Photodegradation Process Research Articles

Development of heterogeneous photocatalysis delafossite structured Ag doped Cd-Cu ferrite spinel nanoparticles for an efficient photodegradation process

The photodegradation of sunset yellow dye was efficiently achieved using Ag-Doped Cd-Cu Spinel Nanoferrite as a photocatalyst under ambient circumstances. The method demonstrates economic feasibility, environmental sustainability, non-toxicity, scalability, and the absence of toxic and volatile organic solvents and surfactants. Ag-doped Cd-Cu spinel nanoferrite (Cd0.5Cu0.5-xAgxFe2O4, x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5) was prepared using the green co-precipitation method. X-ray diffraction patterns represented the formation of a major spinel phase and a minor delafossite phase. XPS spectra show the multiple variant valences of the constituted elements (Cu+, Cu2+, Cd2+, Ag+, Fe2+, Fe3+, and Fe4+). The Mossbauer spectroscopy measurements confirmed the stability of the delafossite phase. The HRTEM, SEM, and elemental mapping indicated homogenous elemental distributions inside the samples. The prepared nanoparticles exhibited large specific surface areas between 94 and 161 m2/g, indicating their potential applications in chemical and biological fields. The UV–visible light absorption of these materials suggested the possibility of their use as photocatalysts under visible light irradiation. Various effects, such as pH, the concentration of dye, catalyst dose, and the amount of H2O2, were studied. The photodegradability of Sunset Yellow increases with higher silver doping as well as the majority of the delafossite phase due to the increase in specific surface area. The COD reduction is 71.5 % in optimum conditions. The possible photocatalytic degradation pathway of Sunset Yellow was suggested based on GC–MS analysis. A reaction mechanism involving HO• as an effective oxidant was proposed.

A light-driving magnetic nanocomposite based on Zn/Fe/Cu embedded in HKUST-1 applied for adsorption/degradation of Indigo carmine and pathogens

An environmentally friendly photocatalytic system (type-II heterojunction) is designed and utilized for rapid removal of Indigo carmine (IC) and pathogens from aqueous samples. This photocatalyst contains ZnFe2O4 magnetic NPs, CuO semiconductor, β-cyclodextrin (β-CD) charge transferor, and HKUST-1 light harvester. After the adsorption and photodegradation process, the nanocomposite was separated magnetically, and the supernatant was taken for the UV-Vis analysis. The maximum adsorption and photodegradation efficiency of 94.45% and 97.67% (pH = 5, in 35 min) were obtained under blue LED light (7.0 W) irradiation, due to the calculations based on UV-Vis spectrophotometer results. Simple preparation via a self-assembly route and facile separation through a superparamagnetic behavior (leading to great recovery) can be mentioned as the most brilliant excellence. Moreover, the photocatalytic performance of this magnetic nanocomposite was preserved after five recycle runs without any substantial reduction in photocatalytic activity. Also, employing a biopolymer, affordability, availability of the raw materials, good thermal stability, facile magnetic separation, simple operation, and high efficiency are upsides of the prepared nanocomposite, making it a superior photocatalyst to previous analogous systems. This nanocomposite (formulated as ZnFe2O4-CuO@β-CD)/HKUST-1) also exhibited antibacterial activity against Gram-positive and -negative strains. Based on BET (porosity) evaluations, the nanocomposite has rendered a surface area of 451.52 m2/g, which led to great adsorption results representing first-order and pseudo-second-order (Freundlich isotherm) kinetic models for the degradation and adsorption processes, respectively.

UV-photodegradation of R6G dye in three-phase fluidized bed reactor: Modeling and optimization using adaptive neuro-fuzzy inference system and artificial neural network

The development of an efficient photoreactor is still the most challenging task in the photocatalytic process. The main challenges include the determination of the optimal hydrodynamic conditions required for the efficient photodegradation of biorecalcitrant pollutants. In this study, a TiO2-ZnO/BAC composite catalyst was applied to investigate the hydrodynamic characteristics of a three-phase fluidized bed reactor in the UV-photodegradation of rhodamine 6G dye. Artificial neural network (ANN) and adaptive neuro-fuzzy inference systems (ANFIS) were used for modeling and optimization of the photodegradation process. From the preliminary study, 70° column inclination angle and 0.028 ms−1 superficial gas velocity, showed good axial solid distribution and average gas holdup. Subsequently, 0.019 ms−1 gas flow rate at 70° column inclination angle was found to be the optimum condition for the removal of rhodamine 6G (97.0 %). Moreover, solid distribution was found to be a dominant limiting factor in the photodegradation process as compared to gas holdup. Meanwhile, sensitivity analysis showed that all the input parameters (lamp position, inclination angle, and superficial gas velocity) were above 10%, confirming a strong influence on the process. The ANN-trainlm and ANFIS-hybrid with R-values of 0.9911 and 0.9546, respectively confirmed that the predicted model fits well with the experimental data. Furthermore, the inclination angle of 70° can be important in solar photoreactors to attain a relatively efficient tilt angle when using solar energy.

