Preparation of Co-Ce@RM catalysts for catalytic ozonation of tetracycline.

In this work, a Co-Ce@RM ozone catalyst was developed using red mud (RM), a by-product of alumina production, as a support material, and its preparation process, catalytic efficiency, and tetracycline (TCN) degradation mechanism were investigated. A comprehensive assessment was carried out using the 3E (environmental, economic, and energy) model. The optimal production conditions for Co-Ce@RM were as follows: The doping ratio of Co and Ce was 1:3, the calcination temperature was 400°C, and the calcination time was 5 h, achieving a maximum removal rate of 87.91% of TCN. The catalyst was characterized using different analytical techniques. Under the conditions of 0.4 L/min ozone aeration rate, with 9% catalyst loading and solution pH 9, the optimal removal rates and chemical oxygen demand by the Co-Ce catalytic ozonation at RM were 94.17% and 75.27%, respectively. Moreover, free radical quenching experiments showed that superoxide radicals (O2 -) and singlet oxygen (1O2) were the main active groups responsible for the degradation of TCN. When characterizing the water quality, it was assumed that TCN undergoes degradation pathways such as demethylation, dehydroxylation, double bond cleavage, and ring-opening reactions under the influence of various active substances. Finally, the 3E evaluation model was deployed to evaluate the Co-Ce@RM catalytic ozonation experiment of TCN wastewater. PRACTITIONER POINTS: The preparation of Co-Ce@RM provides new ideas for resource utilization of red mud. Catalytic ozonation by Co-Ce@RM can produce 1O2 active oxygen groups. The Co-Ce@RM catalyst can maintain a high catalytic activity after 20 cycles. The degradation pathway of the catalytic ozonation of tetracycline was fully analyzed. Catalytic ozone oxidation processes were evaluated by the "3E" (environmental, economic, and energy) model.

Carbon Dot-Based Composite with Color Excitation-Dependent Room-Temperature Phosphorescence for Advanced Optical Encryption and Anticounterfeiting.

The phenomenon of multicolor afterglow emission has attracted considerable attention in information encryption, bioimaging, and sensing. Consequently, there is a growing demand for the development of multicolor afterglow and phosphorescence switching methods utilizing carbon dot (CD) materials. Herein, multicolor room-temperature phosphorescence (RTP) emission in CD-based materials (PM-CD@BA composite) was achieved by developing multiple emission centers and tuning the excitation wavelength. The color of the afterglow observed in this composite covered from the deep-blue to the green region. The experimental results reveal that under heating treatment, the CDs embedded in inorganic boric acid/B2O3 matrix materials and a rigid framework generated in the composite system effectively suppressed the nonradiative transition and promoted the RTP emission. Finally, high-resolution multilevel RTP 2D code data encryption was realized by inkjet printing technology. The developed concepts of information encryption and anticounterfeiting exhibit the significant potential of CD-based afterglow materials applied in advanced optical applications.

Microplastics in wastewater plants: A review of sources, characteristics, distribution and removal technologies.

Microplastics (MPs) are widespread in everyday life, and since wastewater treatment plants (WWTPs) serve as an important route for MPs to enter natural water bodies, a thorough understanding of the distribution and removal of MPs in wastewater treatment plants is of great importance. This article provides a comprehensive overview of the measured distribution of MPs and the current status of their removal in wastewater treatment plants. The main sources of MPs in wastewater treatment plants are personal care products in domestic wastewater, textile clothing and industrial wastewater made from plastics, textile factories and the friction of road tires. The MPs that entered the sewage treatment plant were predominantly in the form of fibers, fragments, granular MPs and other types of MPs. The size of MPs is divided into three categories: <0.5 mm, 0.5-1 mm and 1-5 mm. At all treatment stages in wastewater plants, 56.8-88.4 % of MPs are removed in primary treatment, but the primary sedimentation and degreasing stages remove most MPs. The efficiency of the activated sludge process for secondary treatment is inconsistent and is generally between 42.1 and 99.2 %. The coagulation, filtration and disinfection stages of tertiary treatment all have some MPs removal capacity. In addition, novel removal technologies are also described, such as modified filtration technology, membrane separation technology, electroflocculation, sol-gel and photocatalysis. These novel removal technologies can further limit the entry of microplastics into natural water bodies through sewage treatment plants and improved sewage treatment processes help reduce the risk of MPs entering the natural environment through sewage treatment plants. This article will provide reference for the distribution and removal of microplastics in various levels of WWTPs.

