Treatment Of Pollutants In Wastewater Research Articles

Ammonium changes the pathway of tetrabromobisphenol S degradation by sulfate radical oxidation

Sulfate radical (SO4•-)-based advanced oxidation processes (SR-AOPs) show great potential in the elimination of organic pollutants in wastewater treatment and groundwater remediation. Tetrabromobisphenol S (TBBPS) as an emerging contaminant can be effectively degraded in SR-AOPs. However, the present study found that SO4•- also reacted with ammonium (NH4+), a ubiquitous inorganic nitrogen species in aquatic environments, thus markedly affected the rates and pathways of TBBPS degradation in SR-AOPs. TBBPS underwent β-scission and debromination upon SO4•- attack, leading to various transformation products. The released bromide (Br-) underwent further oxidation by SO4•- to form free bromine which reacted with certain TBBPS intermediates, generating disinfection byproducts (DBPs). When NH4+ was present in such system, the abatement of TBBPS was apparently suppressed. Meanwhile, NH4+ was oxidized by SO4•- to nitrogen dioxide radical (NO2•) which coupled with certain radical intermediates of TBBPS oxidation, yielding nitrophenolic products including 2,6-dibromo-4-nitrophenol (DBNP) and mono-nitro substituted TBBPS. When 10 μM TBBPS was treated by heat activated peroxydisulfate with 1 mM NH4+, the molar yield of DBNP reached 22% in 2 h. More importantly, NH4+ scavenged the in situ formed free bromine to form monobromamine (NH2Br), decreasing regulated DBPs formation but leading to highly toxic dibromoacetonitrile (DBAN). This study broadens the understanding of interactions between the transformation of halogens and NH4+ during SO4•- oxidation. It also reveals the potential environmental risks when SR-AOPs are employed for the organohalogen pollutants degradation in realistic environments where NH4+ is present.

Valorization of spent Aureobasidium pullulans for the removal of toxic pollutant in wastewater treatment

Textile industries are growing rapidly due to increased demand for textile products worldwide. The discharge of textile effluent containing synthetic dyes, chlorides, pigments, aromatic compounds, and heavy metals contributes substantially to water pollution due to its toxicity and chemical composition. This work is focused on the potential usage of treated Aureobasidium pullulans biomass (TAPB) to remove the toxic chemical pollutant, Methylene Blue (MB), from an aqueous solution. Experimental results found that maximum MB removal of 76.5% was observed using TAPB dosage of 3 ​g/L, initial pH 8.0, temperature 30 ​°C, and initial MB concentration of 50 ​mg/L. The maximum biosorption capacity of TAPB was found to be 113.75 ​mg/g using the Langmuir non-linear approach. Successive biosorption and desorption experiments showed better regeneration capacity of TAPB until the fourth trial. These results demonstrated that maximum MB removal (%) could be possible with a small quantity of biomass, consequently offering a minimum size of the contactor and less capital cost requirement for biosorption. It also showed a greater regeneration capacity biosorbent for removing MB. Hence, the feedstock consumption for MB removal could be considerably decreased in large-scale processes.

Enhanced Photocatalytic Degradation of Malachite Green Dye Using Silver-Manganese Oxide Nanoparticles.

Efficient and excellent nanoparticles are required for the degradation of organic dyes in photocatalysis. In this study, silver-manganese oxide nanoparticles (Ag-Mn-NPs) were synthesized through a wet chemical precipitation method and characterized as an advanced catalyst that has enhanced photocatalytic activity under sunlight irradiation. The nanoparticles were characterized using scanning electron microscopy (SEM), XRD, UV-vis light spectra, and energy-dispersive X-ray (EDX) spectroscopy, revealing their spherical and agglomerated form. The EDX spectra confirmed the composition of the nanoparticles, indicating their presence in oxide form. These bimetallic oxide nanoparticles were employed as photocatalysts for the degradation of malachite green (MG) dye under sunlight irradiation in an aqueous medium. The study investigated the effects of various parameters, such as irradiation time, catalyst dosage, recovered catalyst dosage, dye concentration, and pH, on the dye's photodegradation. The results showed that Ag-Mn oxide nanoparticles exhibited high photocatalytic activity, degrading 92% of the dye in 100 min. A longer irradiation time led to increased dye degradation. Moreover, a higher catalyst dosage resulted in a higher dye degradation percentage, with 91% degradation achieved using 0.0017 g of the photocatalyst in 60 min. Increasing the pH of the medium also enhanced the dye degradation, with 99% degradation achieved at pH 10 in 60 min. However, the photodegradation rate decreased with increasing dye concentration. The Ag-Mn oxide nanoparticles demonstrate excellent potential as a reliable visible-light-responsive photocatalyst for the efficient degradation of organic pollutants in wastewater treatment.

