Tetracycline removal using NaIO4 activated by MnSO4: Design and optimization via response surface methodology.

The appearance of recalcitrant organic pollutants such as antibiotics in water bodies has gained a lot of attention owing to their adverse effects on organisms and humans. The current study aims to develop a novel approach to eliminate antibiotic tetracycline (TC) from a synthetic aqueous solution based on the advanced oxidation process triggered by MnSO4-catalyzed NaIO4. A single-factor experiment was performed to observe the impact of pH, NaIO4 concentration, and MnSO4 dosage on TC decomposition, and a three-factor, three-level response surface experiment with TC removal rate as the dependent variable was designed based on the range of factors determined from the single-factor experiment. The single-factor experiment revealed that the ranges of pH, NaIO4 concentration, and MnSO4 dosage need to be further optimized. ANOVA (analysis of variance) results showed that the data from the response surface experiment were consistent with the quadratic model with high R2 (0.9909), and the predicted values were very close to the actual values. After optimization by response surface methodology, the optimal condition obtained was pH = 6.7, [NaIO4] = 0.39 mM, and [MnSO4] = 0.12 mM, corresponding to a TC removal of 96.56%. This optimization condition was fully considered to save the dosage of the high-priced chemical NaIO4.

The utilization of microwaves in revitalizing peroxymonosulfate for tetracycline decomposition: optimization via response surface methodology.

Antibiotic contamination in water has received significant attention in recent years for the reason that the residuals of antibiotics can promote the progression of antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs). It is difficult to treat antibiotics using conventional biological treatment methods. In order to investigate an efficient new method of treating antibiotics in water, in this study, microwave (MW) was employed in revitalizing peroxymonosulfate (PMS) to treat typical antibiotic tetracycline (TC). The Box-Behnken design (BBD) was applied to organize the experimental schemes. The response surface methodology (RSM) optimization was run to derive the best experimental conditions and validated using actual data. Moreover, the main mechanisms of PMS activation via MW were resolved. The results demonstrated that the relationship between TC removal rate and influencing factors was consistent with a quadratic model, where the P-value was less than 0.05, and the model was considered significant. The optimal condition resulting from the model optimization were power = 800 W, [PMS] = 0.4 mM, and pH = 6.0. Under such conditions, the actual removal of TC was 99.3%, very close to the predicted value of 99%. The quenching experiment confirmed that SO4•- and •OH were jointly responsible for TC removal.

Preparation, Characterization, Photochromic Properties, and Mechanism of PMoA/ZnO/PVP Composite Film.

A novel photochromic heteropolyacid-based composite film consisting of phosphomolybdic acid (PMoA), ZnO, and polyvinylpyrrolidone (PVP) was fabricated by a sol-gel process. The microstructure and photochromic properties of the PMoA/ZnO/PVP were characterized via Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible spectroscopy (UV-Vis). The FTIR spectra showed that the basic structures of ZnO and PVP, and the Keggin structure of PMoA in the PMoA/ZnO/PVP composite film, had not been destroyed during the preparation. The TEM images demonstrated that ZnO presented a rod-like structure, while PMoA was spherical, and many PMoA balls adhered to the surface of the ZnO rods. The XPS spectra of Mo 3d indicated that the valency of Mo atoms in the PMoA/ZnO/PVP was changed by visible light exposure. After visible light irradiation, the PMoA/ZnO/PVP varied from slight yellow to blue, while undergoing an opposite color change upon heating. The discoloration mechanism of the PMoA/ZnO/PVP was consistent with the photoelectron transfer mechanism.

Piezoelectric polarization coupled with photoinduced catalytic oxidation technology for environmental pollution control: Recent advances and future prospects.