Catalytic ozonation of reverse osmosis membrane concentrates by catalytic ozonation: Properties and mechanisms.

Ni-Mn@KL ozone catalyst was prepared for the efficient treatment of reverse osmosis membrane concentrates. The working conditions and reaction mechanism of the ozone-catalyzed oxidation by Ni-Mn@KL were systematically studied. Then, a comprehensive CRITIC weighting-coupling coordination evaluation model was established. Ni-Mn@KL was characterized by scanning electron microscopy, BET, X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectrometry, and X-ray fluorescence spectrometry and found to have large specific surface area and homogeneous surface dispersion of striped particles. Under the optimum working conditions with an initial pH of 7.9 (raw water), a reaction height-to-diameter ratio of 10:1, an ozone-aeration intensity of 0.3 L/min, and a catalyst filling rate of 10%, the maximum COD removal rate was 60.5%. Free-radical quenching experiments showed that OH oxidation played a dominant role in the Ni-Mn@KL-catalyzed ozone-oxidation system, and the reaction system conformed to the second-order reaction kinetics law. Ni-Mn@KL catalysts were further confirmed to have good catalytic performance and mechanical performance after repeated utilization. PRACTITIONER POINTS: Ni-Mn@KL catalyst can achieve effective treatment of RO film concentrated liquid. High COD removal rate of RO membrane concentrated liquid was obtained at low cost. Ni-Mn@KL catalyst promotes ozone decomposition to produce ·OH and O2 -· oxidized organic matter. The Ni-Mn@KL catalyst can maintain good stability after repeated use. A CRITIC weight-coupling coordination model was established to evaluate the catalytic ozonation.

Preparation of composite coagulant for the removal of microplastics in water.

In this work, a composite flocculant (polyferric titanium sulfate-polydimethyldiallylammonium chloride [PFTS-PDMDAAC]) with a rich spatial network structure was prepared for the treatment of simulated wastewater containing polystyrene (PS) micro-nanoparticles. Characterization results showed that the surface of the PFTS-PDMDAAC was a three-dimensional network polymer of chain molecules that exhibited good thermal stability and formed an amorphous polymer containing multiply hydroxyl-bridged titanium and iron. When n(OH- ) : n(Fe) = 1:2, n(PO4 3- ) : n(Fe) = 0.35, n(Ti) : n(Fe) = 1:8, n(DMDAAC) : n(Fe) = 5:100, and the polymerization temperature is 60°C, the prepared composite flocculant has the best effect. The effects of dosage, pH, and agitation intensity on the flocculation properties of PFTS-PDMDAAC were also studied. The optimal removal rates of PS-µm and haze by PFTS-PDMDAAC were 85.60% and 90.10%, respectively, at a stirring intensity of 200 rpm, a pH of 9.0, and a PFTS-PDMDAAC dosage of 20 mg/L. The flocs produced by the PFTS-PDMDAAC flocculation were large and compact in structure, and the flocculation mechanism was mainly based on adsorption bridging. Kaolin played a promoting role in the process of PS-µm removal by PFTS-PDMDAAC floc and accelerated the formation of large and dense flocs. This study provided a reference for the coagulation method to remove micro-nanopollutants in the actual water treatment process. PRACTITIONER POINTS: A composite flocculant with rich spatial network structure (PFTS-PDMDAAC) was prepared. PFTS-PDMDAAC can effectively remove micro-nano polystyrene (PS) in wastewater. The floc produced by PFTS-PDMDAAC is large and compact in structure. The flocculation mechanism of PFTS-PDMDAAC is mainly adsorption bridging.

Preparation of Mn/Zn@PG Catalyst for Catalytic Oxidation Treatment of Coal Chemical Wastewater.

