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.
Highlights
Through extraction from ores and further processing into a myriad of uses, heavy metals have been released into the environment over many years
With the objective of improving the surface properties and porous structure of biochars and adsorption towards heavy metals, activation protocols were applied to biochars from wood chips and chicken litter
Activation of biochars was responsible for changes in various chemical properties, and led to significant changes in surface functionality that resulted in increased copper ion adsorption
Summary
Through extraction from ores and further processing into a myriad of uses, heavy metals have been released into the environment over many years. Since they are not biodegradable, they are prone to accumulate. Some heavy metals are carcinogenic, mutagenic, teratogenic and endocrine disruptors while others cause neurological and behavioral changes especially in children [1,2]. Due to their ubiquitous nature, they are often present in wastewater and their effective removal to acceptable levels commonly requires the use of adsorbents. The U.S EPA set the maximum contaminant level for copper in their National Primary Drinking Water Regulations to
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