Synthesis, Properties And Environmental Behaviors Of Hydrogel Loading With Carbendazim

Fungicides used in soil are easily lost, necessitating frequent application and causing many environmental concerns. We loaded hydrogels with carbendazim (MBC) to combine controlled-release and water absorption (WA), synthesizing the hydrogel loading with MBC (H-MBC). Carbendazim was first incorporated into microcapsule, which then recombined with starch-based hydrogel. FTIR and SEM were used to confirm the structure of the microcapsule and the loading of carbendazim into hydrogel. HPLC-MS/MS data showed that structure of carbendazim didn’t change during the process. Three H-MBC with various WA capacities were prepared by controlling the neutralization degree of AA. The optimum absorption property (800g·g-1in deionized H2O (ddH2O) and160g·g-1in tap water) was occurred when the neutralization degree of AA was95%. Release kinetics of H-MBCs was investigated using14C-labeling method. The diffusion parameters of three H-MBCs were0.47,0.57and0.81in ddH2O, indicating a Non-Fickian diffusion. WA affected release profile of carbendazim significantly, the release longevity reaching240h when WA was800g/g in ddH2O. Solution pH also influenced release profiles and the lowest release rate occurred in the lowest pH. Addition of H-MBC (1.3g/kg soil) markedly increased water-holding capacity (WHC) of soil by8.2%. The study indicated that H-MBCs could improve WHC of soil and prolong persistence of carbendazim as well.The behavior and fate of most agrochemicals in soil has been well documented, whereas how the encapsulation of hydrogel would affect their fate in soil remains poorly understood. Based on the synthesis of H-MBC, we explored the bound residue and extractable residue of H-MBC and carbendazim in soil by14C-isotope tracing, and the uptake of14C labeled H-MBC and14C-MBC by Oil spiced cabbage (Brassica chinensis L.) was also studied. The results were as follows:The extractable residue (ER) for both14C labeled H-MBC and14C-MBC decreased with time, reaching10.70%and6.95%of applied amount respectively after34days of incubation. The bound residue (BR) of14C labeled H-MBC and14C-MBC in soil increased first then decreased after a certain time, the inflection point occurred after28days and14days respectively. Around35.71%～52.51%of applied H-MBC and23.87%～43.26%of MBC formed BR, both lower than the maximum BR limitation proposed by EU (<70%of the applied amount). The uptake of both14C labeled H-MBC and14C-MBC by Oil spiced cabbage was limited, about0.08%～1.64%of the applied amount, indicating that neither H-MBC nor MBC would lead to high residue in plant. The disappeared proportions (14C labeled carbon dioxide and/or14C-labeled methanoic acid) constitute30.17%～52.66%of applied14C-labeled H-MBC,32.26%～65.75%of14C-MBC, demonstrating that the encapsulation of hydrogel decreased the volatilization and mineralization of carbendazim derived from H-MBC. The results were helpful to understand the environmental behavior and fate of H-MBC in soil-plant systm.