In this study, Mn/Zn@palygorskite (PG) catalysts with developed pores and good salt tolerance were prepared and applied to the treatment of coal chemical wastewater. A doping ratio of metal elements, calcination temperature, and calcination time was used to optimize the preparation conditions and determine the optimal preparation conditions of the Mn/Zn@PG catalysts. The catalysts, obtained under various preparation conditions, were characterized and analyzed by XRD, SEM, EDS, BET, XRF, XPS, and other techniques. Results showed that the Zn and Mn elements in the Mn/Zn@PG catalyst existed as ZnO and MnO2, respectively. The optimal working conditions of the Mn/Zn@PG catalyst for catalytic oxidation treatment of coal chemical wastewater, obtained through the optimization of working conditions, are the following: reaction time 60 min, wastewater pH = 9.28, ozone ventilation rate 0.2 L/min, catalyst filling ratio 20%. The height-to-diameter ratio of the tower was 6:1. The abrasion resistance and catalytic performance of the Mn/Zn@PG catalyst after repeated use were investigated, and the mechanism of the loss of active components of the Mn/Zn@PG catalyst was explored. The coal chemical wastewater, before and after treatment, was analyzed by UV-vis spectroscopy and 3D fluorescence spectroscopy. The hierarchical-principal component comprehensive evaluation system (AHP-PCA) was established to evaluate the catalytic ozonation process of coal chemical wastewater, so that the overall evaluation of the process performance can be achieved.

Proteomic profile of mouse oocytes after vitrification: A quantitative analysis based on 4D label-free technique.

Mature oocyte cryopreservation represents an important trend for future fertility preservation, however, the relatively low efficiency has hampered its clinical application. Proteomic profiling is a method of choice for the exploration of the molecular mechanism underlying cryoinjuries. Here, a systematic comparison of protein expression between fresh and vitrified oocytes was performed based on the 4D label-free technique, an informative method with high sensitivity. Our results indicated that the oocyte survival rate was significantly reduced after vitrification. Proteomic results showed that 32 proteins were up-regulated, while 77 proteins were down-regulated in vitrified oocytes compared with the fresh counterparts. Gene Ontology (GO) functional analysis revealed that differentially expressed proteins (DEPs) were involved in metabolism, mitochondrial function, cytoskeleton and other cell functions. Moreover, proteins that participated in signaling transduction mechanisms were the largest category based on Clusters of Orthologous Groups of protein/EuKaryotic Orthologous Groups (COG/KOG) functional classification. In addition, over-expressed DEPs were enriched for "nucleus", "protein binding", "membrane", "cytoplasm" as well as mitochondrial function. Furthermore, we discovered that the DEPs were clustered in pyruvate metabolism, citric acid (TCA) cycle and glucose metabolism by Protein-Protein Interaction (PPI) network evaluation. In conclusion, our data demonstrate that vitrification induces multi-level damages in oocytes, the dynamic proteomic profiling will provide systematic insights into uncovering the mechanism underlying cryoinjuries.

Artificially Increasing Cortical Tension Improves Mouse Oocytes Development by Attenuating Meiotic Defects During Vitrification.

Oocyte cryopreservation demonstrates great benefits in the conservation of animal germplasm resources and assisted reproductive technology. However, vitrification causes damages in oocytes, which would lead to the decrease of oocyte quality, and embryonic development post fertilization. Cytoskeleton plays an important role in regulating cell shape, organelle migration, cell division and mechanical signal transduction. Cortical tension is a reflection of the physiological state and contractile ability of cortical cytoskeleton. Appropriate cortical tension is prerequesite for normal oocyte meiosis. In the present study, oocyte cortical tension was examined by evaluating the levels of cortical tension-related protein pERM (Phospho-Ezrin/Radixin/Moesin) and pMRLC (Phospho-Myosin Light Chain 2). We found that the cortical tension of vitrified oocytes was decreased. Increasing cortical tension of vitrified oocytes by adding 10 µg/ml ConA during in vitro culture could significantly improve the polar body extrusion rate and embryo development. Furthermore, increasing the cortical tension could improve spindle positioning, maintain kinetochore-microtubule (KT-MT) attachment, strengthen spindle assembly checkpoint (SAC) activity, and reduce the aneuploidy rate in vitrified oocytes. In conclusion, vitrification induced a remarkable decrease in cortical tension, and increasing the cortical tension could rescue the meiosis defect and improve oocyte quality.

Vascular Derived ECM Improves Therapeutic Index of BMP-2 and Drives Vascularized Bone Regeneration.