Construction of a series of Co(II)-based coordination polymers with boosted photocatalytic activity for the removal of dye contaminants

When symmetrical V-shaped rigid multicarboxylic acid, 3,5-di(2′,4′-dicarboxyphenyl)benzoic acid (ddb), was selected, five structurally coordination polymers (CPs) have been prepared, namely {[Co2(ddb)(dip)(NMP)(H2O)]·3H2O}n (1), {[Co2(ddb)(dpb)(H2O)]·NMP}n (2), {[Co2(ddb)(dib)(H2O)]·H2O}n (3), {[Co5(ddb)2(H2O)12]·4H2O}n (4) and {[Co3(ddb)(μ3-OH)(bpy)2]}n (5) (dip = 2,6-di(1H-imidazol-1-yl)pyridine; dib = 1,4-di(1H-imidazol-1-yl)benzene; bpy = 2,2′-bipyridine, dpb = 1,1′-(2,5-dimethyl-1,4-phenylene)bis(1H-imidazole) and NMP = N-Methyl-2-pyrrolidone). It was revealed that the flexible frameworks as well as different types of coordination environment of ddb were induced by the solvents and assistant linkers, single crystal X-ray crystallography, and thermogravimetric analysis (TGA), were used to characterize these coordination polymers. The photocatalytic degradation properties of all the structures are investigated against different dye like such as Rhodamine (RhB), methyl orange (MO), methylene blue (MB), methyl violet (MV). When compared to other dyes, the degradation efficiency of MV by 2 was quite high. Furthermore, a photodegradation process was proposed and investigated by radical tapping experiment. The Hirshfeld surfaces study demonstrated that these synthesized coordination polymers contain various forms of intermolecular contacts (C⋯C, H⋯C, H⋯H, and O⋯H).

Preparation of 3D BiOI microspheres for highly efficient visible light-induced photocatalytic degradation of tetracycline

Semiconductor photocatalysts for pharmaceutical antibiotic wastewater treatment are subject to increasing attention. Herein, BiOI photocatalysts were prepared by a one-step solvothermal method using ethylene glycol (EG) as solvent and their tetracycline (TC) degradation activities under visible light irradiation were compared. Catalyst preparation temperature, time, and pH conditions were optimized, and the catalyst physicochemical properties were characterized. Solution pH was found to have a significant effect on the morphology, electronic structure, and surface exposed facet of BiOI. Catalysts synthesized in the absence of NaOH presented more regular 3D flower-like microspheres, possessed larger surface area, were composed of many small nanosheets predominantly exposing the (001) facet, and showed better photogenerated electron-hole pairs separation efficiency. The optimized BiOI presents superior TC degradation efficiency (73.6%) under visible light irradiation, and recycling experiments indicated that the catalysts have good stability and reusability. The active species were investigated by free radical trapping experiments, revealing that •O2− plays a major role in the photodegradation process. Possible TC degradation pathways are proposed according to mass spectrometry analysis.

Organo‐Pillared‐Clay: Synthesis, Characterization, and Applications for Treatment of Perfluoroalkyl Substances

AbstractAnthropogenic toxic pollutants are ubiquitous and need to be removed from the environment. This study investigates the preparation of an inorganic‐organic modified clay (organo‐pillared‐clay) for the removal of contaminants. The present work investigates the compositional, structural and sorption properties of modified clay materials for the removal of perfluoroheptanoic acid (PFHpA). The chemical compositions of the clay materials used were determined by interlayer and surface analysis. The results showed changes in interlayer spacing and external surface area due to modification and surfactant addition during the cation exchange reaction. The combination of adsorption and irradiation increased removal efficiency, although photodegradation was partially inhibited. Modified clays show promise for PFHpA remediation, with potential for optimizing photodegradation processes.

