RESUMO
Per- and polyfluoroalkyl substances (PFASs), comprising over 9,000 persistent synthetic organic contaminants, are extensively found in the environment and pose significant risks to both human and ecological health. Among the strategies for addressing PFAS contamination, adsorption processes have proven to be cost-effective. Traditional sorbents such as ion-exchange resins and activated carbon have been found to exhibit low adsorption capacities and slow equilibration times. Recent innovations in porous materials, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and porous organic polymers (POPs), however, offer significant improvements in the efficiency of PFAS adsorption. This review thoroughly examines the latest advancements in these materials, analyzing their mechanisms of adsorption, and concludes by suggesting directions for future research that could further enhance their effectiveness in PFAS management.
RESUMO
Electrochemical sulfion oxidation reaction (SOR) offers a sustainable strategy for sulfion-rich wastewater treatment, which can couple with cathodic hydrogen evolution reaction (HER) for energy-saving hydrogen production. However, the corrosion and passivation of sulfur species render the inferior catalytic SOR performance, and the oxidation product, polysulfide, requires further acidification to recover cheap elementary sulfur. Here, we reported an amorphous high-entropy sulfide catalyst of CuCoNiMnCrSx nanosheets in-situ growth on the nickel foam (CuCoNiMnCrSx/NF) for SOR, which achieved an ultra-low potential of 0.25 V to afford 100 mA cm-2, and stable electrolysis at as high as 1 A cm-2 for 100 h. These were endowed by the manipulated chemical environments surrounding Cu+ sites and the constructed "soft-acid" to "hard-acid" adsorption/desorption sites, enabling synergistically boosted adsorption/desorption process of sulfur species during SOR. Moreover, we developed an electrochemical-chemical tandem process to convert sulfions to value-added thiosulfate, providing a good choice for simultaneous wastewater utilization and hydrogen production.
RESUMO
The textile industry discharges up to 5 % of their dyes in aqueous effluents. Here, use of spent mushroom substrate (SMS) of commercial white button mushroom production and its aqueous extract, SMS tea, was assessed to remove textile dyes from water. A total of 30-90 % and 5-85 % of the dyes was removed after a 24 h incubation in SMS and SMS tea, respectively. Removal of malachite green and remazol brilliant blue R was similar in SMS and its tea. In contrast, removal of crystal violet, orange G, and rose bengal was higher in SMS, explained by sorption to SMS and by the role of non-water-extractable SMS components in discoloration. Heat-treating SMS and its tea, thereby inactivating enzymes, reduced dye removal to 8-58 % and 0-31 %, respectively, indicating that dyes are removed by both enzymatic and non-enzymatic activities. Together, SMS of white button mushroom production has high potential to treat textile-dye-polluted aqueous effluents.
Assuntos
Agaricus , Corantes , Corantes/química , Têxteis , Biodegradação Ambiental , Cor , Indústria Têxtil , Poluentes Químicos da Água , Resíduos IndustriaisRESUMO
Water recovery from waste water has become an essential element of the circular economy in the Baltic Sea region. However, there is little data on the possibility of using water recovered from urban waste water. A survey was conducted to learn the opinions of Poland waste water treatment plant operators. They were asked whether they recovered water for internal or external needs. Respondents indicated opportunities and barriers in this activity. The opinions of 107 operators show that work is underway on closing internal circuits in urban WWTPs. These solutions are technically relatively easy to implement and show measurable benefits (i.e., saving drinking water). However, water recovery for external purposes is rare and is at a very early stage. Despite this, the potential is significant, although many financial, organizational, technical, and mental barriers exist. The most critical challenge is the safe use of reclaimed water and the cost-effectiveness of the solutions. The survey also shows a need for education and involvement of the public.
