Study On The Treatment Of Organic Waste Water With Self-assembled Monolayers(SAMs)

There has been recent interest in using molecules self-assemble technology for materials production and surface modification. The term self-assembly implies the spontaneous adsorption of molecules or nanoparticles onto a substrate and forming self-assemble monolayers. Self-assembled multilayer films are formed by the adsorption of subsequent monolayers of molecules or nanoparticles with some driving force. Self-assembled films show a lot of interesting properties in physics, chemistry, optics and electronic transport. In addition, they have stable structure and simple facture. Therefore, they have potential application in wettability and friction, adsorption, corrosion protection, catalysis, molecular-biology, sensing, patterning, electrochemistry and micro-electronic industry. In this article, we describe the applicatipn of self-assemble technology in environmental protection.First, we made special emphasis on the preparation of two kinds of organosilane self-assembled monolayers and their utility in adsorption for organic pentachlorophenol (PCP) pollutant. We investigated the adsorption behaviour and mechanism. Second, FeOOH riched in soil and water belongs to semiconductor mineral. They have intense influence in poisonous pollutant transfer and transform. In previous research of our team, biominealized nano-FeOOH minerals show strong function of catalysis, oxidation and degradation in FeOOH/organic interfaces although there is no light and H₂O₂. Functionalized self-assemble monolayers can promote and control the deposition of inorganic materials from aqueous solution by imitating general principle of biominealization. A wide variety of minerals are deposited by organisms including metal oxides, sulfides, carbonates, and phosphates. Self-assembled iron oxyhydroxide films can fix the nano-scale FeOOH. It provides opportunity for study (optical) catalysis of iron oxyhydroxide systemly and valuable for environmental repairment and developing new (optical) catalysis materials. We adopted self-assemble monolayers as the template for synthesis nano-scale iron oxyhydroxide films from aqueous Fe(NO₃)₃-HNO₃ system at low temperatures and ascertained the optimum reaction conditions for deposition. Finally, we analysed the crystal structure of iron oxyhydroxide films and laid foundations for subsequent (optical) catalysis research.We adopted traditional dipping-washing method to synthesis self-assemble monolayers. SH-terminated self-assemble monolayers was produced by surfactant of Si(OCH₃)₃ (CH₂)₃-SH, then oxidized to SO₃H-terminated self-assemble monolayers. NH₂-terminated self-assemble monolayers was simply produced by surfactant of Si(OCH₃)₃ (CH₂)₃-NH₂. The two kinds of SAMs will deprotonate or protonate in water and indicate the sulfonate group (-SO₃H) and the amine group (-NH₂) were successfully connected with the matrix. The absence of C-H stretching mode and bending mode of SAMs and N-H bending mode of NH₂/ SiO₂ in the infrared reflection-absorption spectrum further suggested that organosilane self-assembled monolayers are existent on the matrix.The experiments of pentachlorophenol (PCP) adsorption onto the suspensions of the SO₃H/SiO₂ SAMs and the NH₂/SiO₂ SAMs gained some effects, especially SO₃H/SiO₂ SAMs. PCP adsorption onto the suspensions of the SO₃H/SiO₂ SAMs is quite slow which spend about 30 days to reach the balance and the former can be fitted by Freundich equation; PCP adsorption onto the suspensions of the NH₂/SiO₂ SAMs is relatively rapid which spend about 15 days to reach the balance and the former can be fitted by Langmuir equation. The speciation topographic analysis and infrared reflection-absorption spectrum suggested that the surface hydrogen adsorption reaction may be taken place.We adopted SO₃H/SiO₂ SAMs as the template for synthesis the catalysis of nano-scale iron oxyhydroxide from aqueous system at low temperatures by imitating general principle of biominealization. The optimum reaction conditions for deposition involve 70℃of water bath, 2.0 mM Fe (NO₃)₃, pH value of 2.00, reaction time of 6h. We concluded the crystal structure of nano-scale iron oxyhydroxide films is a-FeOOH by TEM, electronic diffraction, XRD and observed the microstructure of the films.