Environmental Treatment Technologies Research Articles

Elucidating the role of S-containing structure in carbon-based catalysts towards efficient H2O2 synthesis in seawater

The on-site sustainable electrochemical synthesis of hydrogen peroxide (H2O2) in natural seawater holds significant practical value in the fields of energy storage and environmental treatment. However, the poisoning of the active sites by ions such as Cl−, Ca2+, and Mg2+ in natural seawater significantly inhibits the ORR activity of the catalyst. Herein, the 2e− ORR performance of S, N co-doped carbon materials in natural seawater was investigated, focusing on the anti-Ca2+/Mg2+ poisoning mechanism of S-doped carbon structures. The data indicate a Faradaic efficiency of 94.2 % for H2O2 production, with a yield of 3.52 mol/(gcat h), and an approximate 100 % sterilization of bacteria and inactivation of chlorella within 10 min. S-doped carbon structures demonstrated enhanced H2O adsorption and dissociation properties during the ORR process, optimized the micro-environment of the catalytic interface, effectively inhibited Ca2+ and Mg2+ deposition. Moreover, S-doping altered the N coordination structure, further enhancing the 2e− ORR selectivity of the catalyst. This study demonstrates the high selectivity of 2e− ORR in natural seawater, offering guidance for designing catalysts using in the complex environment and advancing marine energy storage and environmental treatment technologies.

Porous metal–organic framework-based filters: Synthesis methods and applications for environmental remediation

• MOFilter synthesis methods and environmental applications are summarized. • A comparison of various MOFilter architecture and substrates is provided. • Potential technologies for customizing MOFilter pore morphology are evaluated. • Mechanisms controlling effectiveness and structures of MOFilters are discussed. • Our perspectives on future developments of MOFilters are presented. Hazardous contaminants emitted from anthropogenic activities are widespread and threaten human health and ecological sustainability. Porous metal–organic framework-based filters (MOFilters) are emerging hybrid materials for high-performance environmental treatment technologies. They are widely used for the treatment of environmental problems, including the removal of particulate matter (PM), volatile organic compounds (VOCs), hazardous gases, volatile radioactive species, metal ions, dyes, chemical warfare agents (CWA) and oils. Through customizing their architectures and functionalities, MOFilters can enhance the performance of current environmental treatment technologies. This review summarizes the design concepts and synthesis strategies of MOFilters, and the latest progress and challenges for air purification and water treatment. The underlying mechanisms of contaminant removal via filtration, adsorption and degradation are also summarized to aid the design and optimization of the structural properties of MOFilters for specific applications. This review will guide the design of MOFilters for environmental remediation.

Efficient photocatalytic aerobic oxidation of bisphenol A via gas-liquid-solid triphase interfaces

As a promising environmental treatment technology, photocatalysis has been investigated for decades and even tentatively practiced in actual large-scale applications. However, most researches focus on photocatalytic kinetics (excitation, charge transfer, and surface reaction) but ignore the significant impact of oxygen interfacial mass transfer for photocatalytic aerobic oxidation in aqueous media. Here, we use finite element simulation to demonstrate that during photocatalysis, the remained local oxygen concentration for photocatalysts at a gas-liquid-solid triphase interface is much higher than that dispersed in a bulk liquid phase. Photocatalyst consisting of Au/TiO2 nanoparticles supported at triphase interface shows a non-diffusion limited charge separation for oxygen photoactivation, therefore achieving a photodegradation efficiency of about 85% toward bisphenol A. Furthermore, we develop a flowing triphase photocatalytic system that exhibits a tunable one-way photodegradation efficiency from 10% to 60% and a photostability for up to 50 h of continuous irradiation, further demonstrating the potential for large-scale applications.

