Development of nitrogen-doped graphene/MOF nanocomposites towards adsorptive removal of Cr (VI) from the wastewater of the herbert bickley treatment works

Title : Development of nitrogen-doped graphene/MOF nanocomposites towards adsorptive removal of Cr (VI) from the wastewater of the herbert bickley treatment works

Abstract:

Industrial effluents laden with Cr (VI) pose considerable health risks to human and animal life if left untreated. Hence, in this work, metal–organic framework-5/nitrogen-doped graphene (MOF5/NGO) nanocomposites are fabricated. These materials were produced with increasing NGO loadings (0.05, 0.10 and 0.15 wt. %) to investigate the effect of the NGO content on the chemical and physical properties of the composites. The FTIR spectra show the nanocomposites be to be rich in surface –OH and –COOH functional groups. Raman spectroscopy confirmed bond formation between the MOF-5 and NGO through downshift of the G- and 2D-bands. XRD analysis showed the composites, MOF-5 and the NGO to be highly crystalline while thermogravimetric analysis indicated the thermal stabilities of the composites to be enhanced. SEM studies revealed the NGO flakes to be dispersed on the MOF-5 microstructures prior to adsorption and the disappearance of microstructures post adsorption. The as-synthesized nanocomposites exhibited BET surface area in the range 384.55–395.56 m2 .g− 1 which is a significant increase from that of MOF-5 261.00 m2g− 1. The optimal conditions for maximum Cr(VI) adsorption were determined to be: pH = 2, contact time of 60 min, adsorbent dosage of 6 mg.L− 1,initial Cr(VI) concentration of 0.5 mg.L-1 and temperature of 30 ?C. A maximum adsorption efficiency of 46.1 % was achieved by MOF-5/NGO (0.05 wt. %) and not significantly compromised by competing metal ions. The Cr (VI) removal on MOF-5/NGO nanocomposites is well described by the Langmuir isotherm, confirming a chemisorption process. In addition, the thermodynamic studies confirmed the adsorption process to be favorable, spontaneous and endothermic. The Cr(VI) removal % on MOF-5/NGO from real water is 52.1 %. Therefore, the novel MOF-5/NGO nanocomposite can be applied for efficient Cr(VI) removal from industrial wastewater due to synergistic surface characterized by better adsorption capacity not met by pristine materials.

Biography:

Tshireletso Madumo is a Professional Natural Scientist in Chemical Sciences and a Researcher who possess 10 years of expertise as a Laboratory Scientist from Ekurhuleni Water Care Company: Scientific Services in South  Africa in performing accredited  chemical testing services on water and wastewater matrices to ensure consistent excellence in water care for Green Drop status compliance. Tshireletso holds a National Diploma in Analytical Chemistry, Bachelor of Technology degree in Chemistry from Tshwane University of Technology ,South Africa and a Master’s Degree Chemical Engineering from the University of South Africa. Tshireletso published a paper titled “Development of nitrogen doped graphene/MOF nanocomposites towards adsorptive removal of Cr (VI) from the wastewater of the Herbert Bickley treatment works” in Febuary 2023.Tshireletso have a manuscript titled "Industrial Wastewater Treatment Past and Future Perspectives in Technological advances for Mitigation of Cr(VI) Pollutant accepted for publication in the Open Access book, "Wastewater Treatment - Past and Future Perspectives" in March 2024.Tshireletso is currently a PhD candidate at the University of Johannesburg, South Africa investigating innovative strategies to fabricate mixed matrix membranes for water treatment in alignment with the Sustainability Development Goals(SDGs) particularly SDG 6:Clean Water and Sanitation.