechanistic insights provide a solid foundation for future research and real-world environmental applications.

Optimization of cerium-based metal–organic framework synthesis for maximal sonophotocatalytic tetracycline degradation

Wastewater treatment is inevitably required to alleviate the pollution of water resources by various contaminants such as antibiotics. MOFs are novel materials with photocatalytic activities. In this study, sonophotocatalytic degradation of tetracycline (TC) by the Cerium-based MOF (Ce-MOF) is optimized by modification of its synthesis route. Ce-MOF synthesis by room temperature (RT), hydrothermal (HT), and sonochemical synthesis (SC) are studied. TC degradation experiments revealed the superiority of SC synthesis. The interplay of main synthesis parameters, namely, initial ligand concentration, ultrasound (US) power and time on sonophotocatalytic activity of Ce-MOF, were investigated by response surface methodology model (RSM) utilizing the central composite experimental design (CCD). The optimum SC synthesis conditions are an initial ligand concentration of 8.4 mmol/L, a sonication power of 50 amplitude, and a US time of 60 min. The optimally synthesized Ce-MOF was characterized by infrared spectroscopy, FTIR, XRD, FE-SEM, TEM, zeta potential analysis, diffuse reflectance spectroscopy, particle size analysis, Mott-Schottky analysis, photocurrent analysis, electrochemical impedance spectra, and photoluminescence spectroscopy. The findings indicate that the removal efficiency of TC can reach up to 81.75% within 120 min in an aqueous solution containing an initial TC concentration of 120 ppm and 1 g/L Ce-MOF at pH of 7. Mineralization efficiency of the process is 71% according to COD measurements. The Ce-MOF catalyst retained its chemical stability and remained active upon TC degradation which makes it a promising candidate for wastewater treatment.