Vascularized osteogenesis is essential for successful bone regeneration, yet its realization during large size bone defect healing remains challenging due to the difficulty to couple multiple biological processes. Herein, harnessing the intrinsic angiogenic potential of vascular derived extracellular matrix (vECM) and its specific affinity to growth factors, a vECM/GelMA based hybrid hydrogel delivery system is constructed to achieve optimized bone morphogenetic protein-2 (BMP-2) therapeutic index and provide intrinsic angiogenic induction during bone healing. The incorporation of vECM not only effectively regulates BMP-2 kinetics to match the bone healing timeframe, but also promotes angiogenesis both in vitro and in vivo. In vivo results also show that vECM-mediated BMP-2 release remarkably enhances vascularized bone formation for critical size bone defects. In particular, blood vessel ingrowth stained with CD31 marker in the defect area is substantially encouraged over the course of healing, suggesting incorporation of vECM served roles in both angiogenesis and osteogenesis. Thus, the authors' study exemplifies that affinity of growth factor towards ECM may be a promising strategy to be leveraged to develop sophisticated delivery systems endowed with desirable properties for regenerative medicine applications.

Synthesis and evaluation of cationic flocculant P(DAC-PAPTAC-AM) for flocculation of coal chemical wastewater.

In this study, a high-efficiency cationic flocculant, P(DAC-MAPTAC-AM), was successfully prepared using UV-induced polymerization technology. The monomer Acrylamide (AM): Acryloxyethyl Trimethyl ammonium chloride (DAC): methacrylamido propyl trimethyl ammonium chloride (MAPTAC) ratio, monomer concentration, photoinitiator concentration, urea content, and cationic monomer DAC:MAPTAC ratio, light time, and power of high-pressure mercury lamp were studied. The characteristic groups, characteristic diffraction peaks, and characteristic proton peaks of P(DAC-MAPTAC-AM) were confirmed by fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), 1H nuclear magnetic resonance spectrometer (1H NMR), and scanning electron microscopy (SEM). The effects of dosage, pH value, and velocity gradient (G) value on the removal efficiencies of turbidity, COD, ammonia nitrogen, and total phenol by poly aluminum ferric chloride (PAFC), P(DAC-MAPTAC-AM), and PAFC/P(DAC-MAPTAC-AM) in the flocculation treatment of coal chemical wastewater were investigated. Results showed that the optimal conditions for the flocculation of coal chemical wastewater using P(DAC-MAPTAC-AM) alone are as follows: dosage of 8-12 mg/L, G value of 100-250 s - 1, and pH value of 4-8. The optimal dosage of PAFC is 90-150 mg/L with a pH of 2-12. The optimal dosage for PAFC/P(DAC-MAPTAC-AM) is as follows: PAFC dosage of 90-150 mg/L, P(DAC-MAPTAC-AM) dosage of 8-12 mg/L, and pH range of 2-6. When P(DAC-MAPTAC-AM) was used alone, the optimal removal efficiencies of turbidity, COD, ammonia nitrogen, and total phenol were 81.0%, 35.0%, 75.0%, and 80.3%, respectively. PAFC has good tolerance to wastewater pH and good pH buffering. Thus, the flocculation treatment of coal chemical wastewater using the PAFC/P(DAC-MAPTAC-AM) compound also exhibits excellent resistance and buffering capacity.

Ozone catalytic oxidation capacity of Ti-Co@Al2 O3 for the treatment of biochemical tailwater from the coal chemical industry.

A Ti-Co@γ-Al2 O3 composite catalyst was prepared using impregnation and sol-gel methods to degrade biochemical tailwater from the coal chemical industry, and its preparation conditions (active component doping ratio, load times, and calcination temperature) were optimized through single-factor experiments. The surface properties of the Ti-Co@γ-Al2 O3 composite catalyst and the crystal structure characteristics of the catalytically active components were characterized via scanning electron microscopy-energy dispersive spectrometry, X-ray diffraction, and X-ray fluorescence. The effects of reaction time, initial pH, ozone aeration, and catalyst dosage on degradation performance were investigated through an experiment on the catalytic ozonation degradation of biochemical tail water. Results showed that the optimal conditions were as follows: reaction time of 30 min, pH of 8.2, ozone aeration of 30 mg/min, and catalyst dosage of 20 g/L. The total phenol and total organic carbon removal rates for biochemical tailwater were 66.1% and 57.6%, respectively, in the catalytic system. The mechanism of degradation of organic pollutants by catalytic ozonation was investigated by adding tert-butanol to the catalytic ozone oxidation system. The degradation of chemical oxygen demand in biochemical tailwater was caused primarily by the synergy between the Ti-Co@γ-Al2 O3 catalyst and ozone. PRACTITIONER POINTS: Ti-Co/γ-Al2 O3 catalyst was prepared for the catalytic oxidation of biochemical tail water. The optimal removal rates of total phenol and TOC were 67.7% and 58.8%, respectively. The organic matter was degraded rapidly and efficiently after 5 min of ozone catalytic oxidation reaction. It provides theoretical guidance for the practical application of ozone catalytic oxidation.

