Banana peel as a biosorbent for the decontamination of water pollutants. A review

Pollution of environmental waters and ecosystems is increasing. Adsorption is an effective technique for water decontamination, but is limited by the cost of commercial adsorbents such as activated carbon. Research has thus focused on the recycling and transformation of biowaste as low-cost, biodegradable adsorbents. In particular, banana peel is promising for commercial use due to its wide availability and efficiency. Here, we review the use of natural banana peel for the biosorption of pollutants from water. We discuss the factors controlling pollutants removal, and the regeneration and reuse of the biosorbent. pH of 5.0 to 7.0 is favorable for the removal of cationic pollutants, while pH of 2.0 to 4.0 is suitable for anionic pollutants. Generally, higher pollutant concentration induces lower removal, whereas higher banana peel dosage induces higher removal. Banana peel exhibits efficient removal of pollutants at various temperatures, with adsorption capacities mostly within 1-100 mg/g. Nitric acid is the most efficient eluent for heavy metal desorption from banana peel. Most studies showed efficient biosorbent reuse up to five cycles and above. We also discuss the thermodynamics, kinetics and isotherms of the adsorption process.