In this work, we present the effects of salts on sodium dodecyl benzene sulfonate micellization and on the interfacial performance of a sodium dodecyl benzene sulfonate-heptane-brine system at optimum formulation, i.e., hydrophilic-lipophilic deviation (HLD) = 0. In order to do that, interfacial tension and dilational interfacial rheology properties of surfactant-heptane-water systems at optimum formulation are measured using an interfacial spinning drop tensiometer with an oscillating velocity, which can accurately measure interfacial rheology properties at both low and ultralow interfacial tensions. The brines used contain one of the following salts: MgCl 2 , CaCl 2 , NaCl, NH 4 Cl, NaNO 3 , CH 3 COONa, or Na 2 SO 4 . We performed a one-dimensional salinity scan with each of these salts to achieve an optimum formulation. In relation to the Hofmeister series, we found that, at optimum formulation, systems with chaotropic ions (NH 4 + , NO 3 − ) present interfaces with ultralow interfacial tensions, very low dilational modulus, and a low phase angle, whereas kosmotropic ions (Mg 2+ , Ca 2+ , SO 4 −2 ) generate high interfacial tension and high rigidity monolayers. Intermediate ions in the Hofmeister series (Na + , CH 3 COO − , Cl − ) present interfaces with intermediate properties. Furthermore, according to the Hofmeister series, interfaces can be respectively ordered from higher to lower rigidity for surfactant counterions Mg 2+ > Ca 2+ > Na + > NH 4 + and coions SO 4 2− > CH 3 COO -> Cl − > NO 3 −, which correspond to a saltingout (highest rigidity) and salting-in (lowest rigidity) effect. We observed that counterions have a more significant effect on surfactant-oil-water system properties than those that act as coions.Keywords Hofmeister series Á Interfacial rheology Á Microemulsion Á Micellization Á Salt effects Á Ultralow interfacial tension J Surfact Deterg (2020) 23: 603-615.

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The hygiene tissue industry has an extensive global market that is quickly growing. Market research has indicated that softness is one of consumers’ most highly desired properties. For certain hygiene tissue products (specifically bath tissue), this property can influence prices. A better understanding of the science of softness would allow companies to engineer soft tissue more economically and efficiently. Softness is a subjective perception related to physical aspects that make it challenging to express and measure. Human handfeel panel testing, which ranks the specimens through physical tests, has been recognized as the most reliable method to measure tissue softness. Much effort has been expanded in correlating the panel test results with some measurable properties. In this regard, equipment has been recently developed by combining several different mechanical, surface, and acoustic properties to characterize softness. In comparison with panel tests, these instruments (e.g., tissue softness analyzer) have been found to give equivalent softness metrics. A combination of materials selection and manufacturing operations are used to create softer tissue sheets. This paper reviews the sensation of softness as perceived by the human touch, techniques for measuring softness, the influence of fiber on softness, manufacturing techniques, and additives used for softness enhancement.

Consumers' rising interest in brown tissue papers, perceived as sustainable, has increased the market share and selling prices of such products despite their limited performance. Meanwhile, the current excess of packaging waste in the US has created an opportunity for using old corrugated containerboard (OCC) as an alternative source of brown pulp, despite its inferior tissue-making characteristics relative to bleached fibers. Strength, water absorption capacity, and absorption rate are among the crucial properties of absorbent tissue products. Herein, we studied the feasibility of total chlorine-free treatments, namely, oxygen delignification, alkaline hydrogen peroxide, and ozonation, to improve the tissue-making quality of OCC pulp. The processes evaluated reduced the lignin content (kappa number from 89 to values as low as 55) and generated brightness gains as high as 8.8% ISO units. The strength of the sheets also improved due to the delignification and increase in fiber swelling. Chemically treated OCC resulted in sheets with higher water absorption capacity and absorption rate and fiber slurries with higher freeness compared to sheets and slurries from mechanically refined OCC. Therefore, we demonstrate the application of treatments with low environmental impact to upcycle OCC into a high-quality brown pulp suitable for manufacturing high-performance tissue paper.

The release of soils and impurities from cellulosic surfaces plays a critical role in such processes as the laundering of clothes and the deinking of wastepaper pulps. This article reviews publications that provide evidence about factors that affect such release and the mechanisms by which such factors operate. In general, cellulosic substrates provide advantages for the release of contaminants due to their hydrophilic nature and due to their permeability, allowing the transport of surfactants to contact interfaces with dirt. However, the same permeability of cellulosic material also provides opportunities for contaminants to work themselves into internal crevices and pores, from which they are difficult to remove. The article also reviews aspects of theory related to detergency and how those theories relate to the laundering, deinking, and purifying of substrates based on cellulose and related plant materials. Cellulose and some of its derivatives also can play a role in detergent formulation, especially as builders or as finishes placed on textile surfaces, which sometimes aid in the release of dirt.

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