Polymeric Wet-Strength Agents in the Paper Industry: An Overview of Mechanisms and Current Challenges

Polymeric wet-strength agents are important additives used in the paper industry to improve the mechanical properties of paper products, especially when they come into contact with water. These agents play a crucial role in enhancing the durability, strength, and dimensional stability of paper products. The aim of this review is to provide an overview of the different types of wet-strength agents available and their mechanisms of action. We will also discuss the challenges associated with the use of wet-strength agents and the recent advances in the development of more sustainable and environmentally friendly agents. As the demand for more sustainable and durable paper products continues to grow, the use of wet-strength agents is expected to increase in the coming years.

Environmental Impact Evaluation for Heterogeneously Catalysed Starch Oxidation

Oxidised starch is currently produced from native starch using sodium hypochlorite as an oxidising agent. The use of hypochlorite has undesired side reactions and produces stoichiometric amounts of waste (salt), thus alternative oxidation methods are desired. In this study, the potential of two catalysed starch oxidation methods to reduce the environmental impact (EI) of oxidised starch production are assessed. We compared the EI of oxidation with molecular oxygen (heterogeneously catalysed) and hydrogen peroxide (homogeneously catalysed) to hypochlorite oxidation through life cycle assessment (LCA). The results confirm that hypochlorite oxidation is the main environmental hotspot in the current process of oxidised starch production, and that both hydroperoxide oxidation and molecular oxygen oxidation can significantly lower the EI of the process. The impact reduction is most significant in the categories of freshwater eutrophication (∼67 %), ozone depletion (∼66 %), climate change (35-60 %) and resource use (40 %-78 %) for peroxide and molecular oxygen oxidation, respectively.

Facile preparation of polyoxometalate nanoparticles via a solid-state chemical reaction for aerobic oxidative desulfurization catalysis

Polyoxometalate nanoparticles were synthesized via a concise solid-state reaction method by directly grinding silver nitrate and the polyoxometalate (NH4)5H6PMo4V8O40 at room temperature without the assistance of a surfactant. The as-prepared Ag6(NH4)5PMo4V8O40 (AgPMo4V8) comprised uniform nanoparticles of 50 nm size, which provided significant catalytic oxidative desulfurization (CODS) performance using O2, N2 + O2 or air as an oxidant. The high efficiency of 100% removal was obtained using AgPMo4V8 nanoparticles as a catalyst in treating model refractory sulfurs. The coexistence of Ag+ and PMo4V8O4011- was the main contribution for this CODS procedure, and the Ag+ species was employed as the electron transfer mediator (ETM) and the PMo4V8O4011- anion was used as the electron donor. The internal electron transfer between Ag+/Ag0 and V5+/V4+ allowed AgPMo4V8 to mimic oxygenase to release the activation energy of oxygen. AgPMo4V8 nanoparticles also exhibited potential for practical catalytic application in the CODS of diesel and gasoline to produce ultra-clean oils with a S content lower than 10 ppm under mild reaction conditions using a mixture of N2 and O2, thus favoring industrial application.