ADSORPTION BEHAVIOR OF Cu(II), Pb(II), AND Zn(II) ON SELECTED NATURAL SOILS IN SABAH

INTRODUCTION, MATERIALS AND METHODS, RESULTS AND DISCUSSION, CONCLUSION, REFERENCES

Abstract

Heavy metals in soil can reduce plant fertility and may pose health risks to those who consume the affected plants. Therefore, understanding the soil's ability to retain heavy metals is essential. This study explores the adsorption behaviors of Cu(II), Pb(II), and Zn(II) ions in selected natural soil samples from Sabah, providing insights into their retention capacities and potential environmental implications. The adsorption isotherms were measured using the conventional batch adsorption technique. The results indicate that the adsorption isotherms are satisfactorily described by both the Langmuir and Freundlich models, with R² values mostly exceeding 0.93. Hilltop soil (clay loam) demonstrated the greatest adsorption capacity, exhibiting a distinct metal ion affinity sequence of Cu²⁺ > Pb²⁺ > Zn²⁺. In contrast, clayey sand soils from orchards, rubber plantations, and foothill regions showed a preferential adsorption for Zn²⁺ over Pb²⁺ and Cu²⁺. Despite sharing similar soil classifications, these variations highlight the influence of site-specific properties on metal ion adsorption behavior. It is found that soil adsorption behavior is shaped by mineralogical composition, particle size distribution, organic matter content, pH level, specific surface area and land management practices. These elements influence both the availability of adsorption sites and the order in which adsorption takes place, ultimately determining the soil’s capacity to retain and immobilize substances like heavy metals.