Dataset on chitosan–geopolymer composite: integration mechanism, surface properties, and ion adsorption

The dataset presented here includes synthesis, characterization, and adsorption data for metakaolin-based chitosan–geopolymer composites prepared using different chitosan incorporation strategies and loadings. Three chitosan addition routes were investigated: direct addition of chitosan to the fresh geopolymer paste, pre-dissolution of chitosan in acetic acid before geopolymerization, and pre-dispersion of chitosan in the alkali-activator solution before geopolymerization. Based on the surface enrichment results, the alkali-activator dispersion route was further studied using chitosan loadings of 0.5, 1.0, 1.5, 2.0, and 5.0 wt%. The characterization dataset includes X-ray Fluorescence (XRF), elemental analysis, thermogravimetric analysis (TGA), total organic carbon (TOC), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), zeta potential, and high-resolution transmission electron microscopy (HRTEM). The dataset also includes batch adsorption results for nitrate (NO₃⁻), phosphate (PO₄³⁻), and ammonium (NH₄⁺) as model nutrient pollutants. Adsorption experiments were conducted under different pH conditions to evaluate ion-specific adsorption behavior and the effect of chitosan loading. Additional isotherm and kinetic adsorption datasets were obtained for the best-performing 5.0 wt% chitosan–geopolymer composite using real wastewater.