Energy scarcity and environmental pollution concerns have become substantial impediments to sustainable global economic development. The advent of semiconductor photocatalysis technology provides a potential possibility for effectively alleviating excessive energy consumption and maintaining the long-term stability of the aqueous ecosystem. However, the inefficient transmission efficiency of charge carriers and the high recombination rate of photogenerated electron-hole pairs will culminate in the mediocre catalytic performance observed in conventional semiconductor materials. Fortunately, the piezo-photocatalysis ingeniously integrates the piezoelectric properties of piezoelectric crystals with the optoelectronic properties of semiconductors, thus building a theoretical system of photo-electric-chemical three-phase coupled catalysis. Currently, the photo-mechanical energy synergistic catalytic oxidation degradation process, as a cutting-edge technology based on clean renewable energy, has been perceived as a promising environmental remediation strategy. Herein, a critical review of the application of piezo-photocatalysis in environmental pollution control was delivered. We undertook a comprehensive analysis to elucidate the underlying enhancement mechanism of the piezoelectric effect on photocatalysis in terms of charge migration dynamics and pertinent energy band bending phenomena. In addition, we meticulously summarized diverse innovative methods for introducing vibration energy in piezo-photocatalytic degradation systems (ultrasound, fluid mechanical energy, airflow, self-assembled reactors, etc.). Then, state-of-the-art research advances in the field of environmental pollution control and the corresponding environmental decontamination mechanisms were elaborated based on various integration modes of catalysts (single component, noble metal deposition, heterojunction, coupled substrate materials, etc.). Eventually, an in-depth assessment of current limitations and development trends of piezo-photocatalytic degradation technology has been proposed, along with proactive strategies aimed at surmounting the existing challenges.

The performance of a visible light-responsive material Fe3O4/Bi2WO6 cooperating with peroxymonosulfate to degrade bisphenol A.

In this study, the visible light-responsive catalysts Fe3O4/Bi2WO6 were prepared and characterized by BET, SEM, EDS, XRD, XPS, and MPMS. The performances of five catalysts (0.05 Fe/Bi, 0.13 Fe/Bi, 0.17 Fe/Bi, 0.21 Fe/Bi, and 0.30 Fe/Bi) for photocatalytic degradation of bisphenol A under visible light (300-W Xe lamp) were compared. Among five catalysts, 0.17 Fe/Bi (the molar ratio of Fe3O4 to Bi2WO6 was 0.17) acquired the highest BPA photocatalytic removal of 90.2% at 120 min. With the synergistic effect between Vis/0.17 Fe/Bi and peroxymonosulfate (PMS), the BPA removal obtained was as high as 100% at 90 min ([BPA] = 100 mg/L, [0.17 Fe/Bi] = 1.25 g/L, [PMS] = 2.0 g/L, and T = 25 °C). After five times reused of 0.17 Fe/Bi, its removal of BPA dropped by 13.4% in presence of PMS, which demonstrated 0.17 Fe/Bi possessed relatively stable performance. High BPA degradation was attributed to the attacking effects of various oxide species (SO4•-, •OH, h+, O2•-) generated in the Fe3O4/Bi2WO6/PMS system under the cooperation of photocatalyst Fe3O4/Bi2WO6 and oxidizing agent PMS.

Speciation and transformation of nitrogen for sewage sludge hydrothermal carbonization-influence of temperature and carbonization time.

Hydrothermal carbonization (HTC) is an effective means of energizing high-water-content biomass that can be used to convert sewage sludge (SS) into hydrochar and reduce nitrogen content. To further reduce the emission of NOx during the combustion of hydrochar and seek proper disposal method of liquid product, the mechanism of nitrogen conversion was studied in the range of 180-320 °C and 30-90 min. At 180-220 °C, 42.15-52.91% of the nitrogen in SS was transferred to liquid by hydrolysis of proteins and inorganic salts. At 240-280 °C, the nitrogen in hydrochar was mainly in the form of heterocyclic -N (quaternary-N, pyrrole-N, and pyridine-N). The concentration of NH4+-N increased from 6.82 mg/L (180 °C) to 26.58 mg/L (280 °C) due to the enhancement of the deamination reaction. At 300-320 °C, pyrrole-N (from 15.92% to 9.38%) and pyridine-N (from 5.52% to 3.73%) in the hydrochar were converted to the more stable quaternary-N (from 0.31% to 4.28%). Meanwhile, the NH4+-N and amino-N in the liquid decomposed into NH3. Prolonging the carbonization time promoted the hydrolysis of proteins, the conversion of heterocyclic -N, and the production of NH3. Under optimal reaction conditions (280 °C and 60 min), the nitrogen in the SS is converted to stable forms and the energy balance meets the requirements of circular-economy. The results show that temperature determines the nitrogen form and the carbonization time affects the nitrogen distribution. So HTC has the potential to reduce NOx emissions from SS energy utilization processes.

