LED-light-driven over ZnO/biochar nanocomposite for activation of peroxymonosulfate to enhanced photocatalytic removal of methyl orange dye in aqueous solutions

ABSTRACT

Organic dyes are stable and persistent toxic compounds in the aquatic environment that are refractory to decompose by removal methods such as physico-chemical, optical and biological. Their presence in the aquatic media threatens human and wildlife. Herein, ZnO nanoparticles (NPs) due to good chemical durability, low cost and good photocatalytic performance was anchored on biochar (ZnO@biochar) nanocomposites were synthesized towards activation of peroxymonosulfate (PMS) for the photocatalytic removal of methyl orange (MO) dye. Several methods were used to characterization of the nanocomposites including FESEM, XRD, PL, EDS, FT-IR spectroscopy, and N₂ adsorption/desorption. The results of the techniques demonstrated that the well-dispersed ZnO NPs were loaded onto the biochar surface. According to the particle size distribution graph, the average particle size of 64 nm was obtained for the ZnO NPs. BET analyzes showed that pore volume, the specific surface area (SSA) and average pore size of the synthesized nanocomposite increased. The survey of effective operational parameters indicated that the highest photocatalytic activity for MO removal was in the pH 3 of solution, 5 ppm initial dye concentration, 30 mg ZnO/biochar nanocomposite, and 20 mg PMS dose under LED-50W lamp irradiation (97.03% in the reaction time of 80 min). During the process, the reduction of the total organic carbon (TOC) contents and chemical oxygen demand (COD) were observed. Moreover, the MO degradation kinetics under optimal operating conditions were determined. It is concluded that the ZnO@biochar nanocomposite/PMS process was an efficient degradation method for the decomposition of the dye pollutant.

GRAPHICAL ABSTRACT

KEYWORDS:

• Photocatalytic degradation
• ZnO@biochar
• LED lamp
• peroxymonosulfate
• methyl orange

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical approval

Not applicable.

Competing interests

The authors have no conflict of interest with each other.

Authors’ contributions

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Hadis Saraee, Mohsen Mansouri, Seyyed Abbas Mirzaee and Zahra Noorimotlagh. The first draft of the manuscript was written by Mohsen Mansouri and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Writing - review & editing was carried out by Susana Silva Martinez. All authors are fully aware of this manuscript and have permission to submit the manuscript for possible publication.

Availability of data and materials

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

M. M. thanks the University of Ilam, for the award research fellowship.