Progress in the Development and Application of Permeable Reaction Barriers for Remediation of Dissolved Oil Contaminants in Groundwater

2021 ◽  
Author(s):  
Huan Shen ◽  
Yong Huang ◽  
Yue Su
Keyword(s):  
Reaction Barriers

scholarly journals Encapsulate α-MnO2 nanofiber within graphene layer to tune surface electronic structure for efficient ozone decomposition

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guoxiang Zhu ◽  
Wei Zhu ◽  
Yang Lou ◽  
Jun Ma ◽  
Wenqing Yao ◽  
...  
Keyword(s):  
Graphene Layer ◽  
Water Resistance ◽  
Catalyst Design ◽  
Ozone Decomposition ◽  
Oxygen Species ◽  
Ozone Molecule ◽  
Practical Application ◽  
Surface Electronic Structure ◽  
Reaction Barriers ◽  
Excellent Stability

AbstractMajor challenges encountered when developing manganese-based materials for ozone decomposition are related to the low stability and water inactivation. To solve these problems, a hierarchical structure consisted of graphene encapsulating α-MnO2 nanofiber was developed. The optimized catalyst exhibited a stable ozone conversion efficiency of 80% and excellent stability over 100 h under a relative humidity (RH) of 20%. Even though the RH increased to 50%, the ozone conversion also reached 70%, well beyond the performance of α-MnO2 nanofiber. Here, surface graphite carbon was activated by capturing the electron from inner unsaturated Mn atoms. The excellent stability originated from the moderate local work function, which compromised the reaction barriers in the adsorption of ozone molecule and the desorption of the intermediate oxygen species. The hydrophobic graphene shells hindered the chemisorption of water vapour, consequently enhanced its water resistance. This work offered insights for catalyst design and would promote the practical application of manganese-based catalysts in ozone decomposition.

scholarly journals Experimental and Theoretical Study on the Transformation Behavior of Bisphenol S by Radicals Driven Persulfate Oxidation

2021 ◽  
Author(s):  
Junyan Wei ◽  
Linning Yin ◽  
Ruijuan Qu ◽  
Gadah Al-Basher ◽  
Xiaoxue Pan ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Transformation Behavior ◽  
Bisphenol S ◽  
Persulfate Oxidation ◽  
Water Matrix ◽  
Two Systems ◽  
Initial Ph ◽  
Depth Study ◽  
Reaction Potential ◽  
Reaction Barriers

Abstract An in-depth study on the degradation of bisphenol S (BPS) by both single-walled carbon nanotubes and heat activated persulfate (PS) was investigated in detail. The factors like materials dosage, initial substrate concentration, initial pH and water matrix on removal of BPS were evaluated and 10 µM BPS could be completely removed in 90 min under the optimal conditions of [BPS]0: [PS]0 = 1: 100, T = 25 ℃, pH0 = 7.0, [N-SWCNTs] = 20 mg·L− 1. Fast removal of BPS was also obtained when reaction temperature reached 65 ℃ without catalyst. There were 15 intermediates identified in total; and hydroxylation, sulfate addition, carboxylation, the cleavage of S − C bond and polymerization were considered as the main transformation pathways of BPS in both two systems based on LC-MS analysis. The proportion discrepancy of •OH and SO4•− involved in two systems led to different distribution and abundance of observed products. The results of transition state calculation further confirmed the reaction potential of hydroxylation, hydrogen atom abstraction and sulfate addition, and the minimum reaction barriers were 22.20, 25.06 and 13.85 kJ/mol, respectively. The present work firstly reveals the overall transformation behavior of BPS in radicals-triggered PS system by combining experimental and theoretical study.

DENSITY FUNCTIONAL STUDY OF SELECTED MONO-ZINC AND GEM-DIZINC RADICAL CARBENOID CYCLOPROPANATION REACTIONS: OBSERVATION OF AN EFFICIENT RADICAL ZINC CARBENOID CYCLOPROPANATION REACTION AND THE INFLUENCE OF THE LEAVING GROUP ON RING CLOSURE

2003 ◽  
Vol 02 (03) ◽  
pp. 357-369 ◽  
Author(s):  
CUNYUAN ZHAO ◽  
DONG-QI WANG ◽  
DAVID LEE PHILLIPS
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Radical Reaction ◽  
Ring Closure ◽  
Functional Study ◽  
Reaction Step ◽  
Leaving Group ◽  
Reaction Barriers ◽  
Leaving Groups ◽  
Zinc Carbenoid

We report a theoretical study of the cyclopropanation reactions of EtZnCHI, (EtZn)2CH EtZnCHZnI, and EtZnCIZnI radicals with ethylene. The mono-zinc and gem-dizinc radical carbenoids can undergo cyclopropanation reactions with ethylene via a two-step reaction mechanism similar to that previously reported for the CH2I and IZnCH2 radicals. The barrier for the second reaction step (ring closure) was found to be highly dependent on the leaving group of the cyclopropanation reaction. In some cases, the (di)zinc carbenoid radical undergoes cyclopropanation via a low barrier of about 5–7 kcal/mol on the second reaction step and this is lower than the CH2I radical reaction which has a barrier of about 13.5 kcal/mol for the second reaction step. Our results suggest that in some cases, zinc radical carbenoid species have cyclopropanation reaction barriers that can be competitive with their related molecular Simmons-Smith carbenoid species reactions and produce somewhat different cyclopropanated products and leaving groups.

The Nature of Loading-Dependent Reaction Barriers over Mixed RuO2/TiO2 Catalysts

ACS Catalysis ◽  
2018 ◽  
Vol 8 (6) ◽  
pp. 5526-5532 ◽  
Author(s):  
Hao Li ◽  
Shenjun Zha ◽  
Zhi-Jian Zhao ◽  
Hao Tian ◽  
Sai Chen ◽  
...  
Keyword(s):  
Reaction Barriers

On the Rational Design of Zeolite Clusters for Converging Reaction Barriers: Quantum Study of Aldol Kinetics Confined in HZSM-5

2018 ◽  
Vol 122 (40) ◽  
pp. 23230-23241
Author(s):  
Angela N. Migues ◽  
Qinfang Sun ◽  
S. Vaitheeswaran ◽  
Woody Sherman ◽  
Scott M. Auerbach
Keyword(s):  
Rational Design ◽  
Reaction Barriers

Averaging Techniques for Reaction Barriers in QM/MM Simulations

ChemPhysChem ◽  
2014 ◽  
Vol 15 (15) ◽  
pp. 3264-3269 ◽  
Author(s):  
April M. Cooper ◽  
Johannes Kästner
Keyword(s):  
Reaction Barriers ◽  
Averaging Techniques
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