Degradation Of Organic Contaminants Research Articles

Core–shell CoN@Co ultra-stable nanoparticles on biochar for contamination remediation in water and soil

Nanomaterials have been extensively employed in various applications over the past several decades, however, the stability of functional nanoparticle catalysts (NPCs) for effective degradation of organic contaminants remains a significant challenge. Herein, we present a cost-effective biochar loaded uniformly dispersed ultra-stable Co nanoparticles with an average diameter of 8 nm as a highly efficient peroxymonosulfate (PMS) activation catalyst. The reactive radicals produced from the catalyst/PMS system are able to degrade several model organic pollutants of environmental and public health concerns, including trichlorobiphenyl, bisphenol A and diethyl phthalate, with less pH limitation and Co2+ leaching. Mechanism investigation demonstrates that the CoN plays the key role in the catalyst stability and PMS activation via acid resistance and electron bridging effects, respectively. Meanwhile, the incorporation of nitrogen (N) and sulfur (S) atoms within the substrate is considered to bolster the adhesion strength between metal nanoparticles and the carbon matrix via strong metal-support interaction. The catalyst was further applied in practical treatment of water and soil polluted by organic pollutants, exhibiting a satisfactory degradation efficiency (> 90% in 60 min) for environmental applications.

Metal-Free Activated Carbon Catalytic for Degradation of Organic Contaminants by Peroxydisulfate Activation

Green chemistry has become trending recently, and the discovery of environmentally friendly catalysts is mandatory. Activated carbons (ACs) are one of the most environmentally friendly yet cheap materials that have the potential for catalyst application. Three commercially available ACs from Pancasari, Norit, and Chemical Supply were used as metal-free catalysts for advanced oxidation process (AOP) phenol removal in water in the presence of oxidants peroxydisulfate (PDS), and hydrogen peroxide (H2O2). It was found that ACs were effective to be used as catalysts for activating those oxidants to oxidize phenol in AOP reactions. In this study, the surface area of the catalyst significantly improved the phenol removal efficiency. ACs Pancasari (ACP) with the highest surface area has the best degradation performance of phenol removal with up to 99% removal efficiency in 60 minutes under the condition of [phenol] = 30 mg L-1, [ACP] = 0.2 g L-1, [PDS] = 3.3 mmol L-1, and T = 25oC. it was also found that the degradation process was significantly influenced by reaction temperature. Nevertheless, in this study, ACs display the potential as catalysts in the AOP process for wastewater treatments.

Enhancing photocatalytic degradation of crystal violet dye with g‐C3N4/ZnTiO3 nanocomposites synthesized via a facile approach

AbstractPhotocatalysts that exhibit exceptional performance could be further enhanced for wastewater treatment, particularly in the degradation of organic pollutants and reduction of inorganic heavy metal ions concentrations. This study employed sol–gel techniques was used to create a Type II scheme g‐C3N4/ZnTiO3 (CZT‐2, CZT‐4, and CZT‐6) photocatalyst. FT‐IR, UV‐DRS, XRD, SEM, BET, HR‐TEM, and XPS analysis were conducted to investigate the physical and chemical properties of the g‐C3N4/ZnTiO3 photocatalyst's. An investigation was conducted to evaluate the photocatalytic performance of the synthesized samples. The samples exhibit remarkable efficacy in the degradation of organic contaminants. Among them, CZT‐2 showcased superior photocatalytic performance in the solar light‐induced photodegradation of crystal violet. The photocatalytic activity of g‐C3N4/ZnTiO3 has been significantly enhanced through the establishment of a Type‐II scheme at the interface. This innovative approach efficiently facilitates the separation of photogenerated electron–hole pairs, thereby boosting the photodegradation activity. The discussion also included the chemical process between photocatalysts and crystal violet. The mechanism of the crystal violet‐photocatalyst reaction was also discussed. After undergoing five cycles of reuse, the photocatalyst that was manufactured demonstrated remarkable stability, leading to a reduction in the cost associated with wastewater treatment. The as‐synthesized g‐C3N4/ZnTiO3 composites are very safe for the environment, which suggests that the CZT‐2 composite is very good at getting rid of pollutants.

