Chemical Oxidation Process Research Articles

Easy synthesis of PPy/TiO2/ZnO composites with superior photocatalytic performance, efficient supercapacitors and nitrite sensor

The synthesis of Polypyrrole (PPy)/TiO2/ZnO composites involved a chemical oxidative polymerization process, wherein the addition of TiO2/ZnO was varied from 1 to 10 wt%. The composites' photocatalytic capabilities, supercapacitor performance, and potential use as a nitrite sensor were thoroughly assessed, alongside investigations into their photoluminescence (PL) and morphological characteristics. The strong interaction between TiO2/ZnO and PPy was confirmed using FTIR, UV–Vis, and PL spectroscopy techniques. The composites demonstrated aggregated and spherical-shaped morphological features investigated by FESEM. Such morphological structures of the composites were distinct from the TiO2/ZnO (rod-like) and similar to PPy structure (spherical). However, such composites showed dominating spherical-shaped morphology ensuring a diameter in the range of 50–200 nm. The PPy/TiO2/ZnO composites exhibited significantly enhanced photocatalytic efficiency in methylene blue (MB) removal, achieving a range of 88–93% compared to PPy alone, which only achieved 77.2% MB removal. The Cyclic Voltammetry (CV) data exhibited a promising hybrid supercapacitor performance of the composites with a high capacitance value, good energy density, as well as an excellent power density. The fabricated supercapacitor was capable of lightened up a single red 5 mm LED for a few minutes, indicating the commendable energy storage capacity. A newly developed PPy/TiO2/ZnO composite is potentially used to develop as a sensor probe for the detection of nitrite chemicals using the linear sweep voltammetry (LSV) technique in three electrodes system in room conditions. It is found an excellent sensor results in terms of sensitivity as well as detection limit and satisfactory results when validated with the real samples. These results offer novel insights into the fabrication of PPy/TiO2/ZnO photocatalysts for addressing organic waste treatment, while also presenting promising prospects for potential applications in supercapacitors and sensors.

Electrochemistry in the Teaching Laboratory to Synthesize and Evaluate Catalysts for Water Oxidation and Reduction

Electrochemical analysis is an important skill to teach in chemistry curricula because it is a critical tool in current high-impact chemical research. Electrochemistry enables researchers to analyze a variety of systems extending from molecules to materials that encompass research themes ranging from clean energy to substrate activation in biological systems. Specifically, it can reveal information about catalytic efficiency, the role of catalysts, and the nature of chemical reduction and oxidation (redox) processes. Researchers working in the area of catalysis rely heavily on electrochemistry, using it to identify effective catalysts and to optimize reaction conditions. This talk with describe a laboratory experiment designed for undergraduate chemistry majors. The laboratory experiment begins with an introductory tutorial to electrochemistry by guiding students through the use of several electrochemical techniques using the ferricyanide/ferrocyanide redox couple as a model system. The techniques covered in the tutorial include cyclic voltammetry, differential pulse voltammetry, Tafel analysis, and bulk electrolysis. The protocol then applies these techniques to electrocatalysis by identifying and characterizing catalysts for hydrogen and oxygen generation in the water electrolysis reaction. Electrochemical methods are connected to current chemical research by focusing on catalysis in the context of renewable energy, which is a current societal and curricular imperative. The entire laboratory protocol is suitable for upper-level physical, analytical or inorganic chemistry. Figure 1

Surfactant-enhanced in-situ oxidation of DNAPL source zone: Experiments and numerical modeling

In this study we investigate the synergetic effects of combining surfactant-enhanced dissolution with in-situ oxidation of a pool-dominated PCE DNAPL source zone entrapped in porous media. Flow cell flushing experiments packed with silica sand and natural calcareous soil were conducted with a surfactant (Tween 80) and permanganate (MnO4−) used as dissolution and oxidation agents, respectively. The resultant breakthrough curves exhibited a multiple step behavior with mass removal controlled in the latter stages by the less-accessible DNAPL mass. DNAPL spatial architecture, flow-field heterogeneity, and flushing solution all influenced the remediation effort. When taking into account both the surfactant-enhanced dissolution and permanganate oxidation processes, mass-flux reduction/mass-removal behavior relationships indicated that the inclusion of oxidation in the remediation scheme delayed the drop in mass flux from the source zone, leading to improved DNAPL removal efficiency. Numerical modeling was also performed to further evaluate the efficacy of the surfactant-enhanced chemical oxidation of DNAPL PCE with permanganate. The system of reaction equations available in the multiphase flow simulator UTCHEM were adapted to simulate the chemical oxidation process in the presence of a surfactant. The model results yield lower oxidation reaction rate constants in the presence of Tween 80, indicating that Tween 80 can interfere with the reaction rate. However, the increase in the solubility of PCE in the presence of Tween 80 more than compensates for the decrease in reaction rate constant. Overall, for Tween 80/MnO4− applied at sufficient dosages, more efficient DNAPL zone remediation was achieved compared to surfactant flushing or permanganate oxidation alone.

