Oleic acid and its salts are present among the toxic pollutants in olive oil mill wastewaters. Four lignocellulosic materials modified by grafting quaternary ammonium groups have been tested for the adsorption of the oleate anion from aqueous solutions. viz. cotton fibres. https://www.roneverhart.com/10mm-Male-GRAV-Angled-Quartz-Banger-45/