Textile dye is one of the significant pollutants of water worldwide. However, dumping the textile effluent to the environment is a common in most of the developing countries. Contaminated water in the textile industry may contain various toxic ingredients and people were easily infected with various diseases. The contamination may affect the marine environment and consequently extends around the world. The recycling of waste water is the significant option to reduce the environmental pollution. In particular, adsorption approach is one of the significant strategies to treat dye-contaminated water due to their advantageous of physico-chemical properties. In this review paper, variety of potential adsorbents for dye removal were critically reviewed, focusing on the efficient adsorbent to remediate dye-contaminated water. Specifically, the recent development of adsorbents containing carbon, metal supported adsorbents, surface functionalized gel adsorbents and photo-adsorbents were reviewed focusing on cutting-edge processes. Comparison of degradation efficiency for different adsorbents, synthesis approaches and their physico-chemical properties were assessed in systematic way. The perspective of the adsorbent materials associated with the dye degradation was discussed thoroughly. The evaluation of different advanced materials would contribute to the development of the sustainable dye removal process in near future.
Dyeing the fabric is one of the most polluter of water and textile dyeing is the second-largest polluter of water worldwide (Okafor et al., 2021). According to a United Nations World Water Development report, more than 80% of all the wastewater from different sectors is released to the environment without adequate treatment (Kataki et al., 2021). Releasing the fashion pollution from textile dyeing contaminates the groundwater. The repeated throwing of waste water into the environment reduces the necessary nutrients and fertilities from the soil. According to UNICEF, millions of people die each year due to the drinking of contaminated water (UNICEF, 2019). General public and policy maker should have strong commitment to manage waste water in a sustainable way. Hence, wastewater treatment is a significant issue that has been addressed by several researchers to find a sustainable treatment approach (Ibrahim et al., 2021a, Ibrahim et al., 2021b; Khandaker et al., 2021; Roy et al., 2022; Miah et al., 2021; Swaraz et al., 2021).
Several studies have been concentrated to develop efficient adsorbent for wastewater treatment (Najafi et al., 2021; Qi et al., 2021; Kubra et al., 2021a, Kubra et al., 2021b; Khan et al., 2021a, Khan et al., 2021b; Salman et al., 2021). Carbon and their composite materials was reported promising adsorbent for the removal of different types of dyes (Khan et al., 2021a, Khan et al., 2021b; Ibrahim et al., 2021a, Ibrahim et al., 2021b; Hasan et al., 2021, 2021a; Chowdhury et al., 2021; Rahman et al., 2020). The wide spectrum of waste water treatment using advanced carbon materials with engineered design was reported in the literature (Singh et al., 2021; Sultana et al., 2020). The ensnarement of various active materials with carbon-based composites showed noteworthy benefits because of their high surface area, tunable morphology (Dong et al., 2021). It is reasonable to mention that the complex synthesis process of adsorbent may not viable for industrial application.
Many researchers have focused on the application of the hydrogels and photocatalyst for the removal of dyes and various pollutants over the past few decades (Akter et al., 2021; Pereira et al., 2021; SinarMashuri et al., 2020; Taufiq-Yap et al., 2021; Hayase, 2021). The hydrogels prepared from the polymers are shown efficient for the removal of different kinds of pollutants (Akter et al., 2021). The use of semiconductor photocatalyst has been focused for the removal of pollutants from aqueous solution (Nasir et al., 2021; Suresh et al., 2021; Teo et al., 2021; Mansir et al., 2019; Taufiq-Yap et al., 2019). The narrower bandgap, tunable morphology, reduced electron/hole recombination properties are the main strength of photocatalyst for efficiently removal of contamination from water (Ray et al., 2021; Ghosh et al., 2018; How et al., 2017).