IRON REMOVAL FROM LADEN BIOLEACHING SOLUTION BY PROCESSES OF SOLVENT EXTRACTION AND MAGNETITE SYNTHESIS

Laden leach solution, generated from bioleaching of pyrometallurgical copper slags with a mixed culture of moderately thermophilic bacteria in a bioreactor, contains several base metals (Cu, Co, Zn) and a very high concentration of iron (33,9 g/ L). Further processing of cobalt and zinc to the respective final products requires preparatory iron removal from the laden leach solution. The direct iron removal from that solution as goethite was unacceptable because of the significant co-precipitation of copper and cobalt from the solution. The main aim of this paper is to study magnetite (Fe3O4) synthesis as an approach for iron removal to a value-added product as a step of the processing of a laden solution generated due to the bioleaching of non-ferrous metals in a bioreactor. Ferrous iron oxidation to ferric state was efficient when the addition of H2O2 (30 %) was combined with maintaining the pH 3,1-3,3 with NaOH and air purging. Solvent extraction with 25 % D2EHPA and 7,5 % TBP dissolved in kerosene efficiently separated the dissolved iron and the base metals from the processed solution. However, in the presence of H2, the iron was stripped from the organic solvent with low acid consumption. The applied precise control of the chemical precipitation and oxidation processes at 50 degrees Celsius allowed the iron content (11,7 g/ L) in the stripping solution to be removed efficiently as magnetite (Fe3O4). Based on the chemical content of iron, copper and sulphur, the synthesised nanoparticles of magnetite could be applicable in many sectors (steel, chemical, and electronics).

A novel approach to electromagnetic wave absorbing material design: Utilizing nano-antenna arrays for efficient electromagnetic wave capture

This paper proposes a new and unprecedented strategy for designing efficient and ultra-light electromagnetic wave (EMW) absorbing materials. The strategy utilizes a nano-antenna arrays structure to capture EMW. Specifically, CoNi-layered double hydroxide (CoNi-LDH) nanoneedles are designed on the surface of carbon fiber cloth (CFC) using a solvothermal method, whereafter an in situ chemical oxidative polymerization process is employed to construct polyaniline (PANI) coating on these CoNi-LDH nanoneedles. The resultant composite, named PANI@CoNi-LDH@CFC, possesses the unique shell-core PANI@CoNi-LDH nano-antenna arrays and thus exhibits enhanced EMW absorption performance. The PANI@CoNi-LDH@CFC composite obtains an effective absorption bandwidth of 14.8 GHz (1.0–5.0 mm) and a minimum reflection loss of −57.6 dB. In particular, computer simulation technology confirms that the radar cross section values of PANI@CoNi-LDH@CFC are lower than −16.4 dBm2 in the range of −60°<θ < 60°, indicating a high radar wave attenuation ability. This work pioneers the research on design of nano-antenna arrays structure to strengthen EMW capture and opens up a unique path for constructing high-performance EMW absorbing materials.

