A novel method to screen biodegradability for the early assessment of cellulosic rheology modifiers

Abstract

In this study, we developed a new method for early-stage biodegradability assessment of cellulosic rheology modifiers (CRMs). Viscosity reduction was used as the primary indicator of polymer degradation. Complementary analyses included molecular weight changes (gel permeation chromatography, GPC), total carbohydrate content (TCC), and chemical oxygen demand (COD). Mixed microbial consortia from environmental sources ensured ecologically relevant conditions. Five CRMs including HPC-J (hydroxypropyl cellulose, J type), HPC-M (hydroxypropyl cellulose, M type), HPMC (hydroxypropyl methyl cellulose), HEMC (hydroxyethyl methyl cellulose), and cet-HEC (cetyl hydroxyethyl cellulose) were monitored over 8 weeks. Molecular weight dropped significantly, particularly for HPMC, which exhibited a 46.1-fold decrease, confirming chain scission. TCC declined sharply, with HPC-J surpassing an 85% reduction by day 56, evidencing microbial uptake. Furthermore, a predictive mathematical model was established, revealing the degradation sensitivity factor (‘a’), which ranged from a = 0.48 (for the highly resistant HPMC) to a = 4.85 (for the extremely sensitive cet-HEC). This simple, low-cost approach enables simultaneous small-scale testing as an early biodegradability screen, offering a practical decision tool before moving to standardized protocols and helping identify structural modifications that may hinder microbial breakdown.