# Engineered biosorbents of pomelo (Citrus maxima (Burm.f.) Merr) peels modified with zinc oxide and titanium dioxide for methylene blue dye sorption

## TL;DR

Researchers created biosorbents from pomelo peels mixed with zinc and titanium oxides to efficiently remove methylene blue dye from water.

## Contribution

The novel use of pomelo peels modified with ZnO and TiO2 as biosorbents for methylene blue dye removal is introduced.

## Key findings

- PZTB showed the highest methylene blue dye removal efficiency of over 86%.
- The biosorbents retained over 72% efficiency after three reuse cycles.
- Sorption followed Freundlich isotherm and pseudo-second-order kinetic models.

## Abstract

The pomelo-doped zinc oxide beads (PZB), pomelo-doped titanium dioxide beads (PTB), and pomelo-doped zinc oxide and titanium dioxide beads (PZTB) were synthesized for sorbing methylene blue (MB) dye. Their characterizations were explored by X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy and Focus Ion Beam (FESEM-FIB), Energy Dispersive X-Ray Spectrometer (EDX), and Fourier Transform Infrared Spectroscopy (FT-IR). In addition, their sorbent efficiencies for sorbing MB dye were investigated through batch experiments, sorbent reusability studies, sorption isotherms, kinetics, and thermodynamic studies. They were crystalline phases presenting the specific peaks of zinc oxide (ZnO) or titanium dioxide (TiO2). Their surfaces had lamella structures with coarse surfaces, and they also found specific structures of ZnO or TiO2 on the surfaces. Zn–O or Ti–O–Ti was also detected in PZB or PTB or, PZTB depending upon metal oxide types added into pomelo beaded sorbents. For batch experiments, they could adsorb MB dye of more than 86%, and PZTB showed the highest MB dye removal efficiency. In addition, they could be reused for more than three cycles with high MB dye sorptions of more than 72%. They corresponded to Freundlich and pseudo-second-order kinetic models. Moreover, the increasing temperature affected their decreasing MB dye sorptions which were exothermic processes.