Reaction: Harnessing reactive oxygen species (ROS) for water purification

Shishu Zhu received his PhD from the Harbin Institute of Technology in 2019 and became an associate professor at the South China University of Technology (SCUT) in 2023. His research fields include in situ chemical oxidation processes, the transport and deposition of contaminants, and organic geochemistry. Wenxiao Zheng is a PhD candidate at SCUT. His research focuses on identifying and controlling toxic byproducts in reactive-species-initiated wastewater treatment. Weijian Duan is a research fellow at SCUT. His research focuses on developing cutting-edge electrochemical strategies for nitrogen and carbon removal from wastewater. Chunhua Feng received his PhD from Hong Kong University of Science and Technology in 2007 and then joined SCUT as an assistant professor. He is now a professor at SCUT. His research interests are environmental electrochemistry, reactive-species-based geochemistry, and wastewater treatment. Shishu Zhu received his PhD from the Harbin Institute of Technology in 2019 and became an associate professor at the South China University of Technology (SCUT) in 2023. His research fields include in situ chemical oxidation processes, the transport and deposition of contaminants, and organic geochemistry. Wenxiao Zheng is a PhD candidate at SCUT. His research focuses on identifying and controlling toxic byproducts in reactive-species-initiated wastewater treatment. Weijian Duan is a research fellow at SCUT. His research focuses on developing cutting-edge electrochemical strategies for nitrogen and carbon removal from wastewater. Chunhua Feng received his PhD from Hong Kong University of Science and Technology in 2007 and then joined SCUT as an assistant professor. He is now a professor at SCUT. His research interests are environmental electrochemistry, reactive-species-based geochemistry, and wastewater treatment. Reaction: Avoid fairy dust when engineering water-purification technologiesPaul WesterhoffChemJune 08, 2023In BriefThis Catalysis article discusses the risks of using nanomaterials for water purification and alternative strategies, painting a fuller picture of research in clean water. Full-Text PDF Catalyst: The roles of chemistry in clean water for allYoung-Shin JunChemJune 08, 2023In BriefUnderstanding nanoscale interfacial reactions unlocks the chemistry controls that are critical for generating clean water. This catalysis article discusses three important roles of chemistry in clean water: understanding and controlling evolving interfaces induced by nucleation, deciphering and utilizing hidden interfaces in nanoconfined spaces, and harnessing interfaces with functionalized surfaces. Chemically guided developments of new materials and technologies for purifying clean water can bring all water resources back to one H2O, which supports life for all people. Full-Text PDF

Degradation of Methylene Blue Dye in Wastewater Using Ozonation Method with H2O2 Catalyst

Water pollution is still a serious problem in Indonesia. One of the pollutants that contribute to water pollution is dye. One type of dye that is often used in the textile industry is methylene blue. There are several methods for treating dye waste, one of which is the ozonation method. Ozonation is a chemical oxidation process to remove the color of organic dyes. The catalytic ozonation process can increase the ability of ozone in sewage treatment. The catalyst used is H2O2 which can decompose into OH radicals. OH radicals have a higher reduction potential than other oxidizing agents. Ozonation research with H2O2 catalyst aims to determine changes in the concentration of dyes, COD and BOD5. In testing the ozonation time (0.15,30,45,60) minutes, the pH conditions (5,7,9) and the total mass concentration of H2O2 (0.2,5,5,7,5,10) % showed that the longer the time ozonation, the higher the pH value. and the more H2O2 used, the less concentration of dye, COD and BOD5.

Photocatalytic Degradation of Toluene (Component of Crude Oil) Contaminated Water Using Titanium Dioxide Based Catalyst: A Review

Petroleum industry is one of the fastest growing industry in the world, and it contributes significantly to the profitable development in unindustrialized countries. The wastewater from a petroleum industry consist a wide variety of pollutants like petroleum hydrocarbons, mercaptans, oil and grease, benzene, toluene, ethylbenzene, xylene, phenol, ammonia, sulphide and other organic compounds etc. All these compounds are present as very complex form in discharged water of petroleum industry, which are harmful to the environment and human health directly or indirectly. Pollution of soil-water interface due to the release of hydrocarbons in environment is a major public health concern, and therefore, remediation of these pollutants is needed to reduce risk to human and environment. Various methods such as physical, chemical, biological, and Advanced oxidation processes (AOPs) methods are used to degrade these pollutants from wastewater. The conventional remediation methods can only change the phase of contaminants without destroying them, thereby leading to another pollution problem. This review paper highlights some current treatment methods of toluene contaminated water, and to introduce a proposed method that sought to develop an oleophilic and hydrophobic composite catalyst (ESA-TiO2-FeS2-Kenaf), that would harvest the toluene content, and simultaneously degrade the harvested toluene content using solar light as the energy source.

