Search Results (1,706)

Textile dye effluents containing toxic organic compounds pose serious environmental challenges. In this study, novel Poly(1-vinyl imidazole)-Bis[2-(methacryloyloxy)ethyl] phosphate (PVIB) polymers were synthesized with crosslinker molar fractions ranging from 5% to 80% and were subsequently investigated as advanced adsorbents for textile dye removal. Procion Red (PR), a widely used reactive dye, was selected as the model pollutant. The materials were characterized using FTIR, TGA, DTG, SEM-EDX, WD-XRF, TEM, and BET analyses. Adsorption mechanisms were examined through kinetic, isotherm, and thermodynamic models. Among the synthesized formulations, PVIB20% achieved the best dye removal, reaching an experimental adsorption capacity of 330 mg g⁻¹ within 60 min under acidic to neutral conditions. The kinetic modeling studies identified the pseudo-first-order model as the best fit, indicating a surface-controlled process involving both physical and chemical interactions. Isotherm studies showed that the Langmuir and Redlich–Peterson models provided the best fit, yielding a maximum monolayer adsorption capacity of 765 mg g⁻¹. Thermodynamic analysis revealed that the adsorption was spontaneous, endothermic, and entropy-driven. Overall, PVIB20% demonstrated superior adsorption capacity, rapid kinetics, and strong dye–polymer interactions compared with many conventional and modified adsorbents, which highlights its potential as an efficient and durable material for anionic dye removal from wastewater. Full article

This study aims to present the preparation of date stone activated carbon (DSAC) through physical activation with carbon dioxide. The Brunauer–Emmett–Teller (BET) technique, Boehm titrations, elemental analysis, Raman and Fourier-transform infrared (FTIR) spectroscopy have been used to characterize the raw material (date stone), date stone activated carbon (DSAC) produced, Congo Red (CR) and to investigate the adsorption phenomena. The study of the DSAC porous material revealed the dominance of micropores with a specific surface area greater than 535.9 m² g⁻¹ and an approximate volume value equal to 0.208 cm³ g⁻¹. The Langmuir model predicted an adsorption capacity of approximately 27.77 mg g⁻¹, while a 90% removal efficiency for CR dye was achieved under neutral pH conditions. Thermodynamic analysis confirmed that the adsorption of CR on DSAC has a spontaneous (ΔG° < 0) and exothermic (ΔH° < 0) character. The adsorption mechanism of CR on DSAC was proposed and discussed, based on the determination of electrostatic interactions being identified as a critical factor that controls the adsorption phenomenon of CR on DSAC. A 2³ full factorial design was implemented to systematically investigate the effects of three critical parameters (temperature, adsorbent dosage, and pH) on the adsorption performance. Statistical analysis indicated that all three primary factors significantly influenced the results. The square correlation coefficient of the model (R²-sq of 97.26%) was in good agreement with the statistical model. The variable is considered statistically significant when the p-value is lower than 0.05. These findings, supported by experimental data, strongly indicate that DSAC possesses remarkable potential as a sustainable and effective bio-adsorbent for wastewater remediation applications capable of removing diverse contaminants with high efficiency. Full article

Textile dyeing effluents are characterized by recalcitrant organics and high salinity, requiring robust pretreatments prior to biological polishing. The heterogeneous Fenton-type (HFT) oxidation over Prussian Blue nanoparticles supported on γ-alumina (PBNP/γ-Al₂O₃) was investigated in a liquid batch-recycle packed-bed reactor treating a synthetic textile wastewater (STW) reproducing an industrial dye bath with the Reactive Black 5 (RB5) dye, together with simplified RB5 and RB5 + NaCl matrices. Hydrogen peroxide decay followed pseudo-first-order kinetics. Using fixed initial doses (11, 20, 35 mmol L⁻¹), the catalyst exhibited an early adaptation phase and then reproducible operation: from the fourth reuse onward, both the H₂O₂ decomposition rate constant and DOC removal varied by <10% under identical conditions. Among matrices, STW exhibited the highest oxidant efficiency. With an initial H₂O₂ dose of 11 mmol L⁻¹, the treatment enabled complete discoloration and produced effluents with negligible toxicity. Increasing the initial dose to 20 or 35 mmol L⁻¹ did not improve treatment and led to a decrease in the hydrogen peroxide decomposition rate with reuses and loss of PB ν(C≡N) Raman bands, indicating surface transformation. Overall, PBNP/γ-Al₂O₃ demonstrated reproducible activity and structural resilience in saline, dyeing-relevant matrices at H₂O₂ doses that preserve catalytic integrity, confirming its feasibility as a stable and reusable pretreatment catalyst for saline dyeing effluents, and supporting its integration into hybrid AOP–biological treatment schemes for dyeing wastewater. Full article

