Treatment Of Organic Pollutants Research Articles

Characteristics of Volatile Organic Compounds Emissions and Odor Impact in the Pharmaceutical Industry

Volatile Organic Compounds (VOCs) are not only essential precursors for the formation of ozone and PM2.5, but also hazardous to human health and responsible for unpleasant odors. The pharmaceutical industry has become an important industrial source of VOCs due to China’s large emissions and complex emission chains. In total, 245 VOCs samples were collected and analyzed from 11 typical pharmaceutical companies in Zibo City of the North China Plain, in order to investigate the VOCs emission characteristics and odor impacts. The emission factor for the pharmaceutical industry was 7.97 ± 8.21 g/kg pharmaceuticals, while the main emission links were chimney emissions, equipment sealing leakage, and so on. Finally, considering both purifying efficiency and economic benefits, the multistage absorption (AB) method is most effective for VOCs concentrations below 100 mg/m3, while UV photo-oxygenation combined with adsorption (UVA) is more suitable for concentrations below 300 mg/m3. The Regenerative Thermal Oxidizer (RTO), Catalytic Oxidizer (CO), and Condensation + Adsorption (CA) technologies demonstrated greater stability and efficiency, particularly in the treatment of complex organic pollutants, highlighting their advantages in both VOCs and odor removal at higher concentrations.

Physicochemical, optical and magnetic properties of ZrO2/Fe2O3 nanocomposite and its application in photocatalysis and antibacterial treatment

In this work ZrO2/Fe2O3 nanocomposite was synthesised through hydrothermal method using an innovative approach. X-ray diffraction (XRD) analysis revealed the formation of tetragonal ZrO2 and α-Fe2O3 in the nanocomposite. The FTIR spectra of the prepared samples exhibited characteristic peaks corresponding to ZrO2 and Fe2O3 and UV–Visible spectroscopy reveals that the nanocomposite exhibits a significantly lesser bandgap than the pure nanoparticles as determined by the Kubelka Munk function used for bandgap computation. Photoluminescence analysis substantiates the reduction in the recombination rate in the ZrO2/Fe2O3 nanocomposite as compared to the pure ZrO2 nanoparticles. Reduction in the bandgap as well as the recombination rate makes the nanocomposite favourable in the photocatalytic treatment of organic pollutants. Raman analysis was carried out to study the vibrational characteristics of the samples. Further, the prepared nanocomposite was examined for its applicability in photocatalysis, by analysing its degradation ability on Eosin yellow and Eosin Blue dyes under white light LED irradiation. The composite exhibited significant degradation ability than the pure nanoparticles, which makes it an ideal candidate for the treatment of organic pollutants. The nanocomposite exhibited ferromagnetic behaviour as confirmed through Vibrating sample Magnetometry, so it can be easily retrieved after the treatment. The prepared ZrO2/Fe2O3 nanocomposite was tested for its antibacterial efficacy against two Gram positive bacteria (Enterococcus faecalis, Staphylococcus aureus) and two Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa). From the antibacterial studies it was validated that the nanocomposite exhibited significant antibacterial efficiencies against the bacteria. Hence the prepared nanocomposite has been proved to be a potential candidate for the treatment of organic pollutants as well as for antibacterial treatment.

Shining light on broad-spectrum responded NaYF4:Yb,Er,Tm@Bi@BiOI: Understanding the enhanced photodegradation performance of bisphenol A and mechanisms

This work reported a novel ternary heterogeneous photocatalyst NaYF4:Yb,Er,Tm@Bi@BiOI (NBEG-6h). NBEG-6h exhibits broad-spectrum absorption from ultraviolet to near-infrared. The elimination efficiency of BPA by NBEG-6h under simulated sunlight and near-infrared light irradiation was 88% (24 min) and 93.9% (160 min), respectively. It also has the universality of degrading various pollutants, good reusability and stability. The exceptional photocatalytic activity can be attributed to the absorption of near-infrared light by NaYF4:Yb,Er,Tm, which improves the total efficiency of sunlight utilization. The localized surface plasmon resonance effect of Bi nanoparticles enhances the light absorption performance of the heterostructure. Furthermore, combining Bi and BiOI accelerates carrier migration and improves the separation efficiency of photogenerated electron-hole pairs. h+, ·O2− and 1O2 play the pivotal roles during the photocatalytic process. This research offers new insights into the design, development, and mechanism understanding of full-spectrum-driven heterostructure photocatalysts. It provides an environmentally sustainable approach to the treatment of harmful organic pollutants.

