عنوان مقاله [English]
Due to the problems of deposition of sodium silicate on the equipment and decrease of the service age of implements, deinking of old newspaper was accomplished using organic complex of Sulvy-x in place of sodium silicate.
Sulvy-x was used at four levels of 0.3, 0.5, 0.7 and 1% on the basis of oven dry waste paper and chemical deinking was done. The effect of various charges of Sulvy-x was investigated and on optical and physical properties of deinked pulp compared with those of control sample (ONP recycled using 2% sodium silicate) and its optimum usage was determined. The results of optical properties showed that the brightness of paper increased to 50.8 %ISO and the yellowness decreased to 11.96 %ISO by increasing of Sulvy-x charge up to 0.9%. Also, lower charge of Sulvy-x (0.3%) resulted the highest opacity of 98.63 %ISO. The results of physical properties indicated that the caliper of paper reduced to a minimum value of 109.8 µm. Higher charges of Sulvy-x in deinking process resulted the paper with the higher density. The highest density of 0.546 g/cm3 was observed using 0.9% Sulvy-x. Also, deinking of old newspaper with 0.3% and 0.7% Sulvy-x resulted the pulps with the highest freeness as 435 ml, CSF. In general, using different amount of Sulvy-x in place of sodium silicate resulted the papers with similar brightness, higher opacity and lower caliper compared to those of control sample. However, the paper with higher brightness and density, lower yellowness and desirable opacity could be produced using 0.9% Sulvy-x in chemical deinking of old newspaper.