Background: This research investigation delves into the efficient removal of zinc ions from synthetic wastewater through the utilization of KOH treated guava leaves as an adsorbent. The study employs advanced analytical techniques including SEM, FTIR, XRD, and BET analysis to characterize the physicochemical properties of the treated guava leaves. The research extensively explores the impact of various experimental factors on the adsorption process, encompassing agitation time, adsorbent dosage, pH levels, and desorption, to identify optimal conditions for maximum Zn (II) ion removal. Methods: The research methodology involves subjecting guava leaves treated with KOH to thorough analysis using SEM, FTIR, XRD, and BET techniques to gain insights into their physical and chemical attributes. The study systematically investigates the adsorption process by manipulating crucial parameters such as agitation time, adsorbent dosage, and pH levels. Different isotherm models including Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich are applied to comprehend the adsorption mechanism. Additionally, kinetic calculations are performed, leading to the determination that the pseudo-second-order model best fits the removal of zinc metal. Significant Findings: The research uncovers essential findings regarding the efficacy of KOH treated guava leaves as an adsorbent for zinc ions. Optimum conditions are pH 3 are identified, an adsorbent dosage of 100 mg/L, and an equilibrium period of 20 min, resulting in peak efficiency of the adsorption process. The study reveals an adsorption capacity of 14.5 mg/g for the studied metal, emphasizing the potential of KOH treated guava leaves as an efficient adsorbent for zinc ions. The adsorption capacity is 5.1 mg/g for the untreated guava leaves. The findings underscore the feasibility of utilizing this eco-friendly approach for wastewater management, thereby contributing to environmental remediation and pollution control efforts. The research highlights the practical application of KOH treated guava leaves in wastewater treatment processes, advocating for further exploration and optimization of this sustainable solution to address heavy metal contamination and promote greener technologies for water purification and waste management.

In the last two decades, special concern has been focused on certain drugs such as Metronidazole (MNZ) owing to their potential carcinogenic and mutagenic properties. In the current study, nano zero-valent iron (nZVI) combined with Copper Slag was utilized for the adsorption of MNZ from an aqueous environment. The proper distribution of nZVI was confirmed by surface morphology analysis using FESEM. In addition, the incorporation of nZVI into Copper Slag led to an approximate 82% increase in BET surface area and a more than 20% rise in iron content according to the EDX result, which together contributed to a 90% improvement in MNZ removal efficiency from aqueous solutions. The optimum conditions (initial MNZ concentration of 27.9 mg/L, adsorbent quantity of 6.8 g/L, contact time of 35.5 min, and an initial pH of 5.04) were attained, demonstrating excellent adsorbent removal efficiency through running the CCD design. The Langmuir isotherm accurately described MNZ adsorption on nZVI/Copper Slag, and kinetic modeling showed that the experimental data fit well with the pseudo-first-order. The adsorption of MNZ onto the adsorbent is spontaneous and exothermic, with ∆G° < 0 and ∆S° < 0, indicating thermodynamic favorability and increased order at the solid–solution interface. Furthermore, it indicated excellent reusability and regeneration performance over six consecutive cycles.