Peroxymonosulfate-assisted for facilitating photocatalytic degradation performance of 2D/2D WO3/BiOBr S-scheme heterojunction

The Sulfate-mediated photocatalysis (SR-photo) technology was considered to be a rapid, efficient and green environmental treatment technology. In this study, the two-dimensional/two-dimensional WO3/BiOBr S-scheme heterojunction (2D/2D WOB) were prepared through the hydrothermal method. Subsequently, multiple characterization techniques confirmed that WO3 was successfully loaded on the surface of BiOBr nanosheets and an intimate interaction was formed. Tetracycline (TC) and enrofloxacin (ENR) were used as target pollutants to evaluate the degradation performance of the WOB/SR-photo system. The 1:2 WOB heterojunction exhibited the highest degradation activity, and the remove rate of TC and ENR reached 98% and 87%, respectively, within 60 min. Moreover, radical quenching experiments and electron paramagnetic resonance (EPR) results implied that the 1O2, h+, and ·O2 − played critical roles in the WOB/SR-photo system. The intermediate products of TC degradation were analyzed by liquid chromatography-mass spectrometer (LC-MS), and three possible degradation pathways were inferred. The photoelectrochemical measurement, photoluminescence (PL) and time-resolved PL confirmed that 1:2 WOB composite exhibited the highest transfer rate of charge carriers. Finally, based on the results of UV-DRs, Mott-Schottky curve and Density functional theory (DFT) calculations, the S-scheme WOB heterostructure was determined, and the degradation mechanism of the WOB/SR-photo system was also clarified. This study confirmed the superiority of the SR-photo system and brought dawn to the application of numerous photocatalysts with insufficient performance.

Review on Environmental Treatment of Heavy Pollution Industry

The development of heavy pollution industry has a certain impact on the ecological environment. This paper combs and summarizes the environmental treatment technology of heavy pollution industry from the aspects of air pollution and water pollution. During studing the advantages and disadvantages of various environmental treatment technologies, the authors finds that there are the following problems in the development of environmental treatment technology of heavy pollution industry in China: there is a lack of long-term planning for air pollution environmental treatment; The cost of water pollution control is high and the energy consumption is large. Therefore, relevant environmental governance departments should promote the concept of sustainable development and strengthen the constraints of waste gas and sewage treatment process; Enterprises in heavy pollution industries need to learn and learn from the cutting-edge technologies of environmental governance; Social media positively guide enterprises in heavily polluting industries to protect the ecological environment through public supervision.

Environmental treatment technology for complex coalfield fire zone in a close distance coal seam—A case study

To achieve fast and effective control of complex coalfield fire areas in close-distance coal seams, proposals regarding “blocking air leakage, reducing oxygen, eliminating high temperature, and preventing re-ignition” were put forward. Combined with isotope radon measurement, infrared thermal imaging and ground drilling construction technology, the exact location of coalfield fire source was outlined. According to the characteristics of coalfield fire areas in Liujiamao and Qian’an mines, a set of economical and efficient coalfield fire control and extinguishing plans have been developed, which include the isolation of the production system, treatment of slope, injection of fly ash composite colloid, and excavation. The results show that the combined application of multiple detection technologies can accurately determine the location of fire source and divide three regions according to the temperature distribution. In addition, we developed a set of coalfield fire detection, fire-fighting equipment, fire-fighting materials and data monitoring as one of the coalfield fire control and extinguishing technology. Through the implementation of the plan, the coalfield fire disaster of Liujiamao and Qian’an mines was successfully solved. The successful application of this technology provides theoretical and technical support for similar coalfield fire control and extinguishing.

Analysis on Flue Gas Pollution of Coal-fired Boiler and Its Countermeasures

As the main energy in industrial production, coal resources are widely used in the world. However, in the process of coal combustion will produce a certain amount of pollutants, thus causing adverse effects on the air. The analysis of flue gas treatment of coal-fired boiler aims at improving coal utilization rate, reducing flue gas emission and advocating low-carbon concept. This paper deeply analyzes the flue gas problem of coal-fired boiler, explores the effective environmental treatment technology, and makes contribution to the environmental treatment problem.

Application of AOPs in the treatment of OSPAR chemicals and a comparative cost analysis

The OSPAR priority list entails a strategy, for monitoring the listed chemicals as well as prescribing cessation targets. However, not much is known about the best available technologies for dealing with cases of environmental pollution from these chemicals. On the other hand, Advanced Oxidation Processes (AOPs) are among the most effective environmental treatment technologies. The scientific literature was reviewed for data regarding the application of selected AOPs in the treatment of the chemicals on the OSPAR list with emphasis on the efficacy and cost of the technologies. Remarkably, almost two decades since the OSPAR list was adopted, there are hardly any studies in which the cost applying any AOP to an “OSPAR chemical” related contamination has been explored. When the scope of the study was expanded beyond the OSPAR list and the initially selected AOPs, not much data was found either. It is clear from this study that the subject of the comparative cost evaluations of AOPs is one requiring more attention. The consequence is that some of the vital data required for evaluating the practical applicability of AOPs in real treatment applications is lacking. The review article seeks to draw attention to this gap in the scientific literature.

