A new ecological mineral-carbonaceous material for adsorption of organic pollutants – a step towards a circular economy

Two industrial waste products – namely, cement bypass dust and apple pomace - were used in the synthesis of a new ecological mineral-carbonaceous material intended that can be used for the adsorption of organic pollutants. The raw materials were mixed at initial ratios of 1:5, 1:9, and 1:18, then subjected to pyrolysis in a nitrogen atmosphere at 800°C. The chemical characterization of the resulting mineral-carbonaceous materials showed that the concentrations of Zn, Cd, and Pb were significantly lower than those in the raw and pyrolyzed bypass dust samples, while the concentrations of Na, Mg, Si, and P were higher. The composition and structure of the mineral-carbonaceous materials depend on the initial dust-to-pomace weight ratio. All materials exhibited a mesoporous nature, with specific surface areas more than one hundred times greater than those of the individual substrates. The highest value exhibits the material with the 1:9 bypass dust-to-apple pomace ratio. This material also had a homogenous, fine-grained structure, with the bypass dust completely covered by carbon.After 24 h, approximately 90% of captan was removed from the aqueous solution and adsorbed onto the mineral-carbonaceous materials. The removal efficiency depended on the initial bypass dust-to-apple pomace ratio, with the best performance (97.3%) observed in the material synthesized at the 1:9 ratio. Our results confirm that otherwise useless wastes can serve as suitable substrates for the synthesis of mineral-carbonaceous materials, which can function as adsorbents for organic pollutants and as potential sources of valuable nutrients.