Sodium Persulfate Research Articles

Schwertmannite catalyze persulfate to remove oxytetracycline from wastewater under solar light or UV-254

Oxytetracycline (OTC) pollution has become an important environmental issue. It is an obvious innovation in the field of OTC degradation to comprehensively explore the effect of Schwertmannite (Sch) catalyzed persulfate to degrade OTC under different light conditions, and apply the optimized parameters to remove OTC from actual aquaculture wastewater. Therefore, the effect of sodium persulfate (PS) on the removal of OTC catalyzed by Sch under solar light and UV-254 irradiation was investigated in this study, and the optimized parameters were applied to the OTC removal from actual aquaculture wastewater. The results showed that when 0.8 g/L Sch was added and the concentration of PS was 350 μmol/L, the removal rate of OTC (40 μmol/L) was 89.8% and 92.3% after 3 h and 6 h reactions in dark conditions, respectively. Furthermore, light significantly enhanced the removal efficiency of OTC. The removal rates of OTC in the Sch + PS + OTC system were 96.8% and 99.1% after 3 h and 6 h reactions under UV-254 irradiation, respectively. In addition, it was shown that light accelerated the removal of total organic carbon (TOC); the TOC removal rates after 3 h and 6 h under UV-254 in the Sch + PS + OTC system were 49.8% and 69.7%, respectively. In actual aquaculture wastewater, the removal rates of OTC after 6 h in the Sch + PS + OTC + UV-254 system were 21.7%, 22.7%, 46.1%, 55.1%, 74.1%, 94.5%, and 98.3%, respectively, when the COD concentrations in wastewater were 10,000 mg/L, 5000 mg/L, 2000 mg/L, 1000 mg/L, 500 mg/L, 200 mg/L, and 100 mg/L. The recovery rate of Sch after the reaction in actual aquaculture wastewater was 70.0–99.8%, and the pH after treatment remained neutral. These findings provide theoretical support for the treatment of OTC-containing wastewater via the advanced oxidation technology catalyzed by Sch.

Application of machine learning algorithms in predicting the photocatalytic degradation of perfluorooctanoic acid

ABSTRACT Perfluorooctanoic acid (PFOA) is used in a variety of industries and is highly persistent in the environment, with potential human health risks. Photocatalysis has been extensively used for the decomposition of various organic pollutants, yet its simulation and modeling are challenging. This research aimed to establish different machine learning (ML) algorithms which can simulate and predict the photocatalytic degradation of PFOA. The published results were used to estimate and predict the photocatalytic degradation of PFOA. Statistical criteria including the coefficient of determination (R2 ), mean absolute error (MAE), and mean squared error (MSE) were considered in assessing the best method of modeling. Among the seven ML algorithms pre-screened, Adaptive Boosting (AdaBoost), Gradient Boosting Machine (GBM), and Random Forest (RF) showed the best performance and were chosen for deep modeling and analysis. Grid search was used to optimize the models developed by AdaBoost, GBM, and RF; and permutation variable importance (PVI) was used to analyze the relative importance of different variables. Based on the modeling results, GBM model (R2 = 0.878, MSE = 106.660, MAE = 6.009) and RF model (R2 = 0.867, MSE = 107.500, MAE = 6.796) showed superior performances compared with AdaBoost model (R2 = 0.574, MSE = 388.369, MAE = 16.480). Furthermore, the PVI results suggested that the GBM model provided the best outcome, with the light irradiation time, type of catalyst, dosage of catalyst, solution pH, irradiation intensity, initial PFOA concentration, oxidizing agents (peroxymonosulfate, ammonium persulfate, and sodium persulfate), irradiation wavelength, and solution temperature as the most important process variables in decreasing order.