Pollutant Burden on Pollution Sources in the Wai Batu Merah Watershed, Sirimau District, Ambon City

This study aims to identify sources of pollution and determine the magnitude of the potential pollution load from pollutant sources in the Wai Batu Merah watershed, Sirimau District, Ambon City. The method for identifying sources of pollution is carried out by using saturated or census sampling methods, calculating pollutant loads using direct methods for point source pollutant sources and indirect methods for non-point sources . The direct calculation method uses wastewater discharge data and the results of wastewater quality analysis results from measurements directly at the point source pollutant wastewater treatment plant (WWTP). The wastewater sampling technique uses the grab sampling method. While the indirect method uses effluent factors and supporting data from non-point source pollution sources that have been identified in the Wai Batu Merah watershed. The results showed that the pollutant sources found in the Wai Batu Merah watershed were point sources originating from hotel and health facility activities and non-point sources originating from domestic activities from residential areas, agricultural and livestock businesses, non-point source land (forest and open land), micro, small and medium enterprises (MSMEs), small scale industries and waste. The dominant pollutant source in the Wai Batu Merah watershed comes from domestic non-point sources. The highest point source pollution loads for BOD, COD and TSS parameters in the Wai Batu Merah watershed came from hotel activities in segment 6 with the contribution of each parameter of 17.82 kg/day, 23.82 kg/day and 0.029 kg/day. Meanwhile, the highest non-point source pollution load for BOD, COD and TSS parameters came from non-point source waste in segment 6 with the contribution of each parameter of 2825.3 kg/day, 3884.8 kg/day and 2684.03 kg/day.

Self-cleaning photoelectrocatalytic filtration based on Ca(OH)2/Ti3C2Tx composite nanofiltration membranes for synergistically enhanced separation and degradation of phenolic compounds

Combining photoelectrocatalytic (PEC) and nanofiltration (NF) membranes has emerged as an attractive technology for removing organic pollutants in wastewater treatment, however, the separation and degradation performance are still challenging. Herein, novel composite NF membranes were constructed by cross-linking a Ca(OH)2/Ti3C2Tx (CT) catalyst to a polyamide membrane using tannic acid (TA). In these CT@TA (CTTP) membranes, Ti3C2Tx reduces the charge-transfer resistance and recombination rate of CT, leading to enhanced PEC activity. The optimal CTTP membrane had a high water flux (27.9 L·m−2·h−1·bar−1) and excellent rejection rates for phenolic compounds (phenol: 85.1 %, 4-nitrophenol: 91.1 %, and bisphenol A (BPA): 94.6 %). Under visible-light irradiation with electrical assistance (3 V), the BPA degradation rate (92.2 %) was 13.7 % higher than that under light irradiation alone, and a higher flux recovery rate was achieved (94.1 %). Superoxide (O2−) and hydroxyl (OH) radicals were critical active species in catalytic BPA degradation, and the observed intermediates suggested that the degradation pathway involves oxidation, hydroxylation, and aromatic ring cracking. The developed NF membranes, which exhibit synergistic separation and degradation effects and self-cleaning properties, provide an innovative solution for the treatment of organic pollutants in wastewater.

