Copper(II)-Doped Carbon Dots as Catalyst for Ozone Degradation of Textile Dyes

Application of Engineered Nanomaterials as Nanocatalysts in Catalytic Ozonation: A Review

Given the growing scarcity of water and the continuous increase in emerging pollutants detected in water bodies, there is an imperative need to develop new, more effective, and sustainable treatments for wastewater. Advanced oxidation processes (AOPs) are considered a competitive technology for water treatment. Specifically, ozonation has received notable attention as a promising approach for degrading organic pollutants in wastewater. However, different groups of pollutants are hardly degradable via single ozonation. With continuous development, it has been shown that using engineered nanomaterials as nanocatalysts in catalytic ozonation can increase efficiency by turning this process into a low-selective AOP for pollutant degradation. Nanocatalysts promote ozone decomposition and form active free radicals responsible for increasing the degradation and mineralization of pollutants. This work reviews the performances of different nanomaterials as homogeneous and heterogeneous nanocatalysts in catalytic ozonation. This review focuses on applying metal- and carbon-based engineered nanomaterials as nanocatalysts in catalytic ozonation and on identifying the main future directions for using this type of AOP toward wastewater treatment.

Carbon Dots: Synthesis, Characterizations, and Recent Advancements in Biomedical, Optoelectronics, Sensing, and Catalysis Applications

Carbon nanodots (CNDs), a fascinating carbon-based nanomaterial (typical size 2-10 nm) owing to their superior optical properties, high biocompatibility, and cell penetrability, have tremendous applications in different interdisciplinary fields. Here, in this Review, we first explore the superiority of CNDs over other nanomaterials in the biomedical, optoelectronics, analytical sensing, and photocatalysis domains. Beginning with synthesis, characterization, and purification techniques, we even address fundamental questions surrounding CNDs such as emission origin and excitation-dependent behavior. Then we explore recent advancements in their applications, focusing on biological/biomedical uses like specific organelle bioimaging, drug/gene delivery, biosensing, and photothermal therapy. In optoelectronics, we cover CND-based solar cells, perovskite solar cells, and their role in LEDs and WLEDs. Analytical sensing applications include the detection of metals, hazardous chemicals, and proteins. In catalysis, we examine roles in photocatalysis, CO2 reduction, water splitting, stereospecific synthesis, and pollutant degradation. With this Review, we intend to further spark interest in CNDs and CND-based composites by highlighting their many benefits across a wide range of applications.

A review on existing and emerging approaches for textile wastewater treatments: challenges and future perspectives

This comprehensive review explores the complex environment of textile wastewater treatment technologies, highlighting both well-established and emerging techniques. Textile wastewater poses a significant environmental challenge, containing diverse contaminants and chemicals. The review presents a detailed examination of conventional treatments such as coagulation, flocculation, and biological processes, highlighting their effectiveness and limitations. In textile industry, various textile operations such as sizing, de-sizing, dyeing, bleaching, and mercerization consume large quantities of water generating effluent high in color, chemical oxygen demand, and solids. The dyes, mordants, and variety of other chemicals used in textile processing lead to effluent variable in characteristics. Furthermore, it explores innovative and emerging techniques, including advanced oxidation processes, membrane filtration, and nanotechnology-based solutions. Future perspectives in textile wastewater treatment are discussed in-depth, emphasizing the importance of interdisciplinary research, technological advancements, and the integration of circular economy principles. Numerous dyes used in the textile industry have been shown to have mutagenic, cytotoxic, and ecotoxic potential in studies. Therefore, it is necessary to assess the methods used to remediate textile waste water. Major topics including the chemical composition of textile waste water, the chemistry of the dye molecules, the selection of a treatment technique, the benefits and drawbacks of the various treatment options, and the cost of operation are also addressed. Overall, this review offers a valuable resource for researchers and industry professionals working in the textile industry, pointing towards a more sustainable and environmentally responsible future.

Application of Fluorescent Carbon Dots as Catalysts for the Ring-Opening Reaction of Epoxides

Considering the increased anthropogenic emissions of CO2 into the atmosphere, it is important to develop economic incentives for the use of CO2 capture methodologies. The conversion of CO2 into heterocyclic carbonates shows significant potential. However, there is a need for suitable organocatalysts to reach the required efficiency for these reactions. Given this, there has been an increasing focus on the development of organocatalytic systems consisting of a nucleophile and a hydrogen bond donor (HBD) so that CO2 conversion can occur in ambient conditions. In this work, we evaluated the potential of fluorescent carbon dots (CDs) as catalytic HBDs in the ring-opening reaction of epoxides, which is typically the rate-limiting step of CO2 conversion reactions into heterocyclic carbonates. The obtained results demonstrated that the CDs had a relevant catalytic effect on the studied model reaction, with a rate constant of 0.2361 ± 0.008 h-1, a percentage of reactant conversion of 70.8%, and a rate constant enhancement of 32.2%. These results were better than the studied alternative molecular HBDs. Thus, this study demonstrated that CDs have the potential to be used as HBDs and employed in organocatalyzed CO2 conversion into value-added products.