An extensive exploration of non-conventional sources for preparing NiS and its potential applications in battery and photodegradation processes

In this study, we explore the synthesis of transition metal sulphide nanoparticles, focusing on the effects of different fabrication methods on their morphology and performance. We compare the single source method (S-M) and multisource method (M-M) precursors to understand their contrasting properties. Through comprehensive characterization using PXRD, EDX, SEM, TEM, HRTEM, and XPS, we analyze the resulting nanomaterials. Electrochemical performance is evaluated for NiS nanoparticles produced via the S-M method, specifically in the context of Li/Li+ batteries. Additionally, we assess the photocatalytic activity of both materials across the entire spectrum for dyes such as methyl violet, malachite green, methylene blue, and rhodamine B. Our findings indicate that the S-M method yields nanomaterials with a larger external surface area, leading to superior photocatalytic activity compared to the M-M method. These results highlight the substantial influence of the fabrication method on the final morphology and performance of the synthesized nanomaterials.

Environmental remediation promoted by silver nanoparticles biosynthesized by eucalyptus leaves extract

A simple and low-cost green synthesis method was optimized to prepare stable silver nanoparticles (AgNP) using aqueous Eucalyptus globulus leaves extract. This green method allows to obtain AgNP with spherical morphology and variable size around 25 nm, and it is dependent of the reaction temperature and concentration of the plant extract. AgNP stability was followed during 3 months by zeta potential measurements and a negative zeta range from −30.7 to −33.6 was determined. Biogenic-stabilized AgNP exhibited dual-functional properties as effective in environmental remediation with bacterial growth inhibition and dye photodegradation. Staphylococcus aureus and Escherichia coli were tested for antibacterial activity, and considerable inhibitory activity was found. High photocatalytic degradation of indigo carmine (IC) dye was performed in the presence of the AgNP as catalysts under sunlight irradiation. The degradation efficiency after 2 h of reaction was 37 %, 83 % and 98 % in the presence of UV light, visible light and sunlight irradiation, respectively. The germination of corn kernels test was used to determine the toxicity of the treated IC solutions and the results showed low toxicity after the photodegradation process.

Degradation of Paracetamol in Distilled and Drinking Water via Ag/ZnO Photocatalysis under UV and Natural Sunlight

The present study demonstrates the synthesis and application of Ag/ZnO powder films (thickness of 4 μm) as photocatalysts for natural sunlight and ultraviolet (UV, 315–400 nm) irradiation. The synthesis procedure is simple and eco-friendly, based on the photo-fixation of silver ions onto commercial ZnO powder via UV illumination for the first time. The photocatalytic efficiency of the newly developed films is evaluated through degradation of paracetamol in distilled and drinking water. Our experimental evidences show that the Ag/ZnO nanostructure films are more active than pristine ZnO films in the photodegradation process. Namely, the photocatalytic efficiency of the films modified with 10−2 M concentration of silver ions achieve the highest degradation (D) percentages for paracetamol in both types of water (Ddistilled = 80.97%, Ddrinking = 82.5%) under natural sunlight. Under UV exposure, the degradation percentages are slightly lower but still higher than those achieved by pure ZnO films (Ddistilled = 53.13%, Ddrinking = 61.87%). It is found that the photocatalytic activity grows in direct proportion to the concentration of Ag+ ions: ZnO < Ag 10−4/ZnO < Ag 10−3/ZnO < Ag 10−2/ZnO. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance and photoluminescence spectroscopy are used to characterize the as-prepared ZnO and Ag/ZnO nanostructures. The improved photocatalytic performance of the Ag/ZnO films is mostly attributed to the combination of excited electron transfer from ZnO to Ag and the inhibition of photogenerated electron–hole pair recombination. Furthermore, Ag/ZnO nanostructure films can retain their photocatalytic activity after three cycles of use, highlighting their potential practical application for the treatment of pharmaceutical wastewater in real-world scenarios where natural sunlight is often more readily available than artificial UV light.

Superhydrophilic ZnO nano-needle decorated over nanofibrous PAN membrane and its application towards oil/water separation

