INTRODUCTION

There are many methods available to treat organic pollutants in an aqueous environment such as adsorption, membrane technology, photocatalysis, coagulation, ozonation and biological treatment. The existence of pollutants in the aquatic environment or wastewater not only hinders the transmission of light which threatens the survival of aquatic organisms, but it can also lead to toxicity as well as dysfunction of liver, kidney and reproductive systems in human beings when consumed. Among these contaminants, stand out are dyes, heavy metals, and oily wastewater. Adsorption is a useful unit operation able to remove contaminants from wastewaters. Adsorption has several advantages including low cost, simple operation and implementation, high efficiency, and abundant source for adsorbent synthesis. 

The abundant of biomass waste opens an opportunity in wastewater treatment area.  Synthesis of carbon quantum dots (CQDs) as advanced material using natural carbon precursors is highly preferable considering its low cost, eco-friendly and the unexploited usage of by-product. One of the main crops cultivated is sugarcane with approximately ∼1.6 billion tons annual world production. This crop generates roughly ∼279 million metric tons (MMT) of biomass residues (bagasse and leaves). Sugarcane bagasse (SB) has been explored to be converted to CQDs from SB for naphthalene removal. Additionally, CQDs from sugarcane bagasse has been produced with a high quantum yield approximately at 18.7%. The pairing of CQDs with photocatalyst has shown its unique and promising potential for wastewater treatment. 

The recovery of valuable materials such as manganese from the sludge is an alternative path towards zero dumping of schedule waste as well as away of reducing the possible pollutant release to the environment. It can be achieved through adsorption, as it provides a cheap yet flexible, method which is simple and easy to implement. Several adsorbents have been developed from different materials to enhance the adsorption performance while significantly reducing the cost and being environmentally friendly and sustainable. Natural materials and certain industrial wastes have the potential to be used as a low-cost adsorbent, for instance, agricultural wastes that are usually porous, lightweight and have carboxyl as well as hydroxyl functional group on their surface, are suitable for use as adsorbent.