Adsorption of Zn2+ from synthetic wastewater using dried watermelon rind (D-WMR): An overview of nonlinear and linear regression and error analysis

• Main Authors: Altowayti, W.A.H., Othman, N., Al-Gheethi, A., Dzahir, N.H.B.M., Asharuddin, S.M., Alshalif, A.F., Nasser, I.M., Tajarudin, H.A., Al-Towayti, F.A.H.
• Format: Article
• Published: MDPI 2021
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85118849673&doi=10.3390%2fmolecules26206176&partnerID=40&md5=066a3e03c619e75f3273e3f8a48a0e8a; http://eprints.utp.edu.my/32386/

Sustainable wastewater treatment is one of the biggest issues of the 21st century. Metals such as Zn2+ have been released into the environment due to rapid industrial development. In this study, dried watermelon rind (D-WMR) is used as a low-cost adsorption material to assess natural adsorbents� ability to remove Zn2+ from synthetic wastewater. D-WMR was characterized using scanning electron microscope (SEM) and X-ray fluorescence (XRF). According to the results of the analysis, the D-WMR has two colours, white and black, and a significant concentration of mesoporous silica (83.70). Moreover, after three hours of contact time in a synthetic solution with 400 mg/L Zn2+ concentration at pH 8 and 30 to 40 °C, the highest adsorption capacity of Zn2+ onto 1.5 g D-WMR adsorbent dose with 150 µm particle size was 25 mg/g. The experimental equilibrium data of Zn2+ onto D-WMR was utilized to compare nonlinear and linear isotherm and kinetics models for parameter determination. The best models for fitting equilibrium data were nonlinear Langmuir and pseudo-second models with lower error functions. Consequently, the potential use of D-WMR as a natural adsorbent for Zn2+ removal was highlighted, and error analysis indicated that nonlinear models best explain the adsorption data. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.