Xianqiang Ran

One-pot synthesis of Aluminum-containing ordered mesoporous silica MCM-41 using coal fly ash for phosphate adsorption

The present study offers an economic one-pot synthesis of Al-containing ordered mesoporous silica MCM-41 from the coal fly ash. The samples were characterized by small-angle XRD, N2 adsorption, TEM, mapping, (27)Al MAS NMR, EDX, and NH3-TPD. The effects of pH values to the final mesostructures have also been investigated. The results show that the material prepared at the pH value of 10 displays the largest pore volume of 0.98 cm(3)/g, the highest BET surface area of 1020 m(2)/g, and the lowest Si/Al molar ratio of 2. Using this material as adsorbent for phosphates, the adsorption capacity reaches 64.2mg/g at 298 K, which is much higher than that of large pore mesoporous silica SBA-15 (53.5mg/g), diatomite (62.7 mg/g), and MCM-41 (31.1 mg/g). In addition, the thermodynamics and kinetics for the phosphate adsorption were also investigated. Our present study shows an economic way to treat phosphates using the industrial solid waste of coal fly ash.

Facile preparation of Cu–Mn/CeO2/SBA-15 catalysts using ceria as an auxiliary for advanced oxidation processes

A facile synthetic method was adopted to prepare heterogeneous catalysts using ordered mesoporous silica SBA-15 as matrix, ceria as auxiliary and Cu–Mn as the catalytic active sites, denoted as Cu–Mn/CeO2/SBA-15. Characterization results demonstrate that the metal oxide nanoparticles are well-dispersed inside the mesopores rather than aggregated outside the surface. The particle sizes range from 4.1 to 11.2 nm with an increase in calcination temperature from 300 to 500 °C. The presence of ceria plays a significant role in the formation of well-dispersed metal oxide nanoparticles, and a possible mechanism for the preparation of this heterogeneous catalyst is proposed based on comparable experimental results. Catalytic degradation studies for advanced oxidation processes (AOPs) show that Cu–Mn/CeO2/SBA-15 catalysts can efficiently degrade (>99%) high-concentration dye pollutants (C = 2 g L−1) within 210 min at 70 °C and can retain a good degradation efficiency even at a pH value of 7 when using Rhodamine B as the model pollutant. The excellent AOP catalytic performance could be ascribed to the well-dispersed catalytic nanoparticles inside the mesopores and the catalytic synergic effect of CeO2. Our work here displays a simple method to synthesize heterogeneous catalyst with well-dispersed nano-sized catalytic active sites for AOPs by using CeO2 as the auxiliary agent.

Controllable fabrication of dendritic mesoporous silica–carbon nanospheres for anthracene removal

Dendritic mesoporous silica–carbon nanospheres with a uniform size (∼100 nm), high surface area (646 m2 g−1), large pore volume (1.4 cm3 g−1) and center-radial oriented open mesopore channels (7.3 nm) have been fabricated by combining an oil–water biphase stratification and an in situ carbonization of surfactant template strategy.

Preparation of a mesoporous Cu–Mn/TiO2 composite for the degradation of Acid Red 1

Heterogeneous catalysts which show high catalytic performance, structural stability, and low toxicity, are greatly required to efficiently degenerate organic pollutants in waste water in advanced oxidation processes (AOPs). In this paper, a mesoporous Cu–Mn/TiO2 composite heterogeneous catalyst was successfully prepared, which has a stable crystalline TiO2 mesostructure as the support, and well-dispersed Cu–Mn oxides as the catalytic active sties. Its Cu, Mn content is measured to be 5.7 and 6.0 wt%, and the BET surface area is measured to be 97 m2 g−1 with a pore size of ∼6.0 nm and pore volume of 0.15 cm3 g−1. Using the prepared Cu–Mn/TiO2 composite as an AOPs catalyst for the degeneration of Acid Red 1, it can efficiently (>99%) degenerate the model pollutant in water within only 90 min. Compared with homogeneous catalysts, it can retain its catalytic performance over a wide pH range (3–9) and can be recycled for at least five times while still possessing the decolorization efficiency of 89%. By analyzing the catalytic process, a possible catalytic procedure for the degradation of Acid Red 1 has been proposed. Furthermore, using bulk Cu–Mn oxides, Cu–Mn/P25, and Cu–Mn/SBA-15 as reference catalysts, we propose that the excellent catalytic performance of Cu–Mn/TiO2 could be ascribed to the anatase mesoporous TiO2, which not only offers a stable matrix with high surface area for Cu–Mn catalysts, but also serves as a type of catalytic promoter for the synergistic catalytic degeneration of Acid Red 1.

