Synthesis and characterisation of ammonia intercalated zinc hydroxide chloride hydrate: a potential photocatalyst for methyl orange degradation under sunlight

ABSTRACT

In this work, ammonia intercalated zinc hydroxide chloride hydrate (ZHC-NH₃), Zn₅(OH)₈Cl₂.4[(H₂O)_x(NH₃)_1-x)] was synthesised using precursor, [ZnCl₂.2{HONC(CH₃)₂}] by sol-gel method in presence of ammonia and characterised by FT-IR, SEM-EDX, and XRD analysis. On sintering at 500°C, ZHC-NH₃ transformed to ZnO nanoparticles (ZnO NPs) as confirmed by the XRD patterns. ZHC-NH₃ has nanoplates-like morphology with a positive surface charge (+28.8 mV) while synthesised ZnO nanoparticles (ZnO-NPs) have spherical morphologies with negative surface charge (−8.28 mV). Band gap of 2.7 eV was observed in ZHC-NH₃ while in ZnO NPs it was obtained as 3.3 eV. A comparison has been done on the photocatalytic activities of ZHC-NH₃ and ZnO NPs towards the degradation of methylene blue (cationic dye) and methyl orange (anionic dye) under sunlight and it was found that photo-degradation of anionic dye, methyl orange is superior (96.28%) in presence of ZHC-NH₃ photocatalyst as compared to ZnO photocatalyst (55.42%). The adsorption capacities of ZHC-NH₃ towards Pb²⁺, Cd^2+, and Cr³⁺ heavy metal ions were found 47.00 mg. g⁻¹, 20.40 mg. g^−1, and 48.85 mg. g⁻¹ whereas ZnO-NPs have adsorptions capacities of 46.97 mg. g⁻¹, 43.07 mg. g⁻¹, 29.21 mg. g⁻¹, for Pb²⁺, Cd^2+, and Cr³⁺ heavy metal ions, respectively.

KEYWORDS:

• Zinc hydroxide chloride hydrate
• photocatalyst
• nanoplates
• Sol-gel
• adsorption capacities

Acknowledgments

We are grateful to Manipal University Jaipur’s central analytical facilities for providing characterisation and analysis facilities (SEM, TGA, FT-IR, AAS, and UV studies), as well as MNIT Jaipur’s Material Research Centre for XRD analysis. We are grateful for the financial support provided by Manipal University Jaipur (seed grant number. EF/2017–18/QE04–02)

Disclosure statement

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

Additional information

Funding

This work was supported by the Manipal University Jaipur [EF/2017–18/QE04–02]; Manipal University Jaipur [EF/2017–18/QE04–02].

Notes on contributors

Deepti Sharma

Ms. Deepti Sharmais working as Research Scholar at Manipal University Jaipur, Rajasthan, India. She Completed her M.Phil from Maharshi Dayanand Saraswati University Ajmer, Rajasthan, India. Her Research interests are Modification of metal oxide composites, synthesis and Characterization of photocatalytic activities, photo-oxidation and Water Treatment and Recycling.

A.K. Sinha

Prof. A. K. Sinha is a Vice-Chancellor at Chhatrapati Shivaji Maharaj University, Navi Mumbai-410206, Maharashtra, India. His Research areas are Environmental Geology, Hydrogeology and water quality.

Veena Dhayal

Dr. Veena Dhayalis an Associate Professor in the Department of Chemistry at Manipal University Jaipur, Rajasthan, India. She completed her Ph.D. in Inorganic Chemistry from the University of Rajasthan Jaipur, Rajasthan India, in 2009. Her research areas are Metal-organic Chemistry, Coordination Chemistry, Nano-synthesis: Nano-powder and nano-scaled coatings by Sol-Gel, solvothermal, CVD, dip coating, spray pyrolysis deposition, composites, Corrosion protection, Photo-catalysis.