Search

Corrosion of copper material in drinking water systems causes public health concerns and plumbing failures. This study investigated the early corrosion of new copper surfaces in situ using a novel technique: quartz crystal microbalance with dissipation (QCMD). The QCMD results showed that increasing the water pH from 6.5 to 9.0 and the addition of 6 mg/L orthophosphate at pH 6.5 and 9.0 slowed down the copper surface mass changes as indicated by the reduced changes in frequency (Δf5) at 51–89% and total copper release at 29–72%. The water pH 9.0 without orthophosphate was the most likely to induce localized corrosion relative to other conditions at pH 6.5 and pH 9.0 with orthophosphate. Based on the changes in dissipation values (ΔD5) from QCMD and the morphology, microstructure, and composition of the deposited copper corrosion byproducts, digital microscopy, field-emission scanning electron microscopy with energy dispersive spectroscopy, and X-ray photoelectron spectrometry analyses confirmed that the pH and orthophosphate inhibited copper corrosion with different mechanisms. QCMD provided sensitive, rapid, and continuous responses to mass and surface changes and can be useful for evaluating early water corrosivity to new copper.

Effective recovery of phosphorus from municipal wastewater could be one of the best practical alternatives to protect aquatic environments from eutrophication and save natural phosphorus resources. This paper focuses on validating magnesium carbonate (MgCO(3))-based pellets combined with a bench-scale anoxic/aerobic membrane bioreactor (MBR) system for advanced phosphorus recovery from municipal wastewater. As the flow rate of wastewater into the MgCO(3) column decreased from 10 L/d to 2.5 L/d, the phosphorus recovery rate of the MgCO(3)-based pellets increased from 54.3 to 93.5%. However, the column’s severe clogging was found after a 13-days operation due to the high removal of total suspended solids (TSS) (~82%) through the MgCO(3) column. The anoxic/aerobic MBR introduction provided efficient removal of TSS, organic matter, and ammonia nitrogen before the MgCO(3) column. The combination of MBR with the MgCO(3) column achieved 73.1% phosphorus recovery from municipal wastewater without physical clogging. The P recovery capacity of the MgCO(3)-based pellets was maintained at 0.47 mg ortho-P/g MgCO(3)-based pellet during the continuous operation. Physical and chemical properties of MgCO(3)-based pellets before and after the experiment were characterized using scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area analyzer.

This paper reviews the currently used pretreatment methods for microplastics (MPs) analysis in soil and freshwater sediments, primarily sample processing, pretreatment, and characterization methods for MPs analysis. In addition, analytical tools (e.g., lab instruments), MPs characteristics, and MPs quantity, are included in this review. Prior to pretreatment, soil and sediment samples are typically processed using sieving and drying methods, and a sample quantity of

A variety of methods, including chemical precipitation, biological phosphorus elimination, and adsorption, have been described to effectively eliminate phosphorus (P) in the form of phosphate (PO43–) from wastewater sources. Adsorption is a simple and easy method. It shows excellent removal performance, cost effectiveness, and the substantial option of adsorbent materials. Therefore, it has been recognized as a practical, environmentally friendly, and reliable treatment method for eliminating P. Nanocomposites have been deployed to remove P from wastewater via adsorption. Nanocomposites offer low-temperature alteration, high specific surface area, adjustable surface chemistry, pore size, many adsorption sites, and rapid intraparticle diffusion distances. In this Mini-Review, we have aimed to summarize the last eight years of progress in P removal using graphene-based composites via adsorption. Ultimately, future perspectives have been presented to boost the progress of this encouraging field.