Utilization of waste citrus limetta peel for the green synthesis of iron catalyst and its subsequent application in fluidized-bed Fenton-like process for environmental sustainable treatment of organic pollutant

This work focuses on the environmental friendly synthesis of an iron-based catalyst utilizing extract from waste citrus limetta peels. The main objective is to encourage the sustainable use of bio-waste materials in catalytic processes. This innovative method demonstrates the efficacy of bio-derived materials in catalysis by removing the need for hazardous chemicals. The green-synthesized catalyst was analyzed using many characterization methods, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). These analyzed results give insightful information on the physicochemical properties of green-synthesized catalysts. Furthermore, the prepared catalyst was utilized in a fluidized-bed reactor to facilitate the Fenton degradation of dye effluent, with a specific focus on the commonly used Eosin yellow (EY) dye. The iron catalyst derived from plant-based waste material accomplished an impressive 98% degradation of EY within a 90-minute time frame under optimized working conditions, using a minimal quantity of catalyst. An in-depth analysis was conducted to study the kinetics and process mass transfer in order to improve the comprehension of catalytic processes occurring in the fluidized-bed reactor. The Fenton decomposition of dye effluent is likely to be explained by first-order reaction kinetics. Additionally, confirmed enhanced catalytic durability and decreased deactivation of surface sites of the prepared catalyst after three consecutive oxidation cycles. These findings underscore the potential of this approach in sustainable wastewater treatment, highlighting both its efficiency and cost-effectiveness.

One-step synthesis of magnetic catalysts containing Mn3O4-Fe3O4 from manganese slag for degradation of enrofloxacin by activation of peroxymonosulfate

Landfill disposal of manganese slag is a significant environmental concern on both local and global levels. Using manganese slag to synthesis catalysts to degrade organic pollutants in wastewater is a promising pathway for the solid waste treatment. Here, we propose a simple method to prepare magnetic catalysts containing Mn3O4-Fe3O4 (MMF) using manganese slag as raw materials. The MMF exhibits excellent degradation performance for enrofloxacin (ENR) with 97 % removal efficiency within 30 min and can be rapidly isolated from wastewater by magnet. Electron paramagnetic resonance (EPR) and quenching experiments demonstrated that 1O2 produced by the non-radical pathway is the principal active substance for ENR degradation. X-ray photoelectron spectroscopy (XPS) and density-functional theory (DFT) calculations indicate that Mn and Fe in MMF provide electrons for PMS activation and that the presence of Fe promotes the activation of the PMS and the cycling of Mn. This work paves the way for developing magnetic catalysts from manganese slag for the treatment of organic pollutants via advanced oxidation process.

Photocatalysis of Adsorbed Catechol on Degussa P25 TiO2 at the Air-Solid Interface.

Semiconductor photocatalysis with commercial TiO2 (Degussa P25) has shown significant potential in water treatment of organic pollutants. However, the photoinduced reactions of adsorbed catechol, a phenolic air pollutant from biomass burning and combustion emissions, at the air-solid interface of TiO2 remain unexplored. Herein we examine the photocatalytic decay of catechol in the presence of water vapor, which acts as an electron acceptor. Experiments under variable cut-off wavelengths of irradiation (λcut-off ≥ 320, 400, and 515 nm) distinguish the mechanistic contribution of a ligand-to-metal charge-transfer (LMCT) complex of surface chemisorbed catechol on TiO2. The LMCT complex injects electrons into the conduction band of TiO2 from the highest occupied molecular orbital of catechol by visible light (≥2.11 eV) excitation. The deconvolution of diffuse reflectance UV-visible spectral bands from LMCT complexes of TiO2 with catechol, o-semiquinone radical, and quinone and the quantification of the evolving gaseous products follow a consecutive kinetic model. CO2(g) and CO(g) final oxidation products are monitored by gas chromatography and Fourier-transform infrared spectroscopy. The apparent quantum efficiency at variable λcut-off are determined for reactant loss (Φ- TiO2/catechol = 0.79 ± 0.19) and product growth ΦCO2 = 0.76 ± 0.08). Spectroscopic and electrochemical measurements reveal the energy band diagram for the LMCT of TiO2/catechol. Two photocatalytic mechanisms are analyzed based on chemical transformations and environmental relevance.

