| SHI Wei-cai,CHEN Jun-xu,SONG Qi,CHEN Pu,LIU Ping,ZHANG You-fa.Fabrication of Walnut Shell Filter with Superwettability and Its Performance in Oily Water Treatment[J],52(7):315-324 |
| Fabrication of Walnut Shell Filter with Superwettability and Its Performance in Oily Water Treatment |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.07.029 |
| KeyWord:walnut shell filter wettability oil-water separation hydrophilic and underwater oleophobicity |
| Author | Institution |
| SHI Wei-cai |
Research Institute of Petroleum Engineering Technology of Jiangsu Oilfield, Jiangsu Yangzhou , China |
| CHEN Jun-xu |
School of Materials Science and Engineering, Southeast University, Nanjing , China;Jiangsu Key Laboratory of Advanced Metal Materials Technology, Nanjing , China |
| SONG Qi |
Research Institute of Petroleum Engineering Technology of Jiangsu Oilfield, Jiangsu Yangzhou , China |
| CHEN Pu |
School of Materials Science and Engineering, Southeast University, Nanjing , China;Jiangsu Key Laboratory of Advanced Metal Materials Technology, Nanjing , China |
| LIU Ping |
School of Materials Science and Engineering, Southeast University, Nanjing , China;Jiangsu Key Laboratory of Advanced Metal Materials Technology, Nanjing , China |
| ZHANG You-fa |
School of Materials Science and Engineering, Southeast University, Nanjing , China;Jiangsu Key Laboratory of Advanced Metal Materials Technology, Nanjing , China |
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| Abstract: |
| The walnut shell filter material is widely used as filling material in filtration equipment due to its low cost, strong adsorption and sewage interception capacity. However, the filter material will be gradually contaminated by oil with the increase of service time, resulting in poor filtration effect and poor back-washing efficiency. To solve these problems, the wettability theory based on the lotus leaf effect is applied to the walnut shell filter material. The walnut shell filter material was endowed with superhydrophilicity. The superhydrophilic surface had strong hydration. When the coating surface was wetted by water, a water film was quickly formed on the coating. Due to the incompatibility between the water phase and oil phase, the superhydrophilic coating protected by water film was not easy to be contaminated by oil, so the superhydrophilic surface had excellent anti-fouling performance underwater, showing good underwater oleophobicity. For the parallel experiments, the walnut shell filter material was endowed with superhydrophobicity/superoleophilicity and superamphiphobicity, respectively. The filtration efficiency and long-term performance of walnut shell filters with different wettability were studied. During the experimental process, the walnut shell filter material with the particle size of 1-3 mm was selected. The superhydrophobic modifier was obtained from an ethanol solution of silica sol and fluorosilane. Superhydrophobic and superoleophilic modifier was obtained from ethanol solution of octylsilane and silica sol. A superhydrophilic modifier was obtained from an aqueous solution containing fumed silica and epoxy resin. Then, the filtration performance and long-term performance of walnut shell filter media with different wettability were comprehensively analyzed based on the oil content of the filtrate, the turbidity of the filtrate and the filtration pressure. The results indicated that the superhydrophilic walnut shell filter material showed the best filtration performance and long-term performance. The filtration efficiency of untreated walnut shell filter and these three kinds of filter media was 57.62%, 65.77%, 61.26% and 84.01%, respectively. After filtration by superhydrophilic filter material, the oil content of back-washing liquid was 487.1, 172.4, 505.8 and 786.4 mg/L, respectively and the removal rate of filtrate turbidity was 83.4%. Besides, the back-washing cycle was more than 24 hours, showing good application value and potential. In short, the superhydrophilic filter material had the best filtration effect and the best back-washing ability. In addition, the effect of filtration parameters such as particle size, filter column height, and filtration batch on the filtration effect was further explored. The results showed that the filtration effect increased with the decrease of filter particle size. After filtration by the walnut shell filter with a particle size of 1-2 cm, the oil content of the filtrate was 34.06 mg/L. The filtration efficiency was 50% higher than that of the walnut shell filter with a particle size of 2-3 cm. Besides, the filtration effect increased with the filter column height. After filtration by the walnut shell filter with the filter column height of 5 cm, the oil content of filtrate was 34.06 mg/L, while that of the walnut shell filter with the filter column height of 10 cm was 31.45 mg/L. However, the higher the height of the filter column, the more difficult the back-washing was. Hence, when the filter column height was 5 cm, the walnut shell filter showed the best filtration performance. In short, the hydrophilic and hydrophobic filter material has the best filtration effect and the best back-washing ability. |
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