Abstract: The present invention relates to an apparatus for monitoring the progress of membrane fouling that occurs on pores as well as on the surface of a membrane by means of variations of zeta potential (&zgr;) of a hollow-fiber membrane according to time passage of filtration of a suspension, wherein colloid particles, biopolymers and other inorganic particles are dispersed, and the method thereof. Moreover, the present invention also relates to a method to identify the effect of concentration polarization layer and cake layer which can vary according to the axial position of a hollow-fiber and the developing progress of a membrane fouling by measuring the position-dependent zeta potential of the hollow-fiber membrane.

Abstract: The present invention relates to a method for preparing a heteropolyacid catalyst and method for preparing methacrylic acid using thereof. More particularly, the present invention relates to a method for preparing heteropolyacid catalyst, which is produced by the recrystallization of a heteropolyacid and/or its salt dissolved in a basic organic solvent and heat-treatment, and further to a method for preparing metachrylic acid using thereof, wherein the use of the heteropolyacid catalyst increases the activity of oxidation reaction induced by the modified electronic properties of heteropolyanions and provides high efficiency production of methacrylic acid from methacrolein, since the basic property of solvent inhibits peculiar acidic property of heteropolyacid.

Abstract: The present invention relates to an apparatus for monitoring the progress of membrane fouling that occurs on pores as well as on the surface of a membrane by means of variations of zeta potential (&zgr;) of a hollow-fiber membrane according to time passage of filtration of a suspension, wherein colloid particles, biopolymers and other inorganic particles are dispersed, and the method thereof. Moreover, the present invention also relates to a method to identify the effect of concentration polarization layer and cake layer which can vary according to the axial position of a hollow-fiber and the developing progress of a membrane fouling by measuring the position-dependent zeta potential of the hollow-fiber membrane.

Abstract: A membrane filtration method and an apparatus for continuously monitoring the state of a membrane during the filtration, particularly for membrane fouling due to cake or gel layers of solutes developed on the surfaces of a filtered membrane, by estimating a membrane potential and a membrane solute rejection while making measurements of a set of physical properties of feed, variations of a streaming potential difference across pores of the membrane, variation in pressure differences between an upstream side and a downstream side of the membrane, and concentration differences between the feed and permeate filtered through the membrane.