Nanotoxicology “focuses on determining the adverse effects of nanomaterials on human health and the environment.”

Nanotoxicology “focuses on determining the adverse effects of nanomaterials on human health and the environment.”

2: Clarification mechanism of coagulant

Chemical coagulation is a process in which chemical agents (coagulants) are added to water treatment to make colloidal dispersion system destabilize and agglomerate. In the coagulation process, small suspended particles and colloidal impurities are aggregated into larger solid particles to separate particulate impurities from water, which is called coagulation clarification.

After adding coagulant into water, colloidal particles and other small particles can be polymerized into larger flocs through the comprehensive action of mixing, coagulation and flocculation. The whole process of coagulation and flocculation is called coagulation.

(1) Destabilization and condensation of colloids

Adding electrolyte to water can compress the electric double layer and destabilize the colloid. The main mechanism is that the electric double layer of colloidal particles in water is compressed or neutralized by adding aluminum salt or iron salt coagulant. The coagulant and raw water are mixed rapidly and evenly, and a series of chemical reactions are produced to destabilize. This process takes a short time, generally about 1 min. Some cationic polymers can also play a role in the destabilization and condensation of colloids in water. These polymers have a long chain structure and positive charge in water. Their destabilization and condensation of colloids in water is due to the interaction of van der Waals force adsorption and electrostatic attraction.

(2) Flocculation and formation of floc (alum)

The particle size of the initial flocculate formed by colloid destabilization and coagulation in water is generally more than 1 m. at this time, Brownian motion can no longer push them to collide and form larger particles. In order to make the initial flocs collide with each other to form large flocs, it is necessary to input additional energy into the water to produce a velocity gradient. Sometimes it is necessary to add organic polymer flocculant into water, and the adsorption bridging effect of long chain molecules of flocculant is used to improve the probability of collision and adhesion. Flocculation efficiency usually increases with the increase of flocculate concentration and flocculation time.

Compared with polyaluminum chloride, polyaluminum chloride has the advantages of high density, fast settling speed and wide pH adaptability; the coagulation effect is less affected by temperature than that of polyaluminum sulfate; however, when adding ferric salt, it should be noted that when the equipment is not in normal operation, the iron ions will make the effluent color, and may pollute the subsequent desalination equipment.

Those scientists found that sunscreen residue on the roof installers fingertips were being transferred to the colour bond sheets during installation & with titanium dioxide’s photo-sensitivity & the lovely sun’s help, the paint was literally peeling off those roofs.

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No. EFSA’s role was limited to evaluating the risks linked to titanium dioxide as a food additive. This included an assessment of relevant scientific information on TiO₂, its potential toxicity, and estimates of human dietary exposure. Any legislative or regulatory decisions on the authorisations of food additives are the responsibility of the risk managers (i.e. European Commission and Member States).

Research supports that applying titanium dioxide to the skin in the form of sunscreens, makeup, and other topical products does not pose any health risks. 

Metal detectors can not only detect a variety of metals at various depths depending on the size of the object, but some can even detect the differences between various metals. This differentiation is done by measuring the deflection of the magnetic field generated by the metal detector. Titanium is often used in medical implants, so patients with implants that contain titanium often have to make this known to airport security personnel in order to pass inspection.

Following the EU’s ban on E171, the FDA told the Guardian that, based on current evidence, titanium dioxide as a food additive is safe.  “The available safety studies do not demonstrate safety concerns connected to the use of titanium dioxide as a color additive.”

One of the key advantages of using anatase titanium dioxide in coatings is its superior UV resistance. This makes it ideal for outdoor applications where coatings are exposed to sunlight and other environmental factors that can degrade the finish over time. Anatase titanium dioxide helps to protect the underlying surface from UV rays, preventing fading and deterioration.