Colorants ultrafiltration

Koyuncu et al. [56] presented pilot-scale studies on the treatment of pulp and paper mill effluents using two-stage membrane filtrations, ultrafiltration and reverse osmosis [56]. The combination of UF and RO resulted in very high removals of COD, color, and conductivity from the effluents. At the end of a single pass with seawater membrane, the initial COD, color and conductivity values were reduced to 10-20 mg/L, 0-100 PCCU (platinum cobalt color units) and 200-300 ps/cm, respectively. Nearly complete color removals were achieved in the RO experiments with seawater membranes. 

Chemical differences between these fractions of DOM are apparent, but there is considerable compositional overlap as well. Extraction of humic substances or ultrafiltration removes most of the colored DOM from water samples and most of the dissolved lignin (Ertel et al., 1986 Opsahl and Benner, 1998). This is consistent with the observation that many humic and fulvic acids have molecular masses greater than the cutoff (1000 Da) of the membranes used for DOM isolation by ultrafiltration (Thurman, 1985). 

This invention relates to methods of preparing inulin from milled Jerusalem artichoke tubers by crystallization and drying. Water-soluble substances are separated from water-insoluble fibrous components. Following heating (80 to 85°C for 1 to 3 min), filtration, ultrafiltration, and nanofiltration steps remove protein and colored substances. The inulin is crystallized from the concentrated juice. 

Color can be reduced in RO feed water using coagulation/clarification with hydroxide flocculants, ultrafiltration and nanofiltration, adsorption of activated carbon, and ultraviolet radiation (see Chapters 8.1.1,8.1.9,8.1.4, and 8.1.8, respectively). 

Rwabahizi, S. and Wrolstad, R.E. 1988. Effects of mold contamination and ultrafiltration on the color stability of strawberry juice and concentrate. J. Food Sci. 53(3) 857—861, 872. 

Methods of functional group analysis that are based on pKa values of the functional groups (all potentiometric methods) can only yield operationally defined estimates of the concentration of a particular class of acidic functional groups. For this reason, an increased reliance on spectroscopic methods of functional group analysis is recommended. Only total acidity, as determined by the barium hydroxide method, appears to be a potentially accurate potentiometric method of analysis, if some type of ultrafiltration technique is used whenever normal filtration fails to remove all color from reaction mixtures. 

Powdered activated carbon may also be coupled to ultrafiltration (UF). This hybrid system, referred to in the literature as the PAC/UF process, incorporates the adsorption capabilities of activated carbon and the microorganism and particle removal ability of the UF membranes [71]. Combined with coagulation as a pre-treatment, tlie coupling has been successfully applied to the treatment of domestic wastewater [72]. Mdtivier-Pignon et al. [73] have proposed a combination of ultrafiltration with activated carbon cloth to treat complex aqueous solutions with suspended solids, colloids and dissolved organic molecules, like highly colored wastewaters from ink manufacture. 

Most wines certainly contain mucilaginous substances that act as protective colloids mannoproteins. Their existence is demonstrated by the elimination of the protective effect after fine ultrafiltration or dialysis. This phenomenon is well known in red wines, where colloidal coloring matter and tannins inhibit tartrate precipitation. It also exists in white wines and may be attributed to neutral polysaccharides (gum). According to the desired result, these substances may either be eliminated by fine filtration (e.g. to facilitate tartrate stabilization) or, on the contrary, protective colloids such as gum arabic may be added to a clear wine just before bottling to compensate for insufficient natural protection. 

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