Swine manure char as an adsorbent for mitigation of p‐cresol

Abstract

There is a significant interest in synthesizing inexpensive adsorbents for mitigating pollutants emitted from animal agriculture industry such as p‐cresol. Biochar, a byproduct obtained from thermochemical biomass processing is one such source of adsorbent materials. However, presently there is not enough quantitative information on adsorption of p‐cresol on biochar. Hence, the goal of this research is to investigate swine manure char as an inexpensive adsorbent for removal of p‐cresol from an aqueous system. Swine manure was gasified for 15 min at 704°C to obtain gasified manure char. The char was characterized using physical and chemical techniques. Batch experiments were performed in duplicates at 25°C, 35°C, and 45°C to determine the adsorption isotherms and kinetics. Results indicated that gasification enhanced surface area and acid value of manure from 11.42 ± 0.20 to 49.12 ± 0.79 m2 g−1 and 7.81 ± 0.05 to 8.57 ± 0.01, respectively. The enhanced basicity of the resultant char promoted chemisorption of p‐cresol on char surface with maximum adsorption capacities of 7.63 mg g−1 (25°C), 14.99 mg g−1 (35°C), and 14.84 mg g−1 (45°C). Langmuir and Freundlich models suggested that adsorption of p‐cresol on char was favorable. Kinetic analysis of the data also confirmed chemisorption of p‐cresol while the analysis of transport processes suggested that internal diffusion of p‐cresol within the pores was the rate‐limiting step. Use of biochar as an adsorbent for p‐cresol will add value to gasification byproducts and simultaneously reduce water and air pollution associated with swine farming operations. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 125–131, 2015