Degradation Rate Research Articles

Alkali-decorated carbon nitride enhances the removal of enrofloxacin by ferrihydrite-H2O2 system: Mechanistic insights and degradation pathways

Antibiotic pollution affects water quality. Based on the ferrihydrite-H2O2 (Fh-H2O2) photo-Fenton system, alkali-decorated carbon nitride was introduced, and KC3N4/Fh, with ·OH and ·O2− as the primary reactive oxygen species, was synthesized for the degradation of veterinary antibiotic enrofloxacin in water. The modification with KOH induced the formation of cyano groups and nitrogen vacancies in KC3N4/Fh. The presence of cyano groups altered the original charge distribution and energy band structure of the material, thereby establishing an internal electric field. Directed driving of nitrogen vacancies accelerated the transfer of photogenerated charges from the conduction band of KC3N4 to the surface of Fh, facilitating the cycle process of Fe(III) and Fe(II). Meanwhile, the nitrogen vacancies significantly enhanced the adsorption capacity of KC3N4/Fh for H2O2 and accelerated the reaction between the generated Fe(II) and H2O2 to produce ·OH, which subsequently led to the efficient degradation and mineralization of enrofloxacin. The results demonstrated that the degradation rate of enrofloxacin by KC3N4/Fh reached 95.96 % within 30 min, highlighting its high efficiency and stability. Furthermore, KC3N4/Fh exhibited effective degradation of actual effluent under sunlight. This work proposes a novel approach to creating a Fh-H2O2-based photo-Fenton system for the efficient antibiotic degradation.

In-situ electrogenerated persulfate activated by co-existing Cu(II) for sustainable removal of sulfonamides from environmental waters

In this study, in-situ electrogenerated persulfate (E-PS) was proposed as an alternative to the conventional addition of persulfate for advanced oxidation processes (AOPs) with facilitating conversion of co-existing Cu(II) to Cu(I) to degrade antibiotics without requiring any external supply of chemical additives. The degradation rate of sulfamethoxazole (SMX) by E/Cu(Ⅱ)/Na2SO4 system (C0(Cu(Ⅱ))=1mM, C0(Na2SO4)=1mM, E=25V) was 93.3% at t=90min. Quenching combined with electron paramagnetic resonance (EPR) tests revealed that SO4•-, •OH and Cu(Ⅲ) were the primary contributors to SMX degradation. Solution pH, co-existing anions and organic matter affected the degradation performance of SMX. Four degradation pathways were proposed based on transformed products (TPs) determination, with pathways I and II being the dominant ones involving the cleavage of S-N bond in SMX. Ecological structure activity relationships (ECOSAR) program analysis implied that the TPs exhibited lower toxicity levels toward aquatic organisms compared to that of SMX. Additionally, the E/Cu(II)/Na2SO4 system achieved decomposition rates over 80% for various sulfonamides (SAs) and also demonstrated remarkable efficacy for SMX removal in different real waters, including tap water, lake water, river water and aquaculture wastewater, with all exceeding 80% at t=90min. E/Cu(Ⅱ)/Na2SO4 system developed in this study had the potential to be a prospective technique for SAs purification due to its outstanding performance in degrading and detoxifying SAs.

MoS2–CdS Composite Photocatalyst for Dye Degradation: Enhanced Apparent Quantum Yield and Reduced Energy Consumption

AbstractThis study investigates the visible light‐assisted photocatalytic degradation of rhodamine B (Rh B) dye using MoS2–CdS nanocomposite. Two crucial operational parameters, illumination time and the weight ratio of MoS2 to CdS, are systematically examined. Approximately, 91.9% of Rh B solution with a concentration of 10 mg/L is degraded by the MoS2–CdS photocatalyst under 60 min of illumination, with a photocatalyst dosage of 0.5 g/L. The results are consistent with a pseudo‐first‐order kinetic model, wherein the degradation rate constant of CdS increases fourfold after amalgamation with MoS2. The formation of the composite with MoS2 results in 1.72 times increase in the apparent quantum yield and 3.15 times decrease in the electrical energy consumption per order of CdS nanorods under similar experimental conditions. The investigation also comprehensively explores the reactive species responsible for Rh B degradation under visible light in the presence of MoS2–CdS photocatalyst. This analysis confirms that both hydroxyl and superoxide anion radicals play a dominant role in Rh B degradation. These findings underscore the potential practical applications of MoS2–CdS nanorods in eco‐friendly water treatment technologies, offering efficient and sustainable solutions to contemporary environmental challenges.

