Search

Dewar photoproduct (Dewar PP) is the valence isomer of (6-4) photoproduct ((6-4)PP) in photodamaged DNA. Compared to the extensive studied CPD photoproducts, the underlying repair mechanisms for the (6-4)PP, and especially for the Dewar PP, are not well-established to date. In this paper, the repair mechanism of DNA Dewar photoproduct T(dew)C in (6-4) photolyase was elucidated using hybrid density functional theory. Our results showed that, during the repair process, the T(dew)C has to isomerize to T(6-4)C photolesion first via direct C6′–N3′ bond cleavage facilitated by electron injection. This isomerization mechanism is energetically much more efficient than other possible rearrangement pathways. The calculations provide a theoretical interpretation to recent experimental observations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two sulfides exhibit high adsorption capacities and ultrafast removal of Eu3+. • Selective Eu3+ adsorption against interfering ions in natural water. • Lanthanides recovery from acidic industrial wastewaters is realized. • The adsorption mechanism is ion exchange between Eu3+ and cations. • The soft Lewis basic and flexible layer is beneficial to selective Eu3+ uptake. Efficient and selective capture of lanthanides from radioactive wastewater containing excessive diverse concentrated salts is challenging but urgently demanded for environmental protection and human health. Herein, we present an effective approach for Eu3+ uptake from complex aqueous solutions by using two layered sulfide adsorbents (Me 2 NH 2) 2 (Ga 2 Sb 2 S 7)·H 2 O (FJSM-GAS-1) and (Et 2 NH 2) 2 (Ga 2 Sb 2 S 7)·H 2 O (FJSM-GAS-2). Both adsorbents exhibit ultrafast kinetics (within 2 min) and high absorption capacities for Eu3+ (127.7 and 115.8 mg/g for FJSM-GAS-1 and FJSM-GAS-2 , respectively). The distribution coefficient (K d) can be as high as 6.39 × 105 and 6.00 × 105 mL/g for FJSM-GAS-1 and FJSM-GAS-2 , respectively, exceeding that of reported Eu3+ adsorbents. They still display high selectivity for Eu3+ in presence of excessive competitive cations (e.g., Na+ and K+). Particularly, high K d values remain for Eu3+ removal from Eu3+-contaminated tap, lake and sea water, and lanthanides recovery from acidic industrial wastewater. Absorbed Eu3+ ions can be facilely eluted using a low-cost method. The adsorption mechanism, illuminated via DFT calculations coupled with characterizations of EA, Raman, XPS and EXAFS, is ion exchange between Eu3+ and interlayered cations owing to the strong interactions between Eu3+ and framework S2−. This work confirms that layered sulfides are promising adsorbents for efficient removal of lanthanides/actinides from wastewater for environmental remediation. [ABSTRACT FROM AUTHOR]