Biodegradation of Hydrogels from Oxyethylated Lignins in Model Soils

Abstract

Since cross-linked hydrogels from oxyethylated lignins (OELs) are progressively more regarded as water-retaining soil improvements based on sustainable and biorenewable resources, an effort is made here to gain some insight into the biodegradation behavior of these materials. For this purpose, model soils with defined sand/lignin and sand/OEL ratios were incubated in a closed system under laboratory conditions, and carbon dioxide evolved by microbial lignin and OEL decomposition was determined. OELs with different oxyethylation/cross-linking degrees and water absorption capacities were included into the experiments and compared with respective types of parent technical soft wood and hard wood lignins. The results suggest a medium-to long-term biodegradability of OELs ensuring a long-term functionality of the hydrogel materials on the one hand and a subsequent integration of respective degradation products into the natural carbon cycles on the other hand. It was found that the short-term carbon mineralization rates of OELs are markedly lower compared to that of parent lignins and strongly dependent on (1) lignin type, (2) cross-linking/oxyethylation degrees of OEL, (3) corresponding swelling properties, and (4) OEL concentrations in model soils.

Robust Protein Hydrogels from Silkworm Silk

“…Hydrogels that contain large amount of water in their three-dimension network structures are mechanically stable materials, which only swell but do not dissolve in aqueous solutions. − It is known that hydrogels have wide application but always are limited due to their poor mechanical performance, especially when high strength is needed. , In recent years, many researchers have devoted themselves to developing hydrogels exhibiting excellent mechanical properties. Among all of the efforts, double-network hydrogels, topological hydrogels, and nanocomposite-hydrogels, reported by Gong, Okumura, and Haraguchi, separately, have drawn much attention because of their substantially improved mechanical behavior. − However, these hydrogels are not flawless as their biocompatibility is unsatisfactory while their degradation product is probably toxic, which severely limits their utilization in the biomedical fields. − …”

Quantitative Analysis of the Etherification Degree of Phenolic Hydroxyl Groups in Oxyethylated Lignins: Correlation of Selective Aminolysis with FTIR Spectroscopy

“…Following this approach, OELs with hydrogel character were obtained from pine kraft lignin, spruce and beech organosolv lignin, , birch acetic acid lignin, and wheat straw alkali lignin. Because of various beneficial features such as high water absorption capacity, high water retention and water release, mechanical stiffness, and biodegradability, OELs are suitable as water storing biomaterials, e.g., for agricultural applications and soil rehabilitation. ,, …”

Fotodegradação de hidrogel de poliacrilamida na presença de substâncias químicas para o uso na agricultura

“…Entretanto, apesar das propriedades promissoras que os polímeros hidrorretentores apresentam, quando adicionados ao solo, podem ser degradados devido à presença de microrganismos, altas temperaturas, efeito do pH, radiação ultravioleta, e, principalmente, os sais provenientes de adubações e calagem [5,6]. Os subprodutos originados de sua degradação podem ser prejudiciais à saúde dos seres vivos e ao plantio, pois podem vir a liberar a acrilamida, um provável carcinogênico ao humano em todos os tipos de vias [7].…”