Surface engineering is gaining increasing relevance in various industrial sectors and in research, and in this sense, zeta potential measurements, being a physicochemical parameter of interface, are key to linking the functionality of a coating with its application environment. In this work, different stabilizing agents with different chemical structure and electrical charge were used to improve the stability of the TiO2 particles. The influence of the electrophoretic deposition (EPD) parameters (potential and deposition time) and the concentration of chitosan and TiO2 in suspension were studied to find the best deposition performance on the titanium substrate. The composition and structure of the coatings were evaluated by infrared spectroscopies (FT-IR) and scanning electron microscopy (SEM). It was observed that the TiO2 particles were dispersed in the chitosan matrix through simultaneous deposition. Corrosion resistance was evaluated by electrochemical polarization curves, indicating a higher corrosion resistance of TiO2 and TiO2-chitosan coatings compared to the pure titanium substrate in a solution of sulfuric acid.
Part of the book: Titanium Dioxide
Industrial wastewater generally contains significant amounts of toxic heavy metals that cause a problem of contamination to the environment. In this chapter, the use of polyelectrolytic waste as new coagulant-flocculating-chelating agents in the separation of Cu, Ni, Zn, Pb, Cd, Cr by a coagulation-flocculation process is discussed. The isoelectric point (ζ = 0) of the residual water was reached with a dose of 2.5 mg chitosan and observed a clarification kinetics = 187.49% T/h, sediment kinetics = 93.96 mm/h and an efficiency of 85% in the removal of heavy metals. With the SEM-EDS analysis and the determination of heavy metals in the treated water, it is shown that the functional groups that chitosan has in its structure have the following order of affinity for the removal of heavy metals from the wastewater model: Cr = 27.64% > Ni = 21.96% > Pb = 21.28% > Zn = 14.68% > Cu = 10.96% > Cd = 3.35% > Ca = 0.12%.
Part of the book: Heavy Metals
The coagulation-flocculation process is one of the conventional technologies used for the treatment of different types of industrial wastewater. The zeta potential is a key parameter that allows to determine the effective pH, the type and the correct biopolyelectrolyte dose to return the water quality using coagulation-flocculation. In this chapter, we present the application of a natural cationic biopolyelectrolyte (chitosan) to make the separation and recovery of cellulose fiber more efficient and to increase the reuse of treated water from the pulp and paper industry. The result of the coagulation-flocculation test at pH 5.4 and a chitosan dose = 10 mg/L shows that the treated water has the following values: biochemical oxygen demand = 150 mg O2/L, turbidity = 5 FAU, total suspended solids = 2 mg/L, chemical oxygen demand = 200 mg/L and hardness = 250 mg CaCO3/L. The quality of water obtained allows its discharge to a natural water body, in which it is possible to continue with a biological treatment stage, or to reuse the treated water for the manufacture of paper. Additionally, this coagulation-flocculation process can be coupled to an advanced oxidation process to increase the quality of the water and mineralize the content of organic material.
Part of the book: Wastewater and Water Quality