Ruthenium-induced corneal collagen crosslinking under visible light

Corneal collagen crosslinking (CXL) is a commonly used minimally invasive surgical technique to prevent the progression of corneal ectasias, such as keratoconus. Unfortunately, riboflavin/UV-A light-based CXL procedures have not been successfully applied to all patients, and result in frequent complications, such as corneal haze and endothelial damage. We propose a new method for corneal crosslinking by using a Ruthenium (Ru) based water-soluble photoinitiator and visible light (430 nm). Tris(bipyridine)ruthenium(II) ([Ru(bpy)3]2+) and sodium persulfate (SPS) mixture covalently crosslinks free tyrosine, histidine, and lysine groups under visible light (400–450 nm), which prevents UV-A light-induced cytotoxicity in an efficient and time saving collagen crosslinking procedure. In this study, we investigated the effects of the Ru/visible blue light procedure on the viability and toxicity of human corneal epithelium, limbal, and stromal cells. Then bovine corneas crosslinked with ruthenium mixture and visible light were characterized, and their biomechanical properties were compared with the customized riboflavin/UV-A crosslinking approach in the clinics. Crosslinked corneas with a ruthenium-based CXL approach showed significantly higher young's modulus compared to riboflavin/UV-A light-based method applied to corneas. In addition, crosslinked corneas with both methods were characterized to evaluate the hydrodynamic behavior, optical transparency, and enzymatic resistance. In all biomechanical, biochemical, and optical tests used here, corneas that were crosslinked with ruthenium-based approach demonstrated better results than that of corneas crosslinked with riboflavin/ UV-A. This study is promising to be translated into a non-surgical therapy for all ectatic corneal pathologies as a result of mild conditions introduced here with visible light exposure and a nontoxic ruthenium-based photoinitiator to the cornea. Statement of significanceKeratoconus, one of the most frequent corneal diseases, could be treated with riboflavin and ultraviolet light-based photo-crosslinking application to the cornea of the patients. Unfortunately, this method has irreversible side effects and cannot be applied to all keratoconus patients. In this study, we exploited the photoactivation behavior of an organoruthenium compound to achieve corneal crosslinking. Ruthenium-based organic complex under visible light demonstrated significantly better biocompatibility and superior biomechanical results than riboflavin and ultraviolet light application. This study promises to translate into a new fast, efficient non-surgical therapy option for all ectatic corneal pathologies.

Enhanced removal of tetracycline via advanced oxidation of sodium persulfate and biochar adsorption.

Advanced oxidation of antibiotic tetracycline (TC) is becoming an accessible and efficient technology. The removal of TC from the complex wastewater needs to be lucubrated. In this study, a TC removal system involving degradation and adsorption was established. TC degradation was accomplished by enhanced advanced oxidation via the addition of sodium persulfate (SP) and biochar into simulated wastewater containing Mn2+ and TC wastewater. The adsorption of TC and its derivatives was removed by biochar. The results indicate that the optimized reaction parameters were 3.0g/L of biochar prepared at 600°C (B600) and 400mg/L of SP under acidic condition, and the removal percentage of TC was 87.48%, including 74.23% of degradation and 13.28% of adsorption; the anions Cl-, NO3-, and H2PO4- had negligible effects on the removal of TC in this Mn2+/B600/SP system. The system also functioned well with an aqueous solution with a high chemical oxygen demand (COD) concentration. Electron paramagnetic resonance (EPR) analysis indicated that ·OH and SO4- free radicals were present in the Mn2+/B600/SP system. Based on the testing and analysis results, a removal mechanism and potential TC degradation pathway for this system were proposed. TC can be degraded by ·OH and SO4- via three degradation pathways. Mn2+ can be precipitated as MnO2, and a part of the TC and its derivatives can be adsorbed on the biochar surface. The Mn2+/B600/SP system also performed satisfactorily for a complex aqueous solution with various cations and antibiotics.

CDs@Cr2O3 catalytic degradation of Orange II based on non-radical pathway

Carbon dots (CDs)-modified Cr2O3 (CDs@Cr2O3) composites were synthesized by solvothermal process followed by calcination to improve their catalytic performance. The physical and chemical properties of the composites were determined by XRD, SEM, TEM, BET and XPS. With the aid of sodium persulfate, the activity of CDs@Cr2O3 to oxidize Orange II by non-radicals was studied under various conditions. The experimental results determined the optimal dosage of PDS to be 0.1 g and the degradation results showed that after 45 min, the degradation rate of Orange II reached to 98.4% with the CDs@Cr2O3/PDS/Vis system. The adsorption capacity of CDs@Cr2O3 for Orange II was closely related to pH, and this phenomenon is further explained by the isoelectric point. A series of experiments proved that non-free radicals played a crucial role in the oxidation process, in which singlet oxygen (1O2), superoxide radical (O2•−) and photo-generated holes (h+) were determined as the important reactive oxygen species (ROS). In addition, the present study found that increasing dissolved oxygen could promote the reaction and the catalyst maintained good degradation performance after five cycles suggesting its stability.

