scholarly journals Initiation of condensation of toluene and octane vapours on a Si surface

RSC Advances ◽  
2020 ◽  
Vol 10 (28) ◽  
pp. 16291-16301
Author(s):  
Sima Yaghoubian
Keyword(s):  
Adsorption Isotherm ◽  
Condensation Mode

The use of the zeta adsorption isotherm in determining the condensation mode of toluene on silicon.

Competitive adsorption of organic solvents using modified and unmodified calcium bentonite clay mineral

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Adsorption Isotherm ◽  
Adsorption Capacity ◽  
Organic Solvents ◽  
Competitive Adsorption ◽  
Correlation Factor ◽  
Isotherm Model ◽  
Isotherm Models ◽  
High Concentration ◽  
Dual Purpose ◽  
Calcium Bentonite

Dodecyltrimethylammonium bromide (DTAB)–modified and unmodified calcium bentonite were both used for the competitive adsorption of aromatics (xylene, ethylbenzene and toluene) and petroleum products (gasoline, dual purpose kerosene and diesel) from their aqueous solution. Infrared spectroscopy (IR) and expansion tests (adsorption capacity and Foster swelling) measurement were performed in order to evaluate the performance of the adsorbents. The Foster swelling index and adsorption capacity of the DTAB modified calcium bentonite in the organic solvents follow the trend: xylene > ethylbenzene > toluene > gasoline > dual purpose kerosene (DPK) > diesel > water. However, the adsorption capacity of the adsorbent in diesel outweighed the adsorption capacity in DPK at high concentration of DTAB indicating that diesel has higher affinity for high DTAB concentration than DPK. The percentage removal of the solvent is directly proportional to the concentration of DTAB used in modifying the bentonite as well as the contact time between the adsorbent and the solvent, hence modified calcium bentonite adsorbed a higher percentage of organic solvents than the unmodified calcium bentonite. The adsorption characteristics of both adsorbents improved remarkably after proper agitation of the organic solvents, the unmodified calcium bentonite however adsorbed more water than the modified bentonite. Data obtained from adsorption isotherm models confirms that Freundlich adsorption isotherm model was favored more than Langmuir adsorption isotherm model with the correlation factor (R2) of the former tending more towards unity. The adsorption of ethylbenzene using DTAB modified and unmodified calcium bentonites follow a pseudo second order kinetics mechanism, suggesting that the rate determining step of adsorption involves both the adsorbent and the organic solvent.

Gasoline Desulphurization by Reactive Adsorption on ZnO /Bentonite

2019 ◽  
Vol 70 (1) ◽  
pp. 50-53
Author(s):  
Constantin Sorin Ion ◽  
Mihaela Bombos ◽  
Gabriel Vasilievici ◽  
Vasile Matei
Keyword(s):  
Zinc Oxide ◽  
Adsorption Isotherm ◽  
Operating Temperature ◽  
Continuous System ◽  
Particle Sizes ◽  
Textural Characteristics ◽  
Reactive Adsorption ◽  
Atmospheric Distillation ◽  
Increased Pressure

Desulfurization of atmospheric distillation (DA) gasoline was performed by reactive adsorption on ZnO/ bentonite. The adsorbent was characterized by determining the distribution of particle sizes of zinc oxide powdered, adsorption isotherm and textural characteristics of granulated adsorbent. Adsorption experiments of atmospheric distillation gasoline were performed in continuous system at 280-320oC, 5-25 bar and volume hourly space velocities of 1-1.5 h-1. The adsorption on ZnO/ bentonite has been favored by increased pressure and operating temperature.

Desorption of Cationic Polyacrylamide from Bleached Kraft Pulp Fibers

1987 ◽  
Vol 19 (5-6) ◽  
pp. 939-951 ◽  
Author(s):  
Clifton F. Warren ◽  
R. Gehr
Keyword(s):  
Adsorption Isotherm ◽  
Total Nitrogen ◽  
Kraft Pulp ◽  
Detection System ◽  
Cationic Polyelectrolyte ◽  
Chemiluminescence Detection ◽  
Pulp Fibers ◽  
Paper Manufacturing ◽  
Bleached Kraft Pulp ◽  
Receiving Water

The adsorption and desorption behaviour of a cationic polyelectrolyte contacted with wood pulp fibers was determined by total nitrogen analysis using a pyrolysis/chemiluminescence detection system. Dialysed polymer generated an adsorption isotherm of higher affinity than did non-dialysed polymer. Capacity adsorption was maximized at pH 7, but decreased in the presence of alum depending on the dosage. Desorption of non-dialysed polymer was caused by changes in pH above or below 7.0 as well as by addition of alum. However for the alum doses typically encountered in paper manufacturing, significant desorption is unlikely. Nevertheless, the contaminants in non-dialysed polymers do hinder adsorption, and effluents from those processes using both alum and polymer may contain quantities of unadsorbed or desorbed polyelectrolytes which could be damaging to receiving water bodies.

