Impregnation of zinc oxide nanoparticles on activated carbon synthesised from corncob for appraisal of leachate chemical oxygen demand removal potential

ABSTRACT

An agro-waste corncob was used to prepare activated carbon and loaded with ZnO nanoparticles by using the impregnation method. The FTIR band at 492 cm⁻¹ of zinc oxide nanoparticle-loaded corncob activated carbon (ZnO@CCAc-7) shows the spreading vibrational modes of ZnO. The crystallinity and crystal structure of different prepared materials were analysed using X-ray diffraction (XRD). The specific surface area of ZnO@CCAc-7 was observed to be 148.3 m²/g, which was nearly two times larger than that of efficient corncob activated carbon. The fundamental peaks of carbon, oxygen and ZnO nanoparticle with their atomic percent of C 66.66, O 27.10 and ZnO 6.24 were observed in the SEM-EDX spectrum. The thermal stability of the prepared adsorbent was also analysed using thermogravimetric analysis (TGA). The maximum COD reduction using ZnO@CCAc-7 adsorbent was obtained to be 76.4% at the peak values of pH 6, dose 1.50 g/50 mL, time 160 minutes and temperature 30 ͦC. The various adsorption models Hill, Khan, Redlich–Peterson, Toth, Koble–Corrigan and Freundlich were found close-fitted to the adsorption process. It was observed that the COD removal adsorption technique ensued to a pseudo-first-order rate of kinetics. The negative value of Gibb’s free ΔG⁰ and positive values of the enthalpy change (∆H° = 25.64 kJmol-1) indicates that the process of COD removal using ZnO@CCAc-7 adsorbent was spontaneous and endothermic in nature. Furthermore, response surface methodology with a subset of Central composite design was also studied in detail to optimise the COD removal efficiency.

KEYWORDS:

• Corncob
• ZnO nanoparticle
• adsorption
• leachate
• central composite design
• kinetic models

Highlights

• The efficient activated carbon was prepared using corncob agro waste.

• ZnO nanoparticles were loaded on activated biochar for preeminent texture properties.

• The maximum COD removal from landfill leachate was 76.4%.

• RSM-CCD results were more significant for the adsorption study.

Nomenclature

Table

Acknowledgments

The authors acknowledge the TEQIP-III GJUS&T, Hisar, for financial support with letter number TEQIP-III/2018/1841-1142 to perform this study.

Disclosure statement

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

Ethical approval

The article does not have any work related to human participants or animals done by any author.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/03067319.2022.2100256

Additional information

Funding

This work was supported by the World Bank [TEQIP-III/2018/1841-1142].