China
Africa
Explore chapters and articles related to this topic
Processing and Chemical Pollutants in Industries
Published in Pankaj Chowdhary, Sujata Mani, New Technologies for Reclamation of Industrial Wastewater, 2021
Paper machine produces cleanest process water in the plant, and excessive water production in paper machines is purified through filtration to be reused in the papermaking process. Furthermore, when high water quality is required, the used water is subjected to further treatment such as ultra-filtration (UF). The processing water in papermaking operations consists of a variety of additives together with mineral filler products such as clays, calcium carbonate, and titanium dioxide. In the fiber slurry sizing agents like alkenyl succinic anhydride, alkyl ketene dimer or rosin products are added in the form of a slurry. In the case of producing colored papers, dyes are used along with these compounds but in low amounts, where removal of dyes becomes the primary treatment because of its high visibility.
SIMS: Secondary Ion Mass Spectrometry
Published in Terrance E. Conners, Sujit Banerjee, Surface Analysis of Paper, 2020
Lisa D. Detter-Hoskin, Kenneth L. Busch
The most recent study published by Brinen evaluated the use of surface spectroscopies (ESCA and SIMS) to monitor the distribution of both commercial and experimental sizes (internal and external) that had been applied to paper.18 Since sizes are typically added in small amounts to paper (e.g. 2 to 4 lb per ton), conventional spectroscopies lack the sensitivity to evaluate them. The use of ESCA and SIMS (particularly ToF SIMS) enable the size to be detected, and the spatial distribution determined. ESCA is suited to monitor the long aliphatic functional groups typical of most sizes. An ESCA C Is spectrum would be collected from an untreated paper sample, and the location and shape of the C Is peak(s) would be evaluated. A C Is spectrum of a sized paper would also be collected and compared to the spectrum obtained from the control. If size was present, the intensity of the C Is peaks would increase, shifts in the eV-position of the C peaks would be expected, and the shape of the C Is peak(s) might change. If heteroatoms are associated with the size, large shifts in the C Is peak are likely. While ESCA can give insight to the chemical environment of certain elements, its disadvantage is that it cannot provide direct structural information about such materials. However, SIMS can be used to identify size in paper and its distribution. From the presence of molecular ions (M+) (or protonated (M+H)+ or deprotonated (M-H)- molecular ions, or perhaps even derivatized molecular ions) in the SIMS spectrum (along with characteristic fragmentation patterns), it is very possible to identify the exact chemical nature of the size. In this study, Brinen observed the molecular ions of several sizes. The internal sizes examined included stearic acid, stearic anhydride, N-Cl-stearamide, alkyl ketene dimer (AKD), and ASA. The surface sizes evaluated consisted of styrene acrylic type resin and styrene/fluorinated-acrylic type resin.
Effect of different ions present in fresh water on performance of polyvinylamine based ASA emulsion
Published in Journal of Dispersion Science and Technology, 2020
Ashish Kumar, Nishi K. Bhardwaj, Surendra P. Singh
Alkenyl succinic anhydride (ASA) is an alkaline sizing agent most widely used in a number of alkaline paper grades. ASA is also known as a cellulose reactive sizing agent that provides resistance to aqueous penetration at varying degrees to paper by diminishing the hydrophilic property of cellulosic fibers. ASA is a synthetic sizing agent recognized for its on spot sizing degree or on machine sizing behviour. It produces sizing in paper quicker than other sizing chemicals viz. rosin and alkyl ketene dimer (AKD). ASA undergoes hydrolysis by reacting with the surrounding water molecules or if the wet end conditions are not controlled properly.[1–3] ASA is reaction product of isomerized olefin and maleic anhydride. Formation of succinic anhydride takes place which is highly reactive and will make complex by reacting with the hydroxyl groups of cellulose, starch and water. The sizing takes place on the paper machine itself immediately without any excessive drying unlike AKD sizing.[4–7] Apart from the merits of its high reactivity there are some demerits of the high reactive ASA molecules. The two main problems with the ASA sizing are (a) low shelf life of ASA emulsion, and (b) the sticky actions of hydrolyzed ASA.[8,9] Alkenyl succinic acid is the byproduct of ASA hydrolysis which is formed by the reaction of ASA and water which is detrimental to sizing. Freshly prepared ASA emulsion should be consumed within short period of time i.e. within a few minutes.[10] The various factors affecting the quality and shelf life of ASA emulsion are pH, temperature, viscosity of the ASA sample and particle size distribution (PSD) of ASA emulsion.