Assuntos
Águas Residuárias , Polônia , Purificação da Água/métodos , Eliminação de Resíduos Líquidos/métodosRESUMO
Affordable and swiftly available h-BN@SnO2/TiO2 photocatalysts are being developed through an easy hydrothermally approach was used urea as boric acid precursors. With their constructed photo catalysts, the effect of h-BN@SnO2/TiO2 has been investigated under the assessment of Adsorption agents utilizing X-ray diffraction pattern (XRD), Scanning electron microscopy, Energy dispersive spectroscopic analysis (SEM/EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), and Burner Emit Teller (BET) isotherm testing methods, which also indicated that SnO2/TiO2 and h-BN have been tightly bound together. Because turquoise blue (TB) and Methyl orange (MO) fabric dyes can be found in the industrial wastewater being processed, the photo catalytic degradation process happens to be applied. According to the advantageous linkages of h-BN@SnO2/TiO2 photocatalysts, fantastic efficacy in breakdown towards hazardous compounds has been found. For the decomposition of Turquoise blue (TB) and Methyl orange (MO), the h-BN@SnO2/TiO2 catalysts proved the best performance stability (0.0386 min-1 and 1.524min-1) but were significantly 22 times quicker. Optical catalysis has additionally demonstrated extraordinary resilience and durability throughout five reprocessed efforts. On top of that, an approach enabling photocatalytic breakdown of harmful substances upon h-BN@SnO2/TiO2 has been presented.
Assuntos
Corantes , Compostos de Estanho , Titânio , Águas Residuárias , Poluentes Químicos da Água , Titânio/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise , Corantes/química , Compostos de Estanho/química , Águas Residuárias/química , Catálise , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodos , Têxteis/análise , FotóliseRESUMO
Alginate hydrogel is highly efficient for water filtration due to its anti-fouling nature and formation of strong hydration membranes. However, poor mechanical properties of alginate hydrogel membrane limit its installation in water treatment. There is a need to enhance mechanical properties of alginate hydrogel membranes using eco-friendly, cost-effective materials and technologies. In this work, hydroentangled non-woven from cotton waste (comber noil) fibers was prepared. This non-woven was immersed in solution of sodium alginate (0.5 %, 1 %, 1.5 %) followed by dipping in calcium chloride solution which resulted in gel formation on and into cotton fibers. The successful formation of gel on non-woven fabric was confirmed through FTIR (Fourier transform infrared spectroscopy) and properties of this composite membrane were analyzed by SEM (Scanning electron microscopy), XRD (X-ray diffraction), DSC (Differential scanning calorimeter), water contact, water flux, oil-water filtration, air permeability, tensile strength, and porosity tests. The results showed that porosity of prepared hydrogel membranes decreased with increasing alginate concentration from 0.5 % to 1.5 % which resulted in decreased water permeation flux from 2655 h-1/m2 to 475 h-1/m2. The prepared membrane has separation efficiencies for the oil-water mixture in the range of 97.5 % to 99.5 %. Moreover, the developed samples also showed significant antibacterial activity as well as improved mechanical properties. The strength of the prepared membrane is in the range of 40 N to 80 N. The developed sodium alginate hydrogel-based non-woven membrane could have potential applications for commercial water filtration systems.
Assuntos
Alginatos , Hidrogéis , Hidrogéis/química , Alginatos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Cloreto de Cálcio , AntibacterianosRESUMO
This work reports silver nanoparticles (AgNPs) supported on biopolymer carboxymethyl cellulose beads (Ag-CMC) serves as an efficient catalyst in the reduction process of p-nitrophenol (p-NP) and methyl orange (MO). For Ag-CMC synthesis, first CMC beads were prepared by crosslinking the CMC solution in aluminium nitrate solution and then the CMC beads were introduced into AgNO3 solution to adsorb Ag ions. Field emission scanning electron microscopy (FE-SEM) analysis suggests the uniform distribution of Ag nanoparticles on the CMC beads. The X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis revealed the metallic and fcc planes of AgNPs, respectively, in the Ag-CMC catalyst. The Ag-CMC catalyst exhibits remarkable reduction activity for the p-NP and MO dyes with the highest rate constant (kapp) of a chemical reaction is 0.519 and 0.697 min-1, respectively. Comparative reduction studies of Ag-CMC with CMC, Fe-CMC and Co-CMC disclosed that Ag-CMC containing AgNPs is an important factore in reducing the organic pollutants like p-NP and MO dyes. During the recyclability tests, the Ag-CMC also maintained high reduction activity, which suggests that CMC protects the AgNPs from leaching during dye reduction reactions.
