A comprehensive review on application of plant-based bioadsorbents for Congo red removal

Abstract

Rapid development of global printing and dyeing industry has enhanced the need of different dyes. Congo red (CR) dye is one of widely used dyes in dyeing industry due to its high chromaticity. So, CR with high chemical oxygen demand and biological toxicity imposes serious environmental issues. Study of removal of most resistant dyes such as CR can pave way for removal of other resistant dyes also. There are a lot of methods which can be employed for CR removal, but adsorption method has been found very efficient and economical for the removal of dyes with the material applied as an adsorbent playing a key rule. In this prospect, usage of bioadsorbents has been extensively investigated due to their distinctive properties, cost-effectiveness, easy availability, and green nature, which enable them to be utilized as adsorbents. The focus of this review is to elaborate the role of plant-based bioadsorbents for removal of CR dye via most efficient method of adsorption with critical comparison of different bioadsorbents through their isothermal, kinetic, and thermodynamic studies. In this regard, plant-based adsorbents are described here in detail. Moreover, the effect of different parameters such as pH, dosage, and surface morphology on activity is discussed here followed by regeneration of bioadsorbents. Thus, this review gives deep insight into the role of bioadsorbents for eradication of CR with insight for selection of the best candidate of bioadsorbent for desired results. Regeneration effectiveness and removal of other dyes along with CR have made bioadsorbents a very cost-effective choice for wastewater treatment. It also gave direction for designing of novel bioadsorbents using plant waste materials for wastewater treatment in future. We hope that the present comprehensive review could deliver scientists with preliminary data and guide the researcher involved in this field, allowing them to concentrate on the research gaps in water remediation. Graphical Abstract: [Figure not available: see fulltext.]