Phytoremediation of Heavy Metal Ions (Hg²⁺ and Cr²⁺) Using Natural Plant Leaves with UV-Vis Spectrophotometric Analysis

Heavy metal contamination, particularly by mercury (Hg²⁺) and chromium ions, represents a critical environmental challenge due to their high toxicity, persistence, and bioaccumulation potential in aquatic ecosystems. Conventional treatment methods such as chemical precipitation, ion exchange, and membrane filtration are often prohibitively expensive, generate toxic sludge, and are ineffective at low metal concentrations (Fu & Wang, 2011; Barakat, 2011). Phytoremediation using plant biomass offers a promising sustainable alternative, leveraging the natural metal-binding capacity of plant cell wall components—including cellulose, hemicellulose, lignin, and pectin—which contain functional groups (carboxyl, hydroxyl, amino) capable of chelating heavy metal ions through biosorption mechanisms (Volesky & Holan, 1995; Demirbas, 2008). This approach is cost-effective, environmentally friendly, and particularly suitable for treating large volumes of wastewater with moderate contamination levels. This research aims to systematically evaluate the biosorption capacity of a specific selected plant species (Available and widespread in Tulkarm city- West bank- Palestine) for removing Hg²⁺ and Cr ions from aqueous solutions. The study will employ UV-Vis spectrophotometry using chromogenic reagents—dithizone for mercury detection (λ = 490 nm) and diphenylcarbazide for chromium analysis (λ = 540 nm)—providing a reliable, accessible analytical method for quantifying metal concentrations before and after treatment (EPA Method 7470A, 1994; EPA Method 7196A, 1992). Comprehensive batch experiments will optimize key operational parameters including contact time, pH (3-9), biosorbent dosage (0.25-5.0 g/L), initial metal concentration (5-100 mg/L), and temperature (15-45°C). Kinetic modeling (pseudo-first-order, pseudo-second-order, intraparticle diffusion) and equilibrium isotherm analysis (Langmuir, Freundlich, Temkin models) will elucidate biosorption mechanisms and determine maximum adsorption capacities (Ho & McKay, 1999; Foo & Hameed, 2010). Biosorbent materials will undergo rigorous characterization using Fourier Transform Infrared Spectroscopy (FTIR) to identify active functional groups, Scanning Electron Microscopy (SEM-EDX) for surface morphology and elemental analysis, (Coates, 2000; Goldstein et al., 2017). Comparative analysis of pre- and post-biosorption FTIR spectra will reveal specific binding mechanisms—whether through ion exchange, complexation, or surface precipitation. Expected outcomes include identification of the most effective plant biosorbent achieving 60-95% removal efficiency with adsorption capacities of 10-50 mg/g, equilibrium times of 60-120 minutes, and optimal pH ranges of 4-6 for mercury and 2-3 for chromium (King et al., 2008; Babu & Gupta, 2008). The significance of this research extends beyond laboratory-scale investigation to practical applications in industrial wastewater treatment (mining, electroplating, tanneries), municipal water purification, and agricultural drainage remediation. By converting readily available agricultural waste and plant biomass into effective biosorbents, this study addresses dual challenges of waste management and water pollution control while supporting sustainable development goals related to clean water access (SDG 6). The findings will contribute to the fundamental understanding of biosorption mechanisms, provide validated UV-Vis analytical protocols accessible to resource-limited laboratories, and offer a green technology alternative that reduces treatment costs by 50-90% compared to conventional methods while minimizing chemical waste generation and environmental impact (Volesky, 2001; Ali et al., 2013). This collaborative three-student project will systematically divide responsibilities across biosorbent preparation and characterization, analytical method development and validation, and batch experimentation with data modeling, ensuring comprehensive investigation of this sustainable remediation technology over an eight-month timeline