Production of cardboard from waste rice husk

Rice husk does not have substantial commercial value and generally present an environmental problem concerning its disposal. This investigation determines the suitability of producing cardboard from rice husk, thus, reducing the amount of pulping material required from virgin wood. Maceration process was used to produce cardboards from their pulps. For comparative evaluation, along with rice husk, bagasse and waste paper were used. The latter were blended in different ratios and their mechanical strength determined. Rice husk contained 15.2% lignin, 20.56% ash with kappa number of 99.48 while bagasse had 13.70% lignin and 2.23% ash with kappa number of 88.39. The maceration period of rice husk and bagasse was between 6 and 15 days and 5–10 days with the corresponding pulp yield of 40.44–46.55% and 46.01–36.76%, respectively. The average lignin content of rice husk pulp and bagasse pulp was 3.09–2.9% and 2.95–2.43%, respectively. The tensile index, edgewise crush resistance, average bursting index of cardboard from rice husk was 11.31 N m/g, 1.11 kN/m and 0.84 kPa m2/g, respectively. For the rice husk mixed bagasse cardboard, the optimal ratios were (20/80), (40/60), and (60/40) with a tensile index of 17.96, 16.66 and 12.94 N m/g, respectively. The edgewise compressive resistance was 2.91, 2.42 and 1.99 kN/m, respectively. The bursting index was 1.88, 1.55, and 1.26 kPa m2/g, respectively. The optimal rice husk mixed waste paper ratio was (20/80) with a tensile index of 21.52 N m/g with an edgewise compressive resistance of 2.75 kN/m and a bursting index of 1.35 kPa m2/g. Thus, these cardboards are suitable for packaging as corrugating medium, wrapping and insulating board.