Fermi energy level synergistic Bi-based electron bridge construction of Z-type heterojunctions to accelerated photogenerated charge transfer for photostability and contaminant mineralization

Advanced oxidation technologies offer new opportunities for pollutant degradation. Despite the existence of numerous photocatalyst heterojunctions for advanced oxidation, their charge transfer and separation efficiency is low due to inadequate interfacial modulation, especially for Type II heterojunctions. Here, through metal reduction, metal defects with regulating the Fermi level and metal electron bridges with facilitate the separation of photo-generated carriers, facilitating the transition from Type II to Z-type heterojunctions. Herein, we designed a Z-Scheme photocatalyst with Bi-based electron bridges (referred to as ‘fishbone-like’ BiVO4/Bi/CuO) synthesized through in situ reduction, utilized for RhB degradation. Under visible light irradiation, the degradation rate of RhB up to 99 % within 120 min, outperforming most previously reported photocatalysts. Notably, the well-designed BiVO4/Bi/CuO exhibits as reaction rate of 4.13 × 10-2 ·min−1, which is 18 times higher than the pure BiVO4. The BiVO4/Bi/CuO photocatalyst demonstrates exceptional stability over 6 reaction cycles spanning 15 h, due to strengthened contact interface of BiVO4/Bi/CuO. The metal Bi can induce the surface plasmon resonance (SPR) effect, enhancing light absorption. Furthermore, Bi-based electron bridges significantly promote the charge transfer across the Z-type heterojunction interface, which were verified by assorted experimental outcomes and density functional theory (DFT) calculations. This work represents a promising platform for the development of highly efficient and stable photocatalysts that have potential in Pollutant degradation applications.

Screening of bile salt hydrolase-producing lactic acid bacteria and evaluation of cholesterol-lowering activity in vitro

Hypercholesterolemia is a great threat to humans. Bile salt hydrolase (BSH)-producing lactic acid bacteria (LAB) may alleviate it, but current screening methods are inadequate. This study aims to establish a more comprehensive and reliable in vitro method to screen BSH-producing LAB with greater potential for anti-hypercholesterolemia. Forty-one LAB were initially isolated from infant feces and 37 strains could produce BSH. Strains with BSH over 2 U/mg for sodium glycodeoxycholate and sodium taurodeoxycholate were used to analyse cholesterol degradation rate, hydrophobicity, self-aggregation, gastric fluid tolerance, and intestinal fluid tolerance. Based on the results of these indicators, Lactococcus lactis Y17, L. rhamnosus Q2, and L. fermentum Q11 with the top scores were considered anti-hypercholesterolemia candidates using a principal component analysis evaluation. Antioxidant and Caco-2 adhesion assays showed that these three strains exhibited excellent antioxidant ability and Caco-2 adhesion ability. Their total antioxidant capacity was above 0.99 μmol/L, while the Caco-2 adhesion rate was higher than 8.22%. Safety assessments, via antibiotic susceptibility and hemolysis tests, confirmed their safety. In the HepG2 cells assay, the TC content of the Y17, Q2, and Q11 groups was reduced by 0.525 mmol/L, 0.426 mmol/L, and 0.581 mmol/L, which verified the potential of the three LAB in anti-hypercholesterolemia. In addition, they could enhance cholesterol uptake and bile acid synthesis in HepG2 cells by upregulating the mRNA expression of bile acid synthase (CYP7A1 and CYP8B1) and cholesterol uptake receptors (NPC1L1 and LDLR). The results showed that the three LAB could be developed into anti-hypercholesterolemia foods with beneficial properties.

