A comprehensive comparison between synthetic and bio-based wet-strength additives for paper manufacturing

Wet-strength additives are vital in maintaining the structural integrity of paper and paper-based products in wet conditions. Most wet-strength additives are synthetically produced and pose environmental and human health risks. Therefore, there is a growing interest in developing natural and environment-friendly wet-strength additives for paper. However, the unavoidable replacement of these harmful wet-strength additives with greener materials to achieve similar wet-strength without compromising product performance, with the added option of sustainability, is challenging. This review discusses up-to-date conventional synthetic, natural, and other wet-strength additives used in developing wet-strength in paper-based products. A detailed description of the additive's reaction mechanisms and working principles for achieving the required wet-strength is also analyzed. Moreover, a detailed comparative literature review of the physio-chemical properties of these wet-strength additives is also discussed. Finally, the paper also discusses the challenges associated with bio-based additives in improving the wet-strength of paper-based products, comparing the well-established synthetic wet-strength additives.