Efficacy of chicken litter and wood biochars and their activated counterparts in heavy metal clean up from wastewater

Authors: Lima, Isabel; Ro, Kyoung; REDDY, G - North Carolina Agricultural And Technical State University; Boykin, Deborah; Klasson, K Thomas

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2015
Publication Date: 9/16/2015
Citation: Lima, I.M., Ro, K.S., Reddy, G.B., Boykin, D.L., Klasson, K.T. 2015. Efficacy of chicken litter and wood biochars and their activated counterparts in heavy metal clean up from wastewater. Agriculture. 5(3):806-825.

Interpretive Summary: It is known that properties of activated biochars are tightly associated with those of the original feedstock as well as pyrolysis and activation conditions. This study utilized pine wood shavings and chicken litter to produce biochars at two different temperatures. Biochars were subsequently activated by steam, acid or base. All materials were characterized for their properties and ability to remediate two well-known heavy metals of concern: copper and arsenic. For wood biochars, significant increases of surface functionality as related to oxygen bearing groups and surface charge were observed upon acid activation which led to increased copper ion uptake. However, oxygen surface groups on the biochars did not explain why chicken litter biochars and steam activated biochars appeared to be significantly superior to wood shavings in positively charged metal ion uptake. For chicken litter, functionality of respective biochars could be related to phosphate containing groups inherited from feedstock composition, favorably positioning this feedstock in metal ion remediation applications.

Technical Abstract: It is known that properties of activated biochars are tightly associated with those of the original feedstock as well as pyrolysis and activation conditions. This study examined two feedstock types, pine wood shavings and chicken litter, to produce biochars at two different pyrolysis temperatures and subsequently activated by steam, acid or base. In order to measure activation efficiency, all materials were characterized for their properties and ability to remediate two well-known heavy metals of concern: copper and arsenic. Base activated biochars were superior in arsenic adsorption, to acid or steam activated samples, but increase in adsorption was not significant to warrant use. For wood biochars, significant increases of surface functionality as related to oxygen bearing groups and surface charge were observed upon acid activation which led to increased copper ion adsorption. However, oxygen bearing functionalities were not sufficient to explain why chicken litter biochars and steam activated biochars appeared to be significantly superior to wood shavings in positively charged metal ion adsorption. For chicken litter, functionality of respective biochars could be related to phosphate containing groups inherited from feedstock composition, favorably positioning this feedstock in metal ion remediation applications.