Co-transport and remobilization of Cu and Pb in quartz column by carbon dots

Carbon nanoparticles such graphene, carbon nanotubes, and carbon dots offer the potential to improve environmental treatment technologies due to their unique properties such as low toxicity and high metal sorption capacity. However, there are no studies on facilitated transport and remobilization of pre-sorbed metals by carbon dot (CD) nanoparticles in quartz sand columns. Here, we investigate the effects of solution ionic strength (IS; 1, 100 and 200 mM NaCl) and pH (Chen et al., 2017; Chen et al., 2010; Cornell and Schwertmann, 2006), initial CD concentration (200, 400, 600 and 800 mg L−1), and clay content (10, 20 and 30%w kaolinite) in quartz sand columns on the transport, retention and remobilization of Cu and Pb in saturated (upward flow) quartz porous media. Batch sorption experiments were employed to underpin the findings of the column transport experiments. Both CD and quartz adsorbed Cu and Pb from water, but adsorption was higher on CD than quartz.Co-transport experiment demonstrated the CD-facilitated transport of Cu and Pb. Sequential transport experiments (first three phases) demonstrated the retention of Cu and Pb in the quartz column, with higher retention of Pb compared to Cu. The Cu and Pb retention was attributed to their sorption on the quartz grains and precipitation under the experimental conditions investigated in this study. Cu retention increased with the increase in ionic strength, pH and clay content. Pb was nearly totally retained in the quartz column at all experimental conditions. The subsequent injection of CD resulted in Cu and Pb remobilization to different extents, except in the presence of high kaolinite concentration. CD is most efficient in remobilizing Cu and Pb at 400 mg L−1 CD concentration and under low ionic strength (ca. 1–100 mM), low pH (ca. 6) and in the absence of clays. Deviation from these conditions results in reduced remobilization of Cu and Pb.

Industrial water treatment and industrial marine outfalls: Achieving the right balance

Industrial water treatment and industrial marine outfalls both function together to reduce the pollutant concentrations in the effluent and mitigate the potential impact on the environment. The former uses environmental treatment technology with energy and material cost considerations, while the latter utilizes the natural assimilation potential of the coastal water environment achievable at the outfall location. Because of their synergistic nature, marine outfalls are now commonly used for the disposal of partially treated domestic and industrial effluents in many coastal cities around the world, with many successful examples of low and acceptable risks to the environment. The objective of this paper is to review their balance from both environmental and economic considerations. We also discuss the end-of-the-pipe and mixing zone approaches for industrial effluents, and give some recommendations particularly for developing countries. Finally, we emphasize that a compulsory and vigorous monitoring program is essential regardless of how the balance is achieved. Open image in new window

Removal of Pb, Cd, Cu and Ni from aqueous solution using nano scale zero valent iron particles

Nanoparticles offer the potential to improve environmental treatment technologies due to their unique properties. Adsorption of metal ions Pb(II), Cd(II), Cu(II), Ni(II) to nano zero valent iron (nZVI) particles of surface iron oxide was examined. nZVI particles were synthesized by reduction of ferric chloride with sodium borohydride. In this work, transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy are applied to study the compositional and structural of nZVI. Batch equilibrium experiments were performed to study the removal efficiency of heavy metal ions. The effect of different parameters such as contact time, initial concentration, pH and nZVI dose on the adsorption process were investigated. The adsorption kinetics well fitted using a pseudo-second order kinetic model. SEM and TEM images showed that of particles were mostly spherical shape in chains with an average size 43.1±11.9nm. The initial sorption rate for all the metals is in order Pb2+>Cu2+>Cd2+>Ni2+. Short adsorption equilibrium contact time favors the application of the adsorption process. The formation of FeOOH on the surface of nZVI could be the main factor of cations removal due to its high adsorption affinity for aqueous solutes. Therefore, with the strong adsorption at pH<6.5 which is representative of several natural groundwater and the ability to adsorb multiple metal ions simultaneously, nZVI may offer a potential remediation method for the removal of metals from water and environment.