Waste to worth: Facile preparation of CaO2 derived from oyster shells for highly efficient degradation of organic contaminants based on Fenton-like system

In recent years, CaO2 has been frequently used as a substitute for H2O2 to address the limitations of H2O2. However, commercially available CaO2 are facing the shortcomings of low purity and limited preparation conditions. Oyster shells can provide superior and abundant biomass calcium element with low cost for developing CaO2. In this work, highly purified CaO2 functional biomaterials were prepared via a facile approach derived from waste oyster shells, which were applied in a Fenton-like system to remove organic pollutants. Experimental results indicated that the oyster shells-derived CaO2 with 100% purity exhibited a greatly enhanced catalytic performance compared with other CaO2 materials in Fenton-like catalytic degradation of organic pollutants, which can be completely removed within 60 s. The high purity of CaO2 would facilitate the release of H2O2 during the Fenton-like catalytic reaction and promote the generation of more active species to oxidize pollutants. Besides, the abundant trace metal elements originated from oyster shells can further motivate the Fenton-like reaction and accelerate the degradation of pollutants, endowing oyster shells-derived CaO2 an excellent catalytic activity. Furthermore, the Fenton-like catalytic mechanism was proposed on basis of tests of radicals trapping and electron spin resonance, validating the vital roles of ⋅OH, ⋅O2– and 1O2 generated throughout the reaction process. This work not only provides a novel and low-cost approach to exploit CaO2 with highly efficient catalytic ability, but also realizes the effective resource utilization of waste shells.

Assessing the Chemical-Free Oxidation of Trace Organic Chemicals by VUV/UV as an Alternative to Conventional UV/H2O2.

Low-pressure mercury lamps with high-purity quartz can emit both vacuum-UV (VUV, 185 nm) and UV (254 nm) and are commercially available and promising for eliminating recalcitrant organic pollutants. The feasibility of VUV/UV as a chemical-free oxidation process was verified and quantitatively assessed by the concept of H2O2 equivalence (EQH2O2), at which UV/H2O2 showed the same performance as VUV/UV for the degradation of trace organic contaminants (TOrCs). Although VUV showed superior H2O activation and oxidation performance, its performance highly varied as a function of light path length (Lp) in water, while that of UV/H2O2 proportionally decreased with decreasing H2O2 dose regardless of Lp. On increasing Lp from 1.0 to 3.0 cm, the EQH2O2 of VUV/UV decreased from 0.81 to 0.22 mM H2O2. Chloride and nitrate hardly influenced UV/H2O2, but they dramatically inhibited VUV/UV. The competitive absorbance of VUV by chloride and nitrate was verified as the main reason. The inhibitory effect was partially compensated by •OH formation from the propagation reactions of chloride or nitrate VUV photolysis, which was verified by kinetic modeling in Kintecus. In water with an Lp of 2.0 cm, the EQH2O2 of VUV/UV decreased from 0.43 to 0.17 mM (60.8% decrease) on increasing the chloride concentration from 0 to 15 mM and to 0.20 mM (53.5% decrease) at 4 mM nitrate. The results of this study provide a comprehensive understanding of VUV/UV oxidation in comparison to UV/H2O2, which underscores the suitability and efficiency of chemical-free oxidation with VUV/UV.

Highly dispersed Pd icosahedra and Ag nanocubes on ultrathin g-C3N4 nanosheet for boosting photocatalytic bacterial inactivation and organic pollutants degradation

