Synthesis of silica-composited biochars from alkali-fused fly ash and agricultural wastes for enhanced adsorption of methylene blue
| Autor: | Lijun Nie, Rongni Dou, Jianteng Sun, Meiqin Chen, Fucai Deng, Guining Lu, Na Peng, Kaifeng Wang, Yongming Zhong |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Langmuir
Environmental Engineering 010504 meteorology & atmospheric sciences Swine 010501 environmental sciences Alkalies 01 natural sciences Coal Ash Adsorption Specific surface area Biochar Environmental Chemistry Animals Waste Management and Disposal 0105 earth and related environmental sciences Chemistry Silicon Dioxide Pollution Manure Methylene Blue Wastewater Chemical engineering Fly ash Charcoal Pyrolysis |
| Zdroj: | The Science of the total environment. 729 |
| ISSN: | 1879-1026 |
| Popis: | 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 °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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect