Plum pits waste biochar as a sustainable and efficient adsorbent targeting water contamination: An in-depth analysis of the impact of pyrolysis parameter changes on the adsorption mechanism

Plum pits represent an abundant agricultural food by-product that remains largely unexploited despite its disposal costs and environmental burden. In this work, plum pits obtained from a distillery were valorized as feedstock for biochar production via slow pyrolysis (300–800°C). The resulting biochars were comprehensively characterized and evaluated for adsorption parameters of methylene blue and Pb²⁺ as model organic and inorganic pollutants. Adsorption efficiency strongly depended on pyrolysis temperature, with methylene blue removal peaking at 700°C and Pb²⁺ removal at 800°C. Principal Component Analysis identified surface area, C:O ratio, and aromaticity of structure as critical factors, while energy normalization highlighted 600°C as the most sustainable pyrolysis condition balancing performance, yield, and energy input. Importantly, preliminary adsorption efficiency tests with real wastewater containing pharmaceuticals and other organic micropollutants demonstrated proof-of-concept applicability of plum pit biochar under complex environmental conditions. Although activation will be further required to enhance sorption efficiency, the results underline that plum pits can be transformed from problematic waste into effective biochars, offering dual benefits for wastewater treatment and sustainable waste management within a circular economy framework.