Pharmaceutical effluent degradation using hydrogen peroxide-supported zerovalent iron nanoparticles catalyst

Pharmaceutical effluents generated during drugs production and application are often times released into the water systems with little or no treatment, which could pose potential danger to the ecosystem. Advanced oxidation processes for organic pollutants treatment have gained wide consideration due to their effectiveness. In this work, hydrogen peroxide (H2O2) and hydrogen peroxide-supported nano zerovalent iron (H2O2@nZVIs) were deployed to study pharmaceutical effluents (PE) degradation via batch experiments, under various reaction time, (H2O2) and (H2O2@nZVIs) concentrations, pH, PE concentration, and temperature. The nZVIs was prepared from the green synthesis of Vernonia amygdalina leaf extract and characterized using different analytical tools such as Fourier Transform-Infrared Spectroscopy (FT-IR), Gas Chromatography Mass Spectroscopy (GC-MS), Scanning Electron Microscopy (SEM), and X-Ray Diffraction Spectroscopy (XRD). The FT-IR results showed the presence of -C = O, -NH, -OH, -C = C and, -C-O functional groups, SEM report showed that the morphology of the nZVIs is round in shape, while GC-MS revealed the presence of several phytochemicals. When the concentration of the effluent was increased from 10 to 30 ml, the percentage decolourization decreased from 74.74 to 51.96% and from 80.36 to 54.38% for H2O2 and H2O2@nZVI respectively, whereas when the contact time was increased from 10 to 60 min, the percentage decolourization rose from 70.39 to 83.49% for H2O2 and from 85.19 to 89.73% when H2O2@nZVI was used. When the effect of pH was assessed, it was observed that on increasing the pH from 2 to 10, the percentage decolourization rose from 74.5 to 80.25% for H2O2, however, with H2O2@nZVI, the percentage decolourization decreased from 81.50 to 68%. Maximum percentage decolourization of 57.10% and 94.56% for H2O2 and H2O2@nZVI was achieved at catalyst volume of 25 ml. For all the parameters tested, the H2O2@nZVIs performed much better indicating that the nZVIs enhanced the decolourization ability of the H2O2. The kinetic results showed that the decolorization of pharmaceutical effluent by both catalysts fitted very well with the second-order model, while thermodynamic properties of enthalpy change were found to be 10.025 and 27.005 kJ/mol/K for H2O2 and H2O2@nZVIs respectively suggesting that the oxidation process is endothermic in nature. This technique employed in using hydrogen peroxide-supported zero valent iron, proved to be highly efficient not only for pharmaceutical effluent degradation but also in the elimination of lead from the effluent.

Light switchable radical and non-radical periodate activation by Fe3O4/g-C3N4 for efficient organic contaminant elimination

Although the heterogeneous activation of periodate (PI) has recently garnered significant attention for organic pollutant degradation, regulating the non-radical and radical reaction pathways remains a challenge. Herein, a Z-scheme Fe3O4/g-C3N4 heterojunction (FCN) was developed to achieve controllable radical and non-radical PI activation using a light switch. In the dark, the interaction between FCN and PI gave rise to metastable surface-activated PI complexes (PI*) via the non-radical pathway, which served as the dominant reactive species for organic elimination. Upon light irradiation, FCN acted as an electron donor for PI activation via the radical pathway, forming iodate radicals (IO3•) for pollutant destruction. Consequently, the FCN/PI/VIS system achieved complete removal of acid orange 7 in 30 min, with a pseudo-first order reaction rate about 3.5 times higher than that of FCN/PI system. The involved reactive species were validated by scavenging tests, electron paramagnetic resonance (EPR) analysis, Raman spectra and electrochemical measurements. Moreover, the light switchable FCN-based PI activation system exhibited high recyclability and practicability for the treatment of various organic pollutants in water. This study provides new insights into the PI activation-mediated wastewater treatment processes.