Effect of pre-oxidation on galena in the flotation separation of chalcopyrite from galena with calcium lignosulfonate as depressant

In this work, to achieve efficient separation of chalcopyrite from galena in Cu–Pb sulfide minerals, pre-oxidation by sodium persulfate (Na2S2O8) was used to magnify the differences in the floatability of two minerals in the presence of calcium lignosulfonate (CLS). The micro-flotation results of chalcopyrite and galena showed that pre-oxidation by Na2S2O8 could strengthen the depression performance of CLS on galena. The strengthening mechanism of Na2S2O8 to CLS adsorption onto the galena surface was revealed by local electrochemical impedance spectroscopy (LEIS), zeta-potential analysis, and X-ray photoelectron spectroscopy (XPS). LEIS showed that oxidation by Na2S2O8 contributed to the adsorption of CLS on the galena surface. XPS analysis demonstrated that the main oxidation species on the galena surface were PbSO4 and Pb(OH)+ in the presence of Na2S2O8 and that CLS interacted with oxidized galena by chemisorption. Zeta potential analysis indicated that a positive oxidation species was adsorbed on the galena surface; moreover, the oxidation species Pb(OH)+ endowed CLS on the galena surface with excellent adsorption performance. These findings are also supported by the results of the solution chemistry calculation. Galena also exhibits terrible surface reactivity and responds poorly to xanthate collectors after interaction with Na2S2O8 and CLS.

Insights into the enhanced fluoranthene degradation in citric acid coupled Fe(II)-activated sodium persulfate system

Abstract Polycyclic aromatic hydrocarbons (PAHs), which are present in contaminated groundwater, have attracted increasing attention because of their serious harm to humans. In this study, the degradation performance of fluoranthene (FLT), a typical tetracyclic PAHs in organic contaminated sites, was investigated in the persulfate (PS)/Fe(II)/citric acid (CA) system. The effects of PS, CA, and Fe(II) doses on FLT degradation were tested. With the molar ratio at 60/20/5/1 of PS/Fe(II)/CA/FLT, FLT removal reached 96.3% in 120 min, much higher than 62% removal without CA at the same PS and Fe(II) doses, indicating that the addition of CA could remarkably enhance the FLT degradation. The water quality conditions (pH, anions and humic acid) were also investigated for their effects on FLT degradation. The results of probe tests, electron paramagnetic resonance detection and scavenging experiments showed that and acted predominantly on FLT degradation. The influence of surfactants on FLT degradation was examined. Furthermore, the primary degradation intermediates of FLT were detected by GC-MS and the possible degradation pathways of FLT were proposed. Finally, the effectiveness of the PS/Fe(II)/CA process for the FLT degradation in actual groundwater demonstrated that the process has a great prospect for the remediation of FLT-contaminated groundwater.

Preparation of Hemicellulose Nanoparticle-Containing Ionic Hydrogels with High Strength, Self-Healing, and UV Resistance and Their Applications as Strain Sensors and Asymmetric Pressure Sensors.

Smart functional fillers can significantly enhance the comprehensive properties of ionic hydrogels, such as their mechanical properties, which are key features of hydrogels in wearable sensor applications. As a plant-derived natural polymer, hemicellulose can serve as smart functional fillers. In this study, tannic acid-modified hemicellulose nanoparticles (TA@HC) and Fe3+ were used in the preparation of PAA/TA@HC/Fe3+ hydrogels. The addition of TA@HC and Fe3+ in the sodium persulfate (SPS) and acrylic acid (AA) polymerization system resulted in a fast gelation process that was completed within a short time (as short as 30 s) at room temperature. The catechol-rich TA and Fe3+ system allows for quick activation of SPS to produce free radicals, generating abundant hydroxyl groups in a short period of time, which was responsible for the fast gelation. Furthermore, due to the TA@HC effect and the dynamic catechol (TA)-Fe3+ redox system, the PAA/TA@HC/Fe3+ hydrogel exhibited excellent mechanical properties with an exceptionally high strain (as high as 5600%), adhesiveness, rapid and efficient self-healing ability, and reproducible self-adhesion onto various substrates. More importantly, asymmetric adhesive PAA/TA@HC/Fe3+ hydrogels were prepared by selective Fe3+ coating of the upper hydrogel surface to render the top surface nonadhesive so that the same hydrogel with different adhesiveness between the upper and bottom surfaces was obtained. The asymmetric adhesive hydrogel design permits the adhesive side to fit comfortably to the skin and the nonadhesive side showing anti-interference against various different pollutant materials, accurately serving as a pressure sensor.

