Gang Cheng,Xin Zhou,Chongyu Du,Guotao Hu,Qian Lin,Hongyan Pan
The purpose of this study was to prepare a novel and efficient adsorbent for the removal of trace Pb(II) from phosphoric acid. Manganese oxide/sulfur-oxygen doped carbon nanotube composites (CNTs-S-O-Mn) were prepared from multi-walled carbon nanotubes modified with nitric acid, mercaptoacetic acid, acetic anhydride, concentrated sulfuric acid and potassium permanganate. Characterisation revealed that CNTs-S-O-Mn contained hydroxyl, sulphonate groups, MnO and Mn 3 O 4 . At 298 K, 15.362 mg·L -1 initial concentration of lead ions, and 18.4 % phosphoric acid concentration, the adsorption capacity of the composites for lead ions was 38.65 mg·g −1 , which was higher than that of the unmodified CNTs , 8.04 mg·g −1 . The adsorption kinetic data at 298 K conformed to the quasi-second-order kinetic equation, R 2 = 0.997; 298, adsorption isotherms at 308 and 318 K conformed to the Langmuir equation, R 2 = 0.990–––0.991. The adsorption capacity increased with decreasing phosphoric acid concentration. In this system, the adsorption is affected by a certain concentration of lead ions. Adsorption occurs via chemisorption and is exothermic. Sulfonic acid groups and hydroxyl groups on manganese oxides play an important role in the adsorption of Pb (II) through surface complexation with Pb (II). These results indicate that the removal of trace Pb (II) from phosphoric acid by modified carbon nanotubes is feasible, revealing a new use of carbon nanotubes for phosphoric acid purification.
Zinc ion hybrid capacitors (ZIHCs) are encouraging energy storage devices for large-scale applications. Nevertheless, the electrochemical performance of ZIHCs is often limited by the cathode materials which show low energy density and rate capability practically. One of the efficient strategies to overcome these challenges is the development of advanced carbon cathode materials with abundant physi/chemisorption sites. Herein, we develop a sulfate template strategy to prepare sulfur and oxygen doped carbon nanosheets (SOCNs) as a potential cathode active material for ZIHCs. The as-prepared SOCNs exhibit porous architectures with a large surface area of 1877 m 2 g −1 , substantial structural defects, and high heteroatom-doped contents (O: 7.9 at%, S: 0.7 at%). These exceptional features are vital to enhancing Zn ion storage. Consequently, the SOCN cathode shows a high capacity of 151 mAh g −1 at 0.1 A g −1 , high cycle stability with 83% capacity retention at 5 A g −1 after 4000 cycles, and a superior energy density of 103.1 Wh kg −1 . We also investigate the dynamic adsorption/desorption behaviors of Zn ions and anions of the ZIHCs carbon electrodes during the process of charge and discharge by ex-situ experiments. This work highlights the significance of the integration with a large specific surface area and bountiful heteroatoms in carbon electrodes for achieving high-performance ZIHCs.
Yu Jiang,Jia Wang,Bo Liu,Wei Jiang,Tianyu Zhou,Yunchao Ma,Guangbo Che,Chunbo Liu
Herein, a N,S,O-doped Co/CoO/Co 9 S 8 @carbon hybrid (Co/CoO/Co 9 S 8 @NSOC) has been constructed by calcinating a Co-based metal–organic framework (Co-MOF) with 4,4-bipyridine and 2,5-thiophenedicarboxylic acid as linkers. Co/CoO/Co 9 S 8 @NSOC exhibited a high and recycled catalytic efficiency for peroxymonosulfate (PMS) activation to degrade sulfamethoxazole (SMX, 20 mg/L) with a reaction rate of 1.31 min −1 , which was 5.2 times than that of Co-MOF. The catalytic behavior should be attributed to the rich active sites, lamellar morphology, superhydrophilicity, and magnetism. Furthermore, the Co/CoO/Co 9 S 8 @NSOC was immobilized on a filter membrane (CMFM) to adapt to the flowing system, which could recycle 20 times without losing activity. To employ in a large-scale static environment, the Co/CoO/Co 9 S 8 @NSOC was loaded on the commercial sponge (CoSPG). In a 50 L water tank, the CoSPG realized to decompose 160 mg/L SMX solution with 37 h and had long-term stability over 10 days. Notably, the PMS cost of treating one ton of wastewater is only $0.34, indicating a huge industrial application value.
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