New insights into enhancement of cadmium biosorption from industrial wastewater through Chlorella sorokiniana HMYA based thin-film

Abstract

Cadmium (Cd²⁺) is a non-essential and highly toxic heavy metal released from industrial and agricultural activities such as electroplating, dyeing, battery manufacturing, fertilizer application, fuel combustion, and cigarette smoke. Its environmental persistence leads to bioaccumulation and food chain transfer, posing severe teratogenic, carcinogenic, and neurotoxic risks to ecosystems and human health, necessitating the development of sustainable remediation strategies. We present a novel biosorption system for industrial wastewater using Chlorella sorokiniana HMYA-C based thin film, demonstrating high biosorption efficiency with strong potential for large-scale applications. This novel thin film outperformed both wet biomass and traditional immobilized beads under optimal conditions (pH 7, 25 °C, 2.3 g biomass/16 ml alginate/50 ml metal solution). The algal thin film successfully removed 100%, 80%, 70%, and 64% of Cd²⁺ from aqueous solutions at an initial concentration of 10, 20, 50, and 80 ppm. Furthermore, it remarkably eliminated all of the cadmium from real industrial wastewater which containing 0.4 and 2.4 ppm of Cd²⁺ concentration, highlighting its potential for immediate deployment as a biotechnological tool. After biosorption, the Cd-loaded Chlorella sorokiniana HMYA-C thin film can be safely using mild acidic or chelating agents or converted into biofuels under regulated conditions, while advancing circular bioeconomy principles. Material characterization (FTIR, EDX, SEM, XRD, zeta potential) indicated a porous, heterogeneous surface capable of multilayer adsorption compatible with pseudo-second-order kinetics and Freundlich isotherms. Overall, this innovative microalgae based thin film platform shows great promise for industrial scalability, addressing major economic and environmental concerns while meeting pressing global demands.