Influence of post-treatment strategies on the properties of activated chars from broiler manure

Authors: Lima, Isabel; Boykin, Deborah; Klasson, K Thomas; Uchimiya, Sophie

Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2013
Publication Date: 1/1/2014
Citation: Lima, I.M., Boykin, D.L., Klasson, K.T., Uchimiya, M. 2014. Influence of post-treatment strategies on the properties of activated chars from broiler manure. Chemosphere. 95:96-104.

Interpretive Summary: There are a myriad of carbon rich precursors that can be used advantageously to produce activated carbons or chars, due to their low cost, availability and intrinsic properties. Because of the nature of the raw material, production of granular activated chars from broiler manure results in a significant ash fraction. This study was conducted to determine the influence of several pre- and post-treatment strategies in various physicochemical properties of the resulting activated chars. Broiler manure samples underwent pyrolysis at 700°C for 1 h followed by a 45 min steam activation at 800°C at different water flow rates from 1 to 5 mL/min. Samples were further either water-rinsed or acid-washed and rinsed or used as is. Activated char’s physicochemical properties were selectively affected by both pre- and post-treatments. The amount of ash material removed during post-treatment ranged from 1.1 to 15.1% but washed activated chars were still alkaline with pH ranging from 8.4 to 9.1. Acid washing or water rinsing had no significant effect in the ability of the activated char to uptake copper ions, however it significantly affected surface area, pH, ash content and carbon content. Instead, manure type (litter versus cake) and the activation water flow rate were determining factors in the ability of the chars to remove copper ion from solution, which ranged from 38 mg/g to 104 mg/g of activated char. Moreover, strong positive correlations were found between copper uptake and concentration of certain elements in the activated char such as phosphorous, sulfur, calcium and sodium. Rinsing could suffice as a post treatment strategy for ash reduction since no significant differences in the carbon properties were observed between rinsed and acid washed treatments. Ultimately, rinsing as an alternative to acid washing can lead to production cost savings, due to higher yields and reduced costs associated with acid washing.

Technical Abstract: There are a myriad of carbonaceous precursors that can be used advantageously to produce activated carbons or chars, due to their low cost, availability and intrinsic properties. Because of the nature of the raw material, production of granular activated chars from broiler manure results in a significant ash fraction. This study was conducted to determine the influence of several pre- and post-treatment strategies in various physicochemical and adsorptive properties of the resulting activated chars. Pelletized samples of broiler litter and cake were pyrolyzed at 700°C for 1 h followed by a 45 min steam activation at 800°C at different water flow rates from 1 to 5 mL/min. For each activation strategy, samples were either water-rinsed or acid-washed and rinsed or used as is (no acid wash/rinse). Activated char’s physicochemical and adsorptive properties towards copper ions were selectively affected by both pre- and post-treatments. The amount of ash material removed during post-treatment ranged from 1.1 to 15.1% but washed activated chars were still alkaline with pH ranging from 8.4 to 9.1. Acid washing or water rinsing had no significant effect in the ability of the activated char to adsorb either of the heavy metals, however it significantly affected surface area, pH, ash content and carbon content. Instead, manure type (litter versus cake) and the activation water flow rate were determining factors in copper ion adsorption which ranged from 38 mg/g to 104 mg/g of activated char. Moreover, strong positive correlations were found between copper uptake and concentration of certain elements in the activated char such as phosphorous, sulfur, calcium and sodium. Rinsing could suffice as a post treatment strategy for ash reduction since no significant differences in the carbon properties were observed between rinsed and acid washed treatments.