Analysis of Soil Heavy Metal Absorption with the Application of Biochar Based on Oil Palm (Elaeis guineensis Jacq.) Frond Waste

Abstract

Soil contamination by heavy metals such as cadmium (Cd) and lead (Pb) is an environmental issue that degrades soil quality and poses risks to the health of living organisms. One strategy to reduce heavy metal mobility in soil is the use of biochar derived from biomass waste. This study aimed to analyze the uptake of Cd and Pb in soil following the application of biochar produced from oil palm frond waste via pyrolysis. The biochar was produced at temperatures of 350–400°C for 4 hours, then applied to the soil and incubated for one month. We analyzed heavy metal content using wet digestion, followed by measurements via atomic absorption spectrophotometry (AAS) and ICP-MS. The results demonstrated that the application of oil palm frond biochar reduced Cd and Pb concentrations in the soil through mechanisms such as adsorption, ion exchange, surface complexation, and precipitation. Key biochar characteristics—specifically high surface area, high porosity, and high cation exchange capacity—play a crucial role in immobilizing heavy metals, thereby reducing their bioavailability in the soil. The advantage of this research is that biochar from oil palm frond waste has proven to be highly effective in absorbing up to 100% of cadmium and also successfully reducing lead levels, using inexpensive, readily available, and environmentally friendly materials. This research also introduced innovation in the form of activating the biochar with eco-enzymes to enhance its absorption capacity. In addition to absorbing heavy metals, this biochar also improves soil fertility, providing dual benefits and supporting more sustainable agriculture. The analytical results were compared against the standards set by the International Biochar Initiative (IBI) to evaluate the safety of using the biochar as a soil amendment. The study indicates that oil palm frond biochar can serve as an eco-friendly adsorbent for remediating heavy metal-contaminated soil while offering a sustainable alternative for managing oil palm biomass waste.