Papers by Keyword: TAED

Abstract: The bleaching efficiency of hydrogen peroxide can be promoted by using suitable activator. In our research, two methods were applied to compare the activating ability of three activators, TAED (tetraacetylethylenediamine), acetamide and dicyandiamide. The first part was hydrogen peroxide bleaching. TAED was excellent, because the brightness improvement was the maximum; the viscosity was acceptable. Acetamide was an applied activator in peroxide bleaching，for it could get same effects as TAED if the bleaching process had enough time and enough dosage. In the last part our study was about the kinetics of a lignin model compounds, acetovanillone, in peroxide-alone system, TAED/H2O2 system, acetamide/H2O2 system and dicyandiamide/H2O2 system. The rate constant, k and half-life period, t1/2 can be used to compare the rate of oxidation of acetovanilone. Compared to peroxide-alone system, three systems with activator and H2O2 could accelerate the reactions of hydrogen peroxide and acetovanillone. The t1/2 of TAED/H2O2 system was least of them. It was just 1/5 of t1/2 of peroxide-alone system, 1/4 of t1/2 of acetamide/H2O2 system and dicyandiamide/H2O2 system. The activating ability order of activators was: TAED> acetamide> dicyandiamide.

Abstract: Magnesium-based alkalis and the Chelants (tetra acetyl ethylene diamine (TAED), Sodium Citrate and Opal) for hydrogen peroxide bleaching of bamboo pulp were investigated in this paper. The results showed that the optimal conditions of hydrogen peroxide bleaching of bamboo pulp were as follows: H2O2 4%, Mg(OH)2:NaOH=25%, Sodium Citrate 1%, Opal 1.5%, TAED:H2O2=0.67, temperature 60°C, and time 90 minutes. Under the optimum conditions, the brightness of bamboo pulp can be enhanced from 41.2% ISO to 78.2% ISO, while the brightness of bleached pulp by using the Mg(OH)2-based alkalis was higher than by using NaOH as the alkali source. It can be seen that Sodium Citrate, Opal, and TAED activated H2O2 bleaching needed lower reaction temperature, shorter time, and got better brightness and alleviated environment pollution, compared with the conventional H2O2 bleaching of the same pulp.

Abstract: FAS bleaching (F) and conventional H₂O₂ bleaching (P) as well as TAED activated H₂O₂ bleaching (P_T) of wastepaper de-inked pulp (DIP) were studied in this paper. The results showed that the optimum conditions for FAS bleaching of DIP at 10% consistency were FAS 0.6%, NaOH 0.3%, reaction time 30min, temperature 70°C. Under the same conditions of H₂O₂ 3.0%, NaOH 2.0%, Na₂SiO₃ 3.0％, MgSO₄ 0.05％, the optimum temperature was 80°C and reaction time 90min for conventional hydrogen peroxide bleaching; the optimum TAED dosage was 1.5%, reaction time 60min, temperature 60°C for TAED activated hydrogen peroxide bleaching. Finally a comparison was made between P_TF and PF two-stage bleaching for DIP. The performance of P_TF was better than PF.