Effect of solution parameters on the removal efficiency of humic substances by a reuse material

This paper provides an overview of the ability of polypropylene (PPL), a synthetic polymeric adsorbent made from reused plastic material. The removal of humic substances (HS) in a solution pretreated with dedoxyltrimethylammoniumbromide (DDTMAB), a cationic quaternary ammonium compound (QAC), was studied under various conditions. The removal of HS was achieved in its solute complexed form but also as suspended solids. The conditions of the HS solution, which fluctuation was suspected to have an impact on the performance of the adsorbent, were tested. The parameters investigated included the pH, the initial concentration of the surfactant, and the presence of suspended solids in solution. The results of the laboratory scale experiments showed that PPL removal efficiency of HS is strongly pH dependant with higher removal achieved at pH greater than 7. However, the shift for pH above 7 induced an increase in the optimum doses of DDTMAB as more and more deprotonated HS become available to react with DDTMAB. Ionic strength did have the opposite effect: the increase of ionic strength by addition of NaCl decreased PPL removal of HS.