Efficient Cadmium Removal Using Alginate‐Encapsulated Chlorella sp.: An Innovative Approach for Eco‐Friendly Aquatic Bioremediation

Trace metals are frequently detected in aquatic ecosystems, raising serious concerns due to theirtoxicity to aquatic organisms and their potential transfer to humans through the food chain. Consequently, there is an increasing demand for eco‐friendly bioremediation strategies that preserve aquatic biota and environmental integrity, unlike conventional chemical or physical treatments. Microalgae, particularly Chlorella sp., have emerged as promising candidates for metal removal, especially when immobilized within biocompatible matrices. This study evaluated the cadmium (Cd 2+ ) binding capacity of Chlorella sp. and investigated the kinetics of cadmium retention using alginate‐immobilized cells. For the first time, potentiometric sensors incorporating alginate‐immobilized Chlorella sp. were developed and applied for cadmium detection. The system exhibited a reproducible near‐Nernstian response to Cd 2+ , with a slope of 29 mV per decade and a linear detection range from 10 −3, 42 to 10 −1, 67 M. The maximum cadmium fixation rate reached 205 μM Cd g −1 Chlorella sp. min −1 , with complete saturation achieved within 35–40 min. Cadmium retention involved coupled physicochemical interactions and biologically mediated processes, progressing through four successive stages: rapid surface binding, partial metal release, a transient adjustment phase, and establishment of a stable dynamic equilibrium. These findings highlight alginate‐immobilized Chlorella sp. as a sustainable efficient tool for cadmium bioremediation.