Microwave-Assisted Synthesis of CdS-MOF MIL-101 (Fe) Composite: Characterization and Photocatalytic Performance.

The present study outlines the synthesis of cadmium sulfide-metal-organic framework (CdS-MOF) MIL-101 (Fe) heterojunctions achieved via fast microwave-assisted reactions. Thus, different CdS-MOF MIL-101 (Fe) ratios were prepared to study their effectiveness as photocatalysts. These compounds were employed in the photocatalytic degradation of methylene blue (MB) under UV and visible irradiation. Structural, morphological, textural, compositional, and optical properties of the synthesized compounds determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized to characterize the structural, morphological, textural, compositional, and optical properties. Electrochemical impedance spectroscopy (EIS) was also employed to determine photovoltage and photocurrent densities. The resulting valence band offset (Vfb) and band gap energy values were utilized to construct an energy band scheme. Our research revealed that the CdS-MOF MIL-101 (Fe) heterojunction enhances the efficiency of electron-hole pair separation, thereby mitigating charge carrier recombination effects. Moreover, the type I electronic band structure established an efficient reaction mechanism, effectively suppressing the recombination of photogenerated electron-hole pairs. The photocatalytic system demonstrated exceptional behavior, achieving complete MB removal within 30 min of reaction time and exhibiting outstanding stability and reusability after four reaction cycles. These findings highlight the potential of the synthesized compounds in the field of wastewater treatment for organic pollutants, offering a promising alternative to current environmental issues.

Trivacant Keggin-type polyoxometalate/TiO2 composite for enhanced sonocatalytic degradation of AR88 from aqueous solutions

Polyoxometalates (POMs) have been limited in their widespread use in catalysis in previous studies due to their strong carrier complexation and limited solubility. To overcome this limitation, in this study, Z-type heterojunction composites constructed with trivacant Keggin-type POMs K9SbW9O33·19.5H2O and TiO2 were synthesized by the sol–gel method and used for the sonocatalytic removal of the organic pollutant AR88. The results showed that, compared with pure K9SbW9O33·19.5H2O, the optimum K9SbW9O33·19.5H2O/TiO2 showed a significantly higher sonocatalytic degradation efficiency of 87.2 % for AR88, and the mineralization rate reached 51.8 %. Parameters such as dye pH and sonication power were optimized to determine the best conditions for sonocatalysis. In addition, the K9SbW9O33·19.5H2O/TiO2 Z-type heterojunction composites showed good stability and reusability. The excellent catalytic performance is attributed to the effective separation of charges and holes by the Z-type heterojunction, which enables them to produce active substances for AR88 decomposition. This study demonstrates the high potential of POMs for the application of sonocatalysis in the treatment of organic pollutants.

Efficient tetracycline degradation via flow-through peroxymonosulfate activation by dual heteroatom-doped wood-derived catalytic membrane

