Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 729, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2020.139055
Keywords
Swine manure; Rice straw; Silica; Solid waste; Wastewater contaminant removal
Categories
Funding
- National Key Research and Development Program of China [2018YFC1800704, 2017YFA0207003]
- Natural Science Foundation of Guangdong Province [2018A030307014, 2016A030307010]
- National Natural Science Foundation of China [41701357]
- Science and Technology Planning Project of Guangdong Province [2017A030223010]
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Two types of silica-composited biochars were prepared by mixing swine manure or rice straw with alkali-fused fly ash (AFFA) followed by pyrolysis. A 10% (w/w) AFFA modification improved the specific surface area, pore volume, and average pore size of the biochars. Certain surface oxygen-containing functional groups (i.e., -OH and C-O) in the biochars were protected, and silicon-oxygen bonds (i.e., O-Si-O and O-Si) were strengthened considerably by AFFA modifications during high-temperature pyrolysis. The adsorption capacity of biochar for methylene blue (MB) was enhanced after AFFA modification, and a modified biochar with the highest adsorption capacity was prepared at a pyrolysis temperature of 700 degrees C, pyrolysis holding time of 2 h, and an AFFA proportion of 10%. The MB adsorption capacity of the modified biochars significantly increased when the pH of the solution increased (from 3 to 13). The adsorption data were well described by a pseudo-second-order model and Langmuir isotherms. The maximum MB adsorption capacities of the modified swine manure and rice straw biochars were 143.76 mg/g and 131.58 mg/g, respectively. The adsorption capacities of the AFFA-modified biochars were 10.7-112.3% higher than those of the unmodified biochars. The enhanced MB adsorption capacities of the former appear to be attributed to their increased specific surface areas, increased porosities, strong oxygen-containing functional groups, and high contents of exchangeable sodium ions. These results indicate that industrial and agricultural wastes can be reused to produce novel silica-composited biochars with high MB removal capacity. Accordingly, these biochars could be effectively used to treat wastewater and thus to mitigate solid waste disposal-related problems. (C) 2020 Elsevier B.V. All rights reserved.
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