Aplikasi Fotokatalis TiO2 Dan Alternatifnya Untuk Degradasi Pewarna Sintesis Dalam Limbah Cair

Liquid waste containing synthetic dyes is a significant environmental problem, particularly in the textile industry, such as batik waste. Recent studies have shown the potential of TiO2 photocatalysis in reducing color and Chemical Oxygen Demand (COD) in such waste. In addition to TiO2, ZnO nanoparticles and ZrO2-TiO2 composites have also been tested as alternative photocatalysts for the degradation of synthetic dyes. The use of immobilized TiO2 nanoparticles on various substrates such as plastic sheets, hydrogels, or hybrid films has increased the efficiency of photocatalytic processes and allowed for the separation of photocatalysts from the waste after treatment. Furthermore, the combination of TiO2 with additives such as Mg, Ag, and Fe has enhanced the photocatalytic performance in removing synthetic dyes from wastewater. The use of TiO2-based photocatalytic membranes also enables simultaneous filtration and degradation of pollutants in wastewater treatment. In addition to degrading synthetic dyes, TiO2 photocatalysis has been successfully used to remove natural dyes like Congo red from industrial wastewater. Recent studies have also explored new synthesis methods to obtain TiO2 photocatalysts with enhanced properties, such as TiO2 nanocoating on nanocomposites or TiO2 nanocoating on porous materials. Overall, these studies demonstrate that TiO2 photocatalysis has great potential in liquid waste treatment, particularly in the degradation of synthetic dyes found in textile industry waste like batik waste.

Alk-MXene-TiO2/α-Fe2O3-T: A highly efficient photocatalyst for the extensive treatment of pollutants in wastewater

An alk-MXene-TiO2/α-Fe2O3-T (MTFX) type-Ⅱ heterojunction with Ti3C2 MXene as co-catalyst was successfully prepared by calcination method, which effectively realized the effective separation of electrons and holes in space. Under light conditions, activated PMS was achieved at alk-MXene-TiO2/α-Fe2O3-400 ℃ to treat most of the pollutants in wastewater. The results showed that the degradation rate of most dyes was above 90 %, and the degradation rate of antibiotics TC, SMZ and CIP was above 70 %. At the same time, the metal ion Cr(VI) also showed a certain reduction performance. In addition, the photocatalyst is stable, and the degradation rate of Rhodamine B remains above 70 % after 7 cycles. The results show that alk-MXene-TiO2/α-Fe2O3-T material has good application potential in the treatment of industrial wastewater.

New Insights into Novel Catalysts for Treatment of Pollutants in Wastewater

Water scarcity has become a worldwide problem [...]

Chemical synthesis of silver/titanium dioxide nanoheteroparticles for eradicating pathogenic bacteria and photocatalytically degrading organic dyes in wastewater

Titanium dioxide photocatalysis is a promising technology for the treatment of pollutants in wastewater. However, it remains challenging to overcome its inherent drawbacks, such as a high recombination rate of photogenerated charges and low solar-energy utilization. Herein, Ag/TiO 2 nanoheteroparticles (ATNs) were synthesized using a modified deposition method, and their physical, chemical, antibacterial, and photocatalytic properties were subsequently analyzed. The ATNs with 8 wt% Ag deposition exhibited an excellent antibacterial activity. For Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans, the minimum inhibitory concentrations of ATNs were 250.00, 62.50, 125.00, 250.00, and 62.50 mg/L, whereas the minimum bactericidal concentrations were 250.00, 1000.00, 125.00, 250.00, and 1000.00 mg/L, respectively. The antibacterial activity of the ATNs could be correlated to the amount of Ag deposition. Furthermore, the ATNs with 3 wt% Ag deposition showed 90.1% rhodamine B degradation under simulated sunlight conditions in 90 min. The optimum Ag deposition of 8 wt% effectively promoted the efficient separation of optical charges and improved the photocatalytic properties of the catalyst. Therefore, the ATN composite materials can eliminate pathogenic bacteria and degrade organic pollutants in wastewater. The synthesized ATNs exhibit significant application potential in the field of wastewater treatment.