Assuntos
Nanopartículas Metálicas , Prata , Prata/química , Nanopartículas Metálicas/química , Carboximetilcelulose Sódica , Biopolímeros , Corantes/químicaRESUMO
Antibiotic pollution has become one of the most emerging problems of the modern era. Tinidazole (TDZ) is one the most important nitroimidazole derivative drugs whose use has tremendously increased in the last few years. The proposed research work provides a good alternative cost-effective method for wastewater treatment. In the present investigation, algae were used as a photosensitizer in the treatment of the wastewater that was contaminated with antibiotic residue. The proposed research also provides the probable mechanism involved in the photodegradation of tinidazole. The different factors like concentration and pH of the test solution which play a key role in the photodegradation of drug molecules are also discussed in the present investigation. The result of this study established that the maximum degradation of drug molecules was observed at the algal concentration of 1.6 × 108 Cell/L and approximately 58% of drug molecules were degraded. This study also established that in an acidic medium ie at pH 5 the degradation occurs more efficiently. Results of the current study indicated that the use of algae-induced photodegradation of drug residue became one of the most promising routes for wastewater treatment. The results of the present study provide a new way to treat wastewater contaminated with antibiotics residue.
RESUMO
The study provides a systematic literature review (SLR) encompassing industrial wastewater management research from the past decade, examining enablers, challenges, and prevailing practices. Originating from manufacturing, energy production, and diverse industrial processes, industrial wastewater's handling is critical due to its potential to impact the environment and public health. The research aims to comprehend the current state of industrial wastewater management, pinpoint gaps, and outline future research prospects. The SLR methodology involves scouring the Scopus database, yielding an initial pool of 253 articles. Refinement via search code leaves 101 articles, followed by abstract screening that reduces articles to 79, and finally 66 well-focused articles left for thorough full-text examination. Results underscore the significance of regulatory frameworks, technological innovation, and sustainability considerations as cornerstones for effective wastewater management. However, substantial impediments like; inadequate infrastructure, resource constraints and the necessity for stakeholder collaboration still exist. The study highlights emerging research domains, exemplified by advanced technologies like nanotechnology and bioremediation, alongside the pivotal role of circular economy principles in wastewater management. The SLR offers an exhaustive view of contemporary industrial wastewater management, accentuating the imperative of an all-encompassing approach that integrates regulatory, technological, and sustainability facets. Notably, the research identifies gaps and opportunities for forthcoming exploration, advocating for interdisciplinary research and intensified stakeholder collaboration. The study's insights cater to policymakers, practitioners, and researchers, equipping them to address the challenges and capitalize on prospects in industrial wastewater management effectively.
Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias , Eliminação de Resíduos Líquidos/métodos , Biodegradação AmbientalRESUMO
Dye and textile industries are one of the main causes of water pollution and put the environment and health of society at risk. Developing new materials to decontaminate industrial waste effluents containing dyes as pollutants is challenging due to numerous issues, including tailoring recyclable and biodegradable agents. This study focuses on applying an advanced oxidation process, electro-Fenton for the treatment of dye-containing wastewater using agar-functionalized graphene oxide-immobilized copper ferrite aerogel. The objective is therefore to determine the optimal conditions for the degradation of model pollutants methylene blue (MB). MB was oxidized and degraded through the dark-Fenton process using Agar@GO-CuFe2O4 as a new biobased catalyst. The effect of the operating parameters was then evaluated to determine the optimal conditions. The degradation process was screened for different initial concentrations of dye solution between 10 and 150 mg/l, a volume range of H2O2 between 0.5 and 2.5 ml, and different pH from 2 to 7. The results show that 99.89 % of the MB with the initial concentration of 150 ppm was degraded by 20 mg of the catalyst and 2 ml of H2O2 (30 % W/W) at 40 °C and pH = 6. Pseudo-second-order kinetics satisfactorily describes the experimental data. SYNOPSIS: The prepared catalyst can be applied to oxidize industrial effluents before they are released into the environment.
