Sustainable Bio-Based Adsorbents for Simultaneous and Efficient Removal of Hazardous Dyes from Aqueous Solutions

Dhwani Vara; Stuti Jha; Shweta Bisht; Syed Shahabuddin; Rama Gaur; Suhas; Inderjeet Tyagi

doi:10.3390/toxics12040266

Sustainable Bio-Based Adsorbents for Simultaneous and Efficient Removal of Hazardous Dyes from Aqueous Solutions

Toxics. 2024 Apr 1;12(4):266. doi: 10.3390/toxics12040266.

Authors

Dhwani Vara¹, Stuti Jha¹, Shweta Bisht², Syed Shahabuddin¹, Rama Gaur¹, Suhas³, Inderjeet Tyagi⁴

Affiliations

¹ Department of Chemistry, School of Energy Technology, Pandit Deendayal Energy University, Knowledge Corridor, Raisan, Gandhinagar 382426, Gujarat, India.
² Division of Research and Innovation, School of Applied and Life Sciences, Uttaranchal University, Dehradun 248007, Uttarakhand, India.
³ Department of Chemistry, Gurukul Kangri (Deemed to be University), Hardwar 249404, Uttrakhand, India.
⁴ Centre for DNA Taxonomy, Molecular Systematics Division, Zoological Survey of India, M-Block, New Alipore, Kolkata 700053, West Bengal, India.

Abstract

Dyes provide a notable environmental issue as a result of their intrinsic poisonous and carcinogenic characteristics. An estimated 60,000 metric tons of dyes has been discharged into the environment, leading to a substantial increase in water pollution. The mitigation of these dyes is a substantial and intricate challenge. The primary objective of this research is to conduct a comprehensive analysis of the adsorption of cationic dyes containing positively charged groups such as sulphonates, amines, and triphenylmethanes. The adsorption study was carried out using four different low-cost adsorbents derived from biowaste, specifically Groundnut Shell (GS), Mosambi Peel (MP), Mango Bark (MBARK), and Mango Leaves (ML). The adsorbent materials were characterized using FTIR, UV-Vis spectroscopy, scanning electron microscopy (SEM), point-of-zero charge (PZC), and BET techniques. The adsorption capacity was found to be between 1.5 and 2.2 mg/gm for Groundnut Shell, Mosambi Peel, Mango Bark, and Mango Leaves for individual dye removal (Crystal violet, Methylene blue, Rhodamine B, and Malachite green). It was observed that adsorbent derived from mango bark showed excellent adsorption (%) in a mono-component dye system and, thus, was explored for the simultaneous removal of a mixture of the same dyes. MBARK exhibited an excellent overall dye removal efficiency of 94.44% (Q_e = 2.7 mg/g) for the dye mixture in 60 min. From a detailed kinetic investigation, it was concluded that the adsorption followed the pseudo-second-order model (R²= 0.99963 to 1 for different dyes and adsorbents) hinting at chemisorption. The effect of the pH of the analyte solution and the dosage of adsorbent was also studied for simultaneous removal. The isothermal studies demonstrated that the Langmuir adsorption model (R² = 0.99416) was the best-fitted model, suggesting monolayer adsorption. The adsorption process was predicted to be governed by ion exchange, electrostatic interaction, hydrogen bonding, pi-pi interaction, etc., based on charge, functional groups, and pH of dyes and adsorbent. Thus, this study highlights the application of low-cost biowaste as a potential adsorbent for the mitigation of toxic industrial dyes present in wastewater.

Keywords: adsorption; bio-based adsorbent; cationic dyes; wastewater remediation.

Grants and funding

The authors would like to thank Pandit Deendayal Energy University, Student Research Programme for financial aid for the project (R&D/SRP-2022-004) and the Government of Gujarat for the award of research fellowship (KCG/SHODH/2022-23/202101586) under the Scheme for Developing High-Quality Research.