Engineering surface facet of metallic nanoparticles that decorated on certain substants is an intriguing strategy to modulate photocatalytic capacity. Herein, a novel photocatalyst by doping g-C3N4 nanosheet with Pd icosahedra with {111} facets and Ag nanocubes with {100} facets were firstly synthesized through facile wet-chemical route. The successfully constructed g-C3N4/Pd/Ag composites were employed as a visible-light-driven dual-functional photocatalyst for bacterial inactivation and organic contaminant degradation. Result suggested that 1 × 108 CFU/mL E. coli strains can be totally inactivated by g-C3N4/Pd/Ag within 60 min, outperformed that of {100} faceted enclosed Pd nanocubes functioned g-C3N4/Ag. Also, the optimized g-C3N4/Pd/Ag exhibited ideal photocatalytic performance toward tetracycline and methylene blue degradation. The rate constant was found to be 8.74 × 10−3 and 7.08 × 10−3 min−1, respectively, which was higher than those of bare g-C3N4 and g-C3N4/Pd. Quenching experiment and electron paramagnetic resonance analysis suggested that hole (h+), electron (e−), and superoxide radical (O2−) exerted a key role in the improved capacity. Furthermore, the more positive Fermi level of Pd icosahedra and Ag nanocubes relative to that of g-C3N4 also contributed to the enhanced photocatalytic performance. Collectively, our work can provide in-depth insight into fabricate novel facet-engineering photocatalyst for environmental applications.

Copper-doped ZIF-67/wood aerogel for effective peroxymonosulfate activation

Metal-organic frameworks (MOFs), composed of metal ions and organic linkers, have garnered enormous attention in catalytic application due to their exceptional characteristics such as high specific surface area, low density, large porosity and structural diversity. However, the recycling and performance improvement of MOF should be taken into account in material design. In this work, we fabricated copper-doped metal-organic framework/wood aerogel composites to enhance the activation of peroxymonosulfate (PMS) for the degradation of organic contaminants. Wood Aerogel (WA) was used as suitable carrier to solve the recycling problem, and copper-doped ZIF-67 was developed to enhance the catalytic performance. Copper-doped ZIF-67 (ZIF-67B) was loaded into the cavities of a wood aerogel by in situ wet chemical precipitation, followed by freeze drying to obtain the composite. The effects of copper doping ratio, temperature, catalyst dosage, initial pH and other operational parameters on the degradation of organic pollutants were comprehensively investigated. The catalytic capacity of ZIF-67B@WA (CoxCu(1-x)) was investigated by activating PMS for the removal of Rhodamine B (RhB). The results demonstrate that the degradation efficiency of ZIF-67B@WA (CoxCu(1-x)) towards RhB can achieve 100 % within 15 min, showing exceptional catalytic performance compared with ZIF-67@WA. Even after four consecutive cycles, the degradation efficiency remains at 87.5 %, indicating that the catalyst has good cycle stability. Additionally, possible degradation mechanisms are proposed in this study, in which WA provides high loading active site/area for MOF catalyst and Cu doping can accelerate electron transfer and facilitate the redox cycling of Co2+ and Co3+, thereby enhancing catalytic efficiency. This work expands the application scope of MOF materials in environmental remediation and holds promising prospects.

A novel remediation strategy of mixed calcium peroxide and degrading bacteria for polycyclic aromatic hydrocarbon contaminated water

Polycyclic aromatic hydrocarbons (PAHs) are a class of toxic organic pollutants commonly detected in the aqueous phase. Traditional biodegradation is inefficient and advanced oxidation technologies are expensive. In the current study, a novel strategy was developed using calcium peroxide (CP) and PAH-degrading bacteria (PDB) to effectively augment PAH degradation by 28.62–59.22%. The PDB consisted of the genera Acinetobacter, Stenotrophomonas, and Comamonas. Applying the response surface model (RSM), the most appropriate parameters were identified, and the predictive degradation rates of phenanthrene (Phe), pyrene (Pyr), and ΣPAHs were 98%, 76%, and 84%, respectively. The constructed mixed system could reduce 90% of Phe and more than 60% of ΣPAHs and will perform better at pH 5–7 and lower salinity. Because PAHs tend to bind to dissolved organic matter (DOM) with larger molecular weights, humic acid (HA) had a larger negative effect on the PAH-degradation efficiency of the CP-PDB mixed system than fulvic acid (FA). The proposed PAH-degradation pathways in the mixed system were based on the detection of intermediates at different times. The investigation constructed and optimized a novel environmental PAH-degradation strategy. The synergistic application of PDB and oxidation was extended for organic contaminant degradation in aqueous environments.

