A large number of domestic sewage and industrial waste water are discharged into rivers and lakes, resulting in eutrophication of water bodies, affecting the safety of water and living environment. The algae outbreak will cause the oxygen depletion in the water to lead to the death of the fish. The toxins released by some algae will poison the organisms. We should deal with the algae pollution quickly and effectively. It is an urgent need to control the water pollution.
At present, algae removal in water is often done by manual removal, and the treatment efficiency is low. Researchers have developed a new method for purifying algae: magnetic nanomaterials using solid phase, montmorillonite with porous materials as adsorbents, non-toxic and harmless adsorbents, adsorbents for algal porous materials and bismuth tungstate, a photochemical agent used to degrade algae and algae toxins. The method of scheme preparation is as follows:
(1) First, the adsorbents are evenly dispersed in water and then placed in a water bath reaction tank, through nitrogen protection, and then FeCl3•6H2O and FeCl2•4H2O are put into the water bath reaction tank with the molar ratio of 2:1. The mass ratio of adsorbents to magnetic nanomaterials is controlled in 1:0.4-1.4, and the temperature of water bath is controlled at 60°C -90°C. After mixing 15-30min, the ammonia water with a mass fraction of 30% was added, the pH value of the solution was controlled to 11-13, and the reaction for 2-4h was continued, and the unassembled magnetic nanomaterials and adsorbents were removed.
(2) The compound magnetic adsorbent is prepared with the adsorbent. The compound magnetic adsorbent and the bismuth tungstate photocatalyst precursor are added to the hydrothermal reactor. The mass ratio of the compound magnetic adsorbent and the bismuth tungstate is controlled in the 1:3, the hydrothermal method is at 160 -220°C, and the reaction is 10-24h. The magnetic adsorbent was loaded with light catalyst, and then cooled to room temperature after the reaction was completed. After washing and magnetic separation, the magnetic adsorbent and bismuth tungstate photocatalyst were loaded on the magnetic nanomaterials, and the magnetic compound alga removal agent was obtained by drying the adsorbent and the bismuth tungstate photocatalyst at 60-80°C.
(3) The magnetic compound algae removal agent is added to the eutrophic water containing algae according to the dosage of 0.8- 1.5g/L, stirring for 1-10 minutes, leaving the algae flocculant out for 5-10 minutes, and using magnets to remove the algae flocculant out of the water. The quality of the magnetic compound algae removal agent is better than that made of the algae, and the algae removal agent can adsorb and flocculate the algae and water. Pollutants such as nitrogen and phosphorus, improve the transparency of water, and purify the water quality.