Design of hybrid g-C3N4/GO/MCE photocatalytic membranes with enhanced separation performance under visible-light irradiation

Photocatalytic membranes with concurrent catalytic oxidation and separating functions possess promising potentials for the degradation of organic pollutants in wastewater treatment. Herein, we designed a hybrid photocatalytic membrane (viz., g-C3N4/GO/MCE) by vacuum-filtration-assisted assembling method, consisting of graphitic carbon nitride (g-C3N4) nanosheets as a top layer, graphene oxide (GO) nanosheets as an interlayer, and commercial mixed cellulose ester (MCE) as a substrate layer. The microstructures, chemical compositions, and physicochemical properties of the designed g-C3N4/GO/MCE membranes were systematically characterized by a series of characterization techniques. Particularly, photocatalysis-filtration reactor cells were designed for the evaluation of the simultaneous separation and photocatalytic degradation performance in a single unit using both organic dyes and antibiotics as modeling pollutants in wastewater. Four parameters were adopted to represent the integrated photocatalysis-filtration performance of our designed photocatalytic membranes, including permeance (P), rejection (R’, filtration alone), removal (R, combined photocatalysis-filtration under light-irradiation), and degradation rate (D). The hybrid membranes showed superior permeance and solute removal under visible-light irradiation (300 W, λ > 420 nm), in which the permeance was 20% higher than that of no-irradiation conditions. In addition, 10 consecutive cycling tests and light-on/off cycles of the as-prepared g-C3N4/GO/MCE membrane toward RhB showed quite stable permeance in the range of 268.9 to 352.9 L h−1 m−2 bar−1, and the removal was maintained in the range of 88.4% to 95.4%, indicating excellent long-term stability. Remarkably, it also exhibited good removal performance of antibiotics (e.g., ofloxacin, norfloxacin, sulfamethoxazole, erythromycin, and roxithromycin). Accordingly, the designed hybrid g-C3N4/GO/MCE photocatalytic membranes with excellent photocatalytic activity and photocatalysis-filtration performance are promising for wastewater treatment and water purification applications.

Research progress on key factors of dielectric-barrier discharge plasma for wastewater treatment

Plasma treatment of wastewater is known as a new advanced oxidation process (AOP), which has attracted extensive attention. Dielectric barrier discharge plasma has the characteristics of no vacuum pumping and high electron number density. It has outstanding application value in various forms of plasma. There are many coupling factors that affect the characteristics of dielectric barrier discharge plasma and the effect of wastewater treatment. Optimizing the key parameters is of great significance to improve the treatment efficiency and reduce the treatment cost. This paper introduces the principle, experimental device, potential advantages and application value of dielectric barrier discharge, summarizes the influence rules of key factors such as high voltage power supply characteristics, electrode configuration, carrier gas and reactor design on the characteristics of organic pollutant wastewater treatment by dielectric barrier discharge plasma. The optimization and matching of multiple factors are important problems. This paper provides a useful reference for the engineering application of plasma technology for wastewater treatment.

An Overview of Activated Carbon Preparation from Various Precursors

Activated carbon plays an important role in the industry due to its uniqueness and special characteristics. Originally known as a good adsorbent, activated carbon has a very large surface area and high micro-porosity. Activated carbon has been widely used in petroleum, pharmaceutical, textiles and many other industries. Activated carbon can be derived directly from charcoal through chemical or physical activation. Nonetheless, activated carbon can also be obtained from other carbon precursors, such as biowaste (agricultural, municipal and industries) and natural resources (seed, leaves, fruits and barks). Generally, activated carbon can derive from wastes through four steps; pre-processing of raw materials, thermal-conversion steps (pyrolysis or carbonization), activation, and modification. Both activation and modification were employed in the production of activated carbon to boost its adsorption performance. These steps can be divided into chemical and physical steps that help alter the physical structure of activated carbon and modify the surface chemical properties of activated carbon. Due to its reliability as an adsorbent, activated carbon has been widely used to remove pollutants in wastewater treatment and the demand for activated carbon has been increasing every year. This article reviews methods for preparing activated carbon from various precursors and discussed their performances. This review article aimed to provide recent information on efforts made by various researchers in activated carbon preparation.

