Temporal Changes of Adsorbed Layer Thickness and Electrophoresis of Polystyrene Sulfate Latex Particles after Long Incubation of Oppositely Charged Polyelectrolytes with Different Charge Densities

The different desorption concepts of the two polyelectrolytes PTMA5M and PTMC5M, which have similar molecular weights and differ in the charge density on the polystyrene sulfate latex (PSL) particles by 25 times, and with various charge densities in a long incubation, were systematically investigated based on hydrodynamic adsorbed layer thickness (δH) and electrophoretic mobility (EPM) under two ionic strengths in the present study. Herein, in the case of highly charged polyelectrolyte PTMA5M, desorption continued for 4 h and re-adsorbing proceeded after a longer incubation time higher than 4 h. Meanwhile, in the case of lowly charged polyelectrolyte PTMC5M, an adsorption–desorption equilibrium was suggested to take into account the unchanging of both δH and EPM.

Study on demulsification and deoiling for O/W emulsion by microbubble pretreated resin

The microbubble pretreated resin was used for demulsification and deoiling of the simulated O/W emulsion. The demulsification and deoiling performance and the influencing factors were investigated systematically. Experimental results indicate that the microbubble pretreated resin reaches a 97% oil removal within 80 min; on the contrary, oil removals are 90% and 85% for NaOH solution soaked and un-pretreated resins respectively. After five repeated runs, the oil removal of microbubble pretreated resin can be maintained at over 70%. The demulsification mechanism was revealed by comparing zeta potential, surface tension, contact angle of the emulsion in treatment, and the characterization results of the resin before and after use. Three possible pathways of demulsification were concluded and the ranking contributions can be shown below. Pathway 1: Competitive trapping of surfactant. The cationic groups of the resin combine with the anionic groups of the surfactant and drag them away from the oil particle surface. Pathway 2: Distribution equilibrium of surfactant. Free surfactants in the emulsion are captured by resin and reduce the concentration of uncombined surfactant. This results in surfactants on the oil particle partly detaching from the oil surface to maintain the adsorption-desorption equilibrium of the surfactant. Pathway 3: Adsorption coalescence.

The effect of different nanocatalysts for photocatalytic degradation of methylene blue

The aim of this study was to investigate photodegradation of Methylene Blue (MB) in water by using ZnO and TiO2 nanoparticles. Adsorption and photocatalytic oxidation studies were carried out by using produced TiO2, commercial TiO2 and commercial ZnO nanoparticles. In order to evaluate performance tests, 5 mg/l of MB solution was used. The samples were mixed in the dark for 2 hours for establishing adsorption-desorption equilibrium. The photocatalytic tests of the samples were performed by assessing the decomposition rate of MB solutions under UV light. The results of the photocatalytic showed that the highest color removal efficiencies was obtained by TiO2 catalyst where Methylene blue solution was completely degraded.

Soil Mobility of Allyl Isothiocyanate and Chloropicrin as Influenced by Surfactants and Soil Texture

Methyl bromide (MeBr) was identified as a stratospheric ozone depletory; therefore, the use of MeBr was phased out in the United States in 2005. Chloropicrin (CP) and allyl isothiocyanate (AITC) are MeBr replacements. A mixture of CP and AITC is commonly applied to broaden the pest control spectrum. These two fumigants have low soil mobility; however, their efficacy could be improved if their soil mobility were enhanced. This research was conducted to study the effects of surfactants applied at 5% (v/v) for CP mobility and AITC mobility in soils. Mobility of the CP/AITC mixture applied with a nonionic surfactant comprising oleic, linoleic, and palmitic acids (nonionic-1) and mobility of the CP/AITC mixture applied with a nonionic surfactant comprising C9 hydrocarbon aromatics and calcium alkylarylsuphonate (nonionic-2) were compared with mobility of the CP/AITC mixture applied without surfactants in three soils (Elder sandy loam, Chualar loam, and Blanco clay loam) during a laboratory study. Nonionic-1 surfactant increased the concentration of total leachate collected for AITC by five and CP by 11 compared with CP/AITC applied alone. Surfactants may influence the fumigant mobility in soil by affecting the sorption/desorption equilibrium. Our research suggested that increased AITC mobility and CP mobility in soil with the addition of adding nonionic-1 surfactant may be due to the adsorption behavior of the surfactant in the soil and the solubilizing capability of the surfactant with pesticides.