Assuntos
Corantes , Poluentes Químicos da Água , Ágar , Cobre , Ferro , Peróxido de Hidrogênio , Estresse OxidativoRESUMO
The importance of water for all living organisms is unquestionable and protecting its sources is crucial. In order to reduce water contaminants, like toxic metals and organic dyes, researchers are exploring different techniques, such as adsorption, photocatalytic degradation, and electrolysis. Novel materials are also being sought. In particular, biopolymers like guar gum and xanthan gum, that are eco-friendly, non-toxic, reusable, abundant and cost-effective, have enormous potential. Gum-based nanocomposites can be prepared and used for removing heavy metals and colored dyes by adsorption and degradation, respectively. This review explains the significance of gum-based nanomaterials in waste water treatment, including preparative steps, characterization techniques, kinetics models, and the degradation and adsorption mechanisms involved.
RESUMO
The highly biocompatible nature of carbon dots (CQDs) and potential usage in waste water treatment makes them as one of the effective alternative for treating water pollution. Herein, biogenic carbon dots (CQDs) with size range of 2 nm were prepared from waste coconut husk as a precursor source. The hydrophilic nature and higher surface area of as prepared CQDs has further supported the superior adsorption efficiency of more than 90% for Victoria blue B (VB) dye from waste water samples. Different dye adsorption parameters including adsorbate and adsorbent dosage, pH of reaction media and equilibrium time have been optimized and found that 8 mg of adsorbent was sufficient to remove 70 mg VB dye in 4 mL aqueous solution in 60 min at pH = 7. The adsorption kinetic (2nd order) and isotherms (Freundlich-type) were well followed on prepared CQDs. The reusability studies up to 5 times with minimal decrement of 4% confirm the constancy of CQDs for the adsorptive removal of VB. The methodology presents a greener way for overcoming ecological issues with sustainable materials in an economical manner.
Assuntos
Carbono , Poluentes Químicos da Água , Cocos , Corantes de Rosanilina , Adsorção , Cinética , Concentração de Íons de HidrogênioRESUMO
Chitosan/aspartic acid hydrogels were synthesized for MB dye removal from textile aqueous effluents with different ratios by gelation of chitosan with non-toxic gelling agent, crosslinker, glutaraldehyde (Glu). The obtained hydrogels were characterized by spectral and morphological techniques. The characterization techniques confirmed successful preparations and MB dye adsorption. Batch experiments were done to investigate the effects of adsorbent dose, pH, contact time, temperature, and initial MB dye concentration. The optimum conditions were: adsorbent dose 0.1 g, pH 5, contact time 30 min, and temperature 25 °C for Chitosan-Aspartic Acid Hydrogel 1 (CSAA-HG1) and adsorbent dose 0.4 g, pH 2, contact time 60 min, temperature 25 °C for Chitosan-Aspartic Acid Hydrogel 2 (CSAA-HG2). Adsorption capacity of newly hydrogels CSAA-HG1,2 was compared with each other. Adsorption efficiencies reached 99.85 % for CSAA-HG1 and 99.88 % for CSAA-HG2. MB dye adsorption on CSAA-HG1,2 followed Freundlich isotherm model (R2 = 0.94 and 0.92, respectively). Both adsorbents exhibited pseudo-second-order kinetics for MB dye adsorption (R2 = 1). The negative ΔHo indicated that the MB dye adsorption was exothermic, negative ΔGo confirmed that MB dye adsorption process was spontaneous and low values of ∆So indicated low degree of freedom, ordered MB dye molecules on CSAA-HG1,2 surfaces.