Fabrication, characterization, and performance evaluation of Bi2WO6/TiO2/Fe3O4 photocatalyst responding to visible light for enhancing bisphenol A degradation.

A novel magnetic Bi2WO6/TiO2/Fe3O4 photocatalyst was synthesized by a hydrothermal approach. The pattern, structure, elemental composition, light-absorbing properties, and magnetism of Bi2WO6/TiO2/Fe3O4 were characterized and analyzed. The performance, influencing factors, and mechanism of Bi2WO6/TiO2/Fe3O4 towards bisphenol A (BPA) degradation were investigated and deduced. BPA removal up to 95% was achieved with the addition of 1.25 g/L Bi/Ti/Fe2 (molar ratio of Bi2WO6:TiO2:Fe3O4 = 2:1:0.17) in the solution containing 10 mg/L BPA at pH 5.6. The performance of Bi/Ti/Fe2 was stable for five cycles at least after extracted from the reacted solution by magnet. Photoexcited h+, •OH, and •O2- formed in the reaction mainly contributed to BPA degradation. The Bi/Ti/Fe2 composite was composed of a three-layer petal structure from outside to inside to be Bi2WO6, TiO2, and Fe3O4. This structure was conducive in forming a heterojunction between TiO2 and Bi2WO6, inhibiting the merging of photoexcited e- and h+, and improving the photocatalytic efficiency.

Insight into enhanced degradation of tetracycline over peroxymonosulfate activated via biochar-based nanocomposite: performance and mechanism.

Rice husk biochars (BCs) doped with ferric chloride were prepared by one-pot method, characterized by SEM, EDS, BET, XRD, and FTIR, and utilized to catalyze peroxymonosulfate (PMS) for tetracycline (TC) degradation. Various influencing factors in the BC/PMS/TC system were investigated, as well as the recycling performance of the optimal BC. The mechanism of BC activation of PMS and degradation of TC were analyzed based on the free radicals quenching experiment and the pathways of TC degradation. The results demonstrated that bBC3 was an excellent catalyst with large specific surface area; the amounts of oxidant and catalyst were important factors affecting the catalytic performance of PMS, while pH had less effect on TC degradation; 10 mM of chloride ions inhibited the TC degradation, while 20 mM promoted the TC degradation; other ions and humic acid inhibited the TC degradation at the set concentrations; activation of PMS by bBC3 yielded species with strong oxidative activity, which were primarily responsible for TC degradation. The bBC3 obtained stable performance for removing TC. This study provided a pathway for the deep utilization of waste rice husks besides an effective method for degrading TC.

Activated persulfate by iron-carbon micro electrolysis used for refractory organics degradation in wastewater: a review.

With the rapid economic development, the discharge of industrial wastewater and municipal wastewater containing many refractory organic pollutants is increasing, so there is an urgent need for processes that can treat refractory organics in wastewater. Iron-carbon micro electrolysis and advanced oxidation based on persulfate radicals (SO4-·) have received much attention in the field of organic wastewater treatment. Iron-carbon micro electrolysis activated persulfate (Fe-C/PS) treatment of wastewater is characterized by high oxidation efficiency and no secondary pollution. This paper reviews the mechanism and process of Fe-C/PS, degradation of organics in different wastewater, and the influencing factors. In addition, the degradation efficiency and optimal reaction conditions (oxidant concentration, catalyst concentration, iron-carbon material, and pH) of Fe-C/PS in the treatment of refractory organics in wastewater are summarized. Moreover, the important factors affecting the degradation of organics by Fe-C/PS are presented. Finally, we analyzed the challenges and the prospects for the future of Fe-C/PS in application, and concluded that the main future directions are to improve the degradation efficiency and cost by synthesizing stable and efficient catalysts, optimizing process parameters, and expanding the application scope.

Activation of peroxymonosulfate by biochar and biochar-based materials for degrading refractory organics in water: a review.