Novel chitosan-based flocculants for chromium and nickle removal in wastewater via integrated chelation and flocculation.

Carboxylated chitosan (CPCTS) is used as substrates in the design and synthesis of CPCTS-based flocculants through UV-initiated polymerization techniques. The synthesized flocculants are applied to remove Cr and Ni ions from chromic acid lotion and electroplating wastewater through two-stage flocculation. This study investigates the effect of flocculant dosage, pH, reaction time, and stirring speed on the removal efficiency of Cr and Ni ions. Results indicated that the total Cr removal ratios by CPCTS-graft-polyacrylamide-co-sodium xanthate (CAC) and CPCTS-graft-poly [acrylamide-2-Acrylamido-2-methylpropane sulfonic acid] (CPCTS-g-P(AM-AMPS)) are 94.7% and 94.6%, respectively. The total Ni removal efficiencies by CAC and CPCTS-g-P(AM-AMPS) are 99.3% and 99.4%, respectively. The two-stage flocculation with CPCTS-based flocculants could reduce the total concentrations of Cr and Ni to 1.0 mg/L and 0.5 mg/L, respectively. The relationship of removal capacity and structural properties between the flocculants with different functional groups is established through Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, and X-ray diffraction. The micro-interfacial behavior between the colloidal particles and the solution during the integrated chelation-flocculation are elucidated. Thus, CPCTS-based flocculants could be a potential material for the removal of high amounts of Cr and Ni ions in industrial wastewater.

Electrochemical degradation of oxytetracycline by Ti-Sn-Sb/γ-Al2O3 three-dimensional electrodes.

In this work, Ti-Sn-Sb/γ-Al2O3 particle electrodes were prepared and employed for the degradation of oxytetracycline (OTC) by three-dimensional electrocatalytic technology. Factors associated with the preparation of Ti-Sn-Sb/γ-Al2O3 particle electrodes were investigated. The effects of initial concentration, conductivity, pH value, aeration intensity, current density, plate spacing, and particle electrode dosage on OTC removal were studied. The removal rate of OTC and total organic carbon were achieved approximately 92.0% and 41.0% under the optimal operating condition, respectively. In addition, Ti-Sn-Sb/γ-Al2O3 particle electrode was analyzed by Fourier Transform Infrared spectroscopy (FT-IR), scanning electron microscope (SEM), energy dispersive spectrum analysis (EDX), X-Ray Fluorescence Spectrometer (XRF), and X Ray Diffraction analysis (XRD), which indicated that a significant amount of TiO2, SnO2, and Sb2O3 were formed on the surface of Ti-Sn-Sb/γ-Al2O3 particle electrode. It was also observed that the primary function of Ti-Sn-Sb/γ-Al2O3 particle electrode in the three-dimensional electrode electrolysis process is the strong oxidizing function of ·OH for degrading OTC. Consequently, the analysis of degradation products of oxytetracycline (OTC) demonstrates. In addition, the results and conclusions of this study provide a methodological basis and engineering practice basis for removing the low concentration of antibiotics in water.

Synthesis, Characterization, and Sludge Dewaterability Evaluation of the Chitosan-Based Flocculant CCPAD.

Carboxymethyl chitosan (CMCS), acrylamide, and methacryloxyethyltrimethyl ammonium chloride were used as co-monomers to produce a sludge dewatering agent carboxymethyl chitosan-graft-poly(acrylamide-methacryloxyethyltrimethyl ammonium chloride) (CCPAD) by UV-induced graft polymerization. Single-factor experiments and response surface methodology were employed to investigate and optimize the grafting rate, grafting efficiency, and intrinsic viscosity influenced by the total monomer concentration, CMCS concentration, cationic degree, pH value, and illumination time. The structure, surface morphology, and thermal stability of CCPAD were characterized by infrared spectroscopy, hydrogen nuclear magnetic resonance, X-ray diffraction, scanning electron microscopy, and differential thermal-thermogravimetry. The raw sludge with 97.9% water content was sourced from the concentrated tank of a sewage treatment plant and used in the sludge condition experiments. In addition, CCPAD was applied as the sludge conditioner to investigate the effects of cationic degree, intrinsic viscosity, and pH on the supernatant turbidity, moisture content, specific resistance to filtration, and sludge settling ratio. Moreover, the mechanism of sludge conditioning by CCPAD was discussed by examining the zeta potential and extracellular polymeric substance (EPS) content of the supernatant. The sludge dewatering results confirmed that CCPAD had excellent performance for improving sludge dewaterability.