Adsorption and Decomposition of Peroxides on the Surfaces of Dispersed Oxides Fe2O3, Cr2O3 and V2O5

The adsorption of peroxides on dispersed oxides Fe2O3, Cr2O3 and V2O5 was studied. It is shown that the adsorption of peroxides is described by the Langmuir equation. The adsorption of benzoyl peroxide grows within Fe2O3<Cr2O3<V2O5. Adsorption-desorption equilibrium constants (K) for Cr2O3 and V2O5 are the same, but for Fe2O3 this value is 6 times higher. The decomposition of peroxides is observed in the solution and on the surface of adsorbents. The effective activation energy (E) of the thermal decomposition of peroxides in the studied systems is in the range of 80–140 kJ/mol. The activation energy of degradation of peroxides on the surface (Es) of the dispersed oxides studied is lower. The degradation reaction of peroxides on the surface of Fe2O3 and V2O5 has an oxidation-reducing nature, during which free radicals are produced. On the surface of Cr2O3, there is a heterolytic decay of peroxides. The parameters of the reaction of peroxides decomposition are found. The decomposition of peroxides in the presence of Fe2O3, Cr2O3 and V2O5 in styrene is accompanied by the formation of polystyrene both in the solution and on the surface of the adsorbent.

Modification to L-H Kinetics Model and Its Application in the Investigation on Photodegradation of Gaseous Benzene by Nitrogen-Doped TiO2

In this paper, the Langmuir-Hinshelwood (L-H) model has been used to investigate the kinetics of photodegradation of gaseous benzene by nitrogen-doped TiO2 (N-TiO2) at 25 °C under visible light irradiation. Experimental results show that the photoreaction coefficient kpm increased from 3.992 × 10−6 mol·kg−1·s−1 to 11.55 × 10−6 mol·kg−1·s−1 along with increasing illumination intensity. However, the adsorption equilibrium constant KL decreased from 1139 to 597 m3·mol−1 when the illumination intensity increased from 36.7 × 104 lx to 75.1 × 104 lx, whereas it was 2761 m3·mol−1 in the absence of light. This is contrary to the fact that KL should be a constant if the temperature was fixed. This phenomenon can be attributed to the breaking of the adsorption-desorption equilibrium by photocatalytically decomposition. To compensate for the disequilibrium of the adsorption-desorption process, photoreaction coefficient kpm was introduced to the expression of KL and the compensation form was denoted as Km. KL is an indicator of the adsorption capacity of TiO2 while Km is only an indicator of the coverage ratio of TiO2 surface. The modified L-H model has been experimentally verified so it is expected to be used to predict the kinetics of the photocatalytic degradation of gaseous benzene.

Heterojunctions of silver–iron oxide on graphene for laser-coupled oxygen reduction reactions

We report a two-step hybridization of N-doped graphene and Ag-decorated Fe2O3 hematite to realize a balanced oxygen adsorption/desorption equilibrium and a laser-coupled ORR (LORR).

The effect of increasing CO2concentration and flow rate on amine still performance in meeting gas sale specifications

The main purpose of this study is to examine the effect of increasing CO2removal and flow rate on performance of an amine still. The amine still is located in Field X in South East Sumatra at a new gas well producing gases with a rich CO2content. The still uses activated MDEA as the amine and has an IMTP 40-type packing column. Two film and desorption equilibrium curve theories were employed to analyse the amine still design conditions. Design equations were utilized to find the slope of the equilibrium curve. A slope of the equilibrium curve of 45° in the amine still is obtained in this study. The maximum liquid CO2composition of the amine still feedstock (xo) which can be separated to produce lean amine according to the specification design flow rate is 0.0307. The total flow rate of CO2-rich amine at xo= 0.029 is 761,157.6 kg/hour; the total flow rate of CO2-rich amine atxo= 0.0295 is 628,861.1 kg/hour; the total flow rate of CO2- rich amine at xo= 0.03 is 513,962.6 kg/hour; and the total flow rate of CO2-rich amine at xo= 0.0305 is 409,575.3 kg/hour.