H2O2预氧化对负载铁制备污泥炭基催化剂效能的影响

以城市污水厂二沉池污泥为原料,考察了不同H_2O_2投加量下污泥预氧化对铁负载污泥形成前驱体及其热解后制得炭基催化剂性能的影响,研究了污泥预氧化对强化铁负载制备均一分散型污泥炭基催化剂的机理.结果表明,污泥预氧化促进了污泥细胞破解,降低了絮体颗粒粒径和表面Zeta电位,使铁负载量增加、铁活性位点在污泥载体上的分散性明显增强,形成炭基催化剂保持着高催化活性,其稳定性显著增加.对模拟含铬黑T染料废水的多相芬顿降解试验说明,当污泥预氧化H_2O_2投加量为2.25%时制备的炭基催化剂,其反应120 min后铬黑T的降解率为91%,略低于未预氧化时污泥炭基催化剂的降解效率(96%);但未预氧化炭基催化剂其反应后溶液中铁离子的溶出量(18.9%)远高于预氧化后形成的催化剂(2.5%),且后者循环3次对铬黑T的降解率仍可达到86%,表现出较强的稳定性.

Effect of H2O2 pre-oxidation on iron loading for preparation of sludge-based carbon catalysts

In this study, the sequential sewage sludge activation by hydrogen peroxide oxidation and Fe³⁺ impregnation was conducted to prepare carbon precursors. The mechanism of enhanced iron interaction with sludge particles was systematically investigated by SEM, Zeta potential, particle size distribution and N₂ adsorption-desorption isotherm. Results indicated that sludge pre-oxidation promoted the destruction of sludge particles and subsequently resulted in the reduction of particle size and zeta potential. The variation enhanced the Fe interaction with sludge particles and made the increment of iron loading onto sludge. Moreover, the aggregated sludge particles also improved the uniform dispersion of Fe oxides and therefore the stability of Fe immobilized sludge carbon as heterogeneous Fenton catalyst. When the as-prepared catalyst was applied for Fenton-like degradation of Black-T, the degradation efficiency can reach 91% for 120 min reaction, which was lower than the catalyst prepared without pre-oxidation. However, further experiments revealed that Fe leaching amount for catalyst prepared without pre-oxidation (18.9%) was much higher than the catalyst prepared by sludge pre-oxidation (2.5%) and the latter had the better reusability, showing the strong stability of the catalyst prepared from sludge pre-oxidation by hydrogen peroxide and iron impregnation.