Mechanisms of stress avoidance and tolerance by plants used in phytoremediation of heavy metals

AbstractHeavy metal pollution of soil is a significant environmental problem and has a negative impact on human health and agriculture. Phytoremediation can be an alternative environmental treatment technology, using the natural ability of plants to take up and accumulate pollutants or transform them. Proper development of plants in contaminated areas (e.g. heavy metals) requires them to generate the appropriate protective mechanisms against the toxic effects of these pollutants. This paper presents an overview of the physiological mechanisms of stress avoidance and tolerance by plants used in phytoremediation of heavy metals.

Removal of Pb(II), Cd(II), Cu(II), and Zn(II) by hematite nanoparticles: effect of sorbent concentration, pH, temperature, and exhaustion

Nanoparticles offer the potential to improve environmental treatment technologies due to their unique properties. Adsorption of metal ions (Pb(II), Cd(II), Cu(II), Zn(II)) to nanohematite was examined as a function of sorbent concentration, pH, temperature, and exhaustion. Adsorption experiments were conducted with 0.05, 0.1, and 0.5 g/L nanoparticles in a pH 8 solution and in spiked San Antonio tap water. The adsorption data showed the ability of nanohematite to remove Pb, Cd, Cu, and Zn species from solution with adsorption increasing as the nanoparticle concentration increased. At 0.5 g/L nanohematite, 100 % Pb species adsorbed, 94 % Cd species adsorbed, 89 % Cu species adsorbed and 100 % Zn species adsorbed. Adsorption kinetics for all metals tested was described by a pseudo second-order rate equation with lead having the fastest rate of adsorption. The effect of temperature on adsorption showed that Pb(II), Cu(II), and Cd(II) underwent an endothermic reaction, while Zn(II) underwent an exothermic reaction. The nanoparticles were able to simultaneously remove multiple metals species (Zn, Cd, Pb, and Cu) from both a pH 8 solution and spiked San Antonio tap water. Exhaustion experiments showed that at pH 8, exhaustion did not occur for the nanoparticles but adsorption does decrease for Cd, Cu, and Zn species but not Pb species. The strong adsorption coupled with the ability to simultaneously remove multiple metal ions offers a potential remediation method for the removal of metals from water.

Electrogenerative Processes for Environmental Applications

AbstractThe applications of electrogenerative processes which could be an alternative to current environmental treatment technologies are briefly reviewed. This process does not require an external supply of energy due to the spontaneous chemical reaction that takes place in the reactor and generates an external flow of current as a by‐product. The operation is attractive in reducing operational costs, especially when dealing with solutions of low ion concentrations. Electrogenerative reactors which can be operated in various configurations and their designs are described. The rate and selectivity for particular reactions can be controlled by varying electrode potentials and with suitable choices of electrodes. This review paper aims to invoke the interest of industries to consider the merits of electrogenerative processes as a replacement for the current processes and practices. The applications of electrogenerative processes to the removal and recovery of metal ions, electrosynthesis of organic chemicals and leaching of sulfide minerals are discussed.

Analytical techniques used for monitoring the biodegradation of fluorinated compounds in waste streams from pharmaceutical production

During the assessment of the environmental impact of new pharmaceutical processes the selection and testing of suitable environmental treatment technologies is carried out. A large component of process waste stream treatment practice is aerobic biotreatment in wastewater treatment plants, as it is cost effective and generally more environmentally friendly than harsher chemical/physical treatments. Pharmaceutical syntheses use a range of halogenated compounds (either as reagents, solvents or intermediates) which pose particular challenges to microbial degradation. This is especially so for some fluorinated compounds due to the resilience to enzymatic cleavage of the C–F bond in some cases. The data presented here were obtained from a case study involving the monitoring of the biodegradation of 4-fluorocinnamic acid by means of a range of chromatographic techniques. These methods were used to monitor not only the disappearance of the compound but also the formation of degradation products in order to confirm mineralisation. In addition mass spectrometry was used to elucidate the metabolic pathway.