Assuntos
Quitosana , Poluentes Químicos da Água , Azul de Metileno/química , Quitosana/química , Ácido Aspártico , Hidrogéis/química , Análise Custo-Benefício , Poluentes Químicos da Água/química , Concentração de Íons de Hidrogênio , Adsorção , Cinética , Corantes/química , TermodinâmicaRESUMO
Urban domestic sewage is one of the important nitrate (NO-3) sources for surface water; however, their NO-3 concentrations and nitrogen and oxygen isotope values (δ15N-NO-3 and δ18O-NO-3) remain unclear, and the factors affecting NO-3 concentrations and δ15N-NO-3 and δ18O-NO-3 values of effluents in the waste water treatment plant (WWTP) are still unknown. Water samples in the Jiaozuo WWTP were collected to illustrate this question. Influents, clarified water in the secondary sedimentation tank (SST), and effluents of the WWTP were sampled every 8 h. The ammonia (NH+4) concentrations, NO-3 concentrations, and δ15N-NO-3 and δ18O-NO-3 values were analyzed to elucidate the nitrogen transfers through different treatment sections and illustrate the factors affecting the effluent NO-3 concentrations and isotope ratios. The results indicated that â the mean NH+4 concentration was (22.86±2.16) mg·L-1 in the influent and decreased to (3.78±1.98) mg·L-1 in the SST and continuously reduced to (2.70±1.98) mg·L-1 in the effluent of the WWTP. The median NO-3 concentration was 0.62 mg·L-1 in the influent, and the average NO-3 concentration increased to (33.48±3.10) mg·L-1 in the SST and gradually increased to (37.20±4.34) mg·L-1 in the effluent of the WWTP. â¡ The mean values of δ15N-NO-3 and δ18O-NO-3 were (17.1±10.7) and (19.2±2.2) in the influent of the WWTP, the median values of δ15N-NO-3 and δ18O-NO-3 were 11.9 and 6.4 in the SST, and the average values were (12.6±1.9) and (5.7±0.8) in the effluent of the WWTP. ⢠The NH+4 concentrations of influent had significant differences compared to those in the SST and the effluent (P<0.05). The reduction of NH+4 concentrations in the SST was due to the above nitrification during the aerobic treatment process, which transferred NH+4 to NO-3. The NH+4 concentrations in the SST had no significant differences with that in the effluent of the WWTP (P>0.05). ⣠The NO-3 concentrations in the influent had significant differences with those in the SST and the effluent (P<0.05), and minor NO-3 concentrations but relatively high δ15N-NO-3 and δ18O-NO-3 values in the influent were probably due to denitrification during the pipe sewage transportation. The obviously increased NO-3 concentrations (P<0.05) but decreased δ18O-NO-3 values (P<0.05) in the SST and the effluent resulted from water oxygen incorporation during the nitrification. The above results confirmed the impacts of aerobic and anaerobic treatment processes on NO-3 concentrations and isotope ratios of effluent from the WWTP and provided scientific basis for the identification of sewage contributions to surface water nitrate via average δ15N-NO-3 and δ18O-NO-3 values.
