Pyrolysis temperature and steam activation effects on sorption of phosphate on pine sawdust biochars in aqueous solutions

• Published in: Chemical speciation and bioavailability Vol. 28; no. 1-4; pp. 42 - 50
• Main Authors: Lou, Kangyi, Rajapaksha, Anushka Upamali, Ok, Yong Sik, Chang, Scott X.
• Format: Journal Article
• Language: English
• Published: St. Albans Taylor & Francis 01.10.2016; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: Activation; adsorbents; Adsorption; application rate; Aquatic environment; Aqueous solutions; biochar; Black carbon; Charcoal; designer biochar; engineered biochar; Eutrophication; ions; Phosphate; Phosphates; Phosphorus removal; Pyrolysis; Removal; Sawdust; Sorption; Steam; steam activation; surface modification; Temperature; Temperature effects
• ISSN: 0954-2299; 2639-5932; 2047-6523; 2639-5940
• DOI: 10.1080/09542299.2016.1165080

Biochar can be used as an adsorbent for phosphate removal in aquatic environments to treat eutrophication problems. Designing biochars that have large phosphate adsorption capacity through altering pyrolysis conditions and applying activation techniques will improve phosphate removal efficiency. In this study, four pine sawdust biochars were produced at 300 and 550 °C with and without steam activation. Batch sorption experiments including isotherm and kinetic studies were conducted to understand how phosphate removal capabilities and adsorption mechanisms of biochars were affected by pyrolysis temperature and steam activation. Our results showed that the steam activation and pyrolysis temperature did not affect phosphate adsorption by the biochars. The four biochars removed <4% of phosphate from the aqueous solution, which were not affected by the pH of the solution and biochar application rate. The repulsion forces between biochar surfaces and phosphate ions were likely the cause of the low adsorption.