Development of geopolymeric structures to prioritize the use of waste from paper industries

Geopolymers were synthesized using metakaolin obtained from the waste of white paper pulping process. The waste is mainly composed by cellulose, calcium carbonate and kaolin. Chemical and physical procedures were conducted aiming to separate its components and obtain metakaolin. The cellulose was eliminated by burning the waste at 450 °C. The CaCO3 was removed by reacting the material with a 1.8 M HCl solution. The purified kaolin went through heat treatment 850 °C for 2 h, in order to be transformed into metakaolin by dehydroxylation. Geopolymers were produced to assess the performance of the resulting metakaolin. The aluminosilicate alkaline activation was executed using four solutions - composed of 8 M and 12 M of KOH and NaOH, each combined with Na2SiO3 in a 2:1 fixed ratio. The results pointed out that the metakaolin obtained from the waste treatment was a quality one, enabling it to be applied in the development of geopolymers.