ABSTRACT
An improved yield of a composite named Merrifield-pyridoyl-bis-thiourea derivative (MR-PyBTU) was effectively synthesised from the Merrifield Polymer Precursor (MR) and utilised for the adsorption of arsenic trioxide (As3+) ions from wastewater samples containing 1.5 mg/L of As3+ ions. The structure of the (PVAm-MMB) composite was confirmed using various analytical techniques, ensuring successful functionalization. Key experimental conditions namely pH, equilibrium time, starting concentration of As3+ ions, composite dosage, temperature, and choice of eluting agents were systematically optimised. At an ambient temperature, a pH value of 4.5, with 20 minutes of agitation, and an initial concentration of 250 mg/L As3+ ions, the composite demonstrated its highest sorption efficiency at a capacity of 50 mg/g. Equilibrium isotherm analyses indicated that the experimental data aligned more closely with the Langmuir model compared to the Freundlich model. Remarkably, the Langmuir model’s predicted uptake capability of 51.282 mg/g closely matched the actual observed values. Kinetic analyses supported by the pseudo-first-order model accurately described the sorption process, yielding a theoretical sorption capability of 49.113 mg/g. Thermodynamic assessments suggested that the sorption process is exothermic, spontaneous, and more favourable at lower temperatures. Efficient desorption of As3+ ions from the saturated composite was attained with 0.025 M NaOH, reaching approximately 98% efficiency. This composite’s ability to remove As3+ ions from wastewater aligns with Food and Agriculture Organization (WHO) and World Health Organization (FAO) guidelines, ensuring its safe discharge into marine environments after a single treatment cycle. Additionally, the compound 4-amino-N2, N6-bis((3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl) carbamothioyl) pyridine-2,6-dicarboxamide (PyBTU) exhibited potent antioxidant and antibacterial properties against Gram-negative bacteria, Gram-positive bacteria, Escherichia coli, and Bacillus subtilis.
Acknowledgments
The authors extend their appreciation to the Deanship of Research and Graduate Studies at King Khalid University for funding this work under grant number RGP2/144/45.
Disclosure statement
No potential conflict of interest was reported by the author(s).