Facile fabrication of BiOI/ZIF-67 Z-scheme heterojunction photocatalyst for visible-light-driven tetracycline degradation

In this paper, a novel Z-scheme BiOI/ZIF-67 photocatalyst (BOI/ZIF) was successfully prepared using an in-situ growth method, and its effectiveness in degrading tetracycline (TC) under visible light was assessed. Using a range of characterization techniques, the crystal structure, elemental composition, microstructure and optical characteristics of the composite catalyst were examined. Simultaneously, a 30% mass ratio catalyst (BOI/ZIF-30) could remove 91% of TC under visible light, which was 41% and 28% greater than the degradation rates of BiOI and ZIF-67, respectively. These results demonstrated that BOI/ZIF exhibited strong photocatalytic activity and excellent stability. The results of the radical quenching experiment and electron spin resonance revealed that h+ and •O2− were the principal chemical substances responsible for TC degradation, corresponding with the suggested charge transfer mechanism of Z-scheme heterojunction. The Z-scheme heterojunction created between BiOI and ZIF-67 improved the effective separation of photogenerated carriers and boosted the efficiency of TC degradation. This study offers a promising method for designing photocatalytic systems to break down antimicrobial contaminants.

Novel 3D plate-like g-C3N4/BiOCl heterojunction as a highly efficient photocatalyst for the degradation of carbofuran in wastewater under visible light irradiation

The g-C3N4/BiOCl (gCN-BCl) heterojunction photocatalyst was synthesized using a low-temperature precipitation method for effective photocatalytic degradation of carbofuran (CBF). All gCN-BCl composites demonstrate greater efficacy in removing CBF compared to its individual constituents. The synergistic effect of incorporating the 0D structured BiOCl onto the 2D structured g-C3N4 was comprehensively examined using various microscopic, X-ray, and spectroscopic analytical techniques. Additionally, optical and photoelectrochemical analyses were conducted. The findings validated that the interaction between the two semiconductors at the heterointerfaces enhanced remarkable physical and structural stability, promoted high charge separation and transfer properties, and improved photocatalytic degradation. Under optimal conditions, 5-gCN-BCl (0.25 g/L) achieved a CBF (5 mg/L) removal efficiency of 95.7 % under visible light irradiation of 120 min, achieving 3.1- and 5.9-times higher degradation rate than the pure BiOCl and g-C3N4, respectively. The radical trapping experiments indicated that the h+ and •O2− were the primary reactive species involved in the CBF degradation. Furthermore, the potential toxicity of CBF and its intermediates was assessed, revealing that the photocatalytic degradation process significantly lowered the ecotoxicity of pesticide wastewater. The potency of 5-gCN-BCl was also evaluated in tap water and real wastewater samples, with CBF degradation efficiencies of 85.8 %, 47.6 %, and 38.7 % in tap water, municipal, and pesticide industry wastewater, respectively. Additionally, artificial neural network (ANN) modeling was employed to predict and optimize the photocatalytic degradation process, providing further insights into the system’s performance. The outcomes of this work offer valuable insights into the development of heterojunction photocatalysts with superior stability and efficacy for eliminating pesticides from water bodies.

Mechanistic insights into the roles of copper in enhanced peroxymonosulfate activation for tetracycline degradation by copper ferrite composite catalyst

Tetracycline (TC) pollution has attracted great attention due to its wide use, non-biodegradability and potential carcinogenicity. Bimetallic catalysts/peroxymonosulfate (PMS) systems have been considered as powerful technologies for TC degradation. Although the excellent catalytic activity of copper ferrite (CuFe2O4) composite oxides for PMS has been already elucidated, the roles of increased Cu in the degradation especially from non-radical pathways are not clarified clearly. In this study, we prepared a series of CuO/CuFe2O4/Fe2O3 (CCF) catalysts to confirm the key role of molar ratios of Cu: Fe (ranging from 1:2 to 2:1) in the enhanced degradation. The optimized CCF-3 catalyst with the Cu: Fe molar ratio of 2:1 showed the best degradation efficiency up to 95.6 % and the fastest apparent degradation rate of 0.135 min−1 towards TC. In addition, the CCF-3/PMS system showed excellent adaptability and good stability in TC degradation. Importantly, a novel molecular-scale mechanism was proposed. Both radical (SO4∙-, ∙OH, O2∙ –) and non-radical (1O2, direct electron transfer) pathways were associated with the CCF-3/PMS catalytic system, where 1O2 played the dominant roles. The increased Cu significantly boosted the non-radical pathways via promoting the formation of oxygen vacancies (Ov) and its further conversion to 1O2, and facilitating electron transfer between bimetallic Cu/Fe interface. This work provides a deep insight into the formation and reaction mechanisms of non-radical species for CCF/PMS systems, and a novel foundation for the design of CuFe2O4 composite catalysts

