TEMPO-Mediated Oxidation to Improve Deinked Pulp Quality

A bleached virgin hardwood kraft pulp was refined and recycled one time in laboratory. Recycled samples were then oxidized using TEMPO (4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl radical), sodium bromide and sodium hypochlorite, with variation of the latter’s concentration on each sample. Results showed that all papermaking properties, particularly the tear index, were significantly improved at low NaOCl concentrations. At higher NaOCl charges the burst and tensile indices suffered little decrease, while the tear was strongly reduced.

Factors affecting Chloride and Potassium Removal Efficiency of a Recovery Boiler Precipitator Ash Treatment System

A laboratory study was performed to examine the main factors affecting the removal efficiency of chloride (Cl) and potassium (K) of ash treatment systems operated at a temperature between 60 and 100^oC. The results show that the removal efficiency is directly proportional to the amounts of Cl and K in the liquid that have been separated from the ash-water slurry. For a given system, the Cl and K removal efficiency is determined by the concentration of Cl and K in the liquid and by the Degree of solid-liquid Separation (DS). DS, in turn, is greatly affected by the ash concentration in the slurry and the CO₃ content of the ash.