RESUMO
Cross-linked chitin/deacetylated chitin nanocomposite films can be considered as a potential industrial adsorbent for the removal of organic pollutants for water purification. Chitin (C) and deacetylated chitin (dC) nanofibers were extracted from raw chitin and characterized using FTIR, XRD and TGA techniques. The TEM image confirmed the formation of chitin nanofibers with a diameter range of 10-45 nm. The deacetylated chitin nanofibers (DDA-46 %) having 30 nm diameter was evidenced using FESEM. Further, the C/dC nanofibers were prepared at different ratios (80/20, 70/30, 60/40 & 50/50 ratios) and cross-linked. The highest tensile strength of 40 MPa and Young's modulus of 3872 MPa was exhibited by 50/50C/dC. The DMA studies revealed that the storage modulus enhanced by 86 % for 50/50C/dC (9.06 GPa) in comparison to 80/20C/dC nanocomposite. Further, the 50/50C/dC exhibited a maximum adsorption capacity of 30.8 mg/g at pH = 4 in 30 mg/L of Methyl Orange (MO) dye within 120 min. The experimental data agreed with pseudo-second-order model indicating chemisorption process. The adsorption isotherm data was best described by Freundlich model. The nanocomposite film is an effective adsorbent that can be regenerated and recycled for five adsorption-desorption cycle.
Assuntos
Poluentes Ambientais , Nanocompostos , Quitina/química , Adsorção , Cinética , Água/química , Nanocompostos/químicaRESUMO
Textile waste water contains dyes and chemicals that produce harmful vapors and exhaust gases, which is hazardous to the environment and public health. Therefore, it must be carefully treated before discharged. To understand the research evolution in the research area of textile waste water treatment, based on bibliometrics, an in-depth analysis of the publications and hotspots in this area was presented in this paper. For the analysis, totally 6774 papers related to the research area that are published between the year 1964 and 2023 were collected from the Web of Science Core Collection. Using CiteSpace and VOSviewer as bibliometric analysis tools, the collaboration of countries, regions, and organizations was investigated. Besides, an analysis for citation and co-citation of journals, authors, references, and co-occurrence of keywords was performed. The evolution of research hotspots in the three major research directions related to degradation, oxidation, and adsorption is also analyzed in this paper. The analysis results show that researches related to oxidation and adsorption are active in recent years, while nanocomposite adsorbents and graphene oxide are the current research hotspots.
Assuntos
Monitoramento Ambiental , Águas Residuárias , Adsorção , Bibliometria , Gases , TêxteisRESUMO
This article addresses the synthesis of Fe3+doped TiO2nanoparticles with variations of molar concentrations of Fe3+and their adequate use as potential photocatalysts for Photocatalysis applications. Synthesized photocatalysts were characterized thoroughly by different analytical techniques in terms of morphological, chemical, structural, crystalline, optical, electronic structure, surface area etc properties. The occurrence of red shift phenomenon of the energy band gap attributes to the transfer of charges and transition between the d electrons of dopant and conduction band (CB) or valence band (VB) of TiO2. The doping of Fe3+ions generates more trap sites for charge carriers with the surface trap sites. Thorough experimental conclusions revealed that the Fe3+ions necessarily regulate the catalytic property of TiO2nanomaterial. The obtained total degradation efficiency rate of Methylene Blue (MB) was 93.3% in the presence of 0.1 M Fe3+in the host material and for Malachite Green Oxalate the efficiency was 100% in the presence of 0.05 M and 0.1 M Fe3+in the host material. In both the cases the total visible light irradiation time was 90 min. The adsorption properties of the photocatalysts have been also performed in a dark for 90 min in the presence of MB dye. However, till now there are hardly reported photocatalysts which shows complete degradation of these toxic organic dyes by visible light driven photocatalysis. of potential values of valence and conduction band shows the production of active oxidizing species for hydrogen yield and the possible mechanism of the Schottky barrier has been proposed. A schematic diagram of visible light driven Photocatalysis has been pictured showing degradation activity of Fe3+-TiO2catalysts sample.
