A comparison between Moringa oleifera seed presscake extract and polyaluminum chloride in the removal of direct black 19 from synthetic wastewater

As a new coagulant, the efficiency and performance of Moringa oleifera seed presscake extract for the coagulation removal of direct black 19 was investigated under different operation conditions in contrast with polyaluminum chloride (PAC). The results indicated that the removal efficiencies decreased with rising pH for both of the two coagulants in the pH range of 5-9, and Moringa oleifera seed presscake extract was more efficient than PAC at pH 5-8 (P < 0.05). The optimal temperature for the two coagulants was 25 °C, and Moringa oleifera seed presscake extract was also better than PAC at every temperature (P < 0.05). The removal of direct black 19 increased with the increase of dosages of Moringa oleifera seed presscake extract and PAC. Both of NaCl and Na2SO4 increased the coagulation efficiency of Moringa oleifera seed presscake extract. In contrast, NaCl increased the removal percentage of PAC, but Na2SO4 decreased the performance. The suspended solid simulated by kaolin improved the direct black 19 removal. Overall, The Moringa oleifera seed presscake extract is better for direct black 19 removal than PAC (P < 0.05).