Mahmoud Hemmati

Oily wastewater treatment using mullite ceramic membrane

Abstract This paper presents performance of a microfiltration (MF) ceramic membrane for treatment of oily wastewaters. Mullite MF membranes were synthesized from kaolin clay. The effects of different operating parameters such as pressure (0.5–4 bar), volumetric flow rate (0–2 m/s), temperature (15–55°C), oil concentration (250–3000 ppm) and salt concentration(0–200 g/l) on permeate flux (PF), fouling resistance (FR), fouling and rejection (R) were investigated. In order to determine the best operating conditions, 250–3000 ppm condensate gas in water emulsions were employed as synthetic feed. The rejection of total organic carbon (TOC) for the synthetic feeds was found to be more than 94%. The results show that by increasing temperature and pressure, the PF increases. Also, by increasing oil content and salt concentration, the membrane is fouled rapidly and the PF decreases. At low salt concentration (0–25 g/l), PF increases with increasing salt concentration, but at high salt concentration (25–200 g/l), i...

EFFECT OF CARBON NANOTUBES ON THE KINETICS OF IN SITU POLYMERIZATION OF METHYL METHACRYLATE

The effect of carbon nanotubes on the kinetics of free radical polymerization of methyl methacrylate (MMA) was investigated. To do this, pristine, acid treated, alcoholic and methacrylate-modified carbon nanotubes with different loadings were used and Conversion, molecular weight and polydispersity index (PDI) of all samples were monitored during polymerization. The results show that carbon nanotubes induce an induction time to polymerization system which is independent of modification system while decrease in monomer conversion can be improved by developing organic moieties on surface. Molecular weight and polydispersity index for free and attached-on-surface chains were studied separately and different kinetics behaviors were observed for them. Molecular weight of free chains was increased by adding carbon nanotubes while more modified nanotubes resulted in much increased molecular weight. On the other hand, more system stability of more modified nanotubes, which was tested using UV-Visible spectra, resulted in higher molecular weights. Adding more nanotubes in the case of MMA-modified nanotubes caused to determine an optimum loading value to reach maximum molecular weight of free chains which was ascribed to system stability according to UV-Visible results. In this optimum loading value, free chains had minimum PDI value. However, increasing carbon nanotubes content led to decreased molecular weight of attached chains while PDI values increased because of shielding effect as physical phenomenon.

Optimization of conditions in ultrafiltration treatment of produced water by polymeric membrane using Taguchi approach

ABSTRACTIn this study, the ultrafiltration of produced water was studied using a two-stage ultrafiltration process. In the first stage, the influences of operating parameters, including transmembrane pressure, temperature, and cross-flow velocity on the amount of flux decline caused by membrane fouling, were investigated using a polymeric membrane. In order to design the experiments and optimize the experimental results, the Taguchi method was applied. L9 (33) orthogonal array for experimental planning and the smaller-the-better response category was selected to obtain optimum conditions because the lowest flux decline was our aim. Analysis of variance was used to determine the most important parameters affecting the flux decline caused by membrane fouling. The optimum conditions were found at the first level of transmembrane pressure (1.5 bar), second level of temperature (40°C), and third level of cross-flow velocity (1 m/s). In the second stage, performance of ultrafiltration system by the polymeric me...

Poly (Vinylidene Fluride) Membrane Preparation and Characterization: Effects of Mixed Solvents and PEG Molecular Weight

In this study, polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared via immersion precipitation method using a mixture of two solvents triethyl phosphate (TEP) and dimethylacetamide (DMAc), which had different affinities with the nonsolvent (water). Properties of the prepared membranes were characterized using scanning electron microscope (SEM) and contact angle and membrane porosity measurements. The prepared membranes were further investigated in terms of pure water flux and BSA rejection in cross flow filtration experiments. The results showed that by using a mixture of DMAc and TEP as solvent and changing the mixed solvent composition, membranes with different morphologies from sponge‐like to macrovoid containing were obtained. Maximum flux of the prepared membranes with different solvent mixing ratios was obtained for the one with 60%wt TEP in the casting solution of PVDF/TEP‐DMAc/ PEG which equals to 76.8 lm‐2h‐1. The effect of addition of polyethylene glycol with different molecular weight on morphology and performance of the membranes has also been discussed.