The use of electrocoagulation (EC) is a promising method for treating wastewater and removing dyes, due to the due to its simple operation, high removal efficiency, and reduced sludge production (Asfaha et al., 2021; Jing et al., 2021). Therefore, many researchers have concentrated to using electrocoagulation for wastewater treatment. Typically, the electrocoagulation/flocculation process, using composite materials such as aluminium and Iron could increase the environmental pollution levels by introducing non-biodegradable compounds (Igwegbe et al., 2021). The effectiveness of the EC process depends on the electrolyte concentration, pH, current density, applied voltage, operating temperature, electrode material and configurations. These variables would affect the overall removal efficiency, reaction kinetics, and treatment time (Igwegbe et al., 2021). Given the substantial number of studies on electrocoagulation, a conclusion has been reached by several researchers that EC process is efficient for the laboratory-scale tests.
Some emerging novel carbon composite for efficient removal of pollutants has been discussed by several researchers (Dong et al., 2021; Nasrollahzadeh et al., 2021; Janaun et al., 2016). Overall, these articles focused on composition of vcarbon providing limited view regarding to a broad research field. The sustainable bio-adsorbents for waste water treatment were reviewed by several researchers (Sheth et al., 2021; Solangi et al., 2021; Shahat et al., 2021) and effect of various operating parameters and future scope of the bioadsorbent were focused. Reviews on novel metal compoaiteadsorbent for heavy metal adsorption from wastewater have been published (Chai et al., 2021). Some attentions have been paid on the sustainability of dye removal from waste waterusing graphene based materials, especially, broad discussion on the graphene-based hybrid membrane materials were reported (Bhol et al., 2021; Velusamy et al., 2021). Works on the dye removal by photocatalyst and its detail properties have been reported aiming to find the efficient photocatalyst catalyst for waste water treatment (Nasir et al., 2021). An alternative approach to degradate from waste water using metal-organic framework (MOFs) membranes focusing the multifactors influenced on the MOF membranes (Uddin et al., 2021; Yu et al., 2021). However, only a limited review has been focused on the comprehensive catalytic adsorption process for dye degradation from waste water.
An attempt has been made in this review to provide overall catalytic adsorption process for dye degradation aiming to find the most efficient adsorption process. A critical discussion on the adsorbent properties and their mechanism involved in the dye degradation process has been provided. A comparison of several group of adsorbents and the future perspective towards the dye degradation has been outlined. This study will be useful to select suitable adsorbent in various dye degradation process and improve the knowledge about the cutting-edged adsorbent.
Adsorption emerges as an appealing technique to eliminate organic and natural pollutants such as dyes from the environment because the disposal of dyes such as azo, anthraquinone, nitrio, etc. into the water bodies may plunge the penetration of sunlight, consequently affect the marine life and environment (Javaid and Qazi, 2019). Adsorption is classified as a surface phenomenon, particularly, the adsorbate (molecule or ion) is adsorbed on the surface of adsorbent without penetrating into the adsorbent structure (Han et al., 2021) as shown in Fig. 1. Adsorption is basically happened in a physical or chemical way when the surface particles of the adsorbent (also known as surface energy) exhibiting irregular or leftover attractive forces that are inequivalent with the particles of bulk adsorbent. In this regard, having all the forces which are stabilized together and the excessive forces would attract adsorbate to the surface of adsorbent (Hessou et al., 2019; Alam et al., 2019; Abbas et al., 2018). Physical adsorption is the interaction between the adsorbent and adsorbate surface via weak van der Waals force where the weak bonding between adsorbate-adsorbent results in a reversible adsorption and desorption processes. Meanwhile, chemisorption is an irreversible process where adsorbate adsorbed to the surface of functional adsorbent through strong covalent bonds or electrostatic attraction, achieving effective separation (Zhou et al., 2019; Abdulkareem-Alsultan et al., 2022; Asikin-Mijan et al., 2021). Mutalib et al. (2020). Chemisorption is usually the monolayer generated on the adsorbent surface and happened at extremely high temperature than the critical temperature. Whilst, physisorption is usually multilayer generated on the adsorbent surface (Xia et al., 2019; Lee et al., 2019; Zainal et al., 2019; Ng et al., 2018). Three main steps to kick start the adsorption process includes (i) transport of dyes molecules to the absorbent's surface from an aqueous solution, (ii) adsorption of them onto the sorbent surface, and (iii) transport within the sorbent particle (Chai et al., 2021; Angove et al., 2019).
Date of Input: 21/02/2022 | Updated: 21/02/2022 | firstname.lastname@example.org