Polymer-inorganic membranes for removal of pesticides from water using pressure-driven technique

Pesticides enter surface and ground waters not only from agricultural lands, but also from the plants, where these substances are produced and packed. Thus, the problem of wastewaters produced by these plants must be solved. This work is devoted to the development of high performance membranes for pressure-driven processes, which would remove pesticides from water and give a possibility to use the concentrate further. Polyamide (PA) and polyvinylidene fluoride (PVDF) microfiltration membranes as well as polyacrylonitrile (PAN) ultrafiltration membrane were modified with hydrated zirconium dioxide (HZD) by a deposition of ion exchanger from sol with ammonia vapour directly in pores of the polymer. The membranes were investigated with SEM method, energy dispersive and FTIR spectra were also recorded. HZD in active layer as well as the products of PA or PAN hydrolysis enhance hydrophilicity of the membrane surface: for instance, the contact angle of water decreases from 69° to 43° for the PA sample. Water test followed by calculation using the Hagen-Poiseuille equation showed a 2–3 times decrease in pore size of the modified membranes comparing with pristine materials. Selectivity of HZD-containing membranes reaches 90–96 % towards bowine serum albumin, and exceeds 99 % in the case of quizalofop-p-ethyl. The highest permeate flux (196 l m–2 h–1bar–1) has been found for the HZD-containing PVDF sample. The pesticide concentration in the permeate was 0.0002–0.008 mg l–1. The posttreatment of the permeate involved adsorption on biochar under dynamic conditions. The method of liquid chromatography showed that after the passage through the column, no pesticide was detected in the permeate or its content was lower than maximal allowable concentration for surface water (0.0001 mg l–1).