Oil spills in the marine environment as well as release of industrial effluent and oily wastewater can pose serious threats to ecosystems and human health. Therefore, designing a filtrating material for treatment of wastewater has been a focus of research. Herein, we employed a simple and low temperature hydrothermal technique to effectively adorn the surface of the electrospun nanofibrous PAN membrane with micro-nano structure of ZnO nano-needles. The proposed membrane integrates a membrane filtration and photodegradation process and has demonstrated improvement in permeability, pollutant eradication, anti-fouling and self-cleaning capabilities. The in-air superhydrophilic NPAN-ZnO nano-needle membrane with micro-nano hierarchal needle architectures captures water and conveys it with underwater superoleophobicity. The substantial amount of pure water flux (7349 ± 200 Lm−2h−1) and separation efficacy (98 ± 1%) justify the membrane's effectiveness in the separation process. The membrane also demonstrated antifouling and self-cleaning characteristics upon UV irradiation after being fouled by BSA and octadecanoic acid, restoring the original flux performance. Furthermore, the membrane has the capability of disintegrating organic and pharmaceutical contaminants found in oily effluent. Given the NPAN-ZnO nano-needle membrane's particular superiority, the technology may inspire the general engineering of multipurpose superwetting polymers materials with intriguing application for complicated oily wastewater treatment.

CoFe2O4/MoS2@Au: Multifunction Z-Scheme Heterojunction for SERS Monitoring and Photocatalytic Degradation of Fungicides

Efficient detection and degradation of fungicides are greatly concerned with aquatic food safety. Herein, a multifunction CoFe2O4/MoS2@Au (ACMS) composite was synthesized for crystal violet (CV) and malachite green (MG) photocatalytic degradation and SERS determination. As the construction of the Z-scheme heterostructure of ACMS, which enhanced the light absorption capability and the separation efficiency of photoexcited carrier significantly, ACMS possessed an excellent photocatalytic performance with a degradation rate of 94.76% for CV under simulated solar light irradiation. Furthermore, the multifunction ACMS exhibited superior SERS capability with a detection limit (LOD) of 4.309 × 10−2 μg L−1 for MG residues in water. And the ACMS substrates could be utilized to determine the MG residues in crucian carp extract, resulting in a recovery rate of 96.00~116.00%. In addition, such multifunction heterojunctions were performed for in situ monitoring of the photodegradation process. This research opened up a novel perspective on the applications of heterojunction-based multifunction materials for food safety control.

Distinguishable Recycling and Photodegradation Processes of Real Industrial Effluents and Blue Dianix Dye in the Presence of Different TQDs Size

Three titanium dioxide quantum dots (TQDs) samples were successfully synthesized at low calcination temperatures via a modified precipitation method at T1 = 330, T2 = 360, and T3 = 400 °C. The synthesized TQDs samples were characterized by: XRD, FE-SEM, HRTEM, and EDX to analyze the crystallinity, purity, and existence of asymmetric circle forms for the TQDs catalysts. Also, the surface area, band gap energy, and crystallite size at different calcination temperatures are 322.32 m2/g, 3.20 eV, and 4.9 nm at 300 °C, 292.39 m2/g, 3.14 eV, and 5.4 nm at 360 °C, and 254.66 m2/g, 3.07 eV, and 6.2 nm at 400 °C, respectively. A xenon photoreactor (70 W/cm2) was used to evaluate the photodegradation process of Blue Dianix dye and sunlight for real industrial effluent treatment. The photocatalytic activity decreases as the crystallite size increases in the TQD samples. Photocatalytic activity of TQDs due to their distinguishable crystalline domain size of less than 10 nm and their high surface area. The photodegradation rate of real industrial effluents was evaluated according to the COD limits permitted by Egyptian environmental law. Also, TOC and COD analyses evaluated 12 recycled samples of TQDs.

Photocatalytic Degradation of Polyethylene Plastics Using MgAl2O4 Nanoparticles Prepared by Solid State Method

In this study, MgAl2O4 nanoparticles with different calcination times were synthesized for photocatalytic applications. Different analyses techniques such as XRD, SEM, EDX, UV-visible, and FTIR were performed to investigate the structural, chemical, optical, and mor-phological properties of the synthesized nanoparticles. XRD analysis revealed the formation MgAl2O4 spinel structure. UV-Visible measurements indicate that MgAl2O4-2 nanoparticles had a narrower energy gap compared to MgAl2O4-1 and MgAl2O4-3. Results of SEM analysis revealed that the synthesized MgAl2O4 nanoparticles consist of small aggregated particles with (40-60 nm) particles size. EDX measurements con-firmed the formation of MgAl2O4 nanoparticles without any impurities. The photocatalytic performance was evaluated by the photodegradation of polyethylene plastics using MgAl2O4 nanoparticles under UV irradiation. The FT-IR measurements before and after the degradation of polyethylene plastics confirm the formation of new functional groups as a result of photodegradation processes.

