Modified halloysite as an adsorbent for prometryn from aqueous solutions

•Prometryn removal from water was performed using halloysite adsorbents.•The best modification of halloysite was the treatment with 96% H2SO4.•The adsorption occurred most effectively at pH 5.•Prometryn desorbed from halloysite only to small degree.

Adsorption behavior of prometryn (2,4-bis (isopropylamino)-6-methylthio-s-triazine) on halloysite minerals has been studied in order to consider the application of such adsorbents in water purification. Halloysite, activated in various ways, was characterized by ASAP, SEM/EDS. Batch mode and flow system have been employed, using prometryn aqueous solutions. Various parameters were studied for both systems. Adsorption capacity was determined as a function of adsorbate concentration, of optimum contact time, optimum dose and adsorbent fragmentation. It was found that at pH = 5 the best adsorptive properties for prometryn are obtained for halloysite treated with 96% H2SO4. Such adsorption matches Langmuir and Freundlich models and is in a good agreement with pseudo-second order kinetic model. The desorption of prometryn from halloysite was also studied. The performed studies show that halloysite treated with 96% H2SO4 holds the great potential for removal of water impurities such as prometryn.