水热炭化对吸附处理染料废水产生的废活性炭的再生效果

为实现废粉末活性炭的循环利用，采用水热炭化对吸附处理染料废水产生的废粉末活性炭进行再生，考察了水热炭化再生温度、再生时间、初始pH和再生次数等因素对废粉末活性炭再生效果的影响.结果表明:将320℃的水热条件下反应8 h得到的再生粉末活性炭用于吸附处理染料废水，色度去除率在95%左右，废粉末活性炭再生率可超过60%，且酸性条件下更有利于活性炭再生.经过5次吸附再生循环，废粉末活性炭再生率为55.54%，再生率仅下降6.06%.红外光谱分析结果表明，新粉末活性炭、废粉末活性炭和再生粉末活性炭的官能团种类基本一致；表面官能团Boehm滴定测定结果显示，再生粉末活性炭表面碱性基团含量降低、酸性基团含量增加.由于升温改变了废粉末活性炭的吸附平衡，有机物从其表面脱附，部分有机物在再生液中降解；此外，废粉末活性炭表面不易挥发和脱附的有机物在高温高压下炭化所得的产物能进一步吸附有机物，因此导致了废粉末活性炭的再生.研究显示，水热炭化对废粉末活性炭有较好的再生效果，具有实际应用价值. 

Regeneration of Spent Powdered Activated Carbon from Adsorption of Dyestuff Wastewater by Hydrothermal Carbonization

In order to recycle spent powdered activated carbon (PAC), the spent PAC produced in the treatment of dye wastewater was regenerated by hydrothermal carbonization. The factors affecting the regeneration of spent PAC, such as hydrothermal carbonization regeneration temperature, regeneration time, initial pH and regeneration times were investigated. The spent PAC obtained by hydrothermal carbonization at 320℃ for 8 h was reused to treat dye wastewater. The removal of color was up to 95%, and the regeneration rate of PAC exceeded 60%. The acidic pH was beneficial to the regeneration of PAC. After five treatment-regeneration cycles, the regeneration rate of spent PAC was 55.54%, only decreased by 6.06%. FTIR showed that the surface functional groups of the original PAC, spent PAC and regenerated PAC were similar. However, the Boehm titration measurements showed that the surface basic groups of the regenerated PAC decreased, while the acidic group increased. The organic pollutants on the spent PAC were desorbed and partly degraded in the regenerated solution as the adsorption equilibrium changed at high temperature. In addition, the products obtained from the low volatile and desorbed organic compounds on the surface of the spent PAC in the high temperature and pressure carbonization process can further adsorb organic pollutants, resulting in regeneration of the spent PAC. This study shows that the hydrothermal carbonization is beneficial to the regeneration of spent PAC and may be used in industry.