Degradation of chloramphenicol using Ti-Sb/attapulgite ceramsite particle electrodes.

Ti-Sb/attapulgite ceramsite particle electrodes were prepared for the efficient degradation of chloramphenicol (CAP) in wastewater. To observe the surface morphology and structural characteristics of the Ti-Sb/attapulgite ceramsite particle electrodes, Fourier transform infrared spectroscopy, X-ray fluorescence, scanning electron microscopy, and X-ray diffraction were used for characterization. Parameters affecting the degradation efficiency and the energy consumption of the Ti-Sb/attapulgite ceramsite particle electrodes, such as current density, electrode distance, initial pH, conductivity, air flow, and packing ratio, were examined. Results showed that the optimal conditions were 20 mA/cm2 current intensity, 3 cm electrode distance, 5,000 µS/cm conductivity, 2.0 L/min air flow, 50.0% packing ratio, and initial pH 1. The removal efficiency of chloramphenicol was 73.7% under the optimal conditions, and the energy consumption was 191.3 (kW h)/kg CAP. PRACTITIONER POINTS: Attapulgite ceramsite with good physical performance was prepared. The removal efficiencies for CAP in water by Ti-Sb/attapulgite ceramsite particle electrodes were studied. CAP was effectively removed by 3-D electrode system. CAP removal was significantly influenced by operational parameters. Three-dimensional electrode system shows good degradation ability.

Characterization and flocculation evaluation of a novel carboxylated chitosan modified flocculant by UV initiated polymerization.

In this work, carboxylated chitosan modified flocculant (CC-g-PCD) was prepared by graft copolymerization technique to enhance the charge-attracting and adhesion of bridges and net-sweeping capacity of flocculants. The dimethyldiallylammonium chloride (DMDAAC), carboxylated chitosan (CMCS), and 3-chloro-2-chloropropyltrimethylammonium chloride (CTA) were utilized for synthesis of CC-g-PCD via photopolymerization techniques. The synthesized CC-g-PCD was characterized by 1H NMR, SEM, XRD, and FTIR, and the characteristic groups on the main chain and surface morphological structure of CC-g-PCD were investigated. The obtained results indicated that CTA and DMDAAC were successfully grafted into the CPCTS. In ordered to evaluate the flocculation performance of CC-g-PCD at various dosages, stirring intensity (G value), and pH value by detecting Chl a, COD, and turbidity, the actual lake water that contains algae was used for flocculation assessment tests. The experimental results of the water sample with flocculation showed that the maximum flocculation efficiency of turbidity (91.1%), Chl a (97.2%), and COD (97.0%) can be achieved by CC-g-PCD at pH 7, G value 200 s-1, and 4.0 mg/L. The comparison results demonstrated that CC-g-PCD had better flocculation efficiency than commercial flocculants. Finally, based on the analysis of algae removal in combination with Zeta potential measurements, the flocculation mechanisms in actual lake water at various dosages and pH values were adsorption bridging and electrical neutralization.

Plasma-induced synthesis of chitosan-g-polyacrylamide and its flocculation performance for algae removal.

Chitosan (CS)-g-polyacrylamide (PAM) is a highly efficient and environmentally friendly flocculant, which was synthesized through plasma-induced graft copolymerization of CS and acrylamide (AM). The effects of monomer concentration, AM:CS ratio, discharge power, discharge time, post-polymerization temperature, and post-polymerization time on the intrinsic viscosity, grafting ratio, and grafting efficiency of CS-g-PAM were investigated. The optimum conditions of graft copolymerization were as follows: 20% monomer concentration, 7:3 AM:CS ratio, 40 W discharge power, 90 s discharge time, 50°C post-polymerization temperature, and 24 h post-polymerization time. The structural characteristics of CS-g-PAM were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. CS-g-PAM exhibited better flocculation efficiency than the commercially available PAM in both diatomite-simulated wastewater and low-turbidity algal water. The optimal turbidity removal efficiency for the diatomite-simulated wastewater was 99.9%, which was obtained with 6 mg L-1 of CS-g-PAM at pH 11.0 and 250 s-1 of velocity gradient. In low-turbidity algal water, the optimal removal efficiencies for chlorophyll-a, turbidity, and COD were 93.6%, 94.5%, and 98.2%, respectively.

