A toxicity decrease on soil microbiota by applying the pesticide picloram anchored onto silica gel

Abstract

A route for picloram (4-amino-3,5,6-trichloropicolinic acid) immobilisation onto silica gel was established after reacting at the first stage, the precursor silylating agent 3-chloropropyltrimethoxysilane with the support. The pesticide was convalently anchored to available chloro groups of the precursor, giving 1.11 mmol g⁻¹ of picloram per gram of silica. IR, ¹³C and ²⁹Si NMR spectra are in agreement with the proposed reaction between nitrogen of the chloride group of the previously anchored silica. The immobilisation of pesticide picloram onto a silica gel surface results in a decrease in its toxicity to soil microbial activity, compared to free pesticide added to soil.