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This work presents the factors that determine the coalescence of the micron-sized oil droplets (<0.4 μm) and the permeation flux by using two different types of commercial flat-sheet microporous polyvinylidene fluoride (PVDF) membranes. Results show that the PVDF-Westran membrane coalesced the oil droplets up to 1.1 μm while the PVDF-Synder membrane enlarged the oil droplets to approximately 5.6 μm. The pore size distribution instead of the both casted and fibrous membrane structures influenced the coalescence of the oil droplets. The membrane feed side that comprised of the smaller pores exhibited better in the coalescence while the pore size on the membrane permeate side did not show the significant effect on the coalescence. The water permeation flux was proportional to the pore size of the membrane feed side while the permeation flux during the coalescence was inversely proportional to the membrane pore size. The oil droplets in the feed solution has reduced the permeation flux about 10 times lower. The addition of the polyacrylamide in the oily water has essentially fouled the membranes at least 1.4 times higher and the foulant has induced the cleavage effect on the oil droplets. [ABSTRACT FROM AUTHOR]

Synthesis of carboxymethylcellulose (CMC) from natural cellulose is an important industrial process. The effect of process parameters on the synthesis process is important information for the efficiency improvement of production process. Most of the previous studies on the effect of process parameters on the synthesis of CMC are based on the One-Factor-At-Time (OFAT); therefore, in this work, the response surface methodology (RSM) was used. Here, the cellulose was converted to CMC through carboxyinethylation process using a technique of William etherification in heterogeneous system. The process parameters studied include the solvent ratio, reaction temperature and reactant ratio (molar ratio of NaOH to SMCA). Meanwhile, the analysis and optimization of the responses of the process, degree of substitution (DS) and yield were also performed using the response surface methodology. The validity of the synthesis process was identified by the determination of CMC spectrum using the fast Fourier infrared spectrometer (FTIR). The analysis of the results shows that carboxymethylation is strongly affected by combination of process parameters studied. The results obtained also show that the optimum responses, degree of substitution (DS) is 0.87 and yield is 1.80, whereas the optimum process parameters, solvent ratio is 0.70v/v, reaction temperature at 56.03°C, and molar ratio of NaOH to SMCA at 1.00mol/mol. These findings conclude that the DS and yield of carboxymethylation of cellulose are strongly affected by the combination of the process parameters. [ABSTRACT FROM AUTHOR]

This study assesses the optical properties and conductivity of PVA–H3PO4 (polyvinyl alcohol–phosphoric acid) polymer film blend irradiated by gamma (γ) rays. The PVA–H3PO4 polymer film blend was prepared by the solvent-casting method at H3PO4 concentrations of 75 v% and 85 v%, and then irradiated up to 25 kGy using γ-rays from the Cobalt-60 isotope source. The optical absorption spectrum was measured using an ultraviolet–visible spectrophotometer over a wavelength range of 200 to 700 nm. It was found that the absorption peaks are in three regions, namely two peaks in the ultraviolet region (310 and 350 nm) and one peak in the visible region (550 nm). The presence of an absorption peak after being exposed to hυ energy indicates a transition of electrons from HOMO to LUMO within the polymer chain. The study of optical absorption shows that the energy band gap (energy gap) depends on the radiation dose and the concentration of H3PO4 in the polymer film blend. The optical absorption, absorption edge, and energy gap decrease with increasing H3PO4 concentration and radiation dose. The interaction between PVA and H3PO4 blend led to an increase in the conductivity of the resulting polymer blend film. [ABSTRACT FROM AUTHOR]