Valorization of rice straw waste: an alternative ceramic raw material

Valorização de resíduo de palha de arroz: uma matéria-prima cerâmica alternativa

In the production of rice a large amount of solid residue is produced, for which alternative utilizations are scarce or are not commonly applied in industry. Rice straw (RS) is a waste product of rice harvest that is generated in equal or greater quantities than the rice itself. RS is frequently burned in open air, which makes it a significant source of pollution. In the search for possible uses of RS, it should be noted that its ash (RSA) is particularly rich in silica, alkaline and alkaline earth metals and may be used as a source of alkalis and silica for the production of triaxial ceramics. The present research work proposes the production of a ceramic raw material from RS for its use in the fabrication of ceramic materials for the construction industry. Based on the chemical and mineralogical composition of RSA created under different thermal conditions, the most suitable RSA for this purpose was that obtained from treating RS at a temperature of 800 ºC for a time of 2 h. The resulting RSA presented high contents of SiO₂ (79.62%), alkaline oxides (K₂O) (10.53%) and alkaline earth oxides (CaO) (2.80%). It is concluded that RSA is a new alternative ceramic raw material that can be used as a replacement for the fluxing (mainly feldspar) and inert (quartz) materials that are used in the production of triaxial ceramics.

agricultural residue; rice straw; rice straw ash; construction material; triaxial ceramics