AVALIAÇÃO DA EFICIÊNCIA DE AGENTES COAGULANTES EM EFLUENTE DE FRIGORÍFICO

In the refrigeration industry, a large amount of water is used throughout processes, generating effluents that need treatment before release. The purpose of this work was to make a comparative study of three coagulants used in the treatment of effluents: Aluminum Polychloride (PAC), Aluminum Sulphate (Al2(SO4)3) and Vegetable Tannin, with the aid of a flocculant (Anionic Polymer) by analyzing COD removal efficiency and turbidity. Jar coagulation / flocculation tests were conducted to optimize the concentration of coagulants. It was found that the natural coagulant presented a small variation in the pH parameter, avoiding the use of chemicals for its correction. The results of turbidity removal percentages indicated a great potential for Tannin when compared to the other chemical coagulants.

Vegetable Tannin as a Sustainable UV Stabilizer for Polyurethane Foams

A vegetable tannin, a flavonoid-type natural polyphenolic compound, was used to promote the stabilization of polyurethane foams against UV radiation. Several polyurethane foams were synthesized by using an isocyanate, and a mixture of ethoxylated cocoalkyl amine and vegetable tannin. The content of vegetable tannin was varied from 0 to 40 wt %. The effects of tannin and water (used as a blowing agent) on the foaming kinetics and cellular morphology of foams were investigated. Samples were subjected to accelerated weathering under UV radiation for 3 to 24 h, and FTIR and DMA analyses were conducted to assess the performance change. The former analysis revealed a strong inhibiting effect of tannin on urethane linkage degradation during the UV treatment. The mechanical properties were significantly affected by the addition of tannin. The capability of the foams to withstand UV radiation was dependent on the amount of tannin. At tannin contents higher than 20%, the decrease in mechanical properties under UV irradiation was almost avoided.

Modification of PA/PU superfine non-woven fiber for “breath” property using collagen and vegetable tannins

Unfigured sea-island superfine fiber PA/PU non-woven (USFSLB) is used to mimic leather’s microstructure as the base of artificial leather. USFSLB has many characteristics and advantages resembling those of natural leather. However, compared with natural leather, the wearing comfort of artificial leather is inferior due to its poor moisture adsorption and permeability. In this work, a “two-step” method of chemical treatment is proposed, in which collagen/chromium-vegetable tannin (C-CrT) is immobilized on nylon fiber of USFSLB to improve its moisture adsorption and permeability (“breath” property). The two-step surface modification involved sulfuric acid hydrolysis and modifying the C-CrT on nylon fiber. Compared with the pristine USFSLB, the tensile strength, the elongation at break, the anti-static performance, the thickness, and the uniformity of C-CrT-treated USFSLB were improved at different levels. Importantly, the C-CrT-treated USFSLB showed excellent moisture adsorption and permeability, especially the liquid wicking rate (LWR) improved by 344%. The self-assembly mechanism of collagen/chromium-vegetable tannin (C-CrT) modified on nylon fibers was analyzed and discussed.