Recent Strategies for the Remediation of Textile Dyes from Wastewater: A Systematic Review

The presence of dye in wastewater causes substantial threats to the environment, and has negative impacts not only on human health but also on the health of other organisms that are part of the ecosystem. Because of the increase in textile manufacturing, the inhabitants of the area, along with other species, are subjected to the potentially hazardous consequences of wastewater discharge from textile and industrial manufacturing. Different types of dyes emanating from textile wastewater have adverse effects on the aquatic environment. Various methods including physical, chemical, and biological strategies are applied in order to reduce the amount of dye pollution in the environment. The development of economical, ecologically acceptable, and efficient strategies for treating dye-containing wastewater is necessary. It has been shown that microbial communities have significant potential for the remediation of hazardous dyes in an environmentally friendly manner. In order to improve the efficacy of dye remediation, numerous cutting-edge strategies, including those based on nanotechnology, microbial biosorbents, bioreactor technology, microbial fuel cells, and genetic engineering, have been utilized. This article addresses the latest developments in physical, chemical, eco-friendly biological and advanced strategies for the efficient mitigation of dye pollution in the environment, along with the related challenges.

Nanomaterial-Based Advanced Oxidation/Reduction Processes for the Degradation of PFAS

This review focuses on a critical analysis of nanocatalysts for advanced reductive processes (ARPs) and oxidation processes (AOPs) designed for the degradation of poly/perfluoroalkyl substances (PFAS) in water. Ozone, ultraviolet and photocatalyzed ARPs and/or AOPs are the basic treatment technologies. Besides the review of the nanomaterials with greater potential as catalysts for advanced processes of PFAS in water, the perspectives for their future development, considering sustainability, are discussed. Moreover, a brief analysis of the current state of the art of ARPs and AOPs for the treatment of PFAS in water is presented.

Magnetic porous Ag2O/Chitin nanostructure adsorbent for eco-friendly effective disposing azo dyes

Water treatment is as much important as it is to satisfying 11 worldwide sustainable development goals out of 17. The removal of Azo is much important as they are toxic and their existence in water, air and food can easily affect humans by triggering allergies, forming tumours etc. Azo contained Dyes Production was banned in many countries. This research aims to synthesize composite Nanorods and Nanospheres and characterize and test to remove Azo dyes from the wastewater. This research used a previously reported method to rapidly synthesize chitin magnetite nanocomposites (ChM) by co-precipitation while irradiating with ultrasound (US). Detailed structural characterization of ChM revealed a crystalline phase analogous to magnetite and spherical morphologies; extending the reaction time to 8 min yielded a "nanorod" type morphology. Both the morphologies displayed a nanoscale limit with particles averaging between 5 and 30 nm in size, resulting the superparamagnetic performance and saturation magnetization values between 45 and 58 emu/g. The nitrogen adsorption-desorption isotherms showed that the surface modification of ChMs resulted in a rise of specific surface area and pore size. Anionic azo dyes (methyl orange (MO) and reactive black 5 (RB5)) adsorption on the surface of nanocomposites was also demonstrated to be pH-dependent, with the reaction favoured for surface-modified samples at pH 4 and unmodified samples at pH 8. Adsorption capacity studies showed that molecule size effect and electrostatic attraction were two distinct adsorption processes for unmodified and modified ChMs. Chitin Magnetite nanoparticles appear to be a substitute for traditional anionic dye adsorbents. Additionally, the two key materials sources, chitin, and magnetite are inexpensive and easily accessible.

Homogeneous and Heterogeneous Catalytic Ozonation of Textile Wastewater: Application and Mechanism

This paper presents an overview of textile wastewater treatment by catalytic ozonation, highlighting the parameters of the process and accompanying mechanisms. Since more than 800,000 tons of dyes are produced annually and thousands of cubic meters of highly polluted textile wastewater have been emitted into the environment every day, this issue has become an environmental concern. Due to the high oxidative potential of ozone (2.08 V) and hydroxyl radical (2.80 V), the main reactive species in catalytic ozonation, the burdensome organic pollutants, including textile dyes, can be successfully decomposed. The paper shows the main groups of catalysts, emphasizing novel structural, nano-structured, and functionalized materials. The examples of catalytic ozonation in the industrial application for real textile wastewater were specially highlighted.

UV-Based Advanced Oxidation Processes of Remazol Brilliant Blue R Dye Catalyzed by Carbon Dots

UV-based advanced oxidation processes (AOPs) (UV/H₂O₂ and UV/S₂O₈^2-) with a titanium(IV)-doped carbon dot, TiP-CD, as a catalyst were developed for the decomposition of Remazol Brilliant Blue R (Reactive Blue 19), an anthraquinone textile dye (at T = 25 °C and pH = 7). The Ti-CD, with marked catalytic UV properties, was successfully synthesized by the one-pot hydrothermal procedure, using L-cysteine as carbon precursor, ethylenediamine as nitrogen source, PEG (polyethylene glycol) as a capping agent, and titanium(IV) isopropoxide (precursor of TiO₂ doping). Contrary to azo dyes (methyl orange, orange II sodium salt, and reactive black 5), which achieved complete degradation in a time interval less than 30 min in the developed AOP systems (UV/H₂O₂, UV/S₂O₈^2-, and UV/TiO₂), the RBB-R showed relatively low degradation rates and low discoloration rate constants. In the presence of the catalyzer, the reaction rate significantly increased, and the pseudo-first-order rate constants for the RBB-R discoloration were UV/3.0 mM H₂O₂/TIP-CD-0.0330 min^-1 and UV/1.02 mM S₂O₈^2-/TIP-CD-0.0345 min^-1.