Coupling acid catalysis and selective oxidation over MoO3-Fe2O3 for chemical looping oxidative dehydrogenation of propane

Redox catalysts play a vital role in chemical looping oxidative dehydrogenation processes, which have recently been considered to be a promising prospect for propylene production. This work describes the coupling of surface acid catalysis and selective oxidation from lattice oxygen over MoO3-Fe2O3 redox catalysts for promoted propylene production. Atomically dispersed Mo species over γ-Fe2O3 introduce effective acid sites for the promotion of propane conversion. In addition, Mo could also regulate the lattice oxygen activity, which makes the oxygen species from the reduction of γ-Fe2O3 to Fe3O4 contribute to selectively oxidative dehydrogenation instead of over-oxidation in pristine γ-Fe2O3. The enhanced surface acidity, coupled with proper lattice oxygen activity, leads to a higher surface reaction rate and moderate oxygen diffusion rate. Consequently, this coupling strategy achieves a robust performance with 49% of propane conversion and 90% of propylene selectivity for at least 300 redox cycles and ultimately demonstrates a potential design strategy for more advanced redox catalysts.

REDUCTION OF COD FROM REACTIVE DYE WASTE WATER

Due to the scarcity of water resources, it is crucial to safeguard public health and well-being. One way to achieve this is by enforcing stringent regulations on the discharge of wastewater effluents to minimize the introduction of harmful substances into water bodies. Furthermore, there is a growing trend to reduce total solids (TS) in wastewater and repurpose them for industrial applications. The treatment of wastewater to a high standard has expanded the potential uses while reducing negative impacts on freshwater ecosystems. Currently, the main environmental issue in wastewater treatment is related to dye effluents. This is because the textile industry consumes a substantial amount of water, resulting in wastewater that contains unused colours and their constituents. Dye-containing wastewater produced by the textile sector is extremely toxic and poses severe challenges for wastewater treatment facilities. Textile effluents contain high levels of colour, TDS, and hazardous metals, which have reduced the ability of contaminants to self-degrade in wastewater. Numerous techniques, such as chemical oxidation, coagulation and adsorption processes, as well as biological processes, are employed to remove dye using traditional methods, but none of these are sufficient on their own to remove dye from wastewater. For instance, biological processes are unsuitable for decolourization of dyes since the majority of the colours are inorganic and harmful to the process microorganisms. Activated carbon is effective for treating soluble colours, while coagulation is better suited for insoluble dyes but not for soluble ones. Due to the product of their degradation, most dyes in particular reactive dyes cause serious environmental problems. Due to the complicated structure and refractory nature of dyes, the degradation of colours from textile effluent is exceedingly hard. Wastewater produced in textile manufacturing plants may contain both natural and synthetic pollutants, the composition of which depends on the production techniques employed. Several parameters are commonly used to evaluate the characteristics of textile wastewater, such as Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Suspended Solids (SS), Dissolved Solids (DS), pH, Chloride, Sodium, and others. The quality of textile wastewater is determined by these parameters, and it is important to take them into account when selecting appropriate treatment methods to ensure that the environment is not adversely impacted.

Self-assembled quantum dots decorated polypyrrole based multifunctional nanocomposite

A modified sol-gel method was used for the synthesis of V/Mn/ZnO (VMZ) self-assembled ternary quantum dots (QDs). The polypyrrole (PPy) was polymerized through the chemical oxidative process. In situ technique was employed for synthesizing VMZ/PPy nanocomposites (NCs). FESEM, TEM, FTIR, UV–visible, Raman, DSC, PL, powder XRD, TGA and DSC were employed to characterize QDs and VMZ/PPy NCs. The theoretical (DFT) method was used to augment the experimental results. For the first time, we are reporting the electrical, adsorption, magnetic, photocatalytic, antibiotic, thermal, and photoluminescent, and anticorrosive properties of VMZ/PPy NCs. VMZ/PPy NCs show a para-magnetic character. The optical band obtained from DFT and UV–visible study was almost similar. For low-carbon steel, the NCs show a maximum of 83.08 ± 0.2% corrosion inhibition efficiency in 1 M HCl. The column packed with silica gel + QDs shows better adsorption capacity than the conventional silica-gel column. The photocatalytic activity of NCs was investigated against methyl-blue dye in UV light. The antibacterial property was investigated against Gram-positive and Gram-negative bacterial strains. The adsorption, magnetic, photocatalytic, electrical, antibiotic, thermal and photoluminescent, and anticorrosive properties of the VMZ/PPy NCs proved it a very good multifunctional nanomaterial.

