[Show abstract][Hide abstract] ABSTRACT: The desorption of CrVI from CrVI-adsorbed Layered Double Hydroxide (CrVI-LDH) and the recycling of LDH adsorbent are the bottleneck that limits the practical application of LDH in treating CrVI-containing industrial wastewater. Given the strong affinity of LDH for CO2, we studied desorption and enrichment of CrVI from CrVI-LDH as well as recycling of LDH in the presence of high-pressure CO2. Results showed that CrVI solution with concentration of 500 mg/L could be enriched over 20 times in each adsorption-desorption cycle. The regenerated LDH maintained the layer structure and the sheets as revealed by XRD and TEM patterns. FT-IR data showed CO2 formed HCO3- at high pressure. The transformation from CO2 to HCO3- followed by the anion-exchange with CrO42- was the critical factor for CrVI desorption and LDH regeneration. A pilot-scale experiment was carried out with 20 L CrVI-containing electroplating wastewater. The concentration of the desorbed CrVI solution could reach up to 10000 mg/L, which could be used in electroplating after appropriate adjustment. The main advantages of this method are high concentration of CrVI, direct reuse of enriched CrVI and efficient regeneration of LDH adsorbent. This method showed promises in recycling CrVI and regenerating LDH in treating industrial wastewater.
No preview · Article · Oct 2013 · ACS Applied Materials & Interfaces
[Show abstract][Hide abstract] ABSTRACT: A color change: X-ray-induced photochromic species are rare and can be used for detection of X-rays. A highly robust X-ray-sensitive material with the discrete structure of a metal-organic complex has been found to show both soft and hard X-ray-induced photochromism at room temperature. A new ligand-to-ligand electron-transfer mechanism was proposed to elucidate this photochromic phenomenon.
No preview · Article · Apr 2012 · Angewandte Chemie International Edition
[Show abstract][Hide abstract] ABSTRACT: Photochromism of N-methyl-4,4'-bipyridinium (MQ(+)) salts and their metal complexes has never been reported. A series of MQ(+) coordinated halozinc complexes [(MQ)ZnX(3)] (X = Cl (1), Br (2), I (3)) and [(MQ)ZnCl(1.53)I(1.47)](2)(MQ)ZnCl(1.68)I(1.32) (4), with better physicochemical stability than halide salts of the MQ(+) cation, have been found to exhibit different photochromic behaviors. Compounds 1-3 are isostructural, but only 1 and 2 show photochromism. Introduction of partial Cl atoms to nonphotochromic compound 3 yields compound 4, which also displays photochromism. The photochromic response of 1, 2, and 4 indicates the presence of their long-lived charge separation states, which originate from X → MQ(+) electron transfer according to ESR and XPS measurements. Studies on the influence of different coordinated halogen atoms demonstrate that the Cl atom may be a more suitable electron donor than Br and I atoms to design redox photochromic metal complexes.
No preview · Article · Mar 2012 · Inorganic Chemistry