The rapid increase in toxic dye wastewater generated from various industries remains a severe public health issue and prime environmental protection concern, posing a major challenge to existing conventional water treatment systems. Consequently, various physicochemical and biological treatment processes have been studied, which exhibit varying removal abilities depending on their experimental constraints. Among them, adsorption is considered to be the most efficient due to its high removal efficiency, easy operation, cost-effectiveness, and recyclability of the adsorbents. Considering this, the present review article focused on presenting a comprehensive summary of the various types of adsorbents such as commercial activated carbon, metal oxide-based, carbon-based, metal–organic framework, and polymer-based adsorbents used in dye remediation of contaminated water. The effects of several critical factors such as initial dye concentration, solution pH, temperature, and adsorbent dose on the dye adsorption performance are also described. In addition, the adsorption mechanisms responsible for dye removal are explained based on electrostatic attraction, ion exchange, surface complexation, and π–π interactions. Finally, critiques, future perspectives, and a summary of the present article are given. Various adsorbents such as carbon-based materials, metal oxides, bio-adsorbents, and polymer-based materials, have been shown to be efficient for the removal of dye pollutants from wastewater. Thus, it is anticipated that dye removal by adsorption can provide a feasible solution for the treatment of dye-laden water.

/pdf/recent-advances-on-the-removal-of-dyes-from-wastewater-using-3bk6szbeul.pdf

Recent advances on the removal of dyes from wastewater using various adsorbents: A critical review

The unavailability of clean drinking water is one of the significant health issues in modern times. Industrial dyes are one of the dominant chemicals that make water unfit for drinking. Among these dyes, methylene blue (MB) is toxic, carcinogenic, and non-biodegradable and can cause a severe threat to human health and environmental safety. It is usually released in natural water sources, which becomes a health threat to human beings and living organisms. Hence, there is a need to develop an environmentally friendly, efficient technology for removing MB from wastewater. Photodegradation is an advanced oxidation process widely used for MB removal. It has the advantages of complete mineralization of dye into simple and nontoxic species with the potential to decrease the processing cost. This review provides a tutorial basis for the readers working in the dye degradation research area. We not only covered the basic principles of the process but also provided a wide range of previously published work on advanced photocatalytic systems (single-component and multi-component photocatalysts). Our study has focused on critical parameters that can affect the photodegradation rate of MB, such as photocatalyst type and loading, irradiation reaction time, pH of reaction media, initial concentration of dye, radical scavengers and oxidising agents. The photodegradation mechanism, reaction pathways, intermediate products, and final products of MB are also summarized. An overview of the future perspectives to utilize MB at an industrial scale is also provided. This paper identifies strategies for the development of effective MB photodegradation systems.

https://www.mdpi.com/2073-4441/14/2/242/pdf?version=1642404093

Review on Methylene Blue: Its Properties, Uses, Toxicity and Photodegradation

Treatments for color removal from wastewater: State of the art.

Several industries release varying concentration of dye-laden effluent with substantial negative consequences for any receiving environmental compartment. The control of water pollution and tighter restriction on wastewater discharge directly into the environment to reduce the potential ecotoxicological effect of dyes is forcing processors to retreat and reuse process water and chemicals. Among the different available technologies, the adsorption process has been recognized to be one of the finest and cost-effective wastewater treatment technologies. Various adsorbents have been utilized to remove toxic dyes from water and wastewater. Here, we review the application of polyaniline-based polymeric adsorbent for the adsorption of dyes which have been received considerable attention. To date, various modifications of polyaniline have been explored to improve the adsorption properties. Review on the application of polyaniline for adsorption of dyes has not been present till date. This article provides relevant literature on the application of various polyaniline composites for removing dyes, and their adsorption capacities with their experimental conditions have been compiled. It is evident from the literature survey that polyaniline provides a better opportunity for scientists for the effective removal of various dye.

Application of polyaniline-based adsorbents for dye removal from water and wastewater—a review

Magsorbents: Potential candidates in wastewater treatment technology – A review on the removal of methylene blue dye

Contamination of water is calling for new techniques to provide safe and clean water for drinking and other usages. Among existing techniques of wastewater treatment, adsorption is one of the most efficient methods. Recently, carbon nanotube-based adsorbents are attracting research and industrial attention due to their large surface area, cylindrical hollow structure and well-flourished mesopores. Raw carbon nanotubes can be modified and adapted to the intended applications and targeted pollutants. Here we review the efficacy of unmodified and modified carbon nanotubes for the removal of dyes from wastewater. Reports show that chemical modification leads to an improvement of the adsorption capacity. The adsorption of dyes on carbon nanotubes depends on the nature of the adsorbent and adsorbate. Adsorption mechanisms involve van der Waals forces, π–π stacking, hydrophobic interactions, hydrogen bonding and electrostatic interactions. Nonetheless, hydrophobicity and cost actually restrict practical applications.

Carbon nanotube-based adsorbents for the removal of dyes from waters: A review

Present investigation explores the possible reusability of synthetically contaminated wastewater containing crystal violet (CV) organic dye using Tectona grandis sawdust (TGSD) waste as a very low-cost adsorbent. The adsorbent was characterized by proximate, SEM/EDX, FTIR, and XRD analyses. Batch adsorption studies were carried under changing conditions of contact time, the initial concentration of CV, pH, TGSD dose, TGSD particle size, and temperature. The experimental data were tested using Langmuir, Freundlich and Temkin isotherm models, and the data were best followed by Langmuir one. The kinetic results were examined in the light of different models and pseudo-second-order was obtained to be best obeyed. The values of ΔH° (28.642 kJ/mol), ΔG° (-10.776 to -7.080 kJ/mol) and ΔS° (121.8 J/K/mol) in the temperature range of 293–323 K suggested the overall process to be spontaneous, endothermic and associated with an increase in randomness. On the basis of experimental results and their analyses, it has been established that TGSD is one of the most effective adsorbents among those obtained from the domestic, agricultural and industrial wastes. Thus this adsorbent can be effectively utilized to make the impure wastewater reusable.

/pdf/exploring-the-reusability-of-synthetically-contaminated-2e33l7zjpz.pdf

Exploring the Reusability of Synthetically Contaminated Wastewater Containing Crystal Violet Dye using Tectona grandis Sawdust as a Very Low-Cost Adsorbent

Preparation, characterization and adsorption studies of the chemically modified Luffa aegyptica peel as a potential adsorbent for the removal of malachite green from aqueous solution

Fouzia Mashkoor

Papers

Application of polyaniline-based adsorbents for dye removal from water and wastewater—a review

Magsorbents: Potential candidates in wastewater treatment technology – A review on the removal of methylene blue dye

Carbon nanotube-based adsorbents for the removal of dyes from waters: A review

Exploring the Reusability of Synthetically Contaminated Wastewater Containing Crystal Violet Dye using Tectona grandis Sawdust as a Very Low-Cost Adsorbent

Preparation, characterization and adsorption studies of the chemically modified Luffa aegyptica peel as a potential adsorbent for the removal of malachite green from aqueous solution