Environmental materials: CO2-adsorbing clays for enhancing soil fertility and agricultural sustainability†

Abstract

To combat desertification and climate change, innovative solutions are crucial for restoring the fertility of desert lands and mitigating the adverse effects of global warming. One promising approach involves utilizing carbon dioxide (CO₂), a major greenhouse gas, as a resource to enhance soil fertility. This study explores the transformation of desert sands into fertile land using CO₂ adsorbed on clays, offering a novel solution to combat desertification and mitigate climate change. We developed CO₂-enriched fertilizers using the solgel method, and the process involved purifying raw kaolinite followed by CTAB intercalation and impregnation with varying concentrations of polyethyleneimine (PEI) (30 and 50%). The prepared fertilizers were analyzed using FTIR, XRD, SEM, and TEM to assess their structural and morphological properties. Furthermore, these adsorbents were evaluated for CO₂ uptake potential. The highest CO₂ adsorption capacity of 167.1 mg g⁻¹ was obtained with CKP-50 much higher than unmodified kaolinite (0.901 mg g⁻¹). FTIR analysis confirmed that CO₂ adsorption on the prepared fertilizers occurred via chemical interaction with amine groups. The CO₂-enriched clays were mixed with sand in appropriate concentrations to support plant growth in desert lands. The plant growth trial showed significant improvements with PEI impregnated samples, S-CKP-30 and S-CKP-50, which supported taller and healthier plants compared to pure kaolinite (S-PK) and CTAB-modified kaolinite (S-CKP-0). By day 30, plants with S-CKP-50 reached 27.1 cm in height demonstrating enhanced plant growth, especially in arid conditions, by improving moisture retention, nutrient availability, and increased CO₂ adsorption. These results showed that our prepared fertilizers, especially S-CKP-50, proved to be the most effective material for CO₂ mitigation and promoting plant growth, hence offering a promising approach to desert reclamation and CO₂ sequestration simultaneously.