Boric acid assisted formation of mesostructured silica: from hollow spheres to hierarchical assembly

A boric acid assisted assembly approach has been provided to prepare mesostructured silica with various morphologies and porosities. The hollow siliceous spheres with ultrasmall size (∼15 nm) can be synthesized under an ultra-dilute CTAB/P123 surfactant concentration, with TEOS as the silica source in a weak acid system. It was also found the ratio of CTAB/P123, the concentration of boric acid and surfactant, the amount of TEOS and the addition of MgSO4 had key roles in controlling the morphologies and porosities. The obtained mesostructure silica possessed ordered structure, uniform morphologies (hollow sphere, tubular and cage-like mesoporous silica), high surface area (304.2–742.0 m2 g−1), tunable large pore volume (0.55–2.07 cm3 g−1) and pore size distribution (2.2–11.8 nm).

Phenyl-functionalized mesoporous silica materials for the rapid and efficient removal of phthalate esters

Phthalate esters (PAEs) are a group of endocrine disrupting compounds, which have been widely used as plasticizers. To alleviate the environmental and health threats from water resources polluted by PAEs, we prepared phenyl functionalized mesoporous silica materials (ph-SBA-15) were synthesized by a simple post-modification approach for rapid and efficient removal of low concentration of di-n-butyl phthalate (DBP) from aqueous solution. Mesostructure, texture, surface chemistry and surface charges were systemically characterized. The obtained ph-SBA-15 possesses a highly ordered mesostructure, a high surface area (418m2/g), uniform mesopores (6.5nm) and high-density organic groups around 11wt.%. Batch adsorption experiments revealed that phenyl modified SBA-15 had an excellent ability to remove DBP with the maximum adsorption capacity up to ∼40mg/g at 25°C. The thermodynamics and kinetics for the adsorption were also investigated, demonstrating an exothermic, multi-layer and fast adsorption process. In addition, DBP adsorption was found to be sensitive to the pH and the uptake was observed to be greatest at around pH 7.0. Furthermore, this material can be effectively regenerated by ethanol.

TiO2 interpenetrating networks decorated with SnO2 nanocrystals: enhanced activity of selective catalytic reduction of NO with NH3

Highly branched TiO2 interpenetrating network architectures decorated with SnO2 nanocrystals were fabricated through a sacrificial-template approach for selective catalytic reduction of NO with ammonia. Such unique architectures demonstrate outstanding catalytic activity for NO conversion (∼90%), high N2 selectivity (∼100%), good stability and strong resistance to SO2 and H2O poisoning over a broad temperature range (75–325 °C).

Mesoporous carbon confined palladium–copper alloy composites for high performance nitrogen selective nitrate reduction electrocatalysis

Palladium–copper (PdCu) alloy has been proved to be a promising electrocatalyst for the reduction of nitrate. The challenges, however, include how to design this catalyst with controllable particle sizes, uniform distribution, and avoiding the leakage and reducing the consumption of noble metals. Herein, we report the synthesis of a mesoporous carbon supported PdCu bimetallic electrocatalyst by using mesoporous silica SBA-15 as the hard template. The PdCu nanoparticles are uniformly embedded in the ordered mesoporous carbon (OMC) framework (PdCu@OMC), leading to a high loading amount of PdCu alloy of ∼22.41 wt%, a large specific surface area of 1091 m2 g−1 and a pore volume of 0.74 cm3 g−1. Significantly, the resultant PdCu@OMC composites deliver superior electrocatalytic capability in 50 mL mixed solution (500 mg of nitric nitrogen per liter) under neutral conditions, with a nitrate conversion yield of 28.7% and a nitrogen selectivity of 74%.