The simultaneous presence of hazardous chemicals and pathogenic microorganisms in wastewater is tremendously endangering the environment and human health. Therefore, developing a mitigation strategy for adequately degrading toxic compounds and inactivating/killing microorganisms is urgently needed to protect ecosystems. In this paper, the synergetic effects of the photocatalytic activity of TiO2 and Cu-TiO2 nanoparticles (NPs) and the oxidation processes of non-thermal atmospheric pressure plasma (NTAPP) were comprehensively investigated for both the inactivation/killing of common water contaminating bacteria (Escherichia coli (E. coli)) and the degradation of direct textile wastewater (DTW). The photocatalytic NPs were synthesized using the hydrothermal method and further characterized employing field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS) and photoluminescence (PL). Results revealed the predominant presence of the typical anatase phase for both the flower-like TiO2 and the multipod-like Cu-TiO2 structures. UV-Vis DRS and PL analyses showed that the addition of Cu dopants reduced the bandgap and increased oxygen defect vacancies of TiO2. The inactivation of E. coli in suspension and degradation of DTW were then examined upon treating the aqueous media with various plasma alone and plasma/NPs conditions (Ar plasma, Ar + O-2 plasma and Ar + N-2 plasma, Ar plasma + TiO2 NPs and Ar plasma + Cu-TiO2 NPs). Primary and secondary excited species such as OH, O, H and N-2* generated in plasma during the processes were recognized by in situ optical emission spectrometry (OES) measurements. Several other spectroscopic analyses were further employed to quantify some reactive oxygen species (ROS) such as OH, H2O2 and O-3 generated during the processes. Moreover, the changes in the pH and electrical conductivity (EC) of the solutions were also assessed. The inactivation of bacteria was examined by the colony-forming unit (CFU) method after plating the treated suspensions on agar, and the degradation of organic compounds in DTW was further validated by measuring the total organic carbon (TOC) removal efficiency. All results collectively revealed that the combinatorial plasma-photocatalysis strategy involving Cu-TiO2 NPs and argon plasma jet produced higher concentrations of ROS and proved to be a promising one-step wastewater treatment effectively killing microorganisms and degrading toxic organic compounds.

Phosphorus (P) or phosphate remediation is a challenging and expensive environmental issue. It could cost billions to maintain and improve the treatment framework, using conventional wastewater treatment plants to meet the requirements of the United States Environmental Protection Agency (USEPA). Eutrophication and hypoxia resulting from phosphorus runoff from commercial and industrial wastewater plants can lead to unwanted algae growth. "Dead zones" are created after algae decay, causing the death of the aquatic life that needs an oxygen-rich environment. The upper limit for in-stream discharge of phosphorus is usually one mg L−1, and further lowering to

The frequent occurrence of per- and polyfluoroalkyl substances (PFAS) in the water environment is a recent global concern. Because of their extraordinarily strong chemical stability caused by the m...

With a wide variety of techniques and compatible materials, three-dimensional (3D) printing is becoming increasingly useful in environmental applications in air, water, and energy. Through the advantages of quick production, cost-effectiveness, customizable design, the ability to produce complex geometries, and more, 3D printing has supported improvements to air quality monitors, filters, membranes, separation devices for water treatment, microbial fuel cells, solar cells, and wind turbines. It also supports sustainable manufacturing through reduced material waste, energy use, and carbon emissions. Applications of 3D printing within four environmental disciplines are described in this article: sustainable manufacturing, air quality, water and wastewater, and alternative energy sources.

Additive manufacturing, or three-dimensional (3D) printing, joins materials layer-by-layer under the control of a computer to create three-dimensional objects. 3D printing is used in many applications, including the automotive industry, the environment, electronics, airplane engines, agriculture, and even architecture. One of the most critical applications of this ultra-modern technology is medicine. 3D printing permits new methods of surgical planning and tissue regeneration, as well as personalization of medical devices and implants. With the development of materials that are both biocompatible and printable, additive manufacturing is becoming increasingly useful in medicine.

Per- and polyfluoroalkyl substances (PFAS), which are present in many waters, have detrimental impacts on human health and the environment. Reverse osmosis (RO) and nanofiltration (NF) have shown excellent PFAS separation performance in water treatment; however, these membrane systems do not destroy PFAS but produce concentrated residual streams that need to be managed. Complete destruction of PFAS in RO and NF concentrate streams is ideal, but long-term sequestration strategies are also employed. Because no single technology is adequate for all situations, a range of processes are reviewed here that hold promise as components of treatment schemes for PFAS-laden membrane system concentrates. Attention is also given to relevant concentration processes because it is beneficial to reduce concentrate volume prior to PFAS destruction or sequestration. Given the costs and challenges of managing PFAS in membrane concentrates, it is critical to evaluate both established and emerging technologies in selecting processes for immediate use and continued research.

