Transforming Cocoa Waste into a Solution for Water Pollution

Biochar from cocoa pod husk, produced via microwave-assisted pyrolysis at 720 W for 15 minutes, effectively adsorbs cadmium ions (Cd2+) from water through physisorption. Influenced by oxygenated functional groups, this sustainable biochar offers a promising solution for water pollution and supports a circular economy.

June 2, 2024

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Correa-Abril, et al (2024) Adsorption dynamics of Cd²⁺(aq) on microwave-synthetized pristine biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More from cocoa pod husk: Green, experimental, and DFT approaches. *iScience*. https://doi.org/10.1016/j.isci.2024.109958

In recent research, biochar derived from cocoa pod husk (CPH) using microwave-assisted pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More (MAP) at 720 W for 15 minutes has emerged as an effective adsorbent for removing cadmium ions (Cd2+) from water. This biochar (BCCPH) features advantageous physicochemical properties, including a modest surface area and a suitable porous structure that facilitate adsorption.

The primary mechanism for Cd2+ removal by BCCPH is physisorption, significantly influenced by the biochar’s oxygen-containing active sites (-COOR, -C(R)O, and -CH2OR). During this adsorption process, the formation of CdCO3 is observed, and experimental data fit well into various kinetic models, providing a comprehensive understanding of the sorption dynamics. The Langmuir model indicates a maximum adsorption capacity of 14.694 mg/g, and thermodynamic studies confirm that the sorption process is both spontaneous and endothermic.

At the molecular level, density functional theory (DFT) calculations reveal that Cd2+ ions prefer binding to surface aromatic carbon atoms on the biochar. This discovery underscores the potential of using BCCPH, produced sustainably via MAP, as a viable method for transforming agricultural waste into effective water-cleaning materials.

This innovative approach not only addresses the issue of cadmium pollution in water but also adds value to agricultural waste, promoting a circular economy, particularly beneficial for resource-limited farming communities. The study aligns with the United Nations’ Sustainable Development Goals, particularly focusing on clean water and sanitation, demonstrating a significant step towards environmental management and sustainable agricultural practices.