The use of magnetic iron oxide based nanoparticles to improve microalgae harvesting in real wastewater

Abstract

A novel approach for harvesting Scenedesmus sp. microalgae from real wastewater by using adsorbents of magnetite-based nanoparticles (Fe 3 O 4 NPs) was tested in this study for the first time for this microalgae. Using these NPs, the harvesting efficiency was even higher than 95%. The optimal conditions (0.14 gNPs/L, a short magnetic separation time of only 8 min and 27 min of contact time) were found using the response surface methodology. The best fitting of the adsorption equilibrium results was achieved by the Langmuir isotherm model, and the maximum adsorption capacity for Scenedesmus sp. reached 3.49 g dry cell weight (DCW)/g Fe 3 O 4 NPs. Zeta potential measurements and the Dubinin-Radushkevich isotherm model analysis pointed out that the main adsorption mechanism between Scenedesmus sp. cells and Fe 3 O 4 NPs was electrostatic interaction.Finally, Fe 3 O 4 NPs were six times successfully reused by combining an alkaline treatment with an ultrasonication process, which implies microalgae lysis. The results herein obtained highlight the potential for magnetic separation of microalgae from wastewater, which is capable of reaching a high harvesting efficiency in a very short time.

Impact of magnetic immobilization on the cell physiology of green unicellular algae Chlorella vulgaris

“…Increase in membrane permeability results in facile mass transfer of nutrition and products and hence increases the cells performance [2,9]. This effect was also reported for magnetic modified microalga cells with high (over 95%) efficiency in cell recovery [11,13].…”

“…Magnetic harvesting has opened a new avenue to functionalize, manipulation, and sedimentation of cells [4][5][6][7]. In a very recent short period of time, this novel approach was examined and employed to harvest a variety of cells, specially microalga as one of the most economical valuable cells [5,[8][9][10][11][12][13].…”

“…Nanoparticles can also attach to the cells surface via nonspecific interactions such as hydrogen bonds, electrostatic, Van der Waals, hydrophobic, and hydrophilic forces [2,3,19,20]. The surface charge of living cells is negative and hence most experiments were performed by employing engineered magnetic nanoparticles with positive functionalities to provide more electrostatic attraction [9,12,13]. If magnetic nanoparticles attach on a particular cell in this order, the cell becomes magnetically responsive and can be easily manipulated using a magnet [9].…”

Magnetophoretic Harvesting of Nannochloropsis oculata Using Iron Oxide Immobilized Beads

“…A higher molecular weight is likely to be nonselective, significantly contributing to the adhesion between microalgae. It can be successful for industrial microalgae strains [32], but also in the case of removing harmful microalgae [5,36]. Figure 5 shows the reusability of Fe 3 O 4 /PS.…”

The Current Role of Chemical Engineering in Solving Environmental Problems

“…All of these are welcome. CE is, by definition, a multidisciplinary approach to real problems (Alonso et al, 2017;Abo Markeb et al, 2019).…”