Removal of P-Nitrophenol by Nano Zero Valent Iron-Cobalt and Activated Persulfate Supported onto Activated Carbon

P-nitrophenol (PNP), a highly toxic carcinogen, is very stable due to its benzene structure. Advanced oxidation technology is becoming the main means for degrading it. A nano iron-cobalt (Co-nZVI) catalyst, supported by granular activated carbon (GAC), was prepared using liquid-phase reduction, and sodium persulfate’s (PS’s) potential to degrade PNP was studied. The Co-nZVI/GAC nanocomposites were classified, and effects of PS dosage, Co-nZVI/GAC dosage, material system type, PNP concentration, initial pH, and material reuse rate on the reaction were investigated. Activated carbon successfully supported iron and cobalt. At 1 mmol/L of PS, the maximum PNP degradation rate was 99.19%, which was unachievable at other dosages. With only Co-nZVI/GAC present, the rate was 69.8%; with activated persulfate present, it increased to 99.19%. The activated PS system was relatively stable under acidic conditions. Catalysis was induced by adding Co-nZVI/GAC (1.5 g/L). When added four times, the catalytic rate was 57%. Liquid chromatography–mass spectrometry (LC-MS) showed that PNP degradation involves the transfer of PNP to p-benzoquinone (PBQ), the main activators being iron(II) and iron(III) and the key active substances being sulfate (SO42−) and hydroxide (·OH). In conclusion, Co-nZVI/GAC-activated PS effectively removes PNP.

Photochemical degradation of dexamethasone by UV/Persulphate, UV/Hydrogen peroxide and UV/free chlorine processes in aqueous solution using response surface methodology (RSM)

ABSTRACT Dexamethasone (DEX) degradation was investigated using three UV-based advanced oxidation processes combined with sodium persulphate, hydrogen peroxide, and free chlorine in aqueous solutions in a bench-scale reactor. The goal was to determine which process would be the best option in terms of DEX degradation without the subsequent generation of toxic compounds. The process performance for DEX degradation followed the UV/S2O8 2−> UV/H2O2> UV/HOCl order under equal conditions. In the UV/S2O8 2− process, sulphate radicals led to a 70.4% DEX degradation. The experimental mineral inhibitory factors showed that nitrite and bicarbonate further decrease the efficiency of the UV/S2O8 2− process. In the optimal conditions, the UV/S2O8 −2 process removed DEX by 100% and had a 74.1% mineralisation. Furthermore, the intermediates were detected using LC-MS/MS, and the cytotoxicity of the UV/S2O8 −2 process effluent was evaluated using human embryonic kidney cultured cells. The treatment of DEX solution by the UV/S2O8 −2 process significantly decreased the toxicity of the effluent. Therefore, it can be concluded that the UV/S2O8 −2 process can be a reliable process for DEX degradation and detoxification in aqueous solutions.

Gold leaching from waste mobile phone PCBs in a solution mixture of sodium persulfate and potassium iodide

Gold is one of the most fascinating resources in the waste mobile phones’ printed circuit boards (WMPPCBs). In this study, a new process for recovering Au from WMPPCBs by the Na2S2O8-KI system was developed. This process comprises a two-stage leaching process to provide a separation of copper and gold from WMPPCBs. 98% Cu and 78% Fe were dissolved by the 1st base metals' leaching (H2SO4-H2O2 leaching) step. The leaching of gold from the solid reside of 2nd leaching step was performed to study the effect of Na2S2O8 concentration, KI concentration, temperature, and solid-liquid ratio in Na2S2O8-KI leaching system. The results showed that removing most of Cu greatly promoted the leaching efficiency of gold in Na2S2O8-KI leaching system. The mechanism of gold leaching was studied by the thermodynamic analysis. Leaching kinetics data showed that gold leaching followed an intermediate-controlled mechanism with Ea, 30.3 kJ mol−1. The best conditions for leaching of gold in Na2S2O8-KI system were determined to be 0.02 M Na2S2O8, 0.15 M KI, 40 ℃, a solid-liquid ratio of 1: 20 (g/mL), and a stirring speed of 200 rpm. Under the optimal leaching parameters, the efficiency of gold leaching from WMPPCBs attained 96% after 120 min. Due to the non-toxic and low-cost properties of Na2S2O8, the Na2S2O8-KI leaching process is more sustainable than conventional processes (cyanide leaching et al.).