RESUMO
The present study reported the improvement of biological treatment for the removal of recalcitrant dyes including aniline blue, reactive black 5, orange II, and crystal violet in contaminated water. The biodegradation efficiency of Fusarium oxysporum was significantly enhanced by the addition of mediators and by adjusting the biomass density and nutrient composition. A supplementation of 1% glucose in culture medium improved the biodegradation efficiency of aniline blue, reactive black 5, orange II, and crystal violet by 2.24, 1.51, 4.46, and 2.1 folds, respectively. Meanwhile, the addition of mediators to culture medium significantly increased the percentages of total removal for aniline blue, reactive black 5, orange II, and crystal violet, reaching 86.07%, 68.29%, 76.35%, and 95.3%, respectively. Interestingly, the fungal culture supplemented with 1% remazol brilliant blue R boosted the biodegradation up to 97.06%, 89.86%, 91.38%, and 86.67% for aniline blue, reactive black 5, orange II, and crystal violet, respectively. Under optimal culture conditions, the fungal culture could degrade these synthetic dyes concentration up to 104 mg/L. The present study demonstrated that different recalcitrant dye types can be efficiently degraded using microorganism such as F. oxysporum.
Assuntos
Corantes , Águas Residuárias , Corantes/química , Violeta Genciana , Biodegradação Ambiental , Têxteis , Lacase/metabolismoRESUMO
Although dissolved inorganic phosphate (DIP) is an important nutrient in the hydrosphere, it is difficult to quantitatively clarify the dynamics of DIP in the hydrosphere using the δ18O value of DIP as a tracer. In this study, we quantified the triple oxygen isotopic compositions (Δ'17O) of DIP relative to VSMOW with the reference line with a slope of 0.528 as an additional tracer to clarify the sources and dynamics of DIP in the hydrosphere. We found significant variation in the Δ'17O values of riverine DIP in urban areas, ranging from -107 × 10-6 to +3 × 10-6, while those of DIP in the effluents from wastewater treatment plants (WWTP) and DIP extracted from the chemical fertilizers showed -56 ± 5 × 10-6 (1SD) and -98 ± 5 × 10-6, respectively. We conclude that both the DIP supplied directly from the artificial loads (the WWTP effluent and chemical fertilizers) showing 17O-depleted Δ'17O values and the DIP turned over via the aquatic biosphere showing 17O-enriched Δ'17O values similar to ambient H2O were the major sources of riverine DIP. High-precision determination of the Δ'17O value of DIP can contribute to quantitative clarification of the dynamics of DIP in the hydrosphere.
Assuntos
Fertilizantes , Fosfatos , Isótopos de Oxigênio/química , Fosfatos/químicaRESUMO
A basic calcination process in one step was employed to create g-C3N4 photocatalytic composites modified by Gd2O3 nanoparticles. SEM (scanning electron microscopy), FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction), EIS (electrochemical impedance spectroscopy), PL (photoluminescence studies) as well as TEM (transmission electron microscopy), XPS (X-ray photoelectron spectroscopy), and CV (cyclic voltammetry) were employed to explain the structural traits, optical properties, and morphological features of the processed photocatalyst. The findings show that Gd2O3 (Gd) does not affect the sample's crystalline structure but rather increases g-C3N4 surface area by spreading it superficially. Furthermore, Gd can redshift the light absorption peak, reduce the energy gap, and improve the efficiency with which photogenerated holes and electrons are removed in g-C3N4. The surface morphology of g-C3N4, in particular, could be significantly enhanced. We similarly employed three distinct photocatalytic complexes of Gd2O3 and g-C3N4 in 1:1, 2:1, and 3:1 proportions to degrade methylene blue (MB). After 100 min in visible light (400-800 nm), the photodegradation rate of composites is 58.8% for 1:1 (GG1), 94.5% for 2:1 (GG2), and 92% for 3:1 (GG3). In addition to the MB dye, the photocatalytic activity of synthesized materials was also studied for methyl orange. The result shows phenomenal degradation values, i.e.; for GG1 86%, GG2 96%, and for GG3 84.6%. The narrow band gap that separates the photogenerated electron and hole enhances g-C3N4 ability to degrade photo-catalytically. From the result, we concluded that the photocurrent and cyclic photocatalytic degradation of methylene blue shows that a composition of 2:1 Gd2O3/g-C3N4 has high photocatalytic stability.