Investigating oxidant-catalyst interactions in the persulfate system: Implications for efficient removal of phenolics and antibiotics

Persulfate (PS) activation by carbon catalyst holds both scientific and practical significance to curb the toxicity effects of organic pollutants in the natural water environment. Here, we investigated a relatively unfamiliar characteristics (i.e., oxidant-catalyst interaction) that influence the removal efficiency in PS activated system, utilizing N-doped mesoporous carbon hollow spheres (N-MCHS; size ∼385 nm) as a catalyst. The selection of this catalyst was motivated by its desired physicochemical characteristics such as high dispersibility, uniformly distributed pores and high specific surface area (1109 m2 g−1) for catalytic application. The removal performance was studied by degrading bisphenol A at very low PS (0.25 mM) and catalyst (10.0 mg L−1) concentrations. Through this study, we established a correlation between the surface charge of N-MCHS and PS interaction on the catalytic performance. Further, electron spin resonance (ESR) and radical scavenger studies were carryout out to prove the nonradical oxidation process. Electrochemical studies provided a strong evidence for PS complexation and electron transfer during oxidative removal of bisphenol A. Additional studies with different phenolics and antibiotics demonstrated that N-doping significantly accelerates the degradation rate and enhances the removal efficiency. The results of present study unveil the potential use of PS+N-MCHS in the degradation of different organic contaminants at low catalyst dosages.

Development of dissolved organic matter-based indicators to understand the degradation of organic contaminants in reverse osmosis concentrate from potable reuse systems

Reverse osmosis (RO)-based treatment of municipal wastewater effluent allows for potable reuse, but this process generates reverse osmosis concentrate (ROC) that needs further treatment before disposal. This study investigated the application of UV-based advanced oxidation processes (AOPs) to degrade nine contaminants of emerging concern (CECs) from real ROC waste streams, using UV-only and UV-AOPs with hydrogen peroxide, free chlorine, and persulfate. Dissolved organic matter (DOM) in ROC was characterized using fluorescence excitation emission matrix data and analyzed by a four-component parallel factor (PARAFAC) analysis model. UV-only treatment showed considerable removal of CECs that displayed high values of quantum yields and molar absorption coefficients. UV-AOP treatment of ROC exhibited heavy scavenging of reactive species during CEC degradation. A probe-based approach established that hydroxyl radical was the dominant reactive species in all UV-AOPs. A kinetic analysis of PARAFAC components of DOM showed that the visible humic-like and protein-like components exhibited the higher reaction kinetics compared to UV humic-like and nutrient-like components. The strong linear correlation of protein-like component and seven of the nine CECs across multiple AOPs indicated that they have similar reactivity, enabling the establishment of chemical-reactivity based surrogates for prediction CEC fate in ROC wastes.

Insight into heterogeneous photo-Fenton degradation of naphthol by natural magnetite: Redundancy analysis and toxicity assessment

Magnetite is a ubiquitous iron mineral in nature and its iron ions are usually isomorphically substituted by Ti and V cations, which shows a high ability for degradation of organic contaminants via the photo-Fenton process. However, numerous reports pay more attention to the activity of synthetic magnetite rather than natural magnetite. Here, three types of natural magnetite (HG01, HG02, and GCL01) with different Ti and V contents were investigated from the perspective of the difference in structural property, catalytic activity, H2O2 decomposition, and reactive oxygen species generation. Structural characterization exhibited that the purity of natural magnetite obeyed the order: GCL01 > HG02 > HG01. HG01 contained the highest Ti content in the form of ilmenite, followed by HG02 and GCL01. Moreover, HG01 yielded the highest photo-Fenton catalytic activity with 99.5 % of naphthol degradation and 96.0 % of H2O2 decomposition after 60 min reaction. The superior activity of HG01 was attributed to the relatively high Ti and V content as demonstrated by redundancy analysis. Mechanistic investigation implied that the Ti and V in the octahedral sites of the magnetite surface can accelerate the electron transfer from Fe(III) to Fe(II), resulting in higher Fenton activity. Besides, ilmenite in HG01 enhanced naphthol degradation because H2O2 accelerated the separation of photoelectron-holes pairs to promote O2− production. Furthermore, as revealed by gas chromatography-mass spectrometry and the toxicity of identified products predicted by the ECOSAR model, the toxicity of naphthol can effectively reduce accompanied by the harmless products generated. The high reusability, low iron ions residual in water, harmless end products, and easily recycled with magnetic separation suggest that natural magnetite has a promising application prospect for wastewater purification.