Insights into highly effective catalytic persulfate activation on oxygen-functionalized mesoporous carbon for ciprofloxacin degradation.

Nanocarbons have been demonstrated as promising carbon catalysts for substituting metal-based catalysts for the green treatment of wastewater. In this study, oxygen-functionalized mesoporous carbon (OCMK-3) was prepared by wet oxidation and exhibited high catalytic performance against ciprofloxacin (CIP) by activation of persulfate. The effects of environmental parameters (pH, temperature, coexisting ions) and process parameters (temperature, sodium persulfate concentration, catalyst agent dosage, initial concentration) on the removal of CIP were investigated. Compared with the pristine ordered mesoporous carbon (CMK-3), the removal efficiency of CIP by OCMK-3 was increased by 32% under optimal conditions. This rise in activity was attributed to the increase in oxygen-containing functional groups, porosity, and specific surface area of OCMK-3 with improved structural defects and electron transfer efficiency. Furthermore, based on active species scavenging experiments, a dual-pathway mechanism of the radical and nonradical pathways was discovered. The rational degradation pathway of CIP was investigated based on liquid chromatography-mass spectrometry (LC-MS). In addition, the OCMK-3/PS system exhibited high decomposition efficiency in pharmaceutical wastewater treatment. This study provides an in-depth mechanism for the degradation of organic pollutants by carbon-based PS-AOPs and provides theoretical support for further studies.

Simultaneous addition of surfactant and oxidant to remediate a polluted soil with chlorinated organic compounds: Slurry and column experiments

The inadequate management of wastes associated with chlorinated organic compounds (COCs) has become a huge environmental problem. Surfactant Enhanced In-Situ Chemical Oxidation (S-ISCO) was studied as a successful technique to remediate polluted sites. This work investigated the reaction between an aqueous solution of nonionic surfactant (Emulse-3®) and an oxidant (sodium persulfate activated with NaOH) with a real polluted soil with a complex mixture of COCs from lindane liquid wastes. Two experimental setups were used. In the first one, the reactions were carried out in batch mode under slurry conditions using different surfactant concentrations (0–10 g·L−1), 210 mM of persulfate and 420 mM of NaOH with an aqueous to soil ratio VL/W = 10 L·kg−1. The runs were carried using a column loaded with the soil in the second experimental setup. The solution of surfactant, oxidant and activator was put in contact with soil in four pore volumes with a ratio aqueous to soil ratio VL/W = 0.2 L·kg−1. Under these experimental conditions, the surfactant addition improved the reduction of COCs compared with the application carried out without surfactant, from 40.1% to values of conversion of 64.8 – 90.4%. However, an excess of surfactant hindered the COCs oxidation and increased the unproductive consumption of the oxidant, resulting in an optimal value of surfactant in the aqueous phase (1–2 g·L−1). A remarkable drop in the surfactant concentration in the aqueous phase and COCs solubilized was noticed in column runs due to the surfactant adsorption.

RECYCLING OF WET-STRENGTH TISSUE PAPER. PART 1. KINETICS OF PAPER DISINTEGRATION AT REPULP-ING PROCESS

The present investigation focuses on disintegration kinetics of wet-strength tissue paper in various termo-alkaline and chemical conditions of batch low-consistency repulping process. As chlorine-free repulping aids, we applied sodium persulfate in its original state and in combination with peroxy activator (chemically activated form of sodium persulfate). Based on a first-order kinetic model, we estimated the influence of repulping conditions on the intensity of wet-strength paper defiberization process by the disintegration rate constant kd. The values of kd were found by linear least-squares curve fitting of the experimental data in the t, ln (F'/100) coordinate system, where F' is non-disintegrated or non-defibrated portion of paper, t – repulping time. The results have shown that the termo-alkaline repulping of wet-strength tissue paper (T=60 °C, pH=10.5) compared with mild conditions of repulping (T=40 °C, pH=8.5) leads to an increase of the rate constant of disintegration kd from 5.6·10-3 min-1 to 9.7·10-3 min-1. Addition of 2% persulfate at termo-alkaline repulping increases the rate constant of disintegration kd up to 14,0·10-3 min-1. Application of chemically activated persulfate under the same conditions allows to further increase the kd up to 23.4·10-3 min-1. Raising the temperature and pH of the pulp during persulfate repulping increases the disintegration rate constant kd nonlinearly. Finally, addition of persulfate along with thermo-alkaline pulp treatment lead to decline repulping time and energy by 31% and 29%. It should be noted, that more significant savings of time and energy (57% and 59% respectively) we found at the application of persulfate in a chemically activated form.

