| Clean water has become a scarce commodity in many parts of the world.To supply the demand for the potable water for the world's population andhigh quality water for industry the available sources of water often need to betreated. The main pollutions in water are heavy metal, organics and bacteria.When heavy metals return to the environment they cannot be biodegraded.The metals can adsorb onto the soil, runoff into rivers or lakes or leach in thegroundwater, which is an important source of drinking water. Because theheavy metals may pose serious problems on building up at various stagesduring the ecobiological cycle, to purify wastewater containing metal ions isnecessary. Organic pollutions widely lie in water. Most of them would harm topeople directly or indirectly. Moreover some of them could change the DNAof cell in human tissue, and cause cancer, abnormality and mutation. Bacteriaare a kind of original biology with single cell, which are distributed widely inthe nature. Bacteria have a consanguineous relationship with the human. Theybadly affect human's health.The contaminations in the aqueous solutions, such as heavy metals,organic matter and bacteria, all do harm to man's health. The heavy metals inthe aqueous solutions mainly come from the drainage of the industrial wastewater, lots of information has been said that some diseases are relative toheavy metal ions in the aqueous solutions. With the development ofexploitation,smelting, transaction and commercial manufacture, heavy metalscome into atmosphere, water and soil environment may cause seriousenvironmental pollution. When the heavy metals of various chemical state orconformation come into natural environment or ecosystem, they will exist,cumulate, transfer and engender harm. Heavy metal ions are difficult tobiodegraded or destroy. Biology ingests heavy metals from environment,heavy metals may accumulate into the organism, hydrophytic plants andterricolous crops, then turn into human through the food chain, heavy metalsdo severe harm to human beings. So we attach important to the source ofheavy metals pollution, the treatment of waste water and the standard ofdrained water increasingly. Most of the organic matters in the aqueoussolutions have acute or chronic, direct or indirect noxious functions, some ofthem can even change the structures of DNA in human tissues. There are 117kinds of the organic matters in drinking water, these matters cause cancer,abnormality and mutation. Therefore to purify wastewater containing organicmatters is necessary. WHO has summarized that 80% of diseases and onethird of death are caused by the polluted drinking water. So it is important toremove the bacteria in the aqueous solutions and let humans drink healthy andclean water.Now there are many waste water treatments and methods, most of themare applied in large scale system. Most of them are used to remove highconcentration pollution but seldom aim at low concentration pollution. Theconventional separation technologies consume vast chemical reagent,demand big place to experiment and cost a lot, then the chemical reagentmay pollute the environment again and the separation technologies are notthorough, so the waste water can not reach the "Integrated WastewaterDischarge Standard GB8978-1996". To solve the problems above and satisfythe developing of the health consciousness and living condition, now weurgently need one kind of efficient and easy operated waste water treatment.Here we research nano-composite water purifying material. By changingthe raw and processed materials and the condition of the preparation, wecontinuously optimize the nano-composite water purifying material. Thenano-aluminium powders have high react activity and big ratio surface area,so we use its hydration reaction to prepare the nano-composite particles. Inour experiment, we respectively choose fiberglass , microcrystallinecellulose,polyethylene fiber and activated carbon fiber as the carrier of thenano-composite particles, and design a series of the comparative experiments.We prepare the nano-composite water purifying material using the four kindsof carries above, and we examine the materials' characterization through theexperiment of removing the contaminations in the aqueous solutions. Theresults showed that the nano-composite water purifying materials made bythe carrier of fiberglass has the maximum saturated adsorption, it show thatfiberglass is better than the other carriers , it can better fix thenano-composite particles, and the material's absorption capability is biggest.Because the adsorption capability of the activated carbon fiber felt, we use itas the underlay of the nano-composite water purifying materials. Hereto weascertain the selection of the raw and processed materials of the materials. Tooptimize the material's adsorption capability, we change the temperature ofthe reaction and the conductions of the reaction to prepare thenano-composite water purifying materials, then we have a lot of comparativeexperiments purifying water, at last we draw a conclusion that the bestconduction to prepare material is that using the ultrasonic precipitationprocess to prepare the nano-composite particles, then fix them on thefiberglass, at last we use the activated carbon fiber felt as the underlay,through roiling and desiccating we can prepare the water purifying materials.Under the above conditions we can prepare the best water purifyingmaterials, they can thoroughly remove the low concentration of cadmiumfrom aqueous solutions, and now the materials have the maximum saturatedadsorption and super adsorption capability. The saturated adsorption is animportant standard to evaluate the material's adsorption capability, we usethe Thomas model to simulate and calculate the adsorbents' saturatedadsorption.The Thomas model has the following form :1exp(())1C0 Qkq0MC0VCe+?=The water purifying material was characterized by XRD, nitrogenadsorption, TEM, SEM and XPS. The average crystal granularity wasobtained by Sherrer formula. The composing and the appearance of thenano-composite particles and the appearance of water purifying material wereconfirmed. The characterization of XPS showed that the mechanism ofadsorption of cadmium in aqueous solutions by the nano-composite waterpurifying materials is chemical adsorption. The nano-composite particles havethe structure of fibers;they have large activity and big ratio surface area. Sothe water purifying materials can fully contact with the contaminations in theaqueous solutions and can thoroughly removal the contaminations.In a word, AlOOH/fiberglass composite nano-water-purifying materialcan remove low concentration heavy metal ions, organic matters, andbacterium from aqueous solution thoroughly, its removal effect and removalcapability was very high. After the research of the compositenano-water-purifying material, we can treat water with low concentrationcontamination effectively and expediently. |
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