Development of a new promising nanocomposite photocatalyst of polyaniline/carboxylated graphene oxide supported on PVA film to remove different ecological pollutants

The process of removing dye and antibiotic contaminants from wastewater is quite challenged, especially with water shortage crisis. In this study, for the first time a composite of polyaniline (PANI) and carboxylated graphene oxide (CGO) supported on polyvinyl alcohol (PVA) film (PVA/PANI/CGO) was investigated as anticipated nanocomposite film that can be used to promote wastewater treatment. The effectiveness of this nanocomposite film in wastewater treatment was optimized in a batch system for the removal of methylene blue (MB) and tetracycline antibiotic (TC). The presence of CGO proved to be significant in both adsorption and photocatalytic process and assist the photocatalytic activity of PANI. The optimized conditions for photodegradation process were assessed by using a response surface methodology model (RSM). The optimum resulting scores at 25 °C and pH equal 7 for achieving 97.8 removal % for MB were 15.3 mg L−1 initial concentration, with using 2 lamps as a maximum light intensity and weight of film equal 0.02 g. While the optimum conditions for TC removal are; 23.9 mg L−1 initial concentration of TC, with using 2 lamps and weight of film equal 0.017 g to achieve 73.1 removal %. For potential usage in wastewater treatment, the produced nanocomposite film appears to be promising.

Modelling and optimisation of MXene-derived TiO2/Ti3C2 synthesis parameters using Response Surface Methodology based on the Box–Behnken factorial design. Enhanced carbamazepine degradation by the Cu-modified TiO2/Ti3C2 photocatalyst

In the present study, a hydrothermal method in a water/ethanol environment was used for the first time to obtain novel Cu/TiO2/Ti3C2 composites with high photocatalytic activity for the degradation of carbamazepine (CBZ) under simulated solar light. The Box–Behnken factorial design was coupled with Response Surface Methodology (RSM) for synthesis parameter optimisation. The effect of different synthesis parameters, including temperature, time and water/ethanol ratio, was for the first time studied in detail. The analysis of variance (ANOVA) was used to verify the adequacy of the proposed model. The water/ethanol ratio was the most influential parameter for anatase crystallite growth and the efficiency of carbamazepine degradation. The TiO2/Ti3C2 sample prepared under the optimised conditions (synthesis time of 17 h, temperature of 220 °C, and water/ethanol ratio of 58:42 v/v) revealed almost 100% of CBZ degradation within 60 min. Furthermore, the surface modification of this sample with 0.25% - 1 wt% of copper resulted in improved photocatalytic activity. For TiO2/Ti3C2 modified with 0.5% of Cu, almost complete CBZ degradation was observed in 40 min of the photodegradation process. Finally, the combination of the photodegradation process with the activation of peroxymonosulphate (PMS) by Cu-TiO2/Ti3C2 resulted in markedly improved carbamazepine degradation and reached 100% within 20 min under simulated solar light irradiation. The degradation mechanism of CBZ was proposed based on trapping experiments, which revealed that •O2− and •SO4− are the main oxidising species involved in carbamazepine degradation. Moreover, the hybrid system exhibited high recyclability and stability during subsequent photodegradation cycles.

Enhanced photocatalytic degradation activity of ZIF-8 doped with Ag2WO4 photocatalyst

BackgroundMethylene blue (MB) is a carcinogenic pollutant that is widely known for its dangerous effects on humans and marine life. MethodsHerein, Ag2WO4-supported ZIF-8 hybrid photocatalyst has been constructed simple using a hydrothermal method. The constructed photocatalysts were described by XRD, FESEM, EDX, UV–visible DRS, TEM, and BET surface area methods. FindingsThe Ag2WO4/ZIF-8 photocatalyst established high photocatalytic degradation performance under visible light toward MB dye, giving 98.3 % photodegradation of 30 mg/l MB and 0.1 g/l photocatalyst dosage in 120 min of irradiation. Also, the photostability was excellent after five rounds. The boosted photodegradation performance was attributed to the synergic mechanism, which proposed the efficient charge separation efficiency and the presence of plasmon Ag in the Ag2WO4/ZIF-8 Z-scheme heterojunction. The trapping experiments illustrated that ·O2- was primary reactive radicals in the photodegradation process of MB. This research opens a new insight into assembling new heterojunction photocatalyst with improved behavior and stability, and presents a new understanding of Surface Plasmon Resonance (SPR)-supported Z-scheme mechanism for environmental application.