scholarly journals Size-Segregated Atmospheric Humic-Like Substances (HULIS) in Shanghai: Abundance, Seasonal Variation, and Source Identification

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 526
Author(s):  
Tianming Sun ◽  
Rui Li ◽  
Ya Meng ◽  
Yu Han ◽  
Hanyun Cheng ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Size Distribution ◽  
Principal Component ◽  
Water Soluble ◽  
Atmospheric Particulate Matter ◽  
Biomass Combustion ◽  
Vehicle Exhaust ◽  
Total Suspended Particulates ◽  
Condensation Mode ◽  
Water Soluble Organic Carbon

Humic-like substances (HULIS) are of great interest due to their optical and chemical characteristics. In this study, a total of 180 samples of atmospheric particulate matter (PM) of different sizes were collected from summer 2018 to spring 2019, in order to analyze the size distribution, to investigate the seasonal variation and then to identify the key sources of HULIS. The annual mean concentration of HULIS in the total suspended particulates reached 5.12 ± 1.42 μg/m3. The HULIS concentration was extremely higher in winter (8.35 ± 2.06 μg/m3) than in autumn (4.88 ± 0.95 μg/m3), in summer (3.62 ± 1.68 μg/m3) and in spring (3.36 ± 0.99 μg/m3). The average annual ratio of water-soluble organic carbon (WSOC) to OC and the ratio of HULIS to WSOC reached 0.546 ± 0.092 and 0.56 ± 0.06, respectively. Throughout the whole year, the size distributions of WSOC and HULIS-C were relatively smooth. The peaks of WSOC appeared at 1.8~3.2 μm and 0.56~1.0 μm, while the peaks of HULIS-C were located at 3.2~5.6 μm, 1.0~1.8 μm and 0.18~0.32 μm. The distribution of the HULIS particle mode was similar in spring, summer and autumn, while there was a lower proportion of the coarse mode and a higher proportion of the condensation mode in winter. By using the comprehensive analysis of principal component analysis (PCA), air mass backward trajectories (AMBTs) and fire point maps, key sources of WSOC and HULIS in Shanghai were identified as biomass combustion (48.42%), coal combustion (17.49%), secondary formation (16.07%) and vehicle exhaust (5.37%). The remaining part might be contributed by crustal dust sources, marine sources and/or other possible sources. This study provides new insight into the characteristics and size distribution of HULIS in Shanghai, thereby providing a practical base for further modeling.

scholarly journals Chemical, electrochemical, thermodynamic and adsorption study of EN8 dual-phase steel with ferrite-martensite structure in 0.5 M H2SO4 using pectin as inhibitor

2021 ◽  
Author(s):  
P. R. Prabhu ◽  
Pavan Hiremath ◽  
Deepa Prabhu ◽  
M. C. Gowrishankar ◽  
B. M. Gurumurthy
Keyword(s):  
Weight Loss ◽  
Adsorption Isotherm ◽  
Surface Analysis ◽  
Potentiodynamic Polarization ◽  
Dual Phase Steel ◽  
Inhibition Efficiency ◽  
Dual Phase ◽  
X Ray ◽  
Enthalpy And Entropy ◽  
Martensite Structure

AbstractThis paper presents the corrosion and inhibition behavior of heat-treated EN8 dual-phase steel with ferrite-martensite structure with pectin in 0.5 M sulphuric acid. The corrosion studies were performed using the weight loss method, electrochemical techniques such as potentiodynamic polarization measurements, and impedance spectroscopy. The study was done at different concentrations of pectin in the temperature range of 40 to 70 °C and immersion time of 1, 3, 5, and 7 h. The results showed that the inhibition performance of pectin has enhanced with an increase in pectin concentration and decreased with the temperature and time of exposure. From the weight loss study, highest inhibition efficiency of 76.43% was achieved at 5.0 g/L at 1 h of exposure at 40 °C. The maximum inhibition efficiency of 62% was obtained with 5.0 g/L of pectin at 40 °C by potentiodynamic polarization method. The energy, enthalpy, and entropy of activation and also thermodynamic parameters like free energy, enthalpy, and entropy of adsorption were assessed and discussed. Appropriate adsorption isotherm was fit to the obtained experimental outcomes and achieved Langmuir adsorption isotherm to be the best fit and obeyed physical adsorption. Surface analysis: scanning electron microscopy, X-ray diffraction techniques, atomic force microscopy, and energy dispersive X-ray were done with and without the addition of pectin. The metal surface appears to be uniform and smooth in the presence of pectin and adsorption was confirmed by surface analysis.

Overall Adsorption Isotherm of Natural Organic Matter

1998 ◽  
Vol 124 (11) ◽  
pp. 1099-1107 ◽  
Author(s):  
Yoshihiko Matsui ◽  
Akira Yuasa ◽  
Fu-Sheng Li
Keyword(s):  
Organic Matter ◽  
Adsorption Isotherm ◽  
Natural Organic Matter
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