Characteristics and mechanisms of phosphorous adsorption by rape straw-derived biochar functionalized with calcium from eggshell

Cao H 1 , Wu X 2 , Syed-Hassan SSA 3 , Zhang S 4 , Mood SH 5 , Milan YJ 5 Show all authors , Garcia-Perez M 5

Affiliations 

  • 1 Key Laboratory of Agricultural Equipment in Mid-lower Yangtze River, College of Engineering, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan 430070, PR China; Department of Biological Systems Engineering, Washington State University, Pullman, WA 99164, USA. Electronic address: chlhust@126.com
  • 2 Key Laboratory of Agricultural Equipment in Mid-lower Yangtze River, College of Engineering, Huazhong Agricultural University, No. 1, Shizishan Street, Hongshan District, Wuhan 430070, PR China
  • 3 Faculty of Chemical Engineering, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
  • 4 College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, PR China
  • 5 Department of Biological Systems Engineering, Washington State University, Pullman, WA 99164, USA
Bioresour Technol, 2020 Dec;318:124063.
PMID: 32905948 DOI: 10.1016/j.biortech.2020.124063

Abstract

Biochar modified with calcium source is acted as an effective adsorbent for phosphorous recovery. In this research, eggshell is used as a low-cost and environmentally friendly calcium source to replace chemical reagents such as CaCO3, Ca(OH)2 and CaCl2 used in the modified biochar production. Biochar derived from rape straw and modified with eggshell shows prominent phosphorous adsorption performance (e.g., equilibrium adsorption amount, 109.7 mg/g). The kinetic and isotherm analysis demonstrate that chemical adsorption process is performed as the main controlled step for the modified biochar adsorption, and the phosphate adsorption process is composed of both monolayer adsorption and multi-layer adsorption. Moreover, it is found from the physicochemical structures comparison before and after phosphate adsorption that Ca-P precipitation, hydrogen bonding and electrostatic attraction are identified as main adsorption mechanisms. In addition, the adsorbed phosphates are mainly distributed inside the space with pore sizes of 15-50 nm.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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