A systematic study on synthesis of CeO2 nanoparticles by various routes

Cerium oxide (CeO2), also known as, ceria, is a well-known n-type semiconductor material. It finds potential roles in various field applications such as catalysis, sensing and antibacterial. It is widely used as a photocatalyst for treatment of waste water pollutants, because of the variable oxidation state of cerium i.e. +3, and +4. Many reports are available in literature which deals with the synthesis and properties of CeO2. The properties of CeO2 are highly dependent on the synthesis conditions such as precursors, additives, calcination temperature and type of synthesis route. In this review article, synthesis of CeO2 by various chemical routes are discussed in detail.

Release and migration of Hg during desulfurization wastewater evaporation process: Whole process evaluation by experimental and theoretical study.

Hot flue gas evaporation technology is an effective strategy for zero liquid discharge of desulfurization wastewater. However, there is a potential risk that heavy metals such as Hg may be released from the wastewater during evaporation, disrupting the original balance of the power plant or even exceeding the Hg emission standard. Wastewater evaporation and Hg release behavior were obtained using a single droplet drying system. At an evaporation temperature of 300°C, approximately 18.5% of Hg was released in the constant wet-bulb temperature period, and the remaining was released in the following evaporation periods. Furthermore, a fixed-bed experiment, in combination with density functional theory calculations, was used to investigate the possible migration mechanisms of released Hg. The results revealed that high HCl concentration, introduced fly ash, and precipitated evaporation products play a crucial role in the fate of Hg, and 85.3% of Hg finally turned into less harmful particulate-bound Hg. This study provides a new and effective strategy for evaluating the migration process of pollutants in wastewater treatment. Moreover, it will serve as an essential reference for advanced wastewater treatment and heavy metals control technologies in the future.

Novel Sb-SnO2 Electrode with Ti3+ Self-Doped Urchin-Like Rutile TiO2 Nanoclusters as the Interlayer for the Effective Degradation of Dye Pollutants.

Stable and efficient SnO2 electrodes are very promising for effectively degrading refractory organic pollutants in wastewater treatment. In this regard, we firstly prepared Ti3+ self-doped urchin-like rutile TiO2 nanoclusters (TiO2-x NCs) on a Ti mesh substrate by hydrothermal and electroreduction to serve as an interlayer for the deposition of Sb-SnO2 . The TiO2-x NCs/Sb-SnO2 anode exhibited a high oxygen evolution potential (2.63 V vs. SCE) and strong ⋅OH generation ability for the enhanced amount of absorbed oxygen species. Thus, the degradation results demonstrated its good rhodamine B (RhB), methylene blue (MB), alizarin yellow R (AYR), and methyl orange (MO) removal performance, with the rate constant increased 5.0, 1.9, 1.9, and 4.7 times, respectively, compared to the control Sb-SnO2 electrode. RhB and AYR degradation mechanisms are also proposed based on the results of high-performance liquid chromatography coupled with mass spectrometry and quenching experiments. More importantly, this unique rutile interlayer prolonged the anode lifetime sixfold, given its good lattice match with SnO2 and the three-dimensional concave-convex structure. Consequently, this work paves a new way for designing the crystal form and structure of the interlayers to obtain efficient and stable SnO2 electrodes for addressing dye wastewater problems.

Efficient activation of peracetic acid via a defect-rich carbon nanotube@Co3O4 three-dimensional network for antibiotic removal: mechanism insights and practical water remediation

Peracetic acid (PAA)-based advanced oxidation processes have garnered increasing attention for eliminating organic pollutants in wastewater treatment.

Visible light assisted degradation of Rhodamin B by reusable S-doped ZnO thin film photocatalyst

The use of zinc oxide-based photocatalysts has been extensively conducted to breakdown harmful pollutants in wastewater treatment. Recently, ZnO doped non-metal can improve photocatalytic activity by reducing charge carrier recombination. Here, S-doped ZnO thin films, with a sulfur dopant of 1 and 5% molar, were synthesized by a seed-mediated hydrothermal process. The enhancement in crystal structure and morphology were noted with the presence of sulfur in the ZnO system. The photocatalytic test shows that the presence of sulfur enhances Rhodamine B (RhB) degradation efficiency up to 92% with reaction rates of 1.67 × 10−2 min−1 under visible light. The S-doped ZnO thin film is potentially applied as a stable photocatalyst for wastewater purification, with a noted photocatalytic efficiency of 75% after repeated use.

