No abstract

The nanocomposite gel prepared from nanoclay and natural polysaccharides showed a good sustained-release property. Herein, a cationic cellulose-modified bentonite–alginate nanocomposite gel was prepared and used to enhance the sustained release of alachlor. The underlying effect and mechanism of the structure of modified bentonite–alginate nanocomposite gels on the release behavior of alachlor were explored by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric (TG) analysis. The results showed that the release of alachlor from the nanocomposite gels was dominated by Fickian diffusion and closely related to the adsorption capacity and permeability of the matrix. The cationic cellulose intercalated into the interlayer space of bentonite through an ion exchange reaction, which significantly enhanced the hydrophobicity of bentonite and its interaction with alachlor. The stacking aggregation of bentonite nanoplatelets and permeability of the gel network were decreased through the electrostatic interaction between cationic cellulose and alginate molecular chains, thus remarkably enhancing the sustained-release property of the nanocomposite gel. The release kinetics revealed that the release rate of alachlor from the nanocomposite gel first decreased and then increased as the content of bentonite and modified bentonite gradually increased. Also, the best sustained-release property of the nanocomposite gel was obtained at bentonite and modified bentonite additions of about 10%, under which the release time of 50% alachlor ( T 50 ) from bentonite–alginate and modified bentonite–alginate nanocomposite gels was 4.4 and 5.6 times longer than the release time from pure alginate gels, respectively.

In our work, a cationic lignin (CL) modified bentonite-alginate nanocomposite gel was prepared and used to enhance the sustained release of alachlor. The underlying gel structure-release property relationships were explored. The results showed that the release of alachlor from nanocomposite gel was dominated by Fickian diffusion and closely related to the adsorption capacity and permeability of the matrix. The adsorption capacity of bentonite for alachlor was remarkably improved due to the modification of CL; Furthermore, the permeability of the matrix was further reduced via the electrostatic interaction between CL and the alginate. The release kinetics demonstrated that the sustained release property of modified bentonite-alginate nanocomposite gels was significantly enhanced. The release time of 50% alachlor from bentonitealginate and modified bentonite-alginate nanocomposite gels was 4.4 and 14.1 times longer than that of the release from pure alginate gel, respectively.