Self-assembled magnetically modified flocculant for separating microalgae and preparation method and application thereof

Abstract

The invention relates to the field of chemical engineering separation and particularly relates to a self-assembled magnetically modified flocculant for separating microalgae and a preparation method and an application thereof. The flocculant is prepared by mixing aminomethylated tannin powder, magnetic particles and water in a ratio of 0.2mg: 0.01g: 1ml to 10mg: 0.5g: 1ml. By using Fe3O4 magnetic particles as nanoscale magnetic particles which are easily assembled with aminomethylated tannin, an assembled magnetic medium has a flocculating performance 5-10 times higher than that of the conventional flocculant but cost 1 / 10 that of the conventional flocculant.

Description

technical field [0001] The invention relates to the field of chemical engineering separation, in particular to a self-assembled magnetically modified flocculant for separating microalgae and a preparation method and application thereof. Background technique [0002] In recent years, the depletion of fossil energy and the increasingly severe environmental pollution have made the search for clean and renewable new energy a hot topic. Microalgae are rich in nutrients such as protein, unsaturated fatty acids, and pigments, and have the advantages of high oil content, short growth cycle, and high biomass. However, due to the small size of microalgae (2-30 μm), the cost of harvesting is too high, and the popularization and application are limited. [0003] Commonly used microalgae harvesting methods include centrifugation, filtration, sedimentation, air flotation, etc. However, due to the small size and low concentration of microalgae, microalgae generally need to be pretreated b...

AI Technical Summary

Problems solved by technology

Guo Chen, Hu Yiru and others from the Institute of Process Technology of the Chinese Academy of Sciences once invented "a method for harvesting microalgae with a magnetic separator", but the modification used in this method is diallyl dimethyl ammonium chloride polymer or polyethylene sulfide. Amines, finally redissolved in cationic polyacrylamide for reconstitution to form a magnetic flocculant, which brings residues of harmful pollutants such as acrylamide to the harvested biomass

Liu and li et al. (Liu D., Li F.T., Zhang B.R. Water Sci. Technol. 2009, 59, 1085) used chitosan-modified magnetic polymers as magnetic separation media to successfully separate cyanobacteria from algal blooms in freshwater, but The synthesis of its magnetic separation medium is relatively complicated, and the magnetic medium cannot be reused due to the influence of ionic strength. In addition, the expensive cost of chitosan greatly increases the cost, and large-scale application is very difficult.

[0006] In addition, Fe 3 o 4 The magnetic particles are irregular granular, and some flocculants cannot self-assemble with them, and cannot assemble the effective flocculant group-iron hydroxide micelles with the magnetic particles to form an effective magnetically modified flocculant

For example, use polyaluminium-iron and magnetic powder to collect Microcystis aeruginosa in fresh water, and the algal cell density is 1-2×10 9 , the collection rate is only 70%, and the requirements for the magnetic field strength are high, and the collection process takes a long time

In addition, there are polyferric chloride, cationic polyacrylamide, etc., and the effect of collecting microalgae cells after mixing them with magnetic particles is not significant