Abstract:The mechanisms regarding the influence of dissolved organics in papermaking whitewater together with metal ions on the fouling of an ultrafiltration (UF) membrane were studied in this paper. A series of experiments were carried out to characterize the organic matters' size and membrane flux. The associated fouling mechanism was investigated using the modified Hermia empirical model, resistance distribution, and specific resistance of the cake layer. The results indicated that the addition of metal ions aggrava… Show more
“…However, the pH dependence of the filters was more distinct. PES is reported to have a negative charge at pH values tested within and a decreasing zeta potential with increasing pH 66 , 67 . Figure 7 Concentration of thiamine recovered following filtration of 125 mL 100 nM thiamine in commercially bottled HPLC grade water pH adjusted to 3.5–6.5 through ( a ) GF/F glass fiber (0.7 μm pore size) and ( b ) 0.2 µm polyethersulfone (PES) filters after vortexing filters in 2 mL alkaline potassium ferricyanide.…”
Thiamine (vitamin B1) is an essential vitamin serving in its diphosphate form as a cofactor for enzymes in the citric acid cycle and pentose-phosphate pathways. Its concentration reported in the pM and nM range in environmental and clinical analyses prompted our consideration of the components used in pre-analytical processing, including the selection of filters, filter apparatuses, and sample vials. The seemingly innocuous use of glass fiber filters, glass filter flasks, and glass vials, ubiquitous in laboratory analysis of clinical and environmental samples, led to marked thiamine losses. 19.3 nM thiamine was recovered from a 100 nM standard following storage in glass autosampler vials and only 1 nM of thiamine was obtained in the filtrate of a 100 nM thiamine stock passed through a borosilicate glass fiber filter. We further observed a significant shift towards phosphorylated derivatives of thiamine when an equimolar mixture of thiamine, thiamine monophosphate, and thiamine diphosphate was stored in glass (most notably non-silanized glass, where a reduction of 54% of the thiamine peak area was observed) versus polypropylene autosampler vials. The selective losses of thiamine could lead to errors in interpreting the distribution of phosphorylated species in samples. Further, some loss of phosphorylated thiamine derivatives selectively to amber glass vials was observed relative to other glass vials. Our results suggest the use of polymeric filters (including nylon and cellulose acetate) and storage container materials (including polycarbonate and polypropylene) for thiamine handling. Losses to cellulose nitrate and polyethersulfone filters were far less substantial than to glass fiber filters, but were still notable given the low concentrations expected in samples. Thiamine losses were negated when thiamine was stored diluted in trichloroacetic acid or as thiochrome formed in situ, both of which are common practices, but not ubiquitous, in thiamine sample preparation.
“…However, the pH dependence of the filters was more distinct. PES is reported to have a negative charge at pH values tested within and a decreasing zeta potential with increasing pH 66 , 67 . Figure 7 Concentration of thiamine recovered following filtration of 125 mL 100 nM thiamine in commercially bottled HPLC grade water pH adjusted to 3.5–6.5 through ( a ) GF/F glass fiber (0.7 μm pore size) and ( b ) 0.2 µm polyethersulfone (PES) filters after vortexing filters in 2 mL alkaline potassium ferricyanide.…”
Thiamine (vitamin B1) is an essential vitamin serving in its diphosphate form as a cofactor for enzymes in the citric acid cycle and pentose-phosphate pathways. Its concentration reported in the pM and nM range in environmental and clinical analyses prompted our consideration of the components used in pre-analytical processing, including the selection of filters, filter apparatuses, and sample vials. The seemingly innocuous use of glass fiber filters, glass filter flasks, and glass vials, ubiquitous in laboratory analysis of clinical and environmental samples, led to marked thiamine losses. 19.3 nM thiamine was recovered from a 100 nM standard following storage in glass autosampler vials and only 1 nM of thiamine was obtained in the filtrate of a 100 nM thiamine stock passed through a borosilicate glass fiber filter. We further observed a significant shift towards phosphorylated derivatives of thiamine when an equimolar mixture of thiamine, thiamine monophosphate, and thiamine diphosphate was stored in glass (most notably non-silanized glass, where a reduction of 54% of the thiamine peak area was observed) versus polypropylene autosampler vials. The selective losses of thiamine could lead to errors in interpreting the distribution of phosphorylated species in samples. Further, some loss of phosphorylated thiamine derivatives selectively to amber glass vials was observed relative to other glass vials. Our results suggest the use of polymeric filters (including nylon and cellulose acetate) and storage container materials (including polycarbonate and polypropylene) for thiamine handling. Losses to cellulose nitrate and polyethersulfone filters were far less substantial than to glass fiber filters, but were still notable given the low concentrations expected in samples. Thiamine losses were negated when thiamine was stored diluted in trichloroacetic acid or as thiochrome formed in situ, both of which are common practices, but not ubiquitous, in thiamine sample preparation.
“…Few scholars have explored the effects of electrolytes on the stability of CS and the mechanism of DCS instability. Interestingly, cultural paper and old newspaper have been widely studied (Francis and Ouchi 2001;Zhang et al 2007;Su et al 2016). The OCC was researched less, as a critical component of recycled paper in the paper industry.…”
The physicochemical properties of dissolved and colloidal substances (DCS) in the old corrugated containers’ (OCC) whitewater were studied. Then, the colloidal substances (CS) were separated from dissolved substances (DS) and the effect of inorganic salts on the stability of CS (not DCS) was studied for the first time. The results showed that many DCS aggregated and attached to the fiber surface when pulping. The primary sources were resin, lignin, adhesives, coating fixatives, and fillers. The colloidal stability of DCS and solids of whitewater differed because the DCS contained less filler. Both Ca2+ and Na+ can affect the stability of CS, but Ca2+ led to more CS instability and aggregated into larger flocculent precipitates. The surprising discovery in the experiment was that when Ca2+ and Na+ were added together, the instability degree of the system was between the addition of Ca2+ and Na+ alone. Ca2+ played a dominant role in affecting the stability of CS, and Na+ competed for adsorption sites.
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