A multifunctional coconut shell biochar modified by titanium dioxide for heavy metal removal in water/soil and tetracycline degradation

Heavy metals and tetracycline pollute the environment and endanger human health. This work prepared a multifunctional coconut shell biochar (Ti-XBC) through NaHCO3 activation and TiO2 modification. The modified coconut shell biochar was characterized by various methods. Ti-4BC exhibited excellent removal performance for heavy metals. The maximum adsorption capacity of Ti-4BC on Cd2+, Pb2+, Cr3+, and Cr6+ reached 104.2, 136.8, 101.2, 112.4 mg/g in water. The adsorption of Ti-4BC for four metal ions had a competitive effect in the binary metal system. It also reduced the mobility of four heavy metal ions in soil. Density functional theory (DFT) calculations were employed to explain the mechanism of heavy metal removal. Additionally, the degradation performance and mechanism of Ti-4BC towards tetracycline were investigated. The results indicated that the maximum degradation rate was 99.4%. Overall, this work developed a multifunctional material capable of both removing heavy metals and degrading antibiotics, addressing the issue of single-function in biochar. This provided a novel approach for tackling complex and diverse environmental pollution scenarios.

Photocatalytic Degradation of Ciprofloxacin HCl using Visible Active BiOS Photocatalyst and Artificial radiation

Ciprofloxacin, a potent biologically active substance, has caused significant environmental issues when present in natural waters. The current study aimed to investigate the visible lightinduced degradation of ciprofloxacin HCl (CFX) using bismuth oxysulfide (BiOS) as a photocatalyst. A new photocatalyst BiOS has been developed and tested for the photocatalytic degradation (PCD) of pharmaceutical pollutants in wastewater using artificial radiation. Specifically, this novel material was examined for its ability to degrade ciprofloxacin HCl (CFX). A nanocomposite of BiOS photocatalyst has been synthesized utilizing the sol-gel method and subsequently characterized using UV-DRS, SEM, and EDAX techniques. A tungsten lamp was utilized to simulate artificial radiation during the PCD of CFX. Based on studies on the ideal operating conditions for the BiOS photocatalyst, the maximum rate of photocatalytic degradation (PCD) was reached at a neutral pH of 7. When compared to a saltfree environment, the rate of PCD was observed to be increased by anionic salts (NaCl, Na2CO3, and (NH4)2SO4). The Cland CO3- ions have notably increased the rate of PCD than SO4- ions. According to Langmuir-Hinshelwood kinetic modeling, the PCD of CFX exhibits a pseudo-first-order reaction behavior. Therefore, it can be said that BiOS is a suitable photocatalyst for treating wastewater from pharmaceutical plants.

Evaluation of Blended Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Properties Containing Various 3HHx Monomers.

Polyhydroxyalkanoate (PHA), specifically poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx), PHBHHx) with physical properties governed by the 3-hydroxyhexanoate (3HHx) mole fraction, is a promising bioplastic. Although engineered strains used to produce P(3HB-co-3HHx) with various 3HHx mole contents and fermentation techniques have been studied, mass production with specific 3HHx fractions and monomers depends on the batch, supply of substrates, and strains, resulting in the time-consuming development of strains and complex culture conditions for P(3HB-co-3HHx). To overcome these limitations, we blended poly(3-hydroxybutyrate) [(P(3HB), produced from C. necator H16] and P(3HB-co-20 mol%3HHx) [from C. necator 2668/pCB81] to prepare films with various 3HHx contents. We evaluated the molecular weight and physical, thermal, and mechanical properties of these films and confirmed the influence of the 3HHx monomer content on the mechanical and thermal properties as well as degradability of the blended P(3HB-co-3HHx) films containing various 3HHx mole fractions, similar to that of original microbial-based P(3HB-co-3HHx). Moreover, the degradation rate analyzed via Microbulbifer sp. was >76% at all blending ratios within 2 days, whereas a weaker effect of the 3HHx mole fraction of the blended polymer on degradation was observed. P(3HB-co-3HHx) could be produced via simple blending using abundantly produced P(3HB) and P(3HB-co-20 mol%HHx), and the resulting copolymer is applicable as a biodegradable plastic.

