新型表面活性剂改性粘土去除赤潮藻研究

REMEDIATION FROM HARMFUL ALGAE BLOOM WITH ORGANO-CLAY PROCESSED SURFACTANT

以赤潮异弯藻为主要研究对象,对其在有机高岭土和有机膨润土作用下的去除情况进行了研究。结果表明,以新型阳离子表面活性剂双烷基聚氧乙烯基三季铵盐改性后的粘土用量为0.03g/L时,在24h内对赤潮异弯藻的去除率可以达到100%,而未经改性的同样用量的粘土并没有对赤潮异弯藻表现出去除作用,这表明改性后的粘土对赤潮异弯藻的去除能力得到了显著的提高。同时还对改性粘土去除赤潮异弯藻的絮凝动力学及其对养殖生物日本对虾仔虾的生态毒性情况进行了研究,发现粘土的种类、用量,改性剂的用量及溶液的pH值等因素都能够影响体系的絮凝沉降速率,通过分析各种影响因素发现在粘土体系中引入有机改性剂是提高其除藻能力的主要因素。另外,毒性实验发现所用改性剂对养殖生物的毒性较小,半致死浓度约为61.9mg/L,比传统的季铵盐的毒性降低了50倍左右,是一种较为安全有效的粘土有机改性剂。

Harmful algal blooms （ HABs）, commonly known as red tide ; it occurred frequently in recent years in many coastal waters, which has caused serious environmental problems with its toxin to aquiculture. To effectively put off the HAB damage, scientists have tried many different countermeasures to remedy the environment; spreading clay was therefore considered as one of the measures. In this paper, two types of clays, kaolinite and bentonite, were tested to remove a red tide organism-Heterosigma akashiwo, a major HAB member in China＇s coastal waters. However, application of natural clays did not produce a satisfactory result, as the coagulation rate was very slow. In order to enhance the capability of remediation,the clays were processed with a new type of surfactant-dialkyl-polyoxyethe-nyl-quatemary ammonium compound （DPQAC）. Before application, the removal rate of the organo-clays was examined. The DPQAC-treated clays showed excellent performance against the red tide organisms（in concentration of 5 × 10^4 -1 × 10^5cell/ml）, reaching nearly 100% of killing in 24 hours with clay concentration of 0. 03g/L（in which the DPQAC concentration was 3mg/L）, while the same concentration of untreated clay did not have such high capability under the same condition. The kinetics of red tide organism coagulation with clays was also studied. The effects of different concentrations of the treated and untreated clays, and various pH values of culture medium on the coagulation rate were examined. The results showed that the algae coagulation rate of kaolinite was faster than that of bentonite ; and increasing clay concentration could accelerate the coagulation, but adding DPQAC in clays could considerably improve the algal removal efficiency. Moreover, the toxicity of DPQAC and the influence of organo-clays on mariculture animals were tested. Shrimp Penaeus japonicus was chosen to be the animal. The results showed that the toxicity of DPQAC was 50 times lower than traditionally used hexadecyhrimethyleamine bromide; the LC50 concentration （lethal to 50% of test organisms） was about 61.9mg/L. Combined with clays, the DPQAC toxicity were decreased obviously. The application of DPQAC-treated clays could not only increase algal removal efficiency but also decrease the toxicity of the surfactant in aquiculture. Adding DPQAC to the clays was proved to be an effective countermeasure for remedying HAB, which provides an alternative in real case application in future for enhancing greatly the performance of HAB prevention in aquiculture.