Evaluation of microalgal-based nanoparticles in the adsorption of heavy metals from wastewater

Bioremediation remains an eco-friendly and inexpensive method employed in getting rid of the toxic compounds like heavy metals present in wastewater. Different microorganisms are being used in either removing or reducing the concentration of heavy metals in wastewater but microalgae have a high affinity for heavy metals. In this study, nanoparticles from microalgae were evaluated for the potential to absorb lead and zinc from pharmaceutical effluent. Silver (AgNPs) and gold nanoparticles (AgNPs) were synthesized from both Nannochloropsis sp (NN) and Chlorella vulgaris (CV). The nanoparticles were introduced into a pharmaceutical effluent and the mixture was allowed to interact for 48 h after which the concentration of zinc and lead was determined using atomic absorption spectrophotometer. The AgNPs of Nannochloropsis sp (NN-AgNPs) and C. vulgaris (CV-AgNPs) had percentage reduction of 70.35 % and 74.62% respectively for zinc. Also gold nanoparticles of Nannochloropsis sp (NN-AuNPs) and C. vulgaris (CV-AuNPs) had percentage reduction of 60.32% and 66.83% respectively for zinc. The concentration of lead was reduced by CV-AgNPs (66.10 %), NN-AgNPs (68.86%), CV-AuNPs (57.41%), and NN-AuNPs (66.53 %). This study has established algal based nanoparticles as adsorbent with affinity for heavy metals and can be adopted for bioremediation of wastewater.