Alireza Zirehpour

This work investigates the use of a silver-based metal–organic framework (MOF) for mitigating biofouling in forward-osmosis thin-film composite (TFC) membranes. This is the first study of the use of MOFs for biofouling control in membranes. MOF nanocrystals were immobilized in the active layer of the membranes via dispersion in the organic solution used for interfacial polymerization. Field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) characterization results showed the presence of the MOF nanocrystals in the active layer of the membranes. The immobilization improved the membrane active layer in terms of hydrophilicity and transport properties without adversely affecting the selectivity. It imparted antibacterial activity to the membranes; the number of live bacteria attached to the membrane surface was over 90% less than that of control membranes. Additionally, the MOF nanocrystals provided biocidal activity that lasted for 6 months. The immobilization improved biofouling resistance in the membranes, whose flux had a decline of 8% after 24 h of operation in biofouling experiments, while that of the control membranes had a greater decline of ∼21%. The better biofouling resistance is due to simultaneous improvement of antiadhesive and antimicrobial properties of the membranes. Fluorescence microscopy and FE-SEM indicated simultaneous improvement in antiadhesive and antimicrobial properties of the TFN membranes, resulting in limited biofilm formation.

In this study, a hydrophilic metal–organic framework (MOF) was applied to improve the performance of a cellulosic membrane for forward osmosis (FO) desalination application.

The effect of operating pressure on olive oil mill wastewater (OMW) purification and filtration efficiency was determined by the evaluation of the flux decline during volume reduction factor (VRF) experiment. One of the other effective factors is the rejection coefficients based on several parameters, which measure the global pollutant content of the OMW, namely chemical oxygen demand, UV absorbance at 254 nm, total phenols, color as well as conductivity. The integrated membrane system (UF-NF) was used in this study and OMW was pre-filtered by three steps tubular microfiltration modules with nominal pore size of 50, 5, and 0.2 micron in series mode and afterward a 35 kDa ultrafiltration membrane. Filtration experiments in concentration mode of the filtration (with recycling of the retentate stream) were performed in laboratory scale, by using three nanofiltration (NF) membranes. The fouling behavior analysis of the NF membranes was also performed by assessment of the flux recovery ratio and degree of the total flux loss (R_t) during VRF experiments. The NF-270 had resulted higher permeate flux than other examined NF membranes, while both NF-90 and self-made NF rejection efficiencies were better than NF-270. On the other hand, the NF-90 had shown better results in comparison with the other NF membranes at high operating pressure. It was concluded that the increasing of the operating pressure enhanced the effects of fouling.