Activated biomass of the green microalga Chlamydomonas variabilis as an efficient biosorbent to remove methylene blue dye from aqueous solutions

Abstract

The raw and activated biomass of a green microalga, Chlamydomonas variabilis , were investigated as adsorbents for the removal of methylene blue (MB) dye from aqueous solutions. Chlamydomonas variabilis was isolated and cultivated to obtain a sufficient algal biomass. The collected biomass was first oven-dried and then activated by H 2SO4. The results obtained showed that the optimum adsorption of MB occurred over 30 min of contact time at pH 7 and an biosorbent dose of 1.5 and 1.0 g·L−1 of dried biomass and activated biosorbent, respectively. Point of zero charge (pHpzc) was recorded at pH 6.8 and 6.9 for dried and activated biomass, respectively. The activated biomass was a more effective biosorbent than was the dried biomass: At a MB concentration of 82.4 mg·L −1, the minimum removal was greater than 98% using 1 g·L −1 activated biomass with a maximum adsorption capacity ( qmax) of 115 mg·g−1, whereas at a MB concentration of 56.4 mg·L −1, the maximum removal did not exceed 80.8% using 1.5 g·L −1 raw biomass with a q max of 18.3 mg·g−1.

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