Eco-friendly and multifunctional lignocellulosic nanofibre additives for enhancing pesticide deposition and retention

One of the globe environmental issues arising from pesticides loss due to sprayed droplets bouncing and rain washing causes severe soil and groundwater pollution. This issue can be tackled by enhancing the deposition of agrichemical sprays and their retention on plant surfaces, which has been proved extremely challenging. Here, we present an eco-friendly system made of surface-modified nanofibres derived from natural lignocellulosic biomass to improve pesticide utilization efficiency via multiple mechanisms. The addition of soft condensed matter polymer cellulose nanofibres (CNFs) could enhance the deposition of droplets on the hydrophobic surface due to the change of rheological properties of the suspension as observed by a high-speed camera. Cationization of CNFs was further proven to enhance the adhesion between droplets and negatively charged plant leaf surfaces via electrostatic interactions. As a result of the combined above effects, the retention rate of fluorescent markers could reach 80% after the rain washing test. In addition, lignin-containing CNFs were also investigated for their capability to protect photosensitive pesticides, whose retention rate increased by 150% due to the anti-UV property of lignin. Quaternized CNFs also enhanced the anti-pest effect of pesticides. Overall, biodegradable and multifunctional CNFs from lignocellulosic biomass were fabricated via relatively simple surface modification and used as additives to sufficiently improve the utilization of pesticides, realizing a sustainable circular economy concept in the agricultural field.