Unveiling Molecular Transformations of Soil Organic Matter after Remediation by Chemical Oxidation Based on ESI-FT-ICR-MS analysis

Remediation of soils contaminated with organic pollutants is often accomplished by chemical oxidation processes using oxidants such as persulfate or H2O2. However, it is unclear how different oxidants transform soil organic matter (SOM) and affect soil ecosystem services. Herein, two chemical oxidation technologies, Fenton reaction (FT) and base-activation of sodium persulfate (BP), were investigated to remediate diesel-polluted soils. The molecular transformation of SOM was analyzed using excitation–emission matrix fluorescence spectroscopy (EEM FS) and electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). Fulvic acid-like substances and lipids were consumed in both treatments, while the contents of lignin-like and tannin-like substances increased after BP treatment. The oxygen to carbon ratios (O/C), modified aromaticity index (AImod), and double bond equivalent (DBE) of SOM increased significantly in BP-treated soil, while these parameters decreased in FT-treated soil (FTS), suggesting the oxygen-containing, unsaturated and aromatic compounds were produced in BPS but removed in FTS. The increased cation exchange capacity (CEC) value (81.47 cmol/kg) and germination index of wheat seed (97%) for the SOM in BPS indicate the possible favorable effect of persulfate-based treatment on soil quality. Overall, this study advances mechanistic understanding of the effects of H2O2- and persulfate-based soil remediation technologies based on the molecular compositions of SOM and soil quality.

Fe-metal organic framework converts mechanical energy with piezoelectric polarization to remove carbamazepine in water: Efficiency, pathway and mechanism

Piezocatalysis is a new technique that directly transforms mechanical energy into chemical energy. Although this approach can potentially be used to replace traditional water treatment methods, the structural tailorability and limited surface area of conventional inorganic piezoelectric materials restrict their catalytic efficiency. Herein, we employed a piezoelectric material made of an organic Fe-metal organic framework (MOFs) to purify water via piezocatalysis. We analyzed the physicochemical properties of MIL-100(Fe), including its piezoelectricity, bandgap structure, and charge separation efficiency. Carbamazepine (CBZ) was used as a representative aqueous drug pollutant, and MIL-100(Fe) removed 92 % of CBZ in 30 min via applying ultrasonication (US), which was 5.1 and 11.5 times higher than either the individual MIL-100(Fe) or US. The mechanical US stresses generated a built-in electric field in MIL-100(Fe) to promoted free charge migration, and also modulated the band structure of the sample. This promoted the production of reactive oxygen species. In this work, shows that porous piezoelectric nanostructures based on MOFs can convert mechanical energy into chemical energy to drive chemical oxidation processes.

Colloidal iron species driven enhanced H2O2 decomposition into hydroxyl radicals for efficient removal of methylene blue from water

Colloids are wide-spread in natural waters and colloid-facilitated transport via adsorption was established as the most important mechanism for the mobilization of aqueous contaminants. This study reports another possible, but reasonable, role of colloids for the contaminants driven by redox reactions. Under the same conditions (pH 6.0, 0.3 ml 30% H2O2, and 25 °C), the degradation efficiencies of methylene blue (MB) at 240 min over Fe colloid, Fe ion, Fe oxide and Fe(OH)3 were 95.38%, 42.66%, 4.42% and 9.40%. We suggested that, Fe colloid can promote the H2O2 based in-situ chemical oxidation process (ISCO) compared with other iron species such as Fe(Ⅲ) ion, Fe oxide and Fe(OH)3 in natural water. Furthermore, the MB removal via adsorption by Fe colloid was only 1.74% at 240 min. Hence, the occurrence, behavior and fate of MB in Fe colloid containing natural water system mainly depends on the reduction-oxidation rather than adsorption-desorption process. Based on the mass balance of colloidal iron species and characterization of iron configurations distribution, Fe oligomers were the active and dominant components for Fe colloid-driven enhanced H2O2 activation among three types of Fe species. The quick and steady conversion of Fe(III) to Fe(II) was proven to be reason why Fe colloid can efficiently react with H2O2 to produce hydroxyl radicals.