Magnetic graphene catalysts were prepared for the removal of antibiotics (sulfamethoxazole, norfloxacin, tetracycline and flumequine) from water. Different proportions of magnetite–graphene from 1 : 0 to 0 : 1 were considered to study the catalytic activation of inorganic peroxides, i.e. peroxymonosulfate (PMS), peroxydisulfate and hydrogen peroxide. The presence of graphene was mainly responsible for the activation, which was most effective in the presence of PMS. A ratio of 20% of magnetite in the solid was enough to achieve complete degradation of antibiotics with high recovery by application of a magnetic field. The performance of the catalyst was further evaluated in a simulated urban wastewater, studying the main parameters affecting the process and the stability in sequential reuses. The non-radical mechanism during the catalytic activation of PMS was hypothesized from kinetic scavenging probes tests. The electron transfer was suggested as the mechanism of the reaction from electron paramagnetic resonance analysis in the presence of D2O. The prepared magnetic catalyst showed high catalytic activity and stability to remove antibiotics from water.

Per- and polyfluoroalkyl substances (PFAS) are a family of fluorinated organic compounds of anthropogenic origin. Due to their unique chemical properties, widespread production, ubiquitous environmental distribution, long-term persistence, bioaccumulative potential, and associated risks for human health, PFAS have been classified as persistent organic pollutants of significant concern. Scientific evidence from the last several decades suggests that their widespread occurrence in the environment correlates with adverse effects on human health and ecology. The presence of PFAS in the aquatic environment demonstrates a close link between the anthroposphere and the hydrological cycle, and concentrations of PFAS in surface and groundwater range in value along the ng L−1–μg L−1 scale. Here, we critically reviewed the research published in the last decade on the global occurrence and distribution of PFAS in the aquatic environment. This is the first study to critically evaluate the occurrence of PFAS at continental scale and the evolving global regulatory responses to manage and mitigate the adverse human health risks posed by PFAS. The review reports that PFAS are ubiquitous despite being phased out—they have been detected in different continents irrespective of the level of industrial development. Their occurrence far from the potential sources suggests that long-range atmospheric transport is an important pathway of PFAS distribution. Recently, several studies have investigated the health impacts of PFAS exposure—they have been detected in biota, drinking water, food, air, and human serum. In response to the emerging information about PFAS toxicity, several countries have provided administrative guidelines for PFAS in water, including Canada, the United Kingdom, Sweden, Norway, Germany, and Australia. In the US, additional regulatory measures are under consideration. Further, many PFAS have now been listed as persistent organic pollutants. This comprehensive review provides crucial baseline information on the global occurrence, distribution, and regulatory framework of PFAS.

This research work explored the synthesis and characterization of magnetic manganese ferrites using a simple combustion method. The purpose of creating the magnetic manganese ferrites was for their planned use as ozonation catalysts. Their magnetic properties allow for their recovery from the treatment system. Magnetic manganese ferrites were prepared by mixing manganese nitrate and iron nitrate in a stoichiometric ratio of 1:2. Polyvinyl alcohol was added to the mixed metal salt solution and the ratio of PVA: total nitrate salt added was varied from 1:1 up to 1:2 by weight. The resulting particles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), tunneling electron microscope (TEM), and Ultraviolet–Visible spectroscopy (UV/Vis). Keywords: Synthesis, Magnetic particles, Water treatment

In recent years, various facile and low-cost methods have been developed for the synthesis of advanced nanostructured photocatalytic materials. These catalysts are required to mitigate the energy crisis, environmental deterioration, including water and air pollution. Among the various semiconductors explored, recently novel classes of polymeric graphitic carbon nitride (g-C3N4)-based heterogeneous photocatalysts have established much greater importance because of their unique physiochemical properties, large surface area, low price, and long service life, ease of synthesis, product scalability, controllable band gap properties, low toxicity, and high photocatalytic activity. The present comprehensive review focuses on recent achievements in a number of facile chemical synthesis methods for semiconducting polymeric carbon nitrides and their heterogeneous nanohybrids with various dopants, nanostructured metals, metal oxides, and nanocarbons, as well as the parameters influencing their physiochemical properties and photocatalytic efficiency, which are discussed with reference to various catalytic applications such as air (NOx) purification, wastewater treatment, hydrogen generation, CO2 reduction, and chemical transformation. The mechanisms for the superior photocatalytic activity of polymeric g-C3N4-based heterogeneous photocatalysts are also discussed. Finally, the challenges, prospects, and future directions for photocatalytic polymeric g-C3N4-based semiconducting materials are described.

