Low pressure DC-plasma system for the modification of polymeric membrane surfaces

The main objectives of this work were to develop a lab-scale direct current (DC) glow discharges plasma system for modification of organic and inorganic membranes. Characteristics of plasma system were presented under the discharge of five gases (Ar, N2, air, O2, and CO2). A Langmuir double probe was used for the evaluation of the electron temperature (Te) and electron density (ne) of plasmas. The current and voltage (I-V) characteristic curves were analyzed. Relationships between breakdown voltage (VB) of gases and products of gas pressure and inter-electrode gap (pd) were studied in form of Paschen curves. The results showed that Te of plasma in various gases was in the range of 4-13 eV, while the ne varied between 108 and 109 cm-3. The plasma generated at different gas pressure and applied voltage is in the normal and abnormal modes. Finally, the constructed DC-plasma system was utilized for modification of polymeric membrane surfaces. Treatment time, discharge power and type of gas were varied. The tailoring of membrane surfaces was analyzed through the water contact angle and percent-weight loss (PWL) measurements, DMTA, AFM, XPS and FTIR spectrum. It could be shown that DC-plasma from this system can be used to modify the surface of polymeric membranes

Surface Modification of Asymmetric Polysulfone/Polyethylene Glycol Membranes by DC Ar-Glow Discharge Plasma

Polysulfone/polyethylene glycol (PSF/PEG) membranes were prepared by dry/wet phase inversion method. Effects of direct current glow discharge plasma using argon as working gas on morphological structures and gas separation properties of membranes were studied. Alteration of membrane characteristics were analyzed by various techniques like contact angle, scanning electron microscope, Fourier transform infrared spectroscopy, and dynamic mechanical thermal analysis. Gas separation properties were measured in terms of permeation and ideal O2/N2 selectivity. Results showed that hydrophilic and gas separation properties of PSF/PEG membranes increased by plasma surface modification. It was also shown that the dosage of PEG and plasma treatment affected the morphological structures and mechanical and gas separation properties. The macro voids and transmembrane structure disappeared with a little amount of PEG dosage. Pore size and mechanical strength tend to decrease with increasing PEG dosage up to 10 wt%. Glass transition temperature (Tg) receded from 201.8 to 143.7°C for pure PSF and PSF/PEG with PEG dosage of 10 wt%. O2 and N2 gases permeation through the 10-minute plasma treated membranes tend to increase. However, the permeation strongly dispersed when treatment time was more extended

Evaluation of Oil Palm Biomass Potential for Bio-oil Production via Pyrolysis Processes

The yield and quality of bio-oil obtained from pyrolysis processes depends on many factors, including pyrolysis types, reactor types, operating conditions and biomass property. The objective of this work was therefore to evaluate the potential of oil palm biomass, including oil palm trunk (OPT), oil palm fronds (OPF), oil palm decanter (DC) and oil palm root (OPR) for producing bio-oil via pyrolysis processes. The potential of oil palm biomass was considered in terms of proximate analysis, ultimate analysis, heating value, equivalent heating value, Thermogravimetric analyser (TGA) and lignocellulose content. The results showed that the moisture content of fried samples was in the range of 7.5-10.7% (w.b), which was relatively low and appropriate for pyrolysis. The volatile content of OPT and OPF was higher than 72% (wt.). The carbon, oxygen and hydrogen content of oil palm samples were in the range of 41.5-45.6, 30.7-40.2 and 5.7-5.9% (wt.), respectively. The higher heating value (HHV) of samples was relatively low compared to the HHV of fossil fuels. The OPT and OPF had high cellulose and hemicellulose content, while provided low lignin content compared to the lignin content of DC and OPR. The TGA results showed that thermal decomposition of samples took place within the range of 200–450 °C, which the lignin content affected the thermal decomposition trend. These results revealed that the selected oil palm biomass had relatively high potential for producing bio-oil via pyrolysis processes, particularly the OPT and OPF

Effective moisture diffusivity, moisture sorption, thermo-physical properties and infrared drying kinetics of germinated paddy