An innovative method for predicting oxidation reaction rate constants by extracting vital information of organic contaminants (OCs) based on diverse molecular representations

The reaction rate constant (k) of oxidants with organic contaminants (OCs) is an important parameter to assess the efficiency of oxidants in removing contaminants. In this study, the degradation of OCs in three oxidation systems was evaluated. The modeling process applied three molecule representations (molecular descriptors (MD), quantum chemical descriptors (QCD) and MACCS fingerprints) and their variable integrations. Models based on integration molecule representations show significant performance improvements. Eventually, the optimal models for ozone, chlorine dioxide and hypochlorite were found to be (MD+QCD)-XGBoost (R2tra = 0.982, Q2tra = 0.715), (MD+QCD+MACCS)-XGBoost (R2tra = 0.982, Q2tra = 0.778), and (MD+QCD+MACCS)-CatBoost (R2tra = 0.856, Q2tra = 0.709) model, respectively. Here, we introduced a new perspective that differed from focusing on machine learning (ML) algorithm optimization. This perspective centered on the input variables (i.e., molecular representations) of models to improve model performance by capturing the key properties of OCs comprehensively. Furthermore, the key effects of pH, ionization potential, orbital energy, polarizability and electronegativity on the oxidation reaction in different oxidation systems were clarified. We hope that the mechanism explanation in this study can provide valuable insights for understanding the mechanism of various oxidation reactions of complex OCs.

Experimental and numerical investigation on the effect of frequency combinations on PFOA defluorination by dual-frequency ultrasound coupling persulfate

Due to the synergistic contribution, dual-frequency ultrasound can significantly enhance the degradation of organic contaminants, but the effects of different frequency combinations have not been clarified and need to be explored. In this study, several frequency combinations were designed firstly both in experimental exploration and numerical simulation within the dual-frequency ultrasound coupling persulfate (PS) system to investigate the effect of frequency combinations on the degradation of perfluorooctanoic acid (PFOA). The monitoring parameters included the defluorination percentage and the simulated maximum expansion ratio (Rmax/R0). The simulated maximum expansion ratios in different frequency combinations showed a high correlation with their defluorination results, indicating that the discrepancy in defluorination effects of different frequency combinations was mostly attributed to their various maximum expansion ratios. Additionally, various maximum expansion ratios could result in different maximum solution temperatures, and the increase in temperature was found positive for PFOA defluorination in this study. In addition, the synergistic parameters that affected the maximum expansion ratio were analyzed, including the phase difference, frequency ratio, and frequency value. The obtained results showed that the maximum expansion ratio varied with different phase differences, and the frequency ratio could affect the variation trend. For the same fundamental frequency, the larger the frequency ratio, the smaller the maximum expansion ratio. Under the same phase difference and frequency ratio, the larger the frequency value, the lower the cavitation.

MnCo/N-C composite nanomaterials derived from MOFs as peroxymonosulfate activators for highly efficient removal of dyes

Fenton-like technology is an eco-friendly and efficient method to degrade organic contaminants. Herein, a bimetallic catalyst with high catalytic activity was obtained by anchoring Co and Mn on N-doped carbon materials (MnCo/N-C) through a one-step pyrolysis process. Peroxymonosulfate (PMS) was activated by cobalt nanoparticles, nitrogen-coordinated metal atoms, and defect sites in MnCo/N-C to produce several reactive species, including SO4•–, 1O2, O2•–, and •OH. The catalyst showed high activity and excellent stability during the catalytic processes. The degradation of 50 mL of rhodamine B solution with a concentration of 0.03 g/L was almost completed in only five minutes by using 0.1 g/L of the catalyst and 0.2 g/L of PMS. Furthermore, the catalyst could be used over a wide pH range of 3–11. Overall, this work provides a simple approach to preparing a more effective and long-lasting Fenton-like catalyst for the degradation of organic contaminants.

