Multi-Metal Detoxification of Contaminated Water Using Hydrothermal Tio₂ Nanorods: Efficient Pb²⁺, Cr⁶⁺, and Cu²⁺ Removal with Kinetic and Isotherm Analysis

Abstract

The growing discharge of heavy metal–contaminated wastewater poses a serious threat to environmental and human health, necessitating the development of efficient, ecofriendly, and cost-effective remediation materials. Semiconductor nanostructures such as ZnO, CuO, CdS, ZnS, iron oxides, and TiO₂ have gained significant attention for water purification applications. Among them, titanium dioxide (TiO₂) stands out due to its large surface area, chemical stability, non-toxicity, hydrophilic nature, low cost, and environmental compatibility. In this study, highly active single-crystalline onedimensional TiO₂ nanorods were synthesized via a facile glycerol-assisted hydrothermal method and evaluated for the adsorption of toxic heavy metal ions, namely Pb(II), Cr(VI), and Cu(II). The synthesized TiO₂ nanorods were thoroughly characterized using XRD, FTIR, Raman spectroscopy, HR-SEM, EDAX, HR-TEM, SAED, and XPS analyses, confirming their anatase phase, high crystallinity, rod-like morphology, and abundant surface hydroxyl groups. Batch adsorption experiments demonstrated high removal efficiencies of 77.6% for Pb(II), 82.75% for Cr(VI), and 86.82% for Cu(II) within 12 hours. The adsorption behavior followed both Langmuir and Freundlich isotherm models, with a better fit to the Langmuir model, indicating monolayer adsorption on a homogeneous surface. Regeneration studies revealed stable performance over multiple cycles, highlighting the reusability of the adsorbent. Overall, the results demonstrate that TiO₂ nanorods are promising, sustainable adsorbents for effective heavy metal remediation in wastewater treatment applications.