Water pollution caused by refractory organics has attracted widespread concern in recent years. At this time peroxymonofulfate (PMS) has been widely used to generate sulfate radicals with high reactivity and potential. The direct reaction rate between PMS and organics is very low. However, the activated PMS has a strong oxidizing ability on organics due to its conversion into sulfate radicals. Recently, the free radicals generated by oxidant PMS and catalyst biochar have proven to be an effective species in dealing with refractory organics. In order to enable researchers to better understand the current research status of PMS/biochar, and to promote the development and application of PMS/biochar system, we have written this review. This review in detail described the mechanism of PMS activated by biochar materials, and summarized the influencing factors of refractory organics degradation in the PMS/biochar system. In addition, the active sites of PMS/biochar, the degradation mechanism of refractory organics, and the reusability of biochar catalysts were also discussed. Finally, the concluding remarks and perspectives were made for future research on the PMS/biochar system in the degradation of refractory organics.

Activated persulfate by iron-based materials used for refractory organics degradation: a review.

Recently, the advanced oxidation processes (AOPs) based on sulfate radicals (SRs) for organics degradation have become the focus of water treatment research as the oxidation ability of SRs are higher than that of hydroxyl radicals (HRs). Since the AOP-SRs can effectively mineralize organics into carbon dioxide and water under the optimized operating conditions, they are used in the degradation of refractory organics such as dyes, pesticides, pharmaceuticals, and industrial additives. SRs can be produced by activating persulfate (PS) with ultraviolet, heat, ultrasound, microwave, transition metals, and carbon. The activation of PS in iron-based transition metals is widely studied because iron is an environmentally friendly and inexpensive material. This article reviews the mechanism and application of several iron-based materials, including ferrous iron (Fe2+), ferric iron (Fe3+), zero-valent iron (Fe0), nano-sized zero-valent iron (nFe0), materials-supported nFe0, and iron-containing compounds for PS activation to degrade refractory organics. In addition, the current challenges and perspectives of the practical application of PS activated by iron-based systems in wastewater treatment are analyzed and prospected.

(4S,5R)-4-Benz-yloxy-5-[4-(cyclo-hexa-ne-carbon-yl)phen-yl]-1-(4-meth-oxy-benz-yl)pyrrolidin-2-one.

The title compound, C32H35NO4, is an unexpected product obtained in the SmI2-mediated radical cross-coupling of a lactam 2-pyridyl sulfone with an arone. The asymmetric unit contains two mol-ecules. In both mol-ecules, the core pyrrolidinone ring adopts an approximate envelope conformation (with the C atom bearling the benzyloxy substituent as the flap) and the cyclo-hexyl ring has a chair conformation. The relative orientation of the two substitutent groups at the 4- and 5-positions of the pyrrolidinone ring is anti in both mol-ecules, with O(benz-yloxy)-C-C-C(benzene) torsion angles of 150.8 (3) and 154.2 (2)°. In the crystal, C-H⋯O inter-actions involving carbonyl groups as acceptors lead to the formation of a tape motif propagating parallel to the a-axis direction.

1-Benzyl-5-ethyl-5-hy-droxy-1H-pyrrol-2(5H)-one.

The title compound, C13H15NO2, was obtained as a by-product in the Grignard reaction of malimide. The dihedral angle between the five-memebred ring (r.m.s. deviation = 0.005 Å) and the benzene ring is 67.20 (14)°. The benzene ring and the ethyl chain lie to the same side of the five-membered ring. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds, generating C(6) chains propagating in [010].

[Biological properties and formation of electrodeposited HA-Ti/HA composite coatings].

In order to improve the bonding strength of the hydroxyapatite (HA) coatings on the metal substrate, we prepared the HA-Ti/HA composite coatings by two-step electrodeposited method, and then we studied the component, microstructure, surface morphologies and the bonding strength of the HA-Ti/HA composite coatings. SBF test and cell culture in vitro were carried out to evaluate the biological properties of the composite coatings. The results showed that the bonding strength of the HA-Ti/HA composite coating (Ti, 51.2wt%) was as high as 21.2 MPa which was 3 times that of pure HA coatings. The coatings' surface was covered by carbonate-apatite layer after being immersed in SBF, and the bone marrow cells attached firmly and proliferated well on the surface of composite coatings. These findings indicate that the composite coatings possess good bioactivity and excellent biocompatibility.