Research On The Kinetics Of Tea And Waste Tea Products To Adsorb Formaldehyde And Development Of The Environment-friendly Flakeboards

In this study, the solutions of four tea components including tea polyphenols(TP), theaflavins (TF), L-theanine (TA), and caffeine ( TC ) were designed to react with formaldehyde under different temperatures and reaction times. The reaction characteristics and sorption kinetics of formaldehyde were analyzed and discussed. Results showed that all of four tea main components had the abilities on free formaldehyde absorption, the formaldehyde reducing effects were TF > TP > TA > CA. TF was the most effective one on free absorbing formaldehyde. After 3 hours, it reached the maximum of formaldehyde absorption. TP had a slower speed on adsorption of formaldehyde, but didn't reach the maximum after 4 hours. TA and CA had a little effect on adsorption of formaldehyde with fluctuant. The relationship between temperature, reactive time of four tea components and formaldehyde were analyzed through adsorption curve. It showed that high temperature promoted formaldehyde absorption, low and normal temperature had no significant difference; the pH of reaction systems were stable through the procedure. The active functional groups and the reaction mechanisms of tea catechins, theafiavins, L-theanine, and caffeine on formaldehyde adsorption were discussed.The tea and waste tea products (black tea residue, green tea residue, oolong tea stalk, pruned tea branch, and stale green tea) were applied to prepare urea-formaldehyde resin and the produce of flakeboards. The formula of resin and the additional proportions with tea and waste tea products on flakeboards were analyzed. The results showed that 200mu (0.074mm) powder of tea and waste tea products to resin at 2% level could effectively reduce the FFE and didn't reduce the properties of resin. The addition of tea and waste tea products in flakeboards could significantly reduce formaldehyde-emission. Compared with blank group, the free formaldehyde emission from pruned tea branch group and stale green tea samples were reduced to 51.3% and 35.5%, respectively. The effects of different additional proportion of tea and waste tea product on the formaldehyde absorbency of flakeboards were 15% > 10% > 5%. And the flakeboards added with green tea residue, pruned tea branch, and stale green tea all had a better static bending strength than blank group. During the post-storage of flakeboards, released formaldehyde from improved flakeboards become stable, the free formaldehyde emission in pruned tea branch group and stale green tea group reduced to 51.87% and 37.60%. Furthermore, the analysis between the reducing amounts of free formaldehyde emission and the contents of main compounds suggested that tea polyphenols, amino acids and theaflavins were correlated with the reduced amounts of formaldehyde.From this study the functions of tea and waste tea products for reducing the formaldehyde in flakeboards was proved. which showed that low quality tea and residue will be very useful in preparation of man-made boards with high quality and low formaldehyde.