Temperature and relative humidity (RH) dependence of moisture sorption phenomena for agricultural products provide valuable information related to the thermodynamics of the system. So the equilibrium moisture contents (EMC), effective moisture diffusivity (Deff) and thermo-physical properties in terms of void fraction, specific heat capacity, and the apparent density of germinated non-waxy Suphanburi 1 paddy were evaluated. Five commonly cited EMC equations were fitted to the experimental data among temperatures of 40-60°C correlating with RH of 0-90%. The results showed that the modified GAB equation was the best function for describing experimental results while those evaluated thermo-physical properties depended on moisture content. To determine drying kinetics model, the simulated values using Midilli et al. (2002) model and Page’s model was the best fitting to exact drying kinetics values for infrared (IR) and hot air (HA) drying, respectively. Finally, the Deff value of paddy dried with IR and HA sources were also evaluated and the calculated Deff value of both HA and IR drying was in order of 10-9 m2/s

Artificial neural network approaches for the sorption isotherms, enthalpy and entropy of heat sorption of two types block rubber products

Knowledge of the temperature and relative humidity (or water activity) dependence of moisture sorption phenomenaof agro-industrial products provides valuable information about changes related to the thermodynamics of the system. Thusthe moisture sorption characteristics in terms of equilibrium moisture contents (EMC), enthalpy and entropy of heat sorptionof natural rubber (NR) for producing STR 20 and skim block rubber were investigated. Simulation modeling of water sorptionisotherms was performed using the 10 non-linear regression EMC models and the multilayer artificial neural network (ANN)approach. The results showed that the predicted EMC results using the modified Oswin model was the best fitting model forboth NR samples. However, the predicted values of ANN model were more accurate than those predicted results using nonlinear regression method. Finally, enthalpy and entropy of heat sorption for both NR samples were evaluated by applying theClausius-Clapeyron equation showing as the negative exponential function of moisture content

Single-phase and multiphase models for temperature and relative humidity calculations during forced convection in a rubber-sheet drying chamber

Computational fluid dynamics modelling of single-phase and multiphase flows was used to simulate the temperature and relative humidity at various locations in an empty rubber-sheet drying chamber. In all planes, unlike the single-phase model, the multiphase model’s temperature distribution is relatively uniform, and the temperature deviations are 0.01-4.73°C in the bottom plane, 0.02-4.05°C in the middle plane, and 0.01-3.84°C in the top plane. The single-phase model results in temperature deviations of 0.55-6.63°C, 0.02-6.02°C and 0.36-3.89°C in the bottom, middle and top planes respectively. Thus, the multiphase model is deemed superior. The inclusion of water vapour in the multiphase model increases the agreement between model and experimental temperature data. The largest temperature deviations occur at the centre-frontal positions of all planes owing to the turbulence of the hot gas at the inlet. In all planes the relati ve humidity is almost uniform, except near the centre-frontal area of the bottom plane. Clearly, the multiphase model is more appropriate for simulating chambers containing rubber sheets, though the diffusion of moisture from rubber sheets needs to be considered as well

Evaluation of Oil Palm Biomass Potential for Bio-oil Production via Pyrolysis Processes

The yield and quality of bio-oil obtained from pyrolysis processes depends on many factors, including pyrolysis types, reactor types, operating conditions and biomass property. The objective of this work was therefore to evaluate the potential of oil palm biomass, including oil palm trunk (OPT), oil palm fronds (OPF), oil palm decanter (DC) and oil palm root (OPR) for producing bio-oil via pyrolysis processes. The potential of oil palm biomass was considered in terms of proximate analysis, ultimate analysis, heating value, equivalent heating value, Thermogravimetric analyser (TGA) and lignocellulose content. The results showed that the moisture content of fried samples was in the range of 7.5-10.7% (w.b), which was relatively low and appropriate for pyrolysis. The volatile content of OPT and OPF was higher than 72% (wt.). The carbon, oxygen and hydrogen content of oil palm samples were in the range of 41.5-45.6, 30.7-40.2 and 5.7-5.9% (wt.), respectively. The higher heating value (HHV) of samples was relatively low compared to the HHV of fossil fuels. The OPT and OPF had high cellulose and hemicellulose content, while provided low lignin content compared to the lignin content of DC and OPR. The TGA results showed that thermal decomposition of samples took place within the range of 200–450 °C, which the lignin content affected the thermal decomposition trend. These results revealed that the selected oil palm biomass had relatively high potential for producing bio-oil via pyrolysis processes, particularly the OPT and OPF

เปรียบเทียบอุณหภูมิผิวหนังบริเวณก้นกบในผู้ใหญ่ที่มีสุขภาพดีขณะนอนบนเบาะโรงพยาบาลและบนเสื่อจูด

Prince of Songkla Universit