Generation of reactive oxygen species through dissolved oxygen activation on defected porous carbon for efficient degradation of antibiotics

Reactive oxygen species (ROS) are the most important practical oxidant for the degradation of various refractory organic pollutants in wastewater treatment. However, it is still challenging to develop self-producing ROS systems without external auxiliary reagents and energies. Herein, a kind of defected porous carbon is constructed to sustainably release ROS for the effective degradation of antibiotics. The as-prepared porous carbon materials possess an outstanding performance yielding 98.0 % removal of common antibiotics at the concentrations of 20 mg/L in 60 min. The results show that superoxide free radical (·O2−) plays the key role in the antibiotic degradation and singlet oxygen (1O2) generation. Density functional theory calculations further reveal that the nonagonal ring structures of carbon-vacancies are likely dominating active centers to chemically adsorb and directly convert dissolved oxygen to ·O2−. This work not only provides a novel carbon material for efficient degradation of antibiotics but also improves the understanding of the oxygen molecule activation on carbon defects.

Heterogeneous Fe(IV)[dbnd]O mediated fenton-like process on Fe-Zr heterojunction for selective oxidation of organic pollutants at near neutral pH

Remarkable heterogeneous Fe(IV)O (≡Fe(IV)O) mediated Fenton-like process on (1 1 0)-(1 0 0) heterojunction of Fe-Zr bimetallic oxide was proposed in this work for selective oxidation of organic pollutants under near-neutral conditions. The formation of heterojunction shortened the Fe-O bond length by 0.14 Å and increased the binding energy of Fe 2p3/2 orbital by 0.8 eV on Fe-Zr (1 1 0)-(1 0 0) interface, compared with that on Fe2O3 (1 1 0) facet. This will promote the cyclic complexes of Fe(II)-[OOH]+ formation on Fe-Zr (1 1 0)-(1 0 0) interface. Besides, energy barrier of Fe(II)-[OOH]+ on (1 1 0)-(1 0 0) heterojunction was 10.6 kJ mol−1 lower than that on Fe2O3 (1 1 0) facet. It will facilitate the inner two-electron transfer process to generate Fe(IV)O. And electrostatic repulsion and electrophilic addition enable Fe(IV)O to selectively oxidize target organic pollutants in the system containing ions and humic acids. This work provides a fundamental information toward the structure-performance relationship between heterojunction structure and Fe(IV)O formation, and it will enlighten the selective oxidation of pollutants in wastewater treatment.

Fabrication of a novel Ti3C2-modified Sb-SnO2 porous electrode for electrochemical oxidation of organic pollutants

Sb-SnO2 is an appealing electrode for degrading organic pollutants in wastewater treatment, albeit further modifications are needed for its inefficient electrochemical oxidation capacity. In this work, we prepared Ti3C2-modified Sb-SnO2 electrode by electrodeposition technology. High-conductive MXene matrix regulated the Sb-Sn alloy nucleation process to decrease its domain size during deposition and generated pores during the annealing process. When introducing 20 mg MXene into the electrolyte, the obtained Sb-SnO2 electrode (Ti3C2-20) presented a larger oxygen evolution over-potential (2.32 V vsSCE), increased amount of active sites, and enlarged electrochemical specific surface area (∼4.4-fold) than the unmodified electrode, resulting in a promoted OH generation ability (∼7.4 times). Methylene blue (MB), methyl orange (MO), norfloxacin (NOR), and P-phenylenediamine (PPD) were effectively degraded by the Ti3C2-20 anode with economic energy consumption. Moreover, the Ti3C2-20 electrode also featured a longer lifetime, almost fivefold, than the unmodified Sb-SnO2 electrode due to its larger loading amount and decreased charge transfer resistance. Consequently, this work offers a new perspective for designing efficient and stable porous electrodes to address water pollution issues.