Fabrication of light-responsively controlled-release herbicide using a nanocomposite

In this work, a light-responsively controlled-release herbicide particle (LCHP) with core-shell structure was developed using a nanocomposite composed of biochar, attapulgite (ATP), glyphosate (Gly), azobenzene (AZO), and amino silicon oil (ASO). Therein, nanonetwork-structured ATP distributed evenly in the pores of biochar to form porous biochar-ATP compound which acts as a carrier to efficiently load plenty of Gly and AZO molecules, obtaining porous biochar-ATP-Gly-AZO granule. Subsequently, the resulting biochar-ATP-Gly-AZO granule was incompletely coated by ASO, forming LCHP with abundant micro pores in the ASO coating. Under UV-Vis light radiation, trans-cis and cis-trans isomer transformation of AZO molecules will occur, acting as light-motivated stirrers to promote the release of Gly from LCHP through those nano pores. Thus LCHP displayed an excellent light-responsively controlled release performance, which could be also demonstrated by pot experiments. Importantly, LCHP possessed a good adhesion performance on surface of weeds leaves, which was greatly favorable for improving the control efficacy on weeds. Besides, coexisting ions (CO32-, SO42-, and Cl-) and pH posed little impact on LCHP release in water, proving the high stability of this technology. Therefore, this work provides a promising approach to control the release and enhance utilization efficiency of herbicide, which has a potential application prospect.