Modeling and Optimization of Activated Nanomagnetic Biochar Derived from Oil Palm Trunk Biomass via Response Surface Methodology for the Removal of Malachite Green Dye

Organic dye pollution poses a serious environmental threat, and while activated carbon (AC) is commonly used to adsorb these dyes, its effectiveness is often limited by challenges in separation and regeneration. To address this, activated nanomagnetic biochar (ANB) was developed via a coprecipitation method, utilizing oil palm trunk biomass to create a variant called ANBO for removing malachite green (MG) from water. The synthesized ANBO's physical characteristics were examined using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) techniques. This study examined the impact of several process variables, including adsorbent dosage (g), time (minutes), and pH, on the percentage of MG eliminated from aqueous solutions, an application of a Box–Behnken design (BBD) with three factors and three levels within the response surface methodology (RSM) framework, ultimately optimizing MG adsorption with ANBO as the adsorbent. Analysis of variance (ANOVA) revealed that adsorbent dosage had the most significant effect ( F  = 142.16), followed by pH ( F  = 37.82) and contact time ( F  = 20.41). The highest removal efficiency was achieved at optimal conditions of 0.08 g of adsorbent, pH 8, and 1 hour. In conclusion, this research supports Sustainable Development Goals 6 (Clean Water and Sanitation) and 3.9, which aim to reduce health risks from hazardous chemicals and pollution by 2030, aligning with the environmental standards set by the local Department of Environment (DOE).