Engineering Ag-Modified BiOCl as an Efficient and Effective Catalyst for Solar Light-Driven Organic Pollutant Degradation and Hydrogen Production.

The direct conversion of solar energy into clean fuels has emerged as an effective approach for future energy production and addressing environmental challenges. This research focuses on the synthesis of BiOCl using a straightforward hydrothermal method with Ag modification achieved through green synthesis. These materials were applied to enhance photocatalytic processes and hydrogen (H2) evolution. Comprehensive characterization of the synthesized photocatalysts was performed by using techniques, such as XRD, SEM, BET, XPS, and UV-vis spectroscopy. The Ag/BiOCl composite demonstrated impressive photocatalytic performance, achieving degradation rates of 96% for RhB, 87.7% for TC, and 85% for HQ under 18 min of solar irradiation. Additionally, a high mineralization rate of 92% was observed through Total Organic Carbon (TOC) analysis. Furthermore, the Ag/BiOCl composite exhibited a significant H2 evolution rate of 565 μmol g-1 h-1, which is nearly double that of pure BiOCl. The interaction between Ag and BiOCl was found to enhance the generation of O2- radicals, as confirmed by radical trapping experiments, with the underlying mechanism elucidated using LC-HRMS. The nanoparticles also demonstrated excellent degradation of industrial waste, highlighting the potential of Ag/BiOCl for use in the purification and sterilization of industrial effluents.

Quantitative Effects of Ecuadorian Silicon-Aluminum Materials on the Degradation Rate and Mechanical Strength Enhancement of Recycled Polyethylene

This study presents an innovation in the use of a native Ecuadorian nanoporous material known as allophane for the reprocessing of greenhouse plastics to obtain a functional polymer that allows for reuse, improving its mechanical properties and/or increasing its lifespan. By achieving this objective, three problems are simultaneously addressed: 1) the need to recycle used plastics in a prominent Ecuadorian flower company committed to environmental preservation, 2) the scientific viability work carried out by the Central University of Ecuador, and 3) the industrial application of recycled plastics and pellet production. Blown film extrusion was used to prepare low-density polyethylene sheets with different amounts of Ecuadorian allophane microparticles (30±5 micrometers) (0.1%, 0.3%, and 0.5% by weight). Mechanical property studies were conducted following ASTM D 882 standards, and thermal stability was characterized using thermogravimetry. The results showed an increase in elongation at break and Young's modulus percentages as the concentration of the additive increased, demonstrating its physical-chemical compatibility. Additionally, the effect on the polymer’s thermal degradation was analyzed, resulting in a directly proportional relationship between activation energy and the concentration of the material. Finally, these results demonstrate that allophane as an additive enhances the mechanical properties of recycled low-density polyethylene (12-36%) and accelerates its thermal degradation process, reducing environmental impact.