Removal of Reactive Blue 19 dye from synthetic wastewater using UV/H2O2 and UV/Cl advanced oxidation processes

AbstractThe textile and dyeing industries are among the largest water‐consuming and polluting industries in the world. The most important feature of the textile dyeing industry wastewater is its color, due to the use of colored materials. Most of these dye compounds are resistant to conventional purification methods and their biodegradation is very low through secondary purification processes, resulting in incomplete removal. Therefore, selecting the optimal method to remove these color compounds is essential. In this study, we studied the removal of an organic dye contaminant (Reactive Blue dye 19 [RB19]) using advanced oxidation processes (AOPs). For this purpose, ultraviolet (UV) mercury lamps with a wavelength of 254 nm and a voltage of W16 inside a reactor were used as an energy source. The experiments were performed in a collimated beam reactor inside a dark chamber. Two oxidizers, sodium hypochlorite (NaOCl) and hydrogen peroxide (H2O2), were used to remove RB19 from the artificial sewage stream. Removal of RB19 with a concentration of 20 mg/L with variable pH (5, 7, and 9), oxidant concentrations (5, 10, and 20 mg/L), and time (5, 10, 15, and 30 min) were investigated during the processes of photolysis, chemical oxidation (by H2O2 and NaOCl), and UV/NaOCl and UV/H2O2 AOPs. The photolysis process did not remove the RB19. The highest removal efficiencies of RB19 by chemical oxidation processes with NaOCl and H2O2, UV/NaOCl, and UV/H2O2 at optimal conditions (pH = 5, [oxidant] = 20 mg/L, RB19 = 20 mg/L, and radiation intensity of 1005 mJ/cm2) were 64.49%, 0.88%, 99.7%, and 13.31%, respectively. These results indicate that the hydroxyl radical was produced, under optimum conditions, more in the acidic medium; thus, the RB19 removal efficiency was higher in the acidic medium. The combination of UV rays with oxidants resulted in the production of more hydroxyl radicals and increased removal efficiency.

Green Carbon Dots: Synthesis, Characterization, Properties and Biomedical Applications.

Carbon dots (CDs) are a new category of crystalline, quasi-spherical fluorescence, "zero-dimensional" carbon nanomaterials with a spatial size between 1 nm to 10 nm and have gained widespread attention in recent years. Green CDs are carbon dots synthesised from renewable biomass such as agro-waste, plants or medicinal plants and other organic biomaterials. Plant-mediated synthesis of CDs is a green chemistry approach that connects nanotechnology with the green synthesis of CDs. Notably, CDs made with green technology are economical and far superior to those manufactured with physicochemical methods due to their exclusive benefits, such as being affordable, having high stability, having a simple protocol, and being safer and eco-benign. Green CDs can be synthesized by using ultrasonic strategy, chemical oxidation, carbonization, solvothermal and hydrothermal processes, and microwave irradiation using various plant-based organic resources. CDs made by green technology have diverse applications in biomedical fields such as bioimaging, biosensing and nanomedicine, which are ascribed to their unique properties, including excellent luminescence effect, strong stability and good biocompatibility. This review mainly focuses on green CDs synthesis, characterization techniques, beneficial properties of plant resource-based green CDs and their biomedical applications. This review article also looks at the research gaps and future research directions for the continuous deepening of the exploration of green CDs.

Enhanced removal of oxytetracycline from aquatic solution using MnOx@Fe3O4 bimetallic nanoparticle coated powdered activated carbon: synergism of adsorption and chemical autocatalytic oxidation processes

The existence of MnOx@Fe3O4 bimetallic nanoparticles improved the adsorption capacities by increasing the adsorption sites of PAC and the self-catalytic reaction extended the service life of MnOx@Fe3O4-PAC without additional use of oxidants.

