M.N. Abu Seman

UV-photografting modification of NF membrane surface for NOM wfouling reduction

Abstract Fouling of natural organic matter is one of the common problems in water treatment plant. Despite physical and chemical treatment normally used to recover the flux loss, membrane surface properties also not less important to be considered. In this study, UV-photografting technique was applied to modify commercial nanofiltration (NF) membrane surface in order to reduce fouling tendency. Neutral hydrophilic N-vinylpyrrolidone has been chosen as the monomer for the UV-photografting. The result revealed that the grafted membrane at optimum conditions exhibits low humic acid fouling tendency compared with the unmodified membrane. In addition, both the unmodified and the UV-grafted polyethersulfone NF membranes were characterized in terms of structural properties (pore size, r p, and ratio of membrane thickness to porosity, Δx/Ak ) using Pore Model in order to evaluate the effect of UV-photografting modification on structural parameters and indirectly influence the membrane performance and fouling as well.

Polyester Thin Film Composite Nanofiltration Membranes Prepared by Interfacial Polymerization Technique for Removal of Humic Acid

Nanofiltration (NF) polyester thin film composite membranes have been prepared through interfacial polymerization using a microporous polyethersulfone membrane as support. The thin polyester layer formed on the top surface of the microporous support layer was produced by the reaction of 6 %w/v of triethanolamine (TEOA) in aqueous solution and a solution containing trimesoyl chloride (TMC) for different reaction times (15, 25, and 35 min). The performance of the membranes was then characterized using permeation experiments with 0.001–0.1 M of salt solutions (NaCl and Na2SO4) and 15 mg/l of humic acid solution as a model for natural organic matter (NOM), normally found in surface water. This study has shown that through the interfacial polymerization technique, the variation of reaction time at a constant monomer concentration of 6 % w/v can affect the properties of the membrane produced and indirectly influences the membrane performance. Increasing the reaction time resulted in decreasing water permeabilities. However, a higher removal of humic acid was observed.

Separation of xylose using a thin-film composite nanofiltration membrane: screening of interfacial polymerization factors

Most hydrolysis studies on biomass produce a high amount of xylose and glucose compared to other monosaccharides. A specially tailored thin-film composite (TFC) membrane prepared via interfacial polymerization (IP) using triethanolamine (TEOA) and trimesoyl chloride (TMC) as monomers on a polyethersulfone (PES) membrane was used to separate xylose from glucose. Differences between the support (PES) and TFC membrane in surface chemistry were probed using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and contact angle. Both membranes were also characterized by field emission scanning electron microscopy (FESEM) and pure water permeability to observe changes to membrane morphology and properties. The performance of the TFC membrane is highly stimulated by variation of preparative factors in IP. This study screens and reports the effect of five preparative factors, namely monomer concentrations (TEOA and TMC), pH of the aqueous phase, reaction time, and curing toward the performance of xylose separation from glucose. A 25−1 fractional factorial design was used to narrow down significant preparative factors, saving lots of time and resources. It was found that curing and reaction time significantly affected the separation of xylose from glucose. High correlation (R2 = 0.9998) between the experimental data and model data was obtained. The developed model in this study is adequate for predicting the xylose separation factor under different IP conditions within the range used. This study will provide valuable guidelines to develop membranes that are specially tailored for xylose separation from glucose as an alternative to the cost intensive chromatographic processes in use.

Study of the Effects and Interaction of Operational Parameters on the Fabrication of Silver Nanoparticles (AgNPs)-Loaded Chitosan-Polylactic Acid-Based Films Using Full Factorial Design

Fabrication of silver nanoparticles-loaded chitosan-polylactic acid-based films was successfully employed for investigating the effect and interaction factors that affect the tensile strength and elongation at break responses. The two factors were the concentration of polyethylene glycol (PEG) 400 and the ratio of polylactic acid (PLA)/chitosan. Analysis of results was performed by using two-level full factorial design (FFD) to avoid the traditional one-factor-at-a-time experiments, and the model constructed by FFD resulted in improved response, reduced process variability, and closer confirmation of response to targeted requirements. Common statistical tools such as analysis of variance (ANOVA), Pareto chart, normal probability plot of the residuals, and main effect plot with its response were used to determine the most important process variables affecting tensile strength and elongation at break responses. The use of FFD allowed for identification of the most significant parameters under tested conditions. From the results of statistical analysis, it could be concluded that both the concentration of polyethylene glycol (PEG) 400 and the ratio of polylactic acid (PLA)/chitosan had significant effect on tensile strength and elongation at break responses. Therefore, the concentration of polyethylene glycol (PEG) 400 and the ratio of polylactic acid (PLA)/chitosan content in the blend films were employed for a surface analysis design in order to achieve an optimal quality of film based on tensile strength and elongation at break responses. From Table 90.1, the standard order 15 (A = 15 %, B = 50/50) showed the best results in tensile strength and elongation at break which are 8.27376 Mpa and 23.4974 %, respectively. The results from FFD could be studied further expanded to a central composite design, in order to fit the measured data to a quadratic model and to calculate response surfaces.