Removal Of Microalgae And Lead Ions In Water By Carbon-based Materials

With the rapid development of international economic integration and international trade, marine biological invasions and heavy metal pollution in water, which are recognized by the Global Environment Fund (GEF) as one of the four major threats to the ocean, have raised increasingly serious harm on marine environment. Therefore, in order to protect the marine environment, effectively control and reduce marine bio-invasion and heavy metal pollution, it urgently need to create a new control techniques against bio-invasion and methods to remove the hazardous heavy metal, which is the important and hot problems on ocean anti-pollution in marine science field.Carbon membranes are used to treat simulate ballast water including Chlorella vulgaris, Dicrateria inornata, Platymonas subcordiform as target algae, respectively. Effects of algae size, transmembrane pressure and crossflow velocity on the steady-state flux are investigated. The results indicate that it is feasible to treat ballast water by carbon membranes with slit-shape pore structure. A decrease in steady-state flux is observed as the algae size increases. High transmembrane pressure is more prone to block the membrane pore and results in the decrease of the steady-state flux. High crossflow velocity will be favorable to increase the steady-state flux owing to the inhibition of fouling layer development through the high shear stress on membrane surface. After treated by carbon membranes, no algae are detected. It indicates that carbon membranes are of potential for ballast water treatment.Removal of Pb2+from aqueous solutions using coconut shell carbon is performed in this paper. Morphology and pore structure characteristic of coconut shell carbon are investigated by SEM and nitrogen adsorption techniques. Effect of adsorption time, coconut shell carbon dosage and initial ion concentration on removal efficiency is also studied, and adsorption kinetics model of Pb2+in removal process is established. The results show that high specific surface area can promote coconut shell carbon to adsorb Pb2+in aqueous solutions and make it easier to reach adsorption equilibrium.Pb2+adsorption uptake decreases with the increase of coconut shell carbon dosage, while the removal efficiency shows a gradual increase trend, and remains unchanged until it reached a certain level. Higher Pb2+concentration enhances adsorption driving force, which is favorable to produce higher Pb2+adsorption uptake. Adsorption data of coconut shell carbon fits well with the Langmuir and Freundlich models. Pb2+removal ability in this work exhibits great competition respect to other carbon-based material. These clearly indicate that coconut shell carbon is a promising adsorbent for removal of heavy metal.