An active and durable perovskite electrode with reversibly phase transition-induced exsolution for protonic ceramic cells

Protonic ceramic cells (PCCs) possess great application potential, attributed to their cleanliness and high energy conversion efficiency. However, designing active air electrodes with both high stability is challenging. Herein, we report a nanospinel-modified perovskite oxide, Nd0.5Ba0.5Mn0.7Co0.15Ni0.15O3−δ-(CoxNiy)3O4 (CNO@NBMCN), obtained by a reversibly phase transition-induced exsolution process, as a highly active and durable air electrode for PCCs. Phase-field simulations reveal the intrinsic mechanism of nanoparticles strongly pinning to the substrate in a high-temperature oxidizing environment. The CNO@NBMCN electrode exhibits remarkable low area specific resistance (0.38 Ω cm2 at 600 °C) and exceptional stability (degradation rate 0.01 % h−1). It is confirmed by soft X-ray absorption spectroscopy that the construction of the heterostructure leads to more distortion in Mn–O octahedra and weaker metal–oxygen bonds, thereby contributing to the formation of oxygen vacancies. And the exceptionally high durability supported by both fast ion surface exchange and charge transfer at triple-phase boundaries. A single cell with the CNO@NBMCN air electrode achieves outstanding performances in the fuel cell (peak power density of 1.28 W cm−2) and electrolysis modes (current density of −2.14 A cm−2 at 1.3 V), recorded at 700 °C. This work inspires innovative design concepts for robust heterogeneous electrocatalysts.

Congruent Long-Term Declines in Carbon and Biodiversity Are a Signature of Forest Degradation.

Recent global policy initiatives aimed at reducing forest degradation require practical definitions of degradation that are readily monitored. However, consistent approaches for monitoring forest degradation over the long term and at broad scales are lacking. We quantified the long-term effects of intensive wood harvest on above-ground carbon and biodiversity at fine resolutions (30 m2) and broad scales (New Brunswick, Canada; 72,908 km2). Model predictions for above-ground biomass were highly correlated with independent data (r = 0.77). After accounting for carbon stored in wood products, net CO2 emissions from forests for the region from 1985 to 2020 were 141 CO2e Tg (4.02 TgCO2e year-1; 32% of all reported emissions). We found strong positive correlations between locations with declines in above-ground carbon and habitats for old-forest bird species, which have lost > 20% habitat over 35 years. High congruence between biodiversity and forest carbon offers potential for policy incentives to conserve both objectives simultaneously and slow rates of forest degradation. These methods could be used to track forest degradation for managed forest regions worldwide.

Efficient Degradation of Methyl Violet 10B Dye by Different Light Sources using Boron-doped TiO2-ZnO Photocatalyst

Boron-doped TiO2-ZnO nanocomposite was prepared by sonochemically using boron trichloride, tetra n-butyl orthotitanate and zinc acetate in appropriate proportion. The as-prepared nanocomposite was successfully characterized by XRD, EDX, SEM and BET techniques The operational factors that affect the rate of photocatalytic degradation of methyl violet 10B present in wastewater were optimized, which include initial dye concentration, catalyst amount, pH level and different light intensities such as incandescent light bulb, UV lamp and sunlight. During sonication under sunlight, it was found that the most effective removal rate achieved was 95% when using 0.02 g of B doped TiO2-ZnO per 100 mL of methyl violet 10B solution. The impact of different dye concentrations on the photocatalytic degradation demonstrated the threshold at which concentrations may be readily eliminated. The most effective pollutant degradation was achieved at 5 ppm. The introduction of oxygen using sonophotocatalysis process into the polluted stream enhanced the photocatalytic breakdown of the pollutants. The photocatalyst can be recycled for four cycles without loss the catalyst stability and the degradation rate obeys first-order kinetics.

Effects of manganese and copper co-doped bioactive glasses with photothermal response on osseous cells

Herein, a series of bioactive glasses with a composition based on SiO2Na2OCaO-P2O5-Bi2O3, doped with either manganese (Mn) or copper (Cu), or a combination of both have been developed. The aim was to create a biocompatible, bioactive material with a photothermal (PT) response for potential use in bone cancer treatment. UV/vis/NIR spectroscopy indicated that the addition of Cu to the glass resulted in a broadband absorption of around 800 nm, while Mn showed an absorption band of around 500 nm. Photoluminescence (PL) spectroscopy, which was performed by exciting the specimen using a 750 nm beam, revealed an emission at 823 nm for all glass compositions, but with varying intensities. When exposed to an 808 nm laser (5 W/cm2), the glass samples exhibited temperature rising, with the sample containing both Mn and Cu, showing the highest absorption peak, reaching 204 °C after 5 min. The degradation rate of the glass in a phosphate-buffered saline (PBS) solution was influenced by the presence of Mn and Cu. Cytotoxic assessment on osteoblast-like cells showed that the presence of Mn promoted cell proliferation by over 20 % after 24 h, but when irradiated with an 808 nm laser, the viability of cells decreased by nearly 60 % due to heat ablation. Finally, the glass sample demonstrated in vitro bioactivity through the formation of a hydroxyapatite layer on its surface when immersed in simulated body fluid.

