天然果胶的絮凝性能研究

Flocculation Properties of Natural Pectin

研究了不同酯化度(DE)的柑橘果胶对高岭土悬浊液和实际城市污水的絮凝效果,通过烧杯混凝试验确定了果胶对高岭土悬浊液的最佳投药量、沉淀时间和pH值,并分析了其絮凝机理。试验表明,果胶具有一定的絮凝作用。对高浓度高岭土悬浊液,超低酯果胶的絮凝效果最好,其次为低酯果胶;而对低浓度高岭土悬浊液和实际城市污水,仅超低酯果胶有絮凝效果。

As a natural polysaccharide,pectin is widely used as food additive due to its gelling and stabilizing abilities.Citrus pectins with different degrees of esterification(DE) were applied to treat Kaolin suspension and municipal wastewater and their flocculation properties were investigated.The results showed that pectins had flocculating activity.Combined with 100 mg·L^(-1) poly aluminum chloride(PAC) solution,citrus pectins with various DE in the concentration of 2.5~12.5 mg·L^(-1) were compared in treating the Kaolin suspension of 5 g·L^(-1) by jar tests.Pectin wth lowest DE had the best flocculation properties,followed by the pectin of lower DE.The optimal dosage for pectins with high and lower DE was 7.5 mg·L^(-1),but the pectin with lowest DE did better at higher dosage.With the same pectins dosage of 10 mg·L^(-1),optimal settling time and pH value were also determined and flocculation mechanism was discussed.The best flocculation effect was obtained at 10 min of the settling time and pH value of 4~5.However,only the pectin with lowest DE could flocculate low-concentration kaolin suspension(0.1 g·L^(-1)) and municipal wastewater,probably due to the strong binding capability of carboxyl groups and Al^(3+),thus more suspended particles could be adsorbed and bridged.The pectin could obviously improve the flocculation.At the PAC dosage of 70 mg·L^(-1) and pectin dosage of 10 mg·L^(-1),the COD_(Cr) and SS removal of the wastewater were up to 89.9% and 86.0% respectively.