In order to address the issue of protonation of functional groups and structural instability on the surface of aerogel due to strong acidic wastewater, a three-dimensional bis-pyridine N cellulose aerogel [PEIPD/carboxymethyl cellulose (CMC)] with protonation resistance was prepared in this paper by grafting pyridine onto polyethylenimine. The adsorption capacity for Cu2+ of the as-prepared aerogel is as high as 1.64 mmol/g (pH 5) and is maintained well in high-acidity solutions (1.15 mmol/g at pH = 2). It reveals high selectivity, splendid anti-interference ability, and also reliable on the recycle performance. Through the zeta potential tests, this adsorbent reveals a rather low zero charge point (pH(pzc) = 2.2). The adsorption of Cu2+ on the adsorbent is consistent with the pseudo-second-order kinetic model and the Langmuir model, suggesting that the adsorption process is dominated by chemisorption in a monolayer. The characterizations by Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy proved pyridine N as responsible binding sites, based on which two possible mechanisms are proposed, including chelation and cation-pi interaction. Density functional theory calculations are further used to precisely investigate the pathway. By comparing the binding energies, molecular electrostatic potentials, electron densities, and differential charge densities, the bis-pyridine N functional group is finally determined to be of much higher affinity to Cu2+ following chelation reaction as designated. By integrating bis-pyridine N with the CMC and understanding their crucial roles, this will provide significant insights into the rational design of aerogel adsorbents to enhance the recovery of Cu from strongly acidic wastewaters.

A novel all-day-active photocatalytic material g-C3N4/SMSO was synthesized by a one-step hydrothermal method in this study. The strongest wavelength of SMSO assisted phosphorescence is 465 nm and the excitation wavelength of gC(3)N(4) is 460 nm, which is a high spectrum conversion efficiency between them. Additionally, SMSO can be excited to generate electron holes under visible light to form type II heterojunction with g-C3N4, which is beneficial to improve the catalytic performance. The best all-day-active catalytic effect was achieved with a mass ratio of g-C3N4 to SMSO is 5:6, and can be applied to a widely pH range (5-8). Finally, the possible photocatalytic degradation mechanism and pathway over g-C3N4/SMSO were proposed based on LC-MS analysis, DFT calculation and quenching experiments. The major reactive species for MB degradation over the g-C3N4/ SMSO under visible light were .O-2, OH and h(+). When the external light source was removed, it seems that the .OH and h(+) played a noteworthy role.

In this study, the PPY/CMC aerogels showed rapid removal of norfloxacin (NOR) within 2 h with a maximum adsorption capacity of 845.7 mg/g and excellent adsorption performance in the pH range of 3-10. The exhaustive Density Functional Theory (DFT) calculations revealed that 7C-7C electron-donor-acceptor (EDA) interactions dominated at different pH. Humic acid (HA) mainly competed with NOR for the sites of 7C-7C EDA interactions on the adsorbent, but only slightly inhibited NOR adsorption at high concentrations due to the weak competitiveness and compensation by NOR-bridging interactions. Background ions mainly competed with NOR for electrostatically interacting sites, but ions in the lower valence state were less competitive and preferentially occupied different adsorption sites, thus hardly affecting the adsorption of NOR. The higher valence state with higher concentration of ions had increased competing ability, and although the bridging interaction can compensate some adsorption sites, it still inhibited the adsorption of NOR. The PPY/CMC aerogels had fine affinity for multiple antibiotics, and the differences in adsorption capacity were determined by the charge and structural properties of the antibiotics themselves. Moreover, excellent recyclability of PPY/CMC aerogels was confirmed after five adsorption-desorption cycles as the diminished performance from 96.8% to 83.7%. These results will help us to understand the structure-performance relationship between contaminants and PPY/CMC aerogels, and prefigure the potential of PPY/CMC aerogels as a novel adsorbent for the removal of multiple antibiotics.

Based on the complicated preparation of current diesel vehicle exhaust gas denitration catalysts, an in-situ deposited composite oxide catalyst, CeO2-WO3 mixed oxide catalyst, was prepared by electrodeposition and hydrothermal methods, which was loaded on the titanium mesh and applied to the selective catalytic reduction denitration of diesel vehicle exhaust. Denitration performance of the catalysts was tested by a fixed bed reactor, and the influence of different electrodeposition time of CeO2 was investigated. The results demonstrate that 20 min is the best electrodeposition time of CeO2 (100% NOx conversion at 250–350 °C). The high dispersion of active CeO2 on WO3 promotes the synergistic effects among different components. The as-prepared catalysts were characterized by SEM, XRD, XPS, H2-TPR, NH3-TPD and in-situ DRIFTS. It is evident that Ce3+ is successfully introduced by loading CeO2, which enhances the chemisorption of oxygen. Meanwhile, the increased acidity including both weak acid and medium-strong acid sites of CeO2-WO3 composite catalyst is observed, which improves the co-adsorption of NH3 on Lewis acid and Brønsted acid simultaneously and facilitates the denitration process. Through the characterization by in-situ DRIFTS, it is elucidated that the NH3-SCR reactions are mainly carried out following the Eley-Rideal (E-R) pathway in a medium-temperature range (250–350 °C).