The widespread use of antibiotics in the medical industry and in animal husbandry has led to significant environmental pollution. Effective purification of high concentrations of tetracycline (TC) in practical pharmaceutical wastewater remains a substantial challenge. The integration of advanced oxidation with membrane separation technology shows great application potential. In this study, a P and N co-doped balsa wood membrane (PNWM) were fabricated using heteroatomic doped biochar material, aiming to synergize filtration and catalytic oxidation. The catalytic activity of the PNWM/peroxymonosulfate (PMS) system was systematically evaluated. Targeting TC as the pollutant, the PNWM/PMS system achieved a degradation efficiency exceeding 97 % within 30 min and a total organic carbon (TOC) removal efficiency of 63.9 %, surpassing the performance of unmodified wood-based membrane. These excellent results were attributed to the doping of N and P atoms, which increased surface defects and specific area, thereby enhancing the adsorption and degradation of TC by PNWM. The graphite N facilitated electron transfer, while pyridine N served as active sites for PMS activation. Additionally, the low electronegativity of the P formed electronic regions of varying intensities on the PNWM surface, contributing to PMS activation. The membrane process also enhanced mass transfer during the degradation process. Both radical (·OH, SO4·ˉ, O2·ˉ) and non-radical (1O2, electron transfer) pathways cooperated in TC degradation in PNWM/PMS system. Consequently, heteroatom-doped biochar film materials prepared through simple methods provide a promising approach for the effective treatment of refractory organic pollutants in wastewater.

Treatment of Organic Pollutant by Advanced Oxidation Processes

The investigation involved the oxidation of urea (UR) in a batch reactor, employing Fenton's reagent. Various parameters, namely reaction time, pH level, ferrous ion dose, and hydrogen peroxide dose, were scrutinized. The reaction time spanned from 30 minutes to 3 hours, revealing a notably positive impact. An optimal pH of 3 was identified for the medium. The concentrations of ferrous ions ranged from 0.2 g/l to 0.53 g/l, with hydrogen peroxide levels ranging from 1 g/l to 2.65 g/l. The impact of hydrogen peroxide was notably significant at a ferrous ion concentration of 0.3 g/l and a pH of 3. Evaluating urea removal efficiency through chemical oxygen demand (COD) calculations showed a maximum efficiency of 86.8%, with a minimum ammonia yield of 6%. Overall, the outcomes underscored the efficacy of the Fenton process in urea treatment.

Structure‐Controlled Interpenetrated MOF@COF via C−C Linkage for Enhanced Photocatalysis

AbstractDiversifying the connecting junctions will be feasible for the controllable collaboration of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) to rationally design multifunction‐integrated heterostructures with enhanced performance, yet it is in the nascent stage. Herein, by intelligently exploiting the polymerization of vinyl group, C−C bond is innovatively introduced to construct the core–shell MOF@COF heterostructures with adjustable shell thickness and rare interpenetrated structure. The unique structure endows prepared C−C‐linked MIL‐68@COF−Vs with more superior visible‐light harvesting and photogenerated carrier separation capability, leading to significantly higher photocatalytic activity and faster degradation rate than pristine MIL‐68‐C=Cs, COF−V, and imine‐linked MIL‐68‐NH2@COF−V. Further, the customized MIL‐68@COF−V is in situ grown as reusable films with dramatically boosted performance under ambient conditions, which realize the highly efficient degradation of tetracycline within 15 min (96.5 %), rhodamine 6G within 25 min (97.6 %), and phenol within 40 min (95.3 %) by solar drive. This work exhibits the distinctive advantages of C−C junction in the MOF@COF construction, and highlights the application prospect of rational‐designed heterostructure in the treatment of persistent organic pollutants.

Structure-Controlled Interpenetrated MOF@COF via C-C Linkage for Enhanced Photocatalysis.

Diversifying the connecting junctions will be feasible for the controllable collaboration of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) to rationally design multifunction-integrated heterostructures with enhanced performance, yet it is in the nascent stage. Herein, by intelligently exploiting the polymerization of vinyl group, C-C bond is innovatively introduced to construct the core-shell MOF@COF heterostructures with adjustable shell thickness and rare interpenetrated structure. The unique structure endows prepared C-C-linked MIL-68@COF-Vs with more superior visible-light harvesting and photogenerated carrier separation capability, leading to significantly higher photocatalytic activity and faster degradation rate than pristine MIL-68-C=Cs, COF-V, and imine-linked MIL-68-NH2@COF-V. Further, the customized MIL-68@COF-V is in situ grown as reusable films with dramatically boosted performance under ambient conditions, which realize the highly efficient degradation of tetracycline within 15 min (96.5 %), rhodamine 6G within 25 min (97.6 %), and phenol within 40 min (95.3 %) by solar drive. This work exhibits the distinctive advantages of C-C junction in the MOF@COF construction, and highlights the application prospect of rational-designed heterostructure in the treatment of persistent organic pollutants.

Enhanced photocatalytic degradation of organic dyes by dual heterojunction of ZnO/NiWO4/V2C MXene

Multiphase composite catalysts can be designed for efficient photocatalytic treatment of organic pollutants in wastewater. Herein, the multiphase ZnO/NiWO4/V2C composite catalysts with dual heterojunction and hierarchically assembled nanoflower structures were constructed via a facile two-step hydrothermal and electrostatic self-assembly method. Utilizing NiWO4 and V2C as co-catalysts, these catalysts effectively degraded cationic dyes, methylene blue (MB) and rhodamine B (RhB) under visible light irradiation. The ZnO/NiWO4/V2C catalyst exhibited higher photocatalytic activity than ZnO in the degradation of MB and RhB, with rate constants of 0.0194 min−1 (a 7.43-fold enhancement) and 0.0176 min−1 (a 3.13-fold enhancement). The higher activity can be attributed to the construction of the double heterojunction using NiWO4 and V2C, which can facilitate efficient electron transport, improve charge separation efficiency, and provide more active sites. After four cycles, the ZnO/NiWO4/V2C catalyst still maintained good stability. Consequently, this work can offer a promising approach for environmental pollution treatment.

Synthesis of Bi-BiPO4-Ag3PO4/PAN composite nanomaterial photocatalyst with the degradation performance for rhodamine B

A highly efficient visible-light-driven photocatalyst Bi-BiPO4-Ag3PO4/PAN was synthesized by electrospinning, in-situ growth, immersion and reduction methods. The prepared composites were characterized by SEM, TEM, XPS, UV–vis, FT-IR and EIS. The results showed that the loading of BiPO4 significantly improved the photocatalytic efficiency of Ag3PO4, and the photocatalytic efficiency was further improved by a certain degree of reduction. When the ratio of BiPO4 to Ag3PO4 is 8 %, the catalyst: reducing agent is 1:2 and the reduction time is 15 min, the degradation rate of rhodamine B was the highest under visible light irradiation (λ ≥ 420 nm). The rate constant of Bi-BiPO4-Ag3PO4/PAN-8 % is (0.01401 min−1) 2.56 times that of pure Ag3PO4 (0.00327 min−1). The photocatalyst also has good degradation performance for different kinds of dyes and antibiotics under visible light irradiation, which is universal and easy to recycle. Free radical trapping experiments showed that •O2− is the main active oxidant affecting the photodegradation of rhodamine B and interacts with h+ and •OH. This study not only provides a new idea for the synthesis of Ag3PO4-based photocatalysts, it is also proved that Bi-BiPO4-Ag3PO4/PAN composite is a promising photocatalyst for the treatment of organic pollutants in water.

Enhanced Photocatalytic Ozonation Using Modified TiO2 With Designed Nucleophilic and Electrophilic Sites.

Photocatalytic ozonation is considered to be a promising approach for the treatment of refractory organic pollutants, but the design of efficient catalyst remains a challenge. Surface modification provides a potential strategy to improve the activity of photocatalytic ozonation. In this work, density functional theory (DFT) calculations were first performed to check the interaction between O3 and TiO2-OH (surface hydroxylated TiO2) or TiO2-F (surface fluorinated TiO2), and the results suggest that TiO2-OH displays better O3 adsorption and activation than does TiO2-F, which is confirmed by experimental results. The surface hydroxyl groups greatly promote the O3 activation, which is beneficial for the generation of reactive oxygen species (ROS). Importantly, TiO2-OH displays better performance towards pollutants (such as berberine hydrochloride) removal than does TiO2-F and most reported ozonation photocatalysts. The total organic carbon (TOC) removal efficiency reaches 84.4 % within two hours. This work highlights the effect of surface hydroxylation on photocatalytic ozonation and provides ideas for the design of efficient photocatalytic ozonation catalysts.

Generation of H2O2 via simultaneous treatment of cotton and organic pollutants in textile wastewater

The textile industry is essential for human life but generates significant amounts of waste cotton and alkaline dye wastewater. These pollutants are difficult to separate and treat, causing numerous environmental issues. Traditional methods struggle to deal with the combined pollution without additives. In this study, we developed a simple hydrothermal process to convert waste cotton and dye wastewater into a non-metal catalyst. This catalyst can degrade dyes using oxygen from the air. Remarkably, it produces a substantial amount of H2O2 after degrading the dyes. This demonstrates that we utilized waste cotton present in textile wastewater as a catalyst precursor and abundant oxygen as an oxidant to convert dye wastewater into valuable H2O2. We also used commercially available cotton cloth as a raw material and achieved good results. Under the optimized conditions, 96 % of the dye was degraded within 4 h, generating 252 μM of H2O2 simultaneously. Additionally, the catalysts performed better under alkaline conditions, with the dye degradation rate increasing by 33 % compared to neutral conditions. This is ideal for alkaline textile mill wastewater. Therefore, our work provides a novel method for the treatment of cotton waste and dyes in textile mills and has broad application prospects.

Enhanced methylene blue degradation by graphene oxide-encapsulated nano zero-valent iron composites: Optimization, mechanistic insights, and environmental implications

Methylene blue (MB) in textile dye wastewater poses a significant environmental challenge due to its high chemical stability and resistance to biodegradation. This study investigates the use of a novel graphene oxide-encapsulated nano zero-valent iron (GO/nZVI) composite for the efficient and sustainable degradation of MB. The GO/nZVI composite was synthesized via hydrothermal co-precipitation and self-assembly methods and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Under optimized conditions, the composite achieved an impressive 99.99 % degradation of MB within 40 min, demonstrating substantial improvements in stability and reusability. The composite retained over 84.5 % of its catalytic activity after five cycles, underscoring its potential for practical wastewater treatment applications. The optimization of reaction conditions through response surface methodology (Box-Behnken design, BBD) facilitated the formation of a core-shell structure, which significantly enhanced electron transfer and radical generation, crucial for MB oxidation. Radical quenching experiments confirmed hydroxyl radicals (·OH) as the primary active species, and gas chromatography-mass spectrometry (GC-MS) analysis elucidated the degradation pathway. This study presents a scalable and environmentally friendly solution for the treatment of recalcitrant organic pollutants, marking a significant advancement in water purification technologies.

Hyper-Cross-Linked Polyindole for Selective Adsorption and Resource Utilization of Organic Pollutants in Water.

Efficient treatment and utilization of organic pollutants in water are difficult for environmental remediation. A new hyper-cross-linked polymer (PIn-HCP) with high specific surface area was constructed via polyindole (PIn) as building blocks. Rich pore structures and abundant adsorption sites in PIn-HCP were obtained by hyper-cross-linking. The specific surface area of PIn-HCP was enhanced from 14.85 to 431.89 m2/g. The adsorption capacities of PIn-HCP-2 for methylene blue (MB), methyl orange (MO), rhodamine B (RhB), and tetracycline hydrochloride (TH) are 902.0, 275.2, 16.0, and 0.0 mg/g, respectively. PIn-HCP also realized selective adsorption of MB, which can better separate MB/RhB and MB/TH. MB is adsorbed onto PIn-HCP via a synergistic mechanism including π-π stacking, electrostatic interaction, cation-π interaction, hydrogen bonding interaction, and ion exchange. The huge conjugated structure of PIn promotes PIn-HCP to selectively adsorb MB. In addition, PIn-HCP also retains the electrochemical properties of PIn. MB can improve the specific capacitance of PIn-HCP up to five times, and it has potential as a supercapacitor electrode. PIn-HCP offers a promising and practical solution for the efficient treatment and utilization of organic pollutants in water.