Electrocatalytic oxidation of tetracycline by Bi-Sn-Sb/γ-Al2O3 three-dimensional particle electrode.

In this work, highly efficient Bi-Sn-Sb/γ-Al2O3 particle electrodes were prepared for effectively degrading tetracycline. The effects of a mass ratio (Sn: Sb), the mass ration of Bi:(Sn + Sb), impregnation times, calcination temperature, and calcination time on the electrocatalytic oxidation capacity of Bi-Sn-Sb/γ-Al2O3 particle electrode was investigated. Conditions in which mass ratio of (Sn: Sb) = 10:1, the mass ratio of Bi:(Sn/Sb) = 1:1, impregnation times 2 h, calcination temperature 500 °C., and calcination time 3 h were considered as optimal preparation conditions for Bi-Sn-Sb/γ-Al2O3 particle electrode. It was cherecterized by infrared spectroscopy (IR), scanning electron microscope (SEM), energy dispersive X-ray detector (EDX), X-Ray Diffraction (XRD), and X-ray fluorescence (XRF) techniques to conforming that the triclinic Bi2O3 formed in the preparation conditions has superior electrocatalytic activity. The electrocatalytic oxidation mechanism of tetracycline by Bi-Sn-Sb/γ-Al2O3 particle electrode is proposed by determining degradation intermediates through LC-MS detection. Electrocatalytic oxidation experiments by adding tert-butyl alcohol indicate that the formation of OH is the primary responsibility for degradating tetracycline. Electrocatalytic degradation of tetracycline at different initial concentration shows that the degradation of tetracycline meets the pseudo first-order kinetics. Results suggest that the three-dimensional electrochemical reactor with Bi-Sn-Sb/γ-Al2O3 particle electrodes could be an alternative for the pretreatment of antibiotic wastewater before biological treatment.

Metal-Crown Ether-Porphyrin Decorated Gold Nanoparticles as High Sensitive Raman Ion Probe.

A kind of gold nanoparticles modified with metal crown ether porphyrin (GNPs-CP) was synthesized and characterized. The surface of the resulting gold particles was partially covered by metal crown ether porphyrin molecules through strong covalent Au-S bond. Based on the coupling effect of metal porphyrin and crown ether, the resulting composite gold nanoparticles can serve as a kind of ion probe. Raman and UV-Vis spectra were utilized to evaluate the ion recognition of the system, both of which changed dramatically when meeting metal ion corresponding to ligand of crown ether. Compared with UV-Vis spectra, Raman spectra of the composites are more sensitive and the limit of detection (LOD) can reach 1 × 10-8 g/mL. The study provides a candidate with higher sensitivity to replace current UV-Vis spectrum based evaluation tool for ion recognition.

UV-initiated synthesis of a novel chitosan-based flocculant with high flocculation efficiency for algal removal.

In this study, maleyl chitosan-graft-polyacrylamide (MHCS-g-PAM), a novel chitosan-based flocculant, was prepared through UV irradiation, and maleyl chitosan (MHCS) was designed and prepared with maleic anhydride and acrylamide (AM) through maleyl acylation reaction. The effects of monomer concentration, MHCS-to-AM ratio, illumination time, initiator concentration, pH on viscosity, and grafting efficiency were investigated to optimize the synthesis of these substances. MHCS-g-PAM was characterized through Fourier transform infrared spectroscopy, nuclear magnetic resonance hydrogen spectroscopy, scanning electron microscopy, and thermal gravimetric analysis. Flocculation mechanisms in alga-containing wastewater at various pH levels and dosages were examined in detail on the basis of zeta potential measurements. Zeta potential experiments indicated that the adsorption-bridging and charge neutralization mechanisms played an important role in algal removal. Flocculation tests on algal removal demonstrated that the flocculation performance of MHCS-g-PAM was more effective than that of cationic polyacrylamide, polyferric sulfate, and polymeric aluminium. The optimal Chl-a and COD removal rate obtained by MHCS-g-PAM was 98.6% and 94.9% at pH7 and 4mg·L-1, respectively.