Effect of pyrolysis temperature on sulfur content, extractable fraction and release of sulfate in corn straw biochar. Issue 62 (18th October 2018)

• Record Type: Journal Article
• Authors: Zhao, Baowei; Xu, Huan; Zhang, Tao; Nan, Xujun; Ma, Fengfeng
• Is Part Of: RSC advances. Volume 8:Issue 62(2018)
• Page Start: 35611
• Page End: 35617
• Publication Date: 2018-10-18
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c8ra06382f
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Low pyrolysis temperature is optimal for biochar to release sulfate and the release kinetics fitted well with a pseudo-second-order model. Abstract : The contents and release of the nutrient elements N, P and K in biochars have been investigated. Sulfur is an indispensable element for plants, but its content and release in biochar are still unclear. The effect of pyrolysis temperature (300, 500 and 700 °C) on the sulfur content, extractable fraction and release of sulfate in corn straw biochars (CS300, CS500 and CS700) was investigated. The biochars were characterized using element analysis, BET, FTIR, and XRD. It was shown that the contents of sulfur in biochars decreased significantly with increasing pyrolysis temperature. The extraction results indicated that the percentages of water extractable-sulfate (W–SO4 2− ) and organosulfur in biochars decreased while those of HCl- and NaH2 PO4 -extractable sulfate (HCl–SO4 2−, NaH2 PO4 –SO4 2− ) increased with pyrolysis temperature. Batch release experiments were conducted to test the effect of contact time and addition of Hoagland nutrient solution (HNS) on the release of sulfate from biochars. The release kinetics fitted well with a pseudo-second-order model. Approximately 10.7 mg g −1 of sulfate was released from CS300 during the initial 2 h, whereas 6.32 and 3.93 mg g −1 were released from CS500 and CS700, respectively. Increasing the amounts of HNS led to negative effects on sulfate release. The results indicate that low-temperatures might be optimal for producing biochar from corn straw to improve the sulfur fertilization.