Analysis of dissolved and colloidal substances in old corrugated containers’ whitewater and dissolved substances’ impact on colloidal substances’ stability

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.

Application of Fenton’s reagent degrades dissolved and colloidal substances in old corrugated container white water

Fenton’s reagent has strong oxidizing properties and can effectively remove refractory organic pollutants. Fenton’s reagent was applied to deal with the dissolved colloidal substance (DCS) in the white water of old corrugated container (OCC). The optimum reaction condition on Fenton treatment was analyzed by response surface methodology (RSM) based on response values of DCS and CODCr. The result indicated that the optimized condition is as following, pH is 2.45, a mass ratio of H2O2 and CODCr is 1.1 and a mole ratio of FeSO4 and H2O2 is 0.35. Under the optimum condition of a single factor experiment, the experimental results showed that the removal rate of CODcr and DCS was 90.68 % and 1.61 g/L respectively, which was consistent with the response surface analysis prediction values. During the Fenton oxidation, the particle sizes of DCS decreased, the ions content and turbidity of the white water decreased, however the electrical conductivity and zeta potential of the white water raised slightly. Gas Chromatography-Mass Spectroscopy (GC-MS) analysis proved that benzoic acid and nonandioic acid can be effectively removed by Fenton’s reagent, however the content of dehydroabietic acid decreased by 24.07 %.

Adsorption of polygalacturonic acid on crosslinked polystyrene spheres with cationic polyelectrolyte

In a papermaking system, severe drawbacks on machine runnability and paper quality occur even as water consumption is not decreased due to a build-up of dissolved and colloidal substances (DCS) in the whitewater.

Some causes of formation of colour during storage of hydrogen-peroxide bleached Norway spruce mechanical pulp

The discolouration of hydrogen-peroxide bleached Norway spruce mechanical pulp during storage in mill systems was studied and the contributions of process water, iron and dyes were evaluated over the visible spectrum. Washing of the pulp made it less sensitive to storage, possibly due to the removal of extractives, lignin-like substances, iron and pulp fines. Storage in white water gave extensive discolouration with a shoulder in the absorption spectrum at around 550- 650 nm. Most of the colour was associated with pulp fines or filler but some colour was also found in smaller fractions and in the water phase. The addition of ferric ions increased the light absorption coefficient during storage, initially at short wavelengths and then over the whole spectrum, but could not explain the increased absorption at 550-650 nm and could not be the only cause of the darkening in the mill system. A cationic basic violet dye gave a shoulder in the absorption spectrum similar to that in the mill system, but the absorption in this area did not increase during storage. Model calculations indicate that ferric ions together with violet and red dyes could explain a major part, but not all, of the colour observed in the mill system after storage. The darkening not accounted for at longer wavelengths and around 550-650 nm is suggested to be related to fines and fillers including dissolved and colloidal substances associated with these particles.