Developing performance-property correlation for fly ash as adsorbent for pulping effluents

Wood based fly ash has a limited use in industry currently, but it can be used as an adsorbent in wastewater treatment systems. In this work, physical (e.g., surface area, pore size) and chemical (e.g., compositions) properties of fly ash were investigated and related to its performance in removing lignocelluloses from a pulping spent liquor (SL). To achieve this goal, two different industrially produced wood-based fly ash (FA) samples, FA1 and FA2, were used. The results revealed that the removals of COD, lignin and turbidity were 80%, 95% and 96% for FA1 and 30%, 25% and 50% for FA2, respectively, under the experimental conditions of 100 g/L dosage at 25 °C for 1 h. The heating value of fly ash was also increased after adsorbing the organic compounds. To investigate the impact of inorganic components, fly ash samples were incinerated at 525 and 900 °C, and then they were used for removing organic materials. The analysis depicted that the removals were limited when incinerated FA1 was used, while incinerated FA2 at 900 °C had more organics removal than FA2. Overall, it was concluded that even though the physical properties of fly ash impacted the adsorption of organics, the chemical compositions of fly ash played a more crucial role on its performance in removing lignocelluloses.