Incorporation of Eichhornia crassipes dry biomass in red ceramics aiming at energy savings during the firing stage

Abstract

The natural variability of clay characteristics and the use of relatively simple processing techniques for the manufacture of red ceramics make it easy to incorporate various types of waste. Among these wastes, fuels have high calorific value due to the amount of organic matter and favor the energy saving in the firing of ceramic products. This research aimed to study the viability of using a phytoremediation waste, dry biomass of Eichhornia crassipes, in the production of red ceramics. After the raw materials characterizations, ceramic pieces with 5 compositions (0, 2.5, 5, 7.5, and 10%wt. Of biomass) were prepared by vacuum extrusion. The pieces were oven dried for 24h then fired at 650, 850, and 1050 °C and had their mechanical properties of dry density, fired bulk density, linear shrinkage, water absorption, and mechanical strength tested. Results showed that incorporations up to 5% of the biomass did not significantly alter the density and the linear shrinkage of the ceramic pieces. The biomass contains 37.7% w/w of carbon and a high calorific value (2.389 kcal/kg) and the ceramic firing stage causes the combustion of the biomass organic compounds, which increases the porosity of the pieces. Therefore, an increase in biomass content tends to enhance water absorption and reduce mechanical strength. Even so, incorporations of 5% of biomass met the standardized limits for red ceramic products and as its firing releases heat that can be harnessed to the process and save up to 51% of energy, its incorporation can be beneficial to the ceramic industry. Furthermore, it represents savings of raw materials for the ceramic industry and an environmentally friendly destination for the waste that would otherwise be landfilled. The incorporation of biomass of Eichhornia crassipes was proven to be feasible, but the quantity and temperature must be controlled.