adsorption of methyl orange onto biosorbent from pistachio shell: effects of different activation methods

Agricultural waste represents a significant source of various bio-products that can help mitigate environmental pollution and greenhouse gas emissions, while also reducing our reliance on fossil resources. this study focuses on the production of high-value biosorbents derived from pistachio hard skin (phs). the biomass of phs was utilized as a precursor for the development of different biosorbents through three distinct activation methods: solvent extraction, chemical activation with phosphoric acid, and pyrolysis processes. the produced biosorbents were characterized using x-ray diffraction (xrd), fourier-transform infrared spectroscopy (ftir), scanning electron microscopy (sem), and energy-dispersive x-ray spectroscopy (eds) analyses. depending on the activation methods employed, the adsorption capacities of the biosorbents for the methyl orange (mo) dye component varied from approximately 100 to 700 mg/g. notably, the maximum adsorption capacity was achieved after the pyrolysis process. furthermore, isotherm studies indicated that the sips and langmuir isotherm models provided a relatively better fit for the experimental data, with r2 values of 0.999 and 0.983, respectively.