Quantitatively extracted Gibbs free-energy (ΔG) as criterion to determine working temperature range of gas sensing-material

2015 ◽  
Author(s):  
Pengcheng Xu ◽  
Haitao Yu ◽  
Xinxin Li
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Gas Sensing ◽  
Temperature Range ◽  
Working Temperature ◽  
Sensing Material

CHLORINE GAS SENSING OF SnO2 NANOCLUSTERS AS A FUNCTION OF TEMPERATURE: A DFT STUDY

2019 ◽  
Vol 26 (04) ◽  
pp. 1850172
Author(s):  
MUDAR AHMED ABDULSATTAR ◽  
ADEEBH L. RESNE ◽  
SHROK ABDULLAH ◽  
RIYADH J. MOHAMMED ◽  
NOON KADHUM ALARED ◽  
...  
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Density Functional ◽  
Tin Dioxide ◽  
Energy Gap ◽  
Gas Sensing ◽  
Free Energy Calculations ◽  
Measured Temperature ◽  
Chlorine Molecule ◽  
Chlorine Gas

Density functional theory combined with Gibbs free energy calculations is used to study the sensing behavior of tin dioxide (SnO[Formula: see text] clusters towards chlorine gas molecules. Studied SnO2 clusters’ results show the known property of tin dioxide being an oxygen-deficient semiconductor with the preferred stoichiometry SnO[Formula: see text]. The kind of reactions that result in sensing Cl2 molecules is investigated. These include oxygen replacement, chlorine molecule dissociation and van der Waals attachment. Oxygen replacement shows an increase in energy gap which is the case experimentally. Optimum sensing operating temperature towards Cl2 molecules that results from the intersection of the highest SnO2 adsorption and desorption Gibbs free energy lines is at 275∘C in agreement with the experimentally measured temperature of 260∘C.

Kinetic Process of Purple Cabbage Pigment on Macro Porous Absorbent Resin

2011 ◽  
Vol 236-238 ◽  
pp. 1987-1990
Author(s):  
Jian Hua Yi ◽  
Zhen Bao Zhu ◽  
Yuan Fang Wu
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Adsorption Kinetics ◽  
Temperature Increase ◽  
Adsorption Process ◽  
Adsorbent Resin ◽  
Temperature Range ◽  
Porous Adsorbent ◽  
Kinetics Of ◽  
Langmuir And Freundlich Models

The adsorption kinetics of purple cabbage pigment (PCP) on LSA-21 macro porous adsorbent resin were studied at different adsorbent resin concentrations (1, 2, 4, 8 g adsorbent resin per liter of purple cabbage extraction solution) for the temperature range of 20~50°C. The results showed that the adsorption of PCP in purple cabbage extraction solution onto LSA-21 macro porous adsorbent resin is highly in agreement with both Langmuir and Freundlich models. Heat of adsorption (ΔH) value of 11.976 kJ/mol indicates the endothermic adsorption process. A decrease of Gibbs free energy (ΔG) with temperature increase also indicates the spontaneous nature of the process.

scholarly journals Fast Response Isopropanol Sensing Properties with Sintered BiFeO3 Nanocrystals

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3829 ◽  
Author(s):  
Hongxiang Xu ◽  
Junhua Xu ◽  
Junlin Wei ◽  
Yamei Zhang
Keyword(s):  
Gas Sensing ◽  
Fast Response ◽  
Gas Detection ◽  
Detection Range ◽  
Sensing Properties ◽  
Working Temperature ◽  
Sensing Material ◽  
Gas Sensing Properties ◽  
Response And Recovery ◽  
Optimum Working

BiFeO3 nanocrystals were applied as the sensing material to isopropanol. The isopropanol sensor based on BiFeO3 nanocrystals shows excellent gas-sensing properties at the optimum working temperature of 240 °C. The sensitivity of as-prepared sensor to 100 ppm isopropanol is 31 and its response and recovery time is as fast as 6 and 17 s. The logarithmic curves of the sensitivity and concentration of BiFeO3 sensors are a very good linear in the low detection range of 2–100 ppm. In addition, the gas sensing mechanism is also discussed. The results suggest that the BiFeO3 nanomaterial can be potentially applied in isopropanol gas detection.

scholarly journals A Gas Sensor Based on Network Nanowire for H2S Monitor in Construction Waste Landfill

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 156
Author(s):  
Pengyu Ren ◽  
Qingwei Shi ◽  
Lingling Qi
Keyword(s):  
Gas Sensor ◽  
Gas Sensing ◽  
Construction Waste ◽  
Waste Landfill ◽  
Working Temperature ◽  
Efficient Detection ◽  
Sensing Material ◽  
Response And Recovery ◽  
Wet Chemical ◽  
Gas Response

As an extremely harmful gas, H2S gas is the major pollutant in construction waste landfill. Herein, a one-dimensional oxide nanomaterial was produced from a simple wet chemical method to serve as a H2S gas sensing material. The SEM observation indicates that the nanomaterial with network structure is constructed by a lot of nanowires with an approximate diameter from 24 nm to 40 nm. The sensing film was formed on a ceramic substrate using a slurry composed of the as-prepared network nanowires. Furthermore, a gas sensing measurement was carried out to determine the gas sensing performances towards the H2S gas. The detection results at different working temperature towards various gas concentrations demonstrate that the network nanowires-based sensor exhibits a higher gas response to H2S as compared to that of the rod-like one. The optimum working temperature of the network and rod-like nanomaterials is both 300 °C, and the corresponding maximum gas response is 24.4 and 13.6, respectively. Namely, the gas response of the network-based gas sensor is almost larger than that of the rod-like oxide. Moreover, the network nanowires-based gas sensor display a faster gas response and recovery speed. In addition, the fabricated gas sensors all exhibit excellent repeatability. Such improved sensing properties may offer a promising potential to realize an efficient detection of harmful H2S gas released from construction waste landfill.

Thermodynamic Properties of Natural Rubber and Isoprene

1966 ◽  
Vol 39 (1) ◽  
pp. 143-148 ◽  
Author(s):  
R. W. Warfield ◽  
M. C. Petree
Keyword(s):  
Free Energy ◽  
Glass Transition ◽  
Thermodynamic Properties ◽  
Natural Rubber ◽  
Specific Heat ◽  
Gibbs Free Energy ◽  
Kcal Mole ◽  
Specific Heat Data ◽  
Temperature Range ◽  
Heat Data

Abstract Using published specific heat data, the entropy, enthalpy, and Gibbs free energy of natural rubber (NR) have been calculated over the temperature range 0 to 320° K. The thermodynamic function Cp/T as a function of T calculated for NR exhibits a maximum at 50° K and another maximum at 210° K, which is associated with the glass transition. The number of classically vibrating units per repeating unit of NR is 6.61 at 300° K. These functions have also been calculated for isoprene over the temperature range 0 to 300° K. At 298.16° K the entropy of polymerization was found to be 24.00 cal mole−1deg−1 and the free energy of polymerization − 10.7 kcal/mole.

Sign in / Sign up

Export Citation Format

Share Document