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There are serious health and environmental risks associated with water pollution from chemical wastewater. This study aims to evaluate the effectiveness of modified Chlorella vulgaris-derived biochar and hydrochar as efficient adsorbents for the removal of cadmium from aqueous solutions. Biochar and hydrochar derived from C. vulgaris were used for this purpose. Both materials were activated with potassium hydroxide, enhancing their adsorption capabilities. The adsorption process was evaluated through batch and column studies, examining various parameters such as contact time, pH and initial cadmium concentration. Results indicate that both biochar and hydrochar demonstrated high efficiency in cadmium removal, with optimum conditions identified. The study also explored adsorption kinetics, revealing a pseudo-second-order model as the most suitable for describing the process. Additionally, thermodynamic analysis indicated the spontaneous and endothermic nature of cadmium adsorption onto both materials. The values of ΔH° and ΔS° were determined for modified biochar, yielding 15.1 and 46.7 kJ/mol, respectively, and also for modified hydrochar, resulting in 14.9 and 46.5 kJ/mol, respectively. This research provides valuable insights into the potential application of C. vulgaris-derived biochar and hydrochar in wastewater remediation, offering an eco-friendly and cost-effective solution for cadmium-contaminated sites.

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  • Modified biochar and hydrochar derived from Chlorella vulgaris microalgae exhibit high efficiency in removing cadmium from aqueous solutions.

  • Determining values for ΔH° and ΔS° contributes to a deeper scientific understanding of biomass-derived materials for the removal of heavy metals.

  • The second-order kinetic model proves useful in explaining the retention of cadmium.

adsorption capacity, environmental, Gibbs free energy, remediation, thermodynamic
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