Analysis of degradation mechanism in polycrystalline silicon thin-film transistors under dynamic off-state stress with fast transition time

Abstract This study represents the investigation into the degradation of polycrystalline silicon (poly-Si) thin-film transistors (TFTs) under dynamic off-state stress, with a focus on transition times as rapid as 1 nanosecond (ns). The study found that dynamic off-state stress with larger amplitude leads to more severe device degradation. Unlike previous studies, both the rising time (t r ) and falling time (t f ) of the pulse significantly influence the hot carrier (HC) degradation in the poly-Si TFTs. The on-state current degradation rate (ΔI on ) after 104 s stress dramatically increases from 11.8% to 80.8% when t r decreases from 500 ns to 1 ns. When t f decreases from 500 ns to 1 ns, ΔI on also dramatically increases from 22.9% to 69.2%. Combined with transient simulations, the source of the carrier for HC degradation is clarified and consequently, a non-equilibrium PN junction degradation model modulated by accumulated electrons is developed.

Degradation of Amoxicillin in Water by Fenton, Photo-fenton and Photocatalysis Using Copper Oxide

In recent years, the presence of drug residues in water has become a major environmental issue. Among these pollutants is amoxicillin. Our aim is to propose effective methods for decontaminating wastewater containing amoxicillin. This study was carried out using the chemical oxygen demand method. This work has shown that hydroxyl radicals can effectively degrade amoxicillin. The rate of hydroxyl radical production from hydrogen peroxide and iron (II) ions increases in the presence of sunlight. Amoxicillin oxidation is optimal at a pH of 3 and a [H2O2]/[Fe2+] ratio of 13.33. Amoxicillin degradation is faster at low concentrations than at high concentrations. The oxidation of amoxicillin by photo-Fenton results in degradation rates of up to 99%. A study of the adsorption of amoxicillin on copper oxides showed that amoxicillin adsorbs weakly to the amoxicillin surface, with an adsorption rate of 17%. However, in the presence of amoxicillin, hydrogen peroxide and sunlight, degradation rates of up to 99% were obtained. This work has shown that the degradation of amoxicillin is better with solar photo Fenton and solar photocatalysis in the presence of copper oxide than with the Fenton process.

Sustainable bioconversion of rice straw into indole-3-acetic acid by Streptomyces coelicoflavus using response surface methodology

AbstractRice straw is an abundant agricultural waste that poses environmental disposal challenges and can be utilized for biotechnological applications. This study investigates the potential of actinobacteria to enhance rice straw biodegradation and sustainable indole-3-acetic acid (IAA) production, addressing the need for sustainable agricultural practices. Certain actinobacteria strains can effectively degrade rice straw while optimizing IAA production under controlled fermentation conditions. Twenty actinobacteria isolates were screened for lignocellulolytic enzyme activity, and ten were selected for rice straw biodegradation. IAA production was further optimized using response surface methodology based on temperature, pH, and agitation speed (RPM). Isolate S16 achieved a degradation rate of 68.75%, while S18 produced the highest IAA concentration (1040.625 μg/mL) under optimized conditions (25 °C, pH 9, 160 RPM). The purified IAA significantly improved Medicago sativa L. growth. Furthermore, the 16S rRNA gene sequence of isolate S18 was identified it as Streptomyces coelicoflavus strain NSH24 with accession number PP 320383.1. These findings underscore the potential of actinobacteria to efficiently convert agricultural waste into valuable bioproducts and promote sustainable farming practices. By transforming rice straw into high-value products like IAA, this approach contributes to a circular economy, offering an environmentally friendly solution for biomass utilization and agricultural sustainability.