Interfacial complexation between Fe3+ and Bi2MoO6 promote efficient persulfate activation via Fe3+/Fe2+ cycle for organic contaminates degradation upon visible light irradiation

To address the observed decrease in efficiency during Fe2+-mediated persulfate (PDS) activation caused by slow electron transfer rates and challenges in cycling between Fe3+/Fe2+ states, we devised a strategy to establish interfacial complexation between Fe3+ and Bi2MoO6 in the presence of PDS. The proposed approach facilitates more efficient capture of photogenerated electrons, thereby accelerating the rate-limiting reduction process of the Fe3+/Fe2+ cycle under visible light irradiation and promoting PDS activation. The Bi2MoO6/Fe3+/PDS/Vis system demonstrates complete degradation of organic pollutants, including Atrazine (ATZ), carbamazepine (CBZ), bisphenol A (BPA), and 2,4-dichlorophenol (DCP) at a concentration of 10 mg/L within a rapid reaction time of 30 min. Radical scavenging experiments and electron paramagnetic resonance spectra (EPR) confirm that the sulfate radical (•SO4−) is the dominant species responsible for organic contaminant degradation. The real-time conversion process between Fe3+ and Fe2+ was monitored by observing changes in iron species forms and concentrations within the reaction system. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy verify the formation of a complexation between Fe3+ and Bi2MoO6, facilitating anchoring of Fe3+ onto material surface. Based on these findings, we propose a reliable mechanism for the activation reaction. This work presents a promising heterogeneous PDS activation method based on Fe3+/Fe2+ cycle for water treatment.

Photocatalytic-based Titanium Dioxide and Its Application in Reducing Organic Pollutant of River Water

The Indonesian region of Sumatra has many rivers, and several of them are currently polluted by household and industrial wastes. Due to this, the river water looks cloudy and not clear. An easy method is needed to reduce the impact of this organic waste pollution. Photocatalysts are known for their ability to destroy organic pollutants which are environmentally friendly, cheap, and have the potential to be widely developed on a large scale. The principal mechanism of photocatalyst are generating the hydroxyl radicals (OH), which act as strong oxidants to mineralize organic contaminants. These principal photocatalyst mechanism includes the generation of hydroxyl radicals (OH), which act as strong oxidants to mineralize organic contaminants. A handy sprayimmobilization method of TiO2 powders on the solid plastic buffer has been utilized in a destroying effluent system. The photocatalytic activity of the TiO2-immobilized transparent plastic were evaluated by the degradation of organic contaminant under sunlight irradiation. The titania catalyst have the most potential destroying impact of about 98% after 10 days of sun irradiation. This investigation proved the potential of titanium oxide in handling organic waste in rivers.
 Keywords: titanium dioxide, photocatalytic, water treatment, river

Properties of Natural Rubber: Magnetite Decorated with Silver Nanoparticles for Catalytic Degradation of Model Organic Contaminant

Properties of Natural Rubber: Magnetite Decorated with Silver Nanoparticles for Catalytic Degradation of Model Organic Contaminant

Highly efficient elimination of organic contaminants by boron-doped biochar modified dual-cathode electro-Fenton system

Electro-Fenton (EF) process stands out as an energy-efficient and highly promising advanced oxidation technology for organic contaminants degradation. However, achieving optimal heterogeneous catalytic conditions for simultaneous H2O2 generation and spontaneous Fe2+ regeneration poses difficulties in conventional EF. This is due to the electric potential difference between H2O2 generation and Fe2+ regeneration at a single cathode. Therefore, the boron doped biochar modified dual-cathode EF (DCEF) system was designed in this work to overcome the defect of conventional EF system, which not only demonstrated outstanding accumulation of H2O2 (>300 mg L-1) but also exhibited a remarkable capability of degradation (>90 %). Furthermore, the system could also adapt to a broad pH range of 3–11. The superior doxycycline (DOX) degradation efficiency of DCEF system could be attributed to the dominant role played by C=O and BCO2 groups in the activation of H2O2 and subsequently generating reactive oxygen species (ROSs), as revealed by XPS analysis and DFT calculation. In addition, the DCEF system achieved an impressive TOC removal efficiency of 70.5 % and a minimal energy consumption (EC) of 0.32 kWh (g TOC)-1. Therefore, this work introduced a DCEF system to address the challenges of conventional EF system, which shed light on the design of wastewater treatment technology and lied the groundwork for a strategy of resource utilization.

Visible-light-induced photocatalytic degradation of organic contaminants by Silver(I)-loaded N-rich porous organic polymers

Heterogeneous photocatalysts with high activity and reactive free radicals can be used to effectively remove water pollutants in harsh environments, which have attracted considerable attention in the environment chemistry. Here, we designed two conjugated organic porous polymers POPs 1-2 with high redox activity and potential π-electron delocalization. Upon combination with silver(I) nitride salt in solution, two metal-anchoring polymeric catalysts POPs 3-4 were successfully constructed, which possessed a strong electron donating ability as well as a high coplanarity and photoelectron properties. Through the loading of AgNO3, the carrier separation ability was effectively improved and the photocatalytic activity of POPs 3-4 was enhanced because of the surface plasmon resonance (SPR) effect of Ag localized at the polymer surface. The photocatalytic results demonstrated that POPs 3-4 could degrade RhB, MO and TC under visible light irradiation. The photodegradation efficiency reached 82.9% for RhB, 28.6% for Mo and 56.6% for TC with the presence of POP-3, and 76.3% for RhB, 51.1% for Mo and 37.7% for TC with the presence of POP-4, respectively. Furthermore, two porous polymer catalysts showed an excellent reusability in heterogenous conditions, the performance results show that the cycle degradation efficiency has been consistently maintained at over 90%. This demonstrates the robust and reliable performance of the material under repeated test conditions. A plausible photocatalytic mechanism triggered by ROS was proposed for the degradation of organic contaminant. This work on silver(I)-anchored porous organic polymers provided a possibility for development of the highly effective photocatalyst materials towards organic pollutants photodegradation under mild conditions.

Enhanced hydrogen peroxide production and organic substrates degradation using atomically dispersed antimony P-doped carbon nitride photocatalysts

In this work atomically dispersed antimony P-doped carbon nitride was prepared with the aim of producing hydrogen peroxide under visible light irradiation and of obtaining organic contaminants degradation. The conjugation of the P-doping can induce significant increase in visible light harvesting, narrowing of band gap energy and shift of the upper edge of the VB to less positive value and the introduction of Sb can efficiently trap oxygen molecules in the Sb-OO end-on structure and at the same time accumulate electrons which act as the photoreduction sites for O2 via a 2e− ORR pathway. Pristine C3N4 and P-doped C3N4 were prepared as references using melamine and ammonium dihydrogen phosphate as precursors and different amount of Sb were added (x = 0.5, 1, 3, 5 mmol) to synthetize Sbx P-doped C3N4. All materials were characterized with multiple techniques, tested for the hydrogen peroxide production and for the degradation of carbamazepine. The pristine C3N4 led to a H2O2 poor production but with the introduced modifications the yield increased and an upward trend during the time was observed. The optimum amount of Sb was found to be 1 mmol and it led to the production of more than 7 times the amount produced by pristine carbon nitride. The degradation of carbamazepine using only visible radiation required prolonged timescales but when we expand the light spectrum to include near-UV, the abatement of the pollutant is achieved in a few hours. The efficiency of the synthesized materials in hydrogen peroxide production suggests possible future developments that take advantage of the excellent peroxide production of atomically dispersed antimony P-doped carbon nitride photocatalysts in Fenton-like processes or involve the use of peroxidase enzymes to achieve enhanced degradative performances.