Abstract
The pollution from wastewater containing synthetic dyes and heavy metals is a serious environmental issue in Indonesia. The situation is associated with the lack of locally sourced membranes to simultaneously integrate physical filtration and chemical adsorption mechanisms (filtro-adsorption). Therefore, this research aims to develop a hybrid paper membrane based on abaca (Musa textilis) fiber pulp and rice husk ash silica using citric acid as a cross-linking agent for the removal of methylene blue (MB) dye and heavy metal ions (Cu²⁺ and Pb²⁺) from synthetic wastewater. The methodology required silica extraction from rice husk ash through an alkaline method and modification of the product with 3-aminopropyltriethoxysilane (APTES)s. There was also membrane fabrication with different variations of silica (0–20% of dry fiber weight) and citric acid (0–15%) contents, as well as characterization through X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS). The results showed that the optimal membrane with 15% silica and 10% citric acid achieved a water flux of 285 L/m²·h·bar and removal efficiencies of >95% for MB (C₀ = 50 mg/L), 78.5 ± 3.2% for Cu²⁺, and 82.3 ± 2.8% for Pb²⁺ (C₀ = 10 mg/L). The two-way analysis of variance (ANOVA) also confirmed that the variations in silica and citric acid content significantly affected the separation performance (p < 0.05). The results showed that the hybrid membrane derived from abundant local agricultural waste had potential as an environmentally friendly wastewater treatment technology.