Yang Mannan,Fang Changqing,Su Jian,Zeng Huilin,Lin Qilang
In this study, waste corrugated paper was used as carbon precursor with KOH-NaOH mixture (mole ratio was 51:49 and the melting point is 170 °C) as activator to prepare porous carbon at different reaction temperature and different mass ratio of KOH-NaOH mixture/waste corrugate paper fiber. The micro-morphology, pore structure information and composition of porous carbon were analyzed, and the formation mechanism of pores was investigated. The effect of activator amount and pyrolysis temperature on the morphology and structure of porous carbon were studied. The adsorption capacity of porous carbon was evaluated with the methylene blue as model pollutant. The effect of adsorbent amount, adsorption time and temperature on the adsorption performance of the porous carbon were analyzed. The maximum specific surface area is 1493.30 m 2 ·g −1 and the maximum adsorption capacity of methylene blue is 518 mg·g −1 . This study provides a new idea for efficient conversion and utilization of waste paper. Graphical abstract
Mao Xisong,Xia Xuewen,Ning Deyang,Li Junqi,Chen Chaoyi,Lan Yuan-Pei
Molten salts synthesis (MSS) is a simple and potential technique for ceria nanoparticles (NPs) production, but the relevant effects of salt medium and cerium precursor on the synthesized ceria NPs need further attention. In the present work, we investigated the influences of frequently employed KCl–LiCl and KOH–NaOH molten flux and typical inorganic cerium precursors on the characterizations and photocatalytic property of ceria NPs. Results show that the CeO 2 NPs obtained in molten KOH–NaOH flux have smaller particle/crystal sizes but more serious agglomeration than that from KCl–LiCl flux. UV–Vis DRS spectra reveal that the ceria synthesized in molten hydroxides from the cerium nitrate precursor has the narrowest band gap of 2.87 eV in studied ceria samples. The ceria NPs obtained from KCl–LiCl flux have wider band gaps of 3.15–3.29 eV and faster recombination rates of photo-generated e − and h + . It was found that the ceria NPs obtained in molten KCl–LiCl salt show better photocatalytic activities for methylene blue (MB) degradation and may be due to the uniform size distribution and well-dispersed particles.
Mao Xisong,Xia Xuewen,Li Junqi,Chen Chaoyi,Zhang Junshan,Ning Deyang,Lan Yuan-Pei
Homogeneously rare-earth (RE=La, Sm and Y) ions doped CeO 2 nanoparticles (NPs) with enhanced photocatalytic performance were synthesized by a facile KOH-NaOH molten flux method. XRD, TEM, EDS mapping and XPS results demonstrate that RE cations have been successfully doped into the CeO 2 lattice, which leads to the lattice expansion/shrinking, and more oxygen vacancies are generated after RE ions doping. The UV-Vis DRS and PL spectra indicate that RE-doped CeO 2 samples have slightly narrower band gaps and significantly reduced photo-generated electron-hole recombination rates. 5% RE ions doped CeO 2 NPs show excellent photocatalytic performances and the photodegradation ratio of methylene blue (MB) increases from 71.63% of undoped CeO 2 to 76.35%, 77.51% and 77.37% for 5%-La, 5%-Sm and 5%-Y-doped CeO 2 NPs, respectively. The obviously reduced recombination rate of e − /h + pairs after RE ions doping may be the critical factor for the enhanced photocatalytic performance.
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