NEW COMPOSITE MATERIALS AND PROCESSES FOR CHEMICAL, PHYSICO-CHEMICAL AND BIOCHEMICAL TECHNOLOGIES OF WATER PURIFICATION

In traditional methods of water purification, the use of chemical reagents leads to the appearance of toxic by-products and wastes that require complex energy-consumption processing technologies. In accordance with the principles of sustainable development and “green” technologies, a significant revision of existing water treatment methods is required. The review highlights the main trends of innovative development of water purification and disinfection technologies. Modifications of water treatment agents (flocculants, sorbents, membranes) by integration of nanoparticles, environmentally compatible materials and “smart” composites into traditional structures are described. The use of composite nanoparticles is promising, particularly the use of particles with the “magnetic core – shell” structure, in which functional elements are attached to the surface, that provide the selective capture of contaminants, including pathogenic microorganisms. The existence of the magnetic core makes it possible to manipulate particles by the applied magnetic field, which is important for their complete extraction from the water upon completion of their functions. The use of new composite flocculants containing inorganic and organic components capable of ensuring highly effective capture of contaminants from the water, significantly reduces the volumes of flocculants and generated sludges and therefore allows to reduce the cost of the sludges processing and the harm of their disposal in the environment. New carbon nanostructures and natural polymers have an important role to play. In the new generation membranes, the disperse nanoparticles may provide antibacterial and photocatalytic properties, resulting in the high efficiency of disinfection and purification. A novel trend is the development of hybrid structures of coagulants and membranes with the properties which are regulated by the external stimulus, which are temperature, pH, light, electric, magnetic and electromagnetic fields. The use of such «smart» structures will increase the purification efficiency, reduce energy consumption and water purification waste volumes, due to the decrease in membranes fouling. The use of biopolymers and composites based on plant raw materials for the water purification is attractive due to their natural decontamination under the influence of the components of the environment, such as air, soil micro-organisms and sunlight, but also due to the absence of the secondary pollution. Among innovative chemical water treatment technologies Advanced Oxidation Processes play an important role, in particular, by involving electromagnetic fields and ultrasonic activation. By these methods, harmful organic impurities and pathogens are destroyed without the intensive use of chemicals or the production of toxic by-products. The integration of biochemical wastewater treatment with a microalgae growing system can become a promising waste-free, cost-effective "green" technology.

Leaching mechanism of strategic metals from superalloy scrap under ultrasonic cavitation

To improve the recovery efficiency of strategic metals from superalloy scrap, an ultrasonic-assisted leaching method was proposed. During the ultrasonic-assisted leaching process, at 60 min, the leaching rates of Re, Ni, Co, Al, Cr, and W are 92.3%, 95.2%, 98.5%, 98.7%, 97.5%, and 27.2%, respectively, which are far superior to those in the normal leaching process at 120 min. The improvement in leaching efficiency can be attributed to the physical and chemical coupling effects of ultrasonic cavitation. The physical effect can prevent the formation of the impeded dissolution layer and encourage contact between solution and superalloy scrap, which improves the leaching rates of strategic metals. The chemical effect can promote the production of hydroxyl radicals in the HCl−H2O2 system, which can enhance the potential of the leaching system, resulting in stimulation of the chemical oxidation process of Re to ReO4−.

A Novel Nanocomposite Based on Triazine Based Covalent Organic Polymer Blended with Porous g-C3N4 for Photo Catalytic Dye Degradation of Rose Bengal and Fast Green.

Metal free visible light active photocatalysts of covalent organic polymers (COPs) and polymeric graphitic carbon nitride (g-C3N4) are interesting porous catalysts that have enormous potential for application in organic pollutant degradation. Imine condensation for COPs, and thermal condensation for g-C3N4 were used to produce the catalysts. FT-IR, Raman, NMR, UV-Vis Spectroscopy, X-ray diffraction, and scanning electron microscopy studies were used to investigate the structural, optical, and morphological features of the metal free catalysts. We have constructed COPs with a π-electron deficient (Lewis acidic) triazine core and π -electron rich (Lewis basic) naphthalene and anthraquinone rings coupled by -O and -N donors in this study. Furthermore, the prepared Bulk-g-C3N4 (B-GCN) was converted to porous g-C3N4 (P-GCN) using a chemical oxidation process, and the generated P-GCN was efficiently mixed with the COP to create a novel nanocomposite for photocatalytic application. Using the anthraquinone-based COP and P-GCN (1:1 ratio, PA-GCN) catalyst, the highest photodegradation efficiencies for the polymeric graphitic carbon nitride of 88.2% and 82.3% were achieved using the Fast green (FG) and Rose bengal (RB) dyes, respectively. The rate constant values of 0.032 and 0.024/min were determined for FG and RB degradation, respectively. Higher activity may be related to the incorporation of COP and PA-GCN, which act significantly well in higher visible light absorption, have superior reactive oxygen generation (ROS), and demonstrate an excellent pollutant-catalyst interaction.