Coagulation using kerosene for magnetic deinking of waste office paper

A method for disintegrating waste office paper using kerosene was reported in our previous paper, which achieved almost a 100% liberation of toner from paper fibers. The liberated toner must be completely separated to realize effective deinking. Recently, a new method for deinking waste officer paper by magnetic separation after hetero-coagulation of magnetic and non-magnetic toner by 1-octadecanol was reported by Augusta et al. Under this method, coagulation was carried out at 72°C. The 1-octadecanol liquid was then cooled to produce strong solid coagulates. As reported in our previous paper, kerosene has the ability to soften toner, and strong coagulates for magnetic separation may be produced by their adhesion when used as a flocculant. The present study investigated the size of toner particles liberated by the kerosene disintegration method, and compared the bonding strength between the toner particles coagulated by the addition of kerosene as a flocculant to those coagulated with 1-octadecanol. After these investigations, the coagulating and deinking properties of kerosene and 1-octadecanol were compared by rejecting toner coagulates with a neodymium-boron magnet. The results showed that nearly perfect deinking can be achieved with little paper loss, even in ambient temperature, due to the large and strong coagulates produced by this method. When kerosene was used in the disintegration and coagulation stages, the average coagulate size was 1114 μm, and a deinking percentage of 98.4% was attained through separation with a neodymium-boron magnet.