Nanoparticles have plenty of active sites in each particle and short travel distance for photoexcitons proved to be beneficial characteristics for photocatalytic hydrogen generation. Noble metal (Au, Ag, Pt, Pd, Ru, and Rh) attached with semiconductor photocatalyst displayed plasmonic oscillations results in localized surface plasmon resonance (LSPR) effect and schottky junction formed to pump the photoelectrons to surface for reactions. Literature reports evidenced that the choice of synthesis method and experimental conditions directly affects the catalytic and optical properties. Hence, this review discusses comprehensive information on chemical methods reported for the preparation of plasmonic photocatalyst that resulted in co-catalyst and visible light sensitizer properties. Recent developments and achievements on plasmonic photocatalyst for hydrogen production in pure water and sacrificial agent containing water are discussed and highlighted.

Hydrothermal technique was employed for the synthesis of N- and B-codoped TiO2 at different atomic percentages and calcination temperatures (350 and 400 °C). Borane tert-butylamine complex was used as a novel precursor for the dopant atoms. The photocatalytic activities of catalysts were evaluated for destruction of bisphenol A (BPA) spiked in clean water and in secondary treated wastewater influent (SWI) collected from the Groundwater Replenishment System GWRS (Orange County, CA, USA), the world's largest water purification system for indirect potable reuse. Results of X-ray photoelectron spectroscopy (XPS) revealed the incorporation of N and B atoms onto TiO2 lattice via substitution of O and/or Ti, and interstitial incorporation mechanisms. Carbon doping (graphite-like carbon; O-C = O) was also evidenced from XPS spectra. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) revealed pristine TiO2 and all doped TiO2 existed in anatase structure. The anatase phase of catalysts was further confirmed by simulation of selected area electron diffraction (SAED) of the catalysts and reported anatase TiO2 using the simulation software CrysTBox (v 1.10). Among all prepared catalysts, 2.0NBT-350 (N + B = 2.0%, calcination = 350 °C) possessed the smallest particle size (12.9 nm), largest BET surface area (108.5 m2/g) and highest visible-light absorption (i.e., λ > 400 nm). Simulated solar light/2.0NBT-350 system exhibited the maximum removal of BPA (0.1 μM) at the optimum catalyst dose of 0.8 g/L in clean water, over three consecutive degradation reuse cycles without any noticeable decrease in its photocatalytic activity. BPA was also successfully removed in SWI water, however with slower kinetics due to hydroxyl radical quenching effect of dissolved organic and inorganic species present in the SWI matrix. Degradation byproducts were identified by LC/Q-TOF-ESI-MS analysis. Six byproducts were found in the reaction mixture, with two compounds were newly identified in the current study. BPA oxidation routes comprised successive BPA hydroxylation, elimination of aromatic ring, ring opening, and cyclization of aliphatic compounds. This study is a promising demonstration for controlled design and synthesis of photocatalysts useful for environmental applications, especially for the treatment of BPA in wastewater effluents.

A magnetically separable bimetallic AgPd/Fe@CNX catalyst has been synthesized and utilized for upgrading of lignin-derived guaiacol to cyclohexanol via hydrodeoxygenation using formic acid as a source of hydrogen under visible light irradiation. A nitrogen-enriched carbonaceous material, carbon nitride (CNX), is obtained via calcination of chitosan, a marine-derived abundant waste material and subsequently utilized as a support for the immobilization of nano-ferrites and silver and palladium nanoparticles. Hydrogen generation from renewable sources such as formic acid and its ideal utilization for the upgrading of biomass-derived guaiacol are the main findings. The synergetic effect of Ag and Pd on the CNX support enhances the decomposition of formic acid which is aptly utilized for the selective defunctionalization of guaiacol at ambient pressure.