| Recent years,with the fastly development of global industry and prosperity of economy,a mass of industry waste water and living sewage were let into water bodies,obviously result in the serious organic pollution.The development of heterogeneous advance oxidation technologies(AOTs) based on the mechanism of natural minerals self-purification is a promising technique for pollution treatment and environmental remediation.It is well known there are abundant FeOOH thin films in the natural environment.Moreover most of the FeOOH minerals reveal photochemistry activity.Taking monotmorillonite as template to prepare FeOOH/Mmt composite nano-material.For one thing,it can fix the FeOOH nanofilm and make the light disperse on the surface of the thin films,for another thing,the samdwich of monotmorillonite improve the surface area and enhance its photocatalysis activity.So it is a potential nano-technique to remediate contaminated water.In this paper,α-FeOOH/Mmt composite nano-material were prepared from aqueous system at low temperatures by imitating general principle of biominealization. Then the RhodamineB and phenol were selected as single model compound to investigate the interface adsorption-photo catalytic decomposition effect and mechanism byα-FeOOH/Mmt andα-Fe2O3/Mmt composite nano-material at the point of theory and application of nano-enviromaterials.The main conclusions of this study are shown as follows:1) The most suitable conditions on preparingα-FeOOH/Mmt were confirmed through correlative experiment:the quality ratio of iron salt to Mmtl:1,water bath time10h,water bath temperature 70℃.2) Theα-FeOOH nanofilms were synthesize successfully on the surface of Mmt from pH 2.1,2 mM iron(Ⅲ) nitrate solutions at water bath temperature 70℃for 10 h, then calcine it in the high temperature of 400℃for 4h,and get theα-Fe2O3/Mmt composite nano-material.3) Choosing Rhodamine B and phenol as the single organic object to test photodegradation activity ofα-FeOOH/ Mmt andα-Fe2O3/Mmt nanofilm catalysts.The concentrion of solution 20mg.L-1,catalyzer 1g.L-1,visible lamp-house 350w xenon lamp as visible lamp-house,the concentrion of H2O2 0mM,5mM.For RhodamineB reaction system,when there was no H2O2 in it,the TOC removing rate were 85%and 71%forα-FeOOH/Mmt andα-Fe2O3/Mmt respectly,adding H2O2 into it,it reached 92%and 96%for each of them;71.9%,60.9%o For phenol reaction system,when there was no H2O2 in it,the transformation efficiency were 71.9%and 60.9%forα-FeOOH/ Mmt andα-Fe2O3/Mmt respectly,adding H2O2 into it,it reached 95.5%and 95.9%for each of them.It was found the transformation efficiency for both of them followed the sequence:the reaction light irradiation with H2O2＞the reaction light irradiation without H2O2,and the reaction of light irradiation＞the dark reaction.4) Comparing the activity ofα-FeOOH/Mmt andα-FeOOH on removing organic pollutants,the result revealledα-FeOOH/Mmt hold the better photocatalysis ability (30%for RhodamineB).Among the certain range,the photocatalysis activity got better with the increase of H2O2 concentration,but once exceeding certain concentration(5mM for phenol),the effect will not change any more.Taking the experiment on RhodamineB as the example to test the stability of theα-FeOOH/Mmt andα-Fe2O3/Mmt nanofilm catalysts,respective reaction up to the 4th run was performed,Multi-run experimental results showed that both of them could have a long-term stability for the transformation and mineralization of RhodamineB.5) The waste water dimethyl sulfoxide with the initial COD 2500mg/l was well deposed by theα-FeOOH/ Mmt andα-Fe2O3/Mmt nanofilm catalysts.In the best conditions,the COD was reduced to about 700mg/l.Comparing their photocatalysis activity with other catalyzersα-FeOOH/SO3H-SAMs,α-FeOOH/TiO2/SO3H-SAMs,α-FeOOH/TiO2/Mmt,they all revealled the good effect with the result that the COD removing rate reached 75%,but thinking about various factors,α-FeOOH/Mmt was the most economical and doable catalyzer.6) Discussing the feasibility of FeOOH/Mmt on removing the chloride in contaminative ground water.Bothα-FeOOH/