Modified Mesoporous Carbon Material (Pb-N-CMK-3) Obtained by a Hard-Templating Route, Dicyandiamide Impregnation and Electrochemical Lead Particles Deposition as an Electrode Material for the U(VI) Ultratrace Determination

In this paper, a dicyandiamide-impregnated mesoporous carbon (N-CMK-3), electrochemically modified in situ with lead film (Pb-N-CMK-3), was tested as an electrode material for U(VI) ultratrace determination. The prepared carbon material was characterized by XRD, SEM-EDX, Raman, FT-IR, XPS analysis and nitrogen sorption measurements. The changes of electrochemical properties of glassy carbon electrodes (GCE) after the N-CMK-3 and Pb-N-CMK-3 modification were studied using CV and EIS methods. The modification of the GCE surface by the N-CMK-3 material and Pb film increases the electroactive area of the electrode and decreases the charge transfer residence and is likely responsible for the electrochemical improvement of the U(VI) analytical signal. Using square-wave adsorptive stripping voltammetry (SWAdSV), two linear calibration ranges extending from 0.05 to 1.0 nM and from 1.0 to 10.0 nM were observed, coupled with the detection and quantification limits of 0.014 and 0.047 nM, respectively. The Pb-N-CMK-3/GCE was successfully applied for U(VI) determination in reference materials (estuarine water SLEW-3 and trace elements in natural water SRM 1640a).

Confined La 2 O 3 particles in mesoporous carbon material for enhanced phosphate adsorption

Novel phosphate adsorbents with confined La 2 O 3 inside mesoporous carbon were fabricated by the solid-state grinding method using pristine mesoporous carbon material CMK-3 (PCMK-3) and oxidized CMK-3 (OCMK-3) as the matrixes (denoted as La 2 O 3 @PCMK-3 and La 2 O 3 @OCMK-3). Compared with pure La 2 O 3 , La 2 O 3 @PCMK-3 and La 2 O 3 @OCMK-3 exhibited higher normalized phosphate adsorption capacity, indicative of efficient loading of La 2 O 3 inside the mesopores of the carbon materials. Furthermore, La 2 O 3 loading led to substantially enhanced phosphate adsorption. The adsorption capacities of La 2 O 3 @OCMK-3 samples were higher than those of La 2 O 3 @PCMK-3 samples, possibly owing to the oxygen-containing groups forming in OCMK-3 during HNO 3 oxidation, which enhanced the dispersion of La 2 O 3 in the mesopores of OCMK-3. The adsorption capacities of La 2 O 3 @PCMK-3 and La 2 O 3 @OCMK-3 increased with the La 2 O 3 loading amount. Phosphate adsorption onto La 2 O 3 (14.7)@PCMK-3 followed the pseudo-second-order kinetics with respect to correlation coefficient values (larger than 0.99). As pH increased from 3.4 to 12.0, the phosphate adsorption amounts of La 2 O 3 (14.7)@PCMK-3 and La 2 O 3 (15.7)@OCMK-3 decreased from 37.64 mg g −1 and 37.08 mg g −1 to 21.92 mg g −1 and 14.18 mg g −1 , respectively. Additionally, La 2 O 3 @PCMK-3 showed higher adsorption selectivity towards phosphate than coexisting Cl − , NO 3 − and SO 4 2 − . The adsorbent La 2 O 3 (14.7)@PCMK-3 remained stable after five regeneration cycles.

UIO-66-NH2-derived mesoporous carbon used as a high-performance anode for the potassium-ion battery

The N-doped mesoporous carbon material prepared by a double-solvent diffusion pyrolysis method with UIO-66-NH2 as a precursor can deliver a high reversible capacity of 346 mA h g−1 at 100 mA g−1 when used as an anode for non-aqueous KIBs.

Oxidation modification of chitosan-based mesoporous carbon by soft template method and the adsorption and release properties of hydroxycamptothecin

Spray drying and a direct carbonization technology were coupled to prepare nitrogen-doped mesoporous carbon nanoparticles (NMCs) using chitosan as a carbon source and nitrogen source precursor and a triblock amphiphilic copolymer (F127) as a soft template, then oxidative modification was performed by ammonium persulfate (APS) to prepare oxidized mesoporous carbon nanoparticles (O-NMCs). The pore structure, chemical composition and wettability of the mesoporous materials were studied before and after oxidative modification, the microscopic morphology, structure, composition and wetting performance of the mesoporous carbon were characterized by transmission electron microscopy (TEM), an X-ray diffractometer (XRD), N2 adsorption–desorption instrument, X-ray photoelectron spectroscopy (XPS), contact angle tests and other analyses, meanwhile influences of the mesoporous carbon material on adsorption and release performance of a poorly-soluble antitumor drug hydroxycamptothecin (HCPT) were investigated. It was demonstrated from results that the surface wettability of the oxidatively-modified mesoporous carbon material was improved, the contact angle of the mesoporous carbon materials was reduced from 133.4° to 58.2° and the saturated adsorption capacity of HCPT was 676.97 mg/g and 647.20 mg/g respectively. The dissolution rate of the raw material hydroxycamptothecin was improved due to the nanopore structure of the mesoporous carbon material, the dissolution rate of mesoporous carbon material-loaded hydroxycamptothecin was increased from 22.7% to respective 83.40% and 81.11%.