Evaluation of mercury adsorption and removal efficacy of pulverized Chlorella (C. vulgaris)

Abstract

Chlorella is a green alga consumed as dietary food supplement in pulverized form. In addition to its high nutritional value, it is reported as an excellent detoxifying agent. Pulverized Chlorella has been reported for removal of cadmium and radioactive strontium from the body. Chlorella adsorbs these metal ions on its surface; thus, the physiological pH of gastrointestinal tract is an important factor which may affect its efficacy. Therefore, the present study aimed to evaluate mercury adsorption and removal efficacy of pulverized Chlorella vulgaris. The adsorption efficacy was investigated in terms of the weight of Chlorella, contact time, mercury concentration, simulated physiological fluids (SGF and SIF) and influence of pH. Langmuir and Freundlich adsorption isotherm models were fitted to determine the maximum adsorption capacity. In addition, mercury removal efficiency of Chlorella was evaluated in mice. The mercury content in major tissues, urine and faeces was estimated. The whole tissue retention of mercury after the treatment with Chlorella was taken as a measure of its mercury removal efficacy. The mercury content was measured using validated atomic absorption spectrometer. Chlorella showed significant increase in adsorption of mercury, and the equilibrium was achieved at 180 min. The maximum adsorption capacity was found to be 111.11, 83.33 and 125 mg g−1Chlorella in water, SGF and SIF, respectively. In mice, Chlorella significantly reduced the deposition of mercury in tissues and facilitated its excretion through faeces. Pulverized Chlorella showed potential adsorption efficiency and may considered a promising agent in counteracting the toxic effects elicited by mercury.