Pengaruh pH dan Konsentrasi Pb²⁺ terhadap Kapasitas Adsorpsi Bioadsorben Daun Rami dalam Air Limbah Artifisial

Lead (Pb²⁺) is a hazardous heavy metal commonly found in industrial wastewater and poses serious risks to human health and the environment due to its toxic and non-biodegradable nature. Therefore, an effective and environmentally friendly treatment method is required to reduce Pb²⁺ concentration in wastewater. This study aimed to evaluate the effect of pH and initial Pb²⁺ concentration on the adsorption capacity of ramie leaf (Boehmeria nivea) bioadsorbent activated with NaOH. The adsorption process was conducted using a batch system with pH variations of 4, 5, and 7 and initial Pb²⁺ concentrations of 20, 25, and 30 mg/L. The residual Pb²⁺ concentration was analyzed using Atomic Absorption Spectrophotometry (AAS), and the adsorption performance was evaluated based on removal efficiency and adsorption capacity (Qe). The results showed that pH and initial Pb²⁺ concentration significantly affected the adsorption performance. The optimum adsorption condition was obtained at pH 5, with a maximum removal efficiency of 99.20% and a total adsorption capacity of 18.56 mg/g. The increase in pH from 4 to 5 enhanced adsorption performance due to reduced competition between H⁺ and Pb²⁺ ions for active sites on the adsorbent surface. Increasing the initial Pb²⁺ concentration tended to increase adsorption capacity, although removal efficiency remained relatively stable due to the limited number of active adsorption sites. The Relative Standard Deviation (RSD) values ranged from 1.56% to 3.37%, indicating good precision and repeatability of the experimental data. These findings demonstrate that NaOH-activated ramie leaves have considerable potential as an effective, low-cost, and environmentally friendly bioadsorbent for Pb²⁺ removal from wastewater.