Eco-synthesis, application and enhanced water-retention properties of cellulosic hydrogels derived from waste papermill sludge as soil amendments
Year: 2025
Type: dissertation
Abstract: Poor water retention in acidic soils and prolonged droughts cause major crop losses each year. In boreal ecosystems this poses a challenge for growing food locally, adding to nutrient insecurity. Hydrogels derived from waste biomass offer a sustainable solution by improving water retention without relying on virgin, petroleum or renewable biomass-based resources, contributing to a circular bioconomy. In this study hydrogel-composites were synthesized (i) from cellulose recovered from waste papermill sludge using energy-efficient protocols, (ii) by crosslinking recovered cellulose with citric acid (iii) followed by incorporating various amounts of biochar (BC) as a biocompatible filler. Four hydrogel composites containing BC compositions of 0 g (CH), 0.5 g (BH0.5), 1 g (BH1.0) and 1.5 g (BH1.5) were synthesized and characterized by Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and swelling studies (study 1). The effects of 1% and 2% (w/w) of cellulose hydrogel (CH) and biochar-incorporated hydrogel (BH) on sandy loam and silty loam soil were evaluated using water retention characteristics and drought resistance (study 2). The energy-efficient extraction with microwave and ultrasonication recovered cellulose in a 81.5% yield with 93.8% purity. The hydrogel composites showed enhanced water retention in the order BH1.0 > CH > BH0.5 > BH1.5. The application of hydrogels significantly (p<0.05) increased field capacity (FC) in both soils. In sandy loam soil, 2% of CH and BH increased the plant available water (PAW) by 313% and 405%, respectively. In drought-simulated pot experiments, tomato plants treated with 2% CH and BH remained fresh for up to 17 days without water, compared to 5 days for untreated soil. Waste papermill sludge cellulose-derived hydrogels exhibited significant potential as agricultural amendments, enhancing water retention and mitigating crop water stress, contributing to United Nations Sustainable Development Goal 12 (Sustainable Consumption and Production).
DOI: 10.48336/8ctb-bt67
Author: Ketheeswaran, Keerthana
Institution: Memorial University of Newfoundland
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6891589487
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