Abstract
Black liquor is a toxic by-product from industrial pulp manufacture. It contains sodium hydroxide that can be used as precursor activator for alkali activated material, which is an aluminosilicate material that can be prepared from thermal activation of solid material containing alumina and silica as precursor and alkali activator solution. In this work, alkali activated mortar was prepared by mixing fly ash as main precursors, aggregate, followed by addition of activator solution containing sodium hydroxide solution and waterglass, and chemical admixture which is lignin or black liquor. The best compressive strength was 34.40 MPa achieved in addition of 10 wt% of black liquor to alkali activated mortar. X-ray diffraction demonstrated the formation of albite in mortars, indicating that geopolymerization have been successfully formed. FTIR spectra showed the presence of siloxo and sialate peaks which commonly found in geopolymerization.
Highlights
Industrial paper manufacture involves a procedure known as the Kraft process, where wood is converted into wood pulp and into paper
In order to enhance the mechanical properties of fly ash-based activated material (AAM), chemical admixture in form of lignin, and black liquor were added to geopolymeric body up to 10%
Control samples demonstrated average compressive strength of 26.40 MPa, while FAL and FABL showed the increased values of compressive strength which is 30.33 MPa and 34.40 MPa, respectively. It shows that the addition of lignin and black liquor increase the compressive strength from sample without admixture. This is due to high concentration of NaOH used in making black liquor (14M), which means there are addition of Na+ in the solution is sufficient to bind silicate in fly ash
Summary
Industrial paper manufacture involves a procedure known as the Kraft process, where wood is converted into wood pulp and into paper This process produces a toxic byproduct referred as black liquor. This primarily liquid mixture of pulping residues (like lignin and hemicellulose) and inorganic chemicals from the Kraft process (sodium hydroxide and sodium sulfide, for example) is toxic and until the invention of recovery boilers in the early 20th century was often released into. Chemical admixture combined with fly ash, which is by product material containing high silica and alumina, was used in production of alkali activated materials. In order to enhance the mechanical properties of fly ash-based AAM, chemical admixture in form of lignin, and black liquor were added to geopolymeric body up to 10% (wt/wt). The effect of various chemical admixtures toward macroscopic and microscopic properties of resulting AAM was evaluated
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