Revealing the effect of humic substance compounds on the aged characteristics and release compounds profiles from photodegradation of polyethylene microplastics

The aim of this study was to investigate the effect of humic substance compounds (humic acid (HA) and fulvic acid (FA)) on the aged characteristics and release compounds profiles from polyethylene microplastics (PE-MPs). Results showed that HA promoted degree of PE-MPs photodegradation with a higher value of weight loss and oxygen atom and lower average particle size (110 μm), compared with the presence of FA during 15 days of irradiation. Likewise, the needle trap microextraction (HS-NTME) combined with gas chromatography/mass spectrometry (GC/MS) analysis revealed that HA and FA promoted a variety of oxygen-containing products (carboxyl acid, phenols and ketones) and siloxanes additives released from photodegradation of PE-MPs. Moreover, HA was found to have a higher ability to generate free radicals (▪OH and O2–) than FA, which accelerated the photooxidation of PE-MPs and led to the different mechanisms of photodegradation pathway of PE-MPs. These findings not only shed light on how humic substances affect photodegradation process of MPs, but also support further investigation into the possible hazard of MPs when co-existing compounds exist in the aqueous system.

Design of Ag@ZnO@Ti3C2 MXene heterojunction photocatalyst for enhanced photocatalytic degradation activity of methylene blue and levofloxacin under visible light irradiation

A ternary Ag@ZnO@Ti3C2 MXene heterojunction (AZM) is synthesized by hybridizing ZnO and Ag nanoparticles with the MXene via a simple hydrothermal and chemical deposition method. The addition of ZnO and Ag can effectively compensate for MXene’s narrow bandgap property, promote charge carrier separation, and improve visible light absorption, thereby enhancing photocatalytic activity. The photocatalytic activity of the AZM is evaluated through the removal efficiency of methylene blue (MB) dye and levofloxacin (LVX) under visible light irradiation. The results show that the optimized ternary AZM heterojunction photocatalysts (AZM-15) possesses the maximum degradation of MB (90.54%) with a reaction rate constant of 0.0473 min−1, while the maximum degradation of LVX (86.76%) has a reaction rate constant of 0.0408 min−1. Moreover, the AZM composite exhibits excellent stability, which explains its MB removal rate of 83.59% and LVX removal rate of 80.03% after five cycles. The results of trapping experiments and EPR demonstrated that the main active species in the MB and LVX photodegradation process are·OH and·O2-. This work not only elucidates a possible mechanism of photocatalytic degradation of organic pollutants but also provides a pathway to design new bandgap photocatalysts for mitigating environmental pollution.

Evaluation of rGO decorated MnO2/NiO nanocomposite for high-performance photocatalytic and supercapacitor applications

To the degradation of dyes and for use as supercapacitors, MnO2/NiO@rGO (MNrGO) nanocomposite (NCs) were synthesized and characterized. X-ray Powder Diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) studies have been utilized to determine the crystalline structure and functional groups of the nanocomposites (NCs). In the photodegradation process, the Methylene blue (MB), Congo red (CR) and Methyl orange (MO) dyes had higher degradation efficiency, such as 98.5 % for MB within 35 min, 83.04 % for CR within 60 min, and 92.47 % for MO within 30 min, respectively. It showed a maximum capacitance value of 391.6 F/g at 0.5 A/g when its electrochemical characteristics were investigated in a 1 M KOH electrolyte solution. One of the main benefits of long-term applications is that the NCs retain 91 % of their electrochemical properties even after 5000 GCD cycles. These metal oxides are well-known as materials for environmental remediation due to their low cost, stability, efficiency, and low impact on the environment. Due to its better performance in both photocatalysis and electrocatalysis, MnO2/NiO@rGO nanohybrid has emerged as a promising long-term catalyst in these two areas.

Spontaneous degradation of methylene blue adsorbed on magnetic biochars

Methylene blue (MB) is one of the most widely studied organic molecules in the treatment of wastewater. Sorption, biodegradation, photodegradation, electrochemical oxidation, ozonation, and other advanced oxidative processes are frequently used to remove this dye from water solutions. The unexpected degradation of MB adsorbed on magnetic biochar from aqueous solution was observed. We found that the conditions of handling, such as drying temperature and storage period, substantially influenced the stability of the dye fixed on the (magnetic) carbon adsorbents. Twelve substances were identified by mass spectrometry as products of decomposition, mostly demethylated, oxidated, and hydroxylated substances. The decomposition of MB was further investigated using non-magnetic carbon biochars and aluminosilicate mineral zeolite. Our findings of the spontaneous decomposition of MB and the identification of the species of degradation offer a new approach to evaluate the mechanism of adsorption, the process of regeneration, and the toxicity of treated solutions.