ABSTRACT: The deactivation and in situ regeneration of anion exchange resin (D261) used as a catalyst in the continuous transesterification of soybean oil with methanol for biodiesel production were studied in a fixed-bed reactor. The chemical and physical structures of the resins were investigated by means of X-ray photoelectron spectrometer (XPS), N2 adsorption/ desorption isotherms, and scanning electron microscope (SEM). The results showed that biodiesel conversion was over 90% within the run time of 4 h but rapidly declined to 23.7% after 8 h. The fouling of organic substances (triglyceride and glycerol) covered on the resin was the main reason leading to the decrease in the biodiesel conversion. The fouling extent on the resin was related to the resin position in the fixed bed. The largest activity loss of the resin occurred at the bottom of the fixed bed. The leakage of OH− groups from the resins, independent of the resin height in the bed, also resulted to the decline of the resin activity. An in situ regeneration method was put forward. The resin regenerated can be restored to the original catalytic activity to perform continuous transesterification for biodiesel production

　　A novel composite catalytic membrane (CCM) was prepared from sulfonated polyethersulfone (SPES) and polyethersulfone (PES) blend supported by non-woven fabrics, as a heterogeneous catalyst to produce biodiesel from continuous esterification of oleic acid with methanol in a flow-through mode. A kinetic model of esterification was established based on a plug-flow assumption. The effects of the CCM structure (thickness, area, porosity, etc.), reaction temperature and the external and internal mass transfer resistances on esterification were investigated. The results showed that the CCM structure had a significant effect on the acid conversion. The external mass transfer resistance could be neglected when the flow rate was over 1.2 ml·min-1. The internal mass transfer resistance impacted on the conversion when membrane thickness was over 1.779 mm. An oleic acid conversion kept over 98.0% for 500 h of continuous running. The conversions obtained from the model are in good agreement with the experimental data.

ABSTRACT: Membrane fouling is a critical problem in membrane filtration processes for water purification. Electrocatalytic membrane reactor (ECMR) was an effective method to avoid membrane fouling and improve water quality. This study focuses on the preparation and characterization of a novel functionalized nano-TiO2 loading electrocatalytic membrane for oily wastewater treatment. A TiO2/carbon membrane used in the reactor is prepared by coating TiO2 as an electrocatalyst via a sol-gel process on a conductive micro-porous carbon membrane. In order to immobilize TiO2 on the carbon membrane, the carbon membrane is first pretreated with HNO3 to generate the oxygen-containing functional groups on its surface. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analyses are used to evaluate the morphology and microstructure of the membranes. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements are employed to illustrate the eletrochemical activity of the TiO2/carbon membrane. The membrane performance is investigated by treating oily wastewater. The oil removal rate increases with a decrease in the liquid hourly space velocity (LHSV) through the ECMR. The COD removal rate was 100% with a LHSV of 7.2 h-1 and 87.4% with a LHSV of 21.6 h-1 during the treatment of 200 mg/L oily water. It suggests that the synergistic effect of electrocatalytic oxidation and membrane separation in the ECMR plays a key role.

Membrane fouling control is a major challenge in the fields of membrane technology for water and wastewater treatment. A novel anti-fouling electrocatalytic membrane reactor was designed and proposed for industrial water treatment in this study. A TiO2/carbon membrane used in the reactor was prepared by coating titanium dioxide as an electrocatalyst via sol-gel process on a conductive micro-porous carbon membrane. The TiO2/carbon membrane, namely the electrocatalytic membrane, functions both as a filter and an anode in conditions of electrolysis. During wastewater treatment, the electrocatalytic membrane generated micro-flows to alleviate concentration polarization and reactive intermediates to indirectly decompose the organic foulants on the membrane surface or in pores into CO2 and H2O, or small biodegradable products. The results show that the electrocatalytic membrane reactor exhibited not only excellent anti-fouling ability and self-cleaning function, but also greater removal efficiency towards oily wastewater treatment compared to conventional membrane filtrations. As new equipment and method it would provide wide prospective applications in the fields of various industrial wastewater purifications.

One of the greatest challenges in membrane fouling studies is the development of non-invasive methods that allow for in situ detection of protein fouling, especially in tubular membrane modules. This study describes the extension of ultrasonic time-domain