Today, The occurrence of herbicides in environments attitudes a potential hazard to aquatic life and displays development forbidding of human embryonic cells, therefore their elimination from the environment is a vigorous job. In this paper, the SBA-15/TiO2 nanocomposite were synthesized utilizing amorphous nanosilica, which was extracted from stem cane ash (SCA) with 92.56% purity. FESEM and TEM images of pure SBA-15 and SBA-15/TiO2 nanocomposite demonstrates which their mean particle size was under 50 nm. The average particles size of TiO2 anatase calculated to be 27.6 nm using the Scherrer’s equation. The BET surface area, total pore volume and average pore diameter of the SBA-15/TiO2 was obtained to be 279.2 m2 g 1, 0.39 cm3 g 1 and 5.64 nm, respectively. For the first time, this nanocomposite was used as photocatalysts for degradation of trifluralin (Tri) and pendimethalin (Pen) herbicides in the aqueous solution. Partial least squares-1 (PLS-1) regression was used for simultaneous measurement of them in aqueous solutions before and after photocatalytic degradation with SBA-15/TiO2 nanocomposite. The values of some parameters such as R2 (0.9951, 0.9872), recovery (101.5, 102.0%) and root mean square error of prediction (0.231, 0.239) for both Tri and Pen were attained by the PLS-1 regression, respectively. The influence of some operational parameters such as initial herbicide concentrations, photocatalyst dosage, irradiation time and pH were also investigated on the photocatalytic performance using the response surface methodology. Conferring to the ANOVA test, the most important factor on the decomposition of herbicides was photocatalyst dosage. The results displayed that the maximum elimination efficiencies under the optimum conditions (pH = 10, photocatalyst dosage 0.2 g L 1, irradiation time 30 min and initial herbicide concentration 60 mg L 1) from the river water for Tri and Pen were attained to be 90% and 82.5%, respectively.
