Significantly improving the Cu2+ removal performance of conducting polymer-based adsorbent from aqueous solution through cross-linking modification

Through cross-linking modification of poly(o-phenylenediamine) (PoPD) to increase the adsorption active sites, the Cu²⁺ adsorption capacity of PoPD was improved significantly. According to FT-IR, XRD, SEM and BET results, both PoPD and the cross-linked PoPD had porous or surface-adhesive porous morphology with a typical mesoporous character, the specific surface area of the latter was increased obviously from the former. Both of them showed excellent Cu²⁺ adsorption capabilities with the maximum adsorption q^exp_max of 76.51 and 85.49 mg·g⁻¹, and the corresponding removal ratios of 60.21% and 68.39%, respectively. The adsorption capacity was increased to its 1.54 times with pentaerythritol tris[3-(1-aziridinyl)propionate] (cross-linking agent-III) as cross-linking agent at pH = 5 and 25°C. Because temperature could affect the adsorption behavior of materials and the adsorption process is endothermic with ΔG < 0, the process should be accompanied by spontaneous chemical changes. The XRD, SEM–EDX mapping and XPS results showed that Cu²⁺ was successfully removed from the aqueous solution. Additionally, the adsorption was mainly based on the cation-π interaction and the formation of Cu-N bonds.     

Probing Water Diffusion Inside Crystals of AlPO-5 by PFG NMR and IRM for Heat Storage Applications

Diffusion of water in the aluminophosphates AlPO-5 is studied using a combination of pulsed field gradient NMR and IR microimaging. The concentration profiles measured by the latter allowed to visualize the process of water sorption and propagation into the crystals of AlPO-5. The self-diffusion coefficients obtained by NMR were one order of magnitude higher values compared to corrected ones from the IR microimaging study. The concentration profiles allowed to visualize the process of water sorption and propagation into the crystals of AlPO-5. The obtained results are compared with experimental and simulation data for the water/AlPO-5 system for the literature and discussed in the context of its potential use for heat storage applications.