Influences of Surface Coating, UV Irradiation and Magnetic Field on the Algae Removal Using Magnetite Nanoparticles

Abstract

Magnetophoretic separation is a promising and sustainable technology for rapid algal separation or removal from water. This work demonstrated the application of magnetic magnetite nanoparticles (MNPs) coated with a cationic polymer, polyethylenimine (PEI), toward the separation of Scenedesmus dimorphus from the medium broth. The influences of surface coating, UV irradiation, and magnetic field on the magnetophoretic separation were systematically examined. After PEI coating, zeta potential of MNPs shifted from −7.9 ± 2.0 to +39.0 ± 3.1 mV at a pH of 7.0, which improved MNPs-algae interaction and helped reduce the dose demand of MNPs (e.g., from 0.2 to 0.1 g·g(–1) while the harvesting efficiency (HE) of over 80% remained unchanged). The extended Derjaguin–Landau–Verwey–Overbeek theory predicted a strong attractive force between PEI-coated MNPs and algae, which supported the improved algal harvesting. Moreover, the HE was greater under the UV365 irradiation than that under the UV254, and increased with the irradiation intensity. Continuous application of the external magnetic field at high strength remarkably improved the algal harvesting. Finally, the reuse of MNPs for multiple cycles of algal harvesting was studied, which aimed at increasing the sustainability and lowering the cost.

Detection of nitrifiers and evaluation of partial nitrification for wastewater treatment: A review

“…Nitrogen contained in wastewater is a pervasive and serious aquatic problem, known as eutrophication that causes excessive growth of algae and cyanobacteria (Conley et al, 2009;Ge et al, 2015aGe et al, , 2015b. To reduce nitrogenous compounds in wastewater, the biological nitrogen removal (BNR) traditionally consisting of nitrification and denitrification is more effective and cost-effective over physicochemical processes.…”

Heteroaggregation between PEI-Coated Magnetic Nanoparticles and Algae: Effect of Particle Size on Algal Harvesting Efficiency

“…−29.0 ± 1.3 mV in the algal medium (Table 1). 28,31 Moreover, all sized uncoated MNPs carried negative charges, while the PEIcoated MNPs were positively charged, which resulted in the electrostatic attraction between PEI-coated MNPs and algae. Algal Separation Using Differently Sized Polyethylenimine-Coated Magnetic Nanoparticles.…”

“…Then, PEI was added into the suspension at a mass ratio of 0.4PEI/MNPs (w/w). 31 The mixture was incubated in the room temperature on a rotatary shaker for 20 min, followed by centrifugation at 5000g for 10 min and rigorous washing with DI water to remove loosely attached or the suspended PEI in the solution. The collected PEI-coated MNPs were stored in DI water; prior to use, the supension was agitated by sonication.…”

Impact of quinoline on activity and microbial culture of partial nitrification process

“…Electrophoresis was performed at 60 °C a 60 V for 16 h. The middle portion of each selected DGGE band was excised, 9 washed, transferred to 1.5 ml centrifuge tube and recycled PCR products with kit SK8183 (Sangon Biotech, China). PCR products were re-amplified and sequenced.…”

“…Wastewaters coming from coal-coking industries usually contain relatively high concentrations of ammonia, beside the quinolinic compounds. Ammonia nitrogen contributes to eutrophication that causes excessive growth of algae and cyanobacteria and becomes harmful for the fauna in the polluted body waters (Ge et al, 2015a). The cost-effective ammonia removal method used to be conventional biological nitrogen removal (BNR) process which consists of nitrification and denitrification.…”