Adsorption of brilliant green dye on Nephelium mutabile (Pulasan) leaves

The main objective of this study is to investigate the ability of Nephelium mutabile (Pulasan) leaves (PL) in removing toxic brilliant green (BG) dye using the adsorption method. Batch experiments were conducted on the adsorption of BG dye using PL with a contact time of 3.5 h. Adsorption isotherm studies were analysed using six isotherm models, namely Langmuir, Freundlich, Temkin, Dubinin-Radushkevich (D-R), Redlich-Peterson (R-P) and Sips, and the results showed that Sips is the model that best fits the experimental data, with a maximum adsorption capacity (amax) of 130.3 mg g-1. The point of zero charge (pHPZC) of PL was found to be at pH 5.29. Regeneration studies showed that PL can be recovered and reused, especially after treatment with NaOH. This study demonstrates that PL can be considered as a reasonably good and cost-effective biosorbent for BG under our experimental conditions.