Remarkable synergy between sawdust biochar and attapulgite/diatomite after co-ball milling to adsorb methylene blue

Fei Jiang; Feiyue Li; Andrew R Zimmerman; Zhongpu Yu; Licheng Ji; Chengcheng Wei; Xueyang Zhang; Bin Gao

doi:10.1039/d3ra01123b

Remarkable synergy between sawdust biochar and attapulgite/diatomite after co-ball milling to adsorb methylene blue

RSC Adv. 2023 May 11;13(21):14384-14392. doi: 10.1039/d3ra01123b. eCollection 2023 May 9.

Authors

Fei Jiang¹, Feiyue Li¹, Andrew R Zimmerman², Zhongpu Yu¹, Licheng Ji¹, Chengcheng Wei¹, Xueyang Zhang³, Bin Gao⁴

Affiliations

¹ College of Resources and Environment Science, Anhui Science and Technology University Fengyang 233100 China lify@ahstu.edu.cn.
² Department of Geological Sciences, University of Florida Gainesville 32611 FL USA.
³ School of Environmental Engineering, Jiangsu Key Laboratory of Industrial Pollution Control and Resource Reuse, Xuzhou University of Technology Xuzhou 221018 PR China.
⁴ Department of Agricultural and Biological Engineering, University of Florida Gainesville 32611 FL USA.

Abstract

Biochar has been recognized as a promising sustainable adsorbent for removing pollutants from wastewater. In this study, two natural minerals, attapulgite (ATP) and diatomite (DE) were co-ball milled with sawdust biochar (pyrolyzed at 600 °C for 2 h) at ratios of 10-40% (w/w) and examined the ability of methylene blue (MB) to be removed from aqueous solutions by them. All the mineral-biochar composites sorbed more MB than both ball milled biochar (MBC) and ball milled mineral alone, indicating there was a positive synergy in co-ball milling biochar with these minerals. The 10% (w/w) composites of ATP:BC (MABC10%) and DE:BC (MDBC10%) had the greatest MB maximum adsorption capacities (modeled by Langmuir isotherm modeling) and were 2.7 and 2.3 times that of MBC, respectively. The adsorption capacities of MABC10% and MDBA10% were 183.0 mg g^-1 and 155.0 mg g^-1 at adsorption equilibrium, respectively. These improvements can be owing to the greater content of oxygen-containing functional groups and higher cation exchange capacity of the MABC10% and MDBC10% composites. In addition, the characterization results also reveal that pore filling, π-π stacking interactions, hydrogen bonding of hydrophilic functional groups, and electrostatic adsorption of oxygen-containing functional groups also contribute prominently to the adsorption of MB. This, along with the greater MB adsorption at higher pH and ionic strengths, suggests the roles in MB adsorption was an electrostatic interaction and an ion exchange mechanism. These results demonstrate that mineral-biochar composites prepared by co-ball milling treatment were promising sorbents of ionic contaminants for environmental applications.