Two-dimensional cage-in-cage carbon-coated FeSeS superlattices with varying degrees of sulfidation (FeSeS@C) are developed for activating peroxymonosulfate (PMS) to effectively degrade diatrizoic acid (DTZ), and the intrinsic origin that govern the activity of FeSeS@C are deeply elucidated. Experimental and theoretical analyses manifested that proper sulfidation led to increased surface acidity of FeSeS@C. The high surface acidity can optimize the exposure and spin state of Fe sites for FeSeS@C-4, a high spin state of Fe (6.27 μ B ) not only regulating PMS adsorption for enhancing the charge density, but also expediting interfacial charge deliver to trigger the efficient PMS activation. Therefore, among FeSeS@C, FeSeS@C-4 exhibited the best degradation performance for DTZ, with first-order kinetic rate constants (k obs ) of 0.232 min −1 and degradation rate of 100 %. This study demonstrates a novel application of cage-in-cage superlattices in environmental remediation and offers new insights into the mechanism of PMS activation by sulfur modification Fe-based catalysts.
Yan Liang,Lv Di,Huang Xinwen,Shi Huixiang,Zhang Geshan
The adsorption behavior of pharmaceuticals and personal care product, Bisphenol-A (BPA), according to four coal-based and four wood-based granular activated carbons modified using outgassing treatment, acidic treatment or alkaline treatment was studied. The adsorption isotherm results indicated that carbon surface acidity played a very important role in the adsorption of BPA. It was found that increasing surface acidity would increase the hydrogen bonding effects and increase adsorption of BPA on activated carbon. The acidic modified sample (F600-A and OLC-A) represented the best adsorption capacity, and the equilibrium adsorption amounts reached 346.42 and 338.55 mg/g, respectively. Further, effects of surface charge and surface basicity were examined. It was found that the adsorbed amount of BPA decreased with the increase of surface charge. Finally, there appeared to be a significant oligomerization phenomenon with BPA molecules onto the surface of activated carbon. OLC and OLC-OG, which have higher micropore percentages, are very effective in hampering the oligomerization of BPA under oxic conditions.
Yan Cui,Lei Qin,Weiwei Kang,Jinghong Ma,Yongzhen Yang,Xuguang Liu
Magnetic carbon nanospheres (MCNSs) dotting with Fe 3 O 4 nanoparticles were synthesized by a simple solvothermal method. Furtherly, KOH activation and HNO 3 acidification of MCNSs were carried out to tune surface structure and property of MCNSs for the sake of adsorption improvement. The results show that both MCNSs and modified MCNSs (MCNSs-KH) have magnetic properties, and can be used as adsorbents for rapid separation and reutilization towards quinoline in coking wastewater. After KOH activation and HNO 3 acidification, the saturated adsorption capacity of MCNSs-KH is improved to 297.21 mg g −1 , much better than that of MCNSs (99.43 mg g −1 ). According to BET and NH 3 -TPD characterizations, KOH activation introduced a large number of pore structures, which significantly increased the specific surface area of MCNSs; HNO 3 acidification further increased the surface acidity of MCNSs, especially C O functional group, which promoted the acid–base interaction with weakly basic quinoline. From the results of adsorption kinetics, isotherm and thermodynamics, the spontaneous and exothermic adsorption process conformed to pseudo-second-order and Langmuir–Freundlich models better.
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