Synergistic mechanism and decopperization kinetics for copper anode slime via an integrated ultrasound-sodium persulfate process

An eco-friendly synergistic decopperization method via ultrasound and sodium persulfate was developed from copper anode slime (CAS), a hazardous solid waste. The advanced oxidation process was applied to the field of metal leaching/enrichment in hydrometallurgy. Electron paramagnetic resonance (EPR) spectroscopy was used to trace the free-radical quenching mechanism in the leaching experiment. The influence of different conditions on copper leaching efficiency was studied. A total of 98.11% of copper was removed by the synergistic process from CAS. By comparison, the leaching efficiency of copper by persulfate leaching under the same conditions was only 66.64%. The kinetics model fitting results indicate that ultrasound reduced the threshold of the leaching reaction. The leaching reaction order values of the H2SO4 and Na2S2O8 concentrations are 0.11 and 0.69, respectively, which shows that persulfate plays a major role in leaching efficiency in the decopperization process. Mineralogical analysis demonstrated that the insoluble copper was effectively transformed into copper sulfate via ultrasound and sodium persulfate. In addition, hazardous solid waste was converted to valuable high-grade metallurgical stock through the enrichment of rare noble metals in CAS using a cooperative process. The novel decopperization method via integrated ultrasound/sodium persulfate has wide application prospects in waste management and recycling in a clean and economical hydrometallurgical process.

Enhanced treatment of oily ink wastewater using a modified degreaser by nano-Fe3O4/Na2S2O8: Efficient coagulation and sedimentation

Ink wastewater is hazardous because it contains oil and refractory pollutants, with high Chroma and turbidity. There are many aromatic compounds in the wastewater, such as benzene, toluene, xylene, and phthalocyanines, azos, and nitroso, which make high chemical oxygen demand (COD) and ammonia nitrogen content. The refractory pollutants are always encapsulated in diverse oil-water systems. Usually a massive degreaser has to be used to destroy the dispersant oil forms under preferred alkaline condition, and advanced oxidation is used for good removal of refractory pollutants under preferred acid condition, which commonly lead to a bad coagulation and sedimentation as a result. In this study, the nano-Fe3O4 (MNPs) activated sodium persulfate (SPS) has been testified to enhance degrease with efficient coagulation and sedimentation. The results showed that the removal of oil, COD, ammonia nitrogen, Chroma and turbidity reached respectively 96.40%, 98.35%, 88.00%, 99.70% and 98.22%, within 40–50 min. The mechanism shows that the catalytic oxidation significantly decreased the Zeta potential of the colloidal particles in the wastewater, which destroyed the steady-state of the colloid and enhanced the effect of coagulation sedimentation. Importantly, the combination of MNPs and colloidal particles successfully promoted the simultaneous production of SO4− and a large amount of HO under weakly alkaline (pH = 7.5–8.0) conditions, which made synergistic oxidation to remove micro-oil and organic pollution efficiently.

Role of defects and oxygen-functional groups in carbon paper cathode for high-performance direct liquid fuel cells

A facile and scalable approach to modify electrodes with achieving excellent performance and low-cost is urgently needed for direct liquid fuel cells (DLFCs). A carbon paper (CP) electrode with porous carbon nanosheets is successfully fabricated by electrochemical exfoliation to enhance the charge transfer and increase reaction sites in DLFCs. After in-situ electrochemical exfoliation for 4 min, the carbon fiber surface becomes porous and rough to enlarge specific surface area and produce abundant defects for the electrode, greatly increasing reaction active sites. In addition, massive oxygen functional groups are introduced to significantly improve the reaction kinetics and wettability of the electrode. The exfoliated CP shows superior electrocatalytic activity with minimum overpotential and highest reduction reaction rate, benefitting from the larger specific surface area, abundant defects, and superhydrophilic property. Moreover, the exfoliated CP without catalysts is directly used as the cathode for a membraneless DLFC with sodium persulfate as an oxidant to yield outstanding performance. The peak power density of the DLFC with the exfoliated CP is 188.6 mW cm−2, 93.4% higher than that with the pristine CP. Results show that a feasible way to acquire excellent cell performance and low cost is obtained by electrochemically exfoliated CP electrode for DLFCs.

Separation of minor actinides from highly acidic solutions using diglycolamide modified mesoporous silica synthesized via a novel “ring-opening click” reaction

Solid-phase extraction represents a promising approach for partitioning of trivalent minor actinides (MAs) from high-level liquid waste, which is crucial for the decontamination of radioactive waste. However, highly acidic effluents poseaformidablechallengefor extraction materials. Herein, the diglycolamide ligands functionalized mesoporous silica robust matrixs were prepared, resulting in rapid and efficient separation of MAs from strong nitric acid media. This paper reports the first modification of SBA-15-type mesoporous silica through a “ring-opening click” reaction under mild conditions. Five modified silica materials with monolayer diglycolamide ligands containing different terminal groups were obtained using low temperature (0–25 °C) procedures. The rigid and open pore structure of SBA-15 is retained under such mild conditions, allowing facile diffusion and open access to the monolayer ligands. The functionalized product SBA-15-DEDGA exhibited a strong affinity for trivalent MAs in highly acidic solutions and could separate trace amounts of radioactive Am(III) from 1 to 8 M nitric acid solutions with high efficiency (> 98%) within 1 min; the largest distribution coefficient exceeded 5 × 104 mL/g. Solid-state nuclear magnetic resonance spectroscopy combined with X-ray photoelectron spectroscopy of Eu(III) revealed that the binding mechanism involves direct coordination of Eu(III) to a tridentate oxygen-binding site. Additionally, selective separation of americium from curium was achieved with separation factors up to 191 ± 20 through oxidation of Am(III) by sodium persulfate. The superlative and efficient sorption performance of these materials demonstrates their utility in the immobilization of trivalent actinides and the separation of americium from curium.

Photoassisted highly efficient activation of persulfate over a single-atom Cu catalyst for tetracycline degradation: Process and mechanism

A single-atomic-site Cu catalyst (SAS-Cu) supported on carbon nitride (CN) material was synthesized by a pyrolyzing coordinated polymer (PCP) strategy. The introduction of a single-atomic Cu site improved the charge transfer and separation efficiency. The reaction rate constant of SAS-Cu1.0 is 4.5 times higher than that of CN. Under the condition of only 0.1 mM sodium persulfate (PS) and 0.1 g/L catalyst, the removal rate of tetracycline (TC) reached 82.5% after 30 min of LED illumination, which greatly improved the utilization of oxidant. Mechanistic analysis shows that there are free radical (•O2-, SO4•-, •OH) and nonradical pathways (1O2 and direct electron transfer) in the system, and they have synergistic effect. Density functional theory (DFT) calculations show that SAS-Cu1.0 can optimize the adsorption and activation of PS. This work illustrates the application value of SAC combined with activated persulfate and the low energy consumption of the LED light in the field of environment, which provides a new strategy for reducing the salinity and treatment cost of treated water.

Photocurable GelMA Adhesives for Corneal Perforations.

The current treatments for the management of corneal and scleral perforations include sutures and adhesives. While sutures are invasive, induce astigmatism and carry a risk of infection, cyanoacrylate glues are toxic, proinflammatory and form an opaque and rough surface that precludes vision. Consequently, the clinical need for a fast curing and strong tissue adhesive with minimised cytotoxicity and host inflammation remains unmet. In this paper, we engineer a gelatine methacryloyl (GelMA) adhesive that can be crosslinked in situ within 2 min using UV or visible light and a riboflavin (RF)/sodium persulfate (SPS) system. Optical coherence tomography (OCT) images demonstrated that the flowable GelMA adhesive could completely fill corneal wounds and restore the ocular curvature by forming a smooth contour on the ocular surface. Further, ex vivo studies in porcine eyes showed that GelMA bioadhesives exhibited burst pressures that were comparable to cyanoacrylates (49 ± 9 kPa), with the hydrogels exhibiting a transmittance (90%), water content (85%) and storage modulus (5 kPa) similar to the human cornea. Finally, using human dermal fibroblasts, we showed that our GelMA adhesive was non-toxic and could effectively support cell adhesion and proliferation. Taken together, the adhesive’s performance, injectability and ease of administration, together with gelatin’s availability and cost-effectiveness, make it a potential stromal filler or sealant for corneal and conjunctival applications.