A previous study has determined that Neochloris alveolaris and Neochloris minuta grown in nitrogen-rich (+N) and nitrogen-depleted (-N) media biosorbed Pb2+, Cd2+, Zn2+, Cu2+, and Ni2+ differently based off of the algae biomass composition and type of hard or soft metal acid based on the Pearson theory of Hard and Soft, Acid and Bases (HSAB). This study aimed to determine the effect of hard acid ionic metal sizes (Cr6+ &lt; Al3+ &lt; Fe3+ &lt; Mo6+ &lt; Ti4+ &lt; Co2+) on the biosorption capacities of the same Neochloris alveolaris and Neochloris minuta algal strains. All of the metal solutions were stirred with the algae at a pH of 5 and at room temperature for one hour. Biosorption capacities (qmax) were determined through the Langmuir, Freundlich, and Temkin adsorption isotherms. The data yielded statistical significant biosorption capacities and adsorption efficiencies. The maximum metal biosorption capacities of Neochloris alveolaris and Neochloris minuta were 129.87 ppm for Al3+, 35.79 ppm for Ti4+, 29.91 ppm for Co2+, 16.78 ppm for Fe3+, 5.95 ppm for Mo6+, and 0.59 ppm for Cr6+. The maximum biosorption capacities of the selected hard acid metals were indicative of an association with the metals’ respective ionic size and covalent indices.

Effects of hard acid metal ion sizes and covalent indices on the biosorption capacities of Neochloris minuta and Neochloris alveolaris under nitrogen deprivation

ACS Spring 2022

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