Brilliant blue, as a pigment food additive, has all the characteristics of printing and dyeing wastewater and belongs to persistent and refractory organic compounds. The photocatalysis–Fenton reaction system consists of two parts: photocatalytic reaction and Fenton reaction. Electrons promote the decomposition of H₂O₂ to produce •OH. In addition, the effective separation of e- and h⁺ by light strengthens the direct oxidation of h⁺, and h⁺ reacts directly with OH⁻ to produce •OH, which can further promote the removal of organic pollutants. In this paper, g-C₃N₄ and Fe/g-C₃N₄ photocatalysts were prepared by the thermal polycondensation method. Fe/g-C₃N₄ of 15 wt% can reach 98.59% under the best degradation environment, and the degradation rate of g-C₃N₄ is only 7.6% under the same conditions. The photocatalytic activity of the catalysts was further studied. Through active species capture experiments, it is known that •OH and •O₂⁻ are the main active species in the system, and the action intensity of •OH is greater than that of •O₂⁻. The degradation reaction mechanism is that H₂O₂ combines with Fe²⁺ in Fe/g-C₃N₄ to generate a large amount of •OH and Fe³⁺, and the combination of Fe-N bonds accelerates the cycle of Fe³⁺/Fe²⁺ and promotes the formation of •OH, thereby accelerating the degradation of target pollutants. •O₂⁻ can reduce Fe³⁺ to Fe²⁺, Fe²⁺ reacts with H₂O₂ to produce •OH, which promotes degradation, and •O₂⁻ itself also plays a role in degradation. In addition, under the optimal experimental conditions obtained by response surface experiments, the fitting degree of first-order reaction kinetics is 0.96642, and the fitting degree of second-order reaction kinetics is 0.57884. Therefore, this reaction is more in line with first-order reaction kinetics. The adsorption rate is only proportional to the concentration of Fe/g-C₃N₄. Full article

The removal of cationic dyes from industrial wastewater presents a significant environmental challenge. This research examines the effectiveness of functionalized cellulose-based silica aerogels as sustainable adsorbents for methylene blue (MB) dye. This research provides a systematic comparative study on the effectiveness of four distinct functionalization strategies, carboxylate (CCNC), double carboxylate (DCCNC), carboxymethyl (CMC), and thiol-modification, applied to cellulose-based silica aerogels as sustainable adsorbents for methylene blue (MB) dye. Cellulose nanocrystals (CNCs) were extracted from sugarcane bagasse waste and subsequently functionalized into carboxylate (CCNC), double carboxylate (DCCNC), carboxymethyl (CMC), and thiol-modified variants. The materials were later integrated into a silica matrix, resulting in the formation of porous aerogel nanocomposites. The materials underwent thorough characterization through FTIR, XRD, SEM, TGA, and BET analyses, validating successful functionalization and the development of mesoporous structures. Batch adsorption tests demonstrated that the CMC-silica aerogel exhibited superior performance, attaining a maximum adsorption capacity of 197 mg/g and complete removal efficiency under ideal circumstances (pH 10, 25 °C, 60 min). The adsorption process is accurately characterized by the Langmuir isotherm and pseudo-second-order kinetic models, signifying monolayer adsorption and chemisorption as the rate-limiting step. The thermodynamic parameters indicate that the adsorption process is exothermic and spontaneous. The CMC-silica aerogel exhibited significant reusability, maintaining over 90% efficiency after six consecutive cycles. The findings illustrate the efficacy of functionalized cellulose–silica aerogels, especially the CMC form, as effective, environmentally sustainable, and reusable adsorbents for the treatment of dye-polluted water. Full article

Tidal dynamics substantially govern nearshore circulation patterns. The discharge of sewage at different tidal stages may have a significant impact on the dilution of pollutants. However, discussions on tidal phase sewage discharge strategy are still rare. This study focuses on the narrow tidal passage in the Ningbo-Zhoushan sea area, which receives a large amount of coastal wastewater, but the role of the unique hydrodynamic processes in the dilution of pollutants in this region remains unclear. By using a combination of on-site measurements and the FVCOM-dye simulation method, the scenario of high-concentration sewage retention in the tidal passage was demonstrated. The coastal residual circulation formed by strong tidal currents confined over 78% of the tracers within a 3 km range near the shore, and a subsurface dye accumulation zone emerged along the 25–50 m isobaths. Monsoon transitions regulated pollution plumes, inducing 5–8% seasonal variability in pollution footprints controlled by wind-tide-stratification interplay. The tidal phase discharge strategy was revealed to be highly effective in this study; both submerged discharge in deep-water zones and intermittent discharge strategies implemented in shallow-water zones significantly reduce the spatial coverage of high-concentration sewage plumes. Our findings highlight the importance of formulating discharge strategies based on tidal phases in typical narrow and deep tidal passages. Full article

Textile dyeing wastewater, rich in recalcitrant organic compounds such as azo and anthraquinone dyes, poses significant environmental concerns. This study investigates the degradation of methyl orange (MO) using two ozone (O₃) oxidation systems—O₃/H₂O₂ and O₃/K₂S₂O₈—and analyzes the degradation products and toxicity via ESR characterization. The O₃/K₂S₂O₈ system shows a higher removal rate in the initial stage (<4 min) due to rapid ·SO₄^- radical generation. However, O₃/H₂O₂ produces more ·OH radicals, leading to better overall degradation performance. The O₃/K₂S₂O₈ system is more effective for pollutants with electron-rich groups, such as Congo red and sulfamethoxazole, while O₃/H₂O₂ performs better in natural lake water. Mechanistic studies reveal that ·O₂^- is the dominant oxidizing species in O₃/H₂O₂, while ·SO₄^- and ·O₂^- dominate in O₃/K₂S₂O₈. The toxicity of degradation products is assessed, showing lower bioaccumulation and developmental toxicity in most intermediate products compared to MO. This research provides valuable insights into the use of combined ozonation-peroxidation coupling technology for effective wastewater treatment. Full article

This study transformed discarded courgette biomass into biochar (BC) via pyrolysis at 500 °C and employed it as an activator of potassium periodate (PI) for atrazine (ATZ) degradation. Characterization analyses confirmed that the synthesized BC possessed a porous structure, a high carbon content (76.13%), crystalline SiO₂, KCl, and CaCO₃ phases, as well as abundant oxygen-containing functional groups (–OH, C=O, C=C, –COOH), which are favorable for catalytic activation. The point of zero charge of 4.25 indicates that the BC surface carries a suitable charge distribution, promoting effective electrostatic interactions under near-neutral pH conditions. Under optimal operating conditions (neutral pH, [ATZ]_o = 7.3 mg/L, [PI]_o = 2.7 mM, [BC]_o = 0.55 g/L, and 25 ± 0.5 °C), the system achieved 99.35% ATZ removal (first-order kinetic rate constant = 0.0601 min⁻¹) and 64.23% TOC mineralization within 60 min. Quenching tests confirmed iodate radicals and singlet oxygen as the primary species, with hydroxyl and superoxide radicals playing secondary roles. The proposed mechanism suggests that electron transfer from oxygen-containing groups on the BC surface activates PI, leading to the generation of reactive oxygen species that facilitate ATZ degradation via synergistic radical and non-radical pathways. The BC catalyst exhibited strong recyclability, with only ~9% efficiency loss after five cycles. The BC/PI system also demonstrated high removal of tetracycline (79.54%) and bisphenol A (85.6%) within 60 min and complete Congo red dye degradation in just 30 min. Application to real industrial wastewater achieved 72.77% ATZ removal, 53.02% mineralization, and a treatment cost of 1.2173 $/m³, demonstrating the practicality and scalability of the BC/PI system for sustainable advanced wastewater treatment. Full article

The fashion and textile industry (FTI) is a significant contributor to greenhouse gas emissions, resource consumption, and waste generation, necessitating sustainable alternatives. Chitosan, a biodegradable and renewable biopolymer, has shown potential in reducing environmental impact throughout the textile lifecycle. However, existing studies often focus on isolated applications rather than its broader role in industrial sustainability. This review synthesises findings from 142 academic studies to assess chitosan’s applications in textile production, dyeing, finishing, and waste management, emphasising its impact on energy efficiency, carbon reduction, and resource circularity. Chitosan’s biodegradability, antimicrobial properties, and affinity for sustainable dyeing offer a viable alternative to synthetic materials while also enhancing wastewater treatment and eco-friendly finishing techniques. By evaluating its contributions to sustainable manufacturing, this review highlights its potential in supporting decarbonisation and circular economy transitions within the textile sector, while also identifying challenges for future research. Full article

The photocatalytic degradation of Crystal Violet (CV) using ZnO-based nanomaterials presents a promising solution for addressing water pollution caused by synthetic dyes. This review highlights the exceptional efficiency of ZnO and its modified forms—such as doped, composite, and heterostructured variants—in degrading CV under both ultraviolet (UV) and solar irradiation. Key advancements include strategic bandgap engineering through doping (e.g., Cd, Mn, Co), innovative heterojunction designs (e.g., n-ZnO/p-Cu₂O, g-C₃N₄/ZnO), and composite formations with graphene oxide, which collectively enhance visible-light absorption and minimize charge recombination. The degradation mechanism, primarily driven by hydroxyl and superoxide radicals, leads to the complete mineralization of CV into non-toxic byproducts. Furthermore, this review emphasizes the emerging role of Artificial Neural Networks (ANNs) as superior tools for optimizing degradation parameters, demonstrating higher predictive accuracy and scalability compared to traditional methods like Response Surface Methodology (RSM). Potential operational challenges and future directions—including machine learning-driven optimization, real-effluent testing potential, and the development of solar-active catalysts—are further discussed. This work not only consolidates recent breakthroughs in ZnO-based photocatalysis but also provides a forward-looking perspective on sustainable wastewater treatment strategies. Full article

The manufacturing techniques, structural features, and optical attributes of titanium dioxide (TiO₂) nanoparticles are highlighted in this study. These nanoparticles are notable for their remarkable photocatalytic activity, cheap cost, chemical stability, and biocompatibility. TiO₂ consists of three polymorph structures: anatase, rutile, and brookite. Because of its electrical characteristics and large surface area, anatase is the most efficient for photocatalysis when exposed to UV light. The crystallinity, size, and shape of titania nanoparticles (NPs) are influenced by diverse production techniques. Sol-gel, hydrothermal, solvothermal, microwave-assisted, and green synthesis with plant extracts are examples of common methods. Different degrees of control over morphology and surface properties are possible with each approach, and these factors ultimately affect functioning. For example, microwave synthesis provides quick reaction rates, whereas sol-gel enables the creation of homogeneous nanoparticles. XRD and SEM structural investigations validate nanostructures with crystallite sizes between 15 and 70 nm. Particle size, synthesis technique, and annealing temperature all affect optical characteristics such as bandgap (3.0–3.3 eV), fluorescence emission, and UV-visible absorbance. Generally speaking, anatase has a smaller crystallite size and a greater bandgap than rutile. TiO₂ nanoparticles are used in gas sensing, food packaging, biomedical coatings, dye-sensitized solar cells (DSSCs), photocatalysis for wastewater treatment, and agriculture. Researchers are actively exploring methods like adding metals or non-metals, making new composite materials, and changing the surface to improve how well they absorb visible light. Full article

Emerging contaminants such as per- and polyfluoroalkyl substances (PFASs) pose significant challenges for conventional wastewater treatment technologies. Non-thermal plasma (NTP) has gained attention as a promising advanced oxidation process capable of degrading persistent pollutants via hydrated electrons and reactive oxygen/nitrogen species under ambient conditions. This review summarizes recent progress in the application and scale-up of NTP for water treatment, with a focus on reactor configurations, degradation mechanisms, and energy efficiency. Key plasma reactor types—including dielectric barrier discharge, corona discharge, plasma jets, and gliding arc discharge—are evaluated for their suitability in large-scale applications. Pilot-scale studies addressing pharmaceuticals, dyes, and PFASs are reviewed to assess scalability, cost, and operational viability. Although NTP systems consistently achieve >80% contaminant removal, optimizing energy use and maintaining performance across complex water matrices remain critical challenges. Hybrid systems integrating NTP with ozonation, ultrafiltration, or cavitation show potential to improve treatment efficacy and reduce energy demands. Future research priorities include reactor design optimization, contaminant-specific plasma tuning, and technoeconomic analysis to support the translation of NTP technologies from lab-scale innovation to field-scale implementation. Full article

The discharge of dye-laden effluents remains an environmental challenge since conventional treatments remove color but not the organic load. This study systematically compared anodic oxidation (AO), electro-Fenton (EF), and photoelectro-Fenton (PEF) processes for three representative industrial dyes, such as Coriasol Red CB, Brown RBH, and Blue VT, and their ternary mixture, using boron-doped diamond (BDD) and Ti/IrO₂–SnO₂–Sb₂O₅ (MMO) anodes. Experiments were conducted in a batch reactor with 50 mM Na₂SO₄ at pH = 3.0 and current densities of 20–60 mA cm⁻². Kinetic analysis showed that AO-BDD was most effective at low pollutant loads, EF-BDD became superior at medium loads due to efficient H₂O₂ electrogeneration, and PEF-MMO dominated at higher loads by fast UVA photolysis of surface Fe(OH)²⁺ complexes. In a ternary mixture of 120 mg L⁻¹ of dyes, EF-BDD and PEF-MMO achieved >98% decolorization in 22–23 min with pseudo-first-order rate constants of 0.111–0.136 min⁻¹, whereas AO processes remained slower. COD assays revealed partial mineralization of 60–80%, with EF-BDD providing the most consistent reduction and PEF-MMO minimizing treatment time. These findings confirm that decolorization overestimates efficiency, and electrode selection must be tailored to dye structure and effluent composition. Process selection rules allow us to conclude that EF-BDD is the best robust dark option, and PEF-MMO, when UVA is available, offers practical guidelines for cost-effective electrochemical treatment of textile wastewater. Full article

Textile industries release dyes into wastewater, and when present above certain levels, these dyes pose serious risks because of their high toxicity. This study investigates the removal of Sunset Yellow (SY) and Methylene Violet (MV) dyes from wastewater using chitosan (CS) and polysilicate acid (pSi) in the structure of aluminum-based coagulants, resulting in hybrid formulations (CS@Al, Al/pSi, and CS@Al/pSi). Among the various treatment methods that have been applied for the removal of dyes, the coagulation/flocculation process was chosen in the present study, as it is a cheap and effective method. Coagulation performance was optimized for pH, coagulant dosage, temperature and mixing time. The Al/pSi coagulant achieved nearly complete SY removal (98.8%) at 25 mg/L dosage and pH 3.0. MV removal in single-dye solutions was limited, with Al/pSi achieving only 26.6% removal at pH 3.0. However, in mixed-dye systems (SY/MV), synergistic interactions increased MV removal up to 94.4% and SY removal to 100%. Hybrid CS@Al/pSi showed lower SY removal (36.4%) for SY at 50 mg/L but provided stable floc formation, particularly in mixtures of anionic and cationic dyes. Application to real textile wastewater confirmed the high efficiency of the optimized coagulants, particularly with Al/pSi_20,A and AlCl₃, indicating their potential for industrial wastewater treatment. SEM, EDS, XRD, and FTIR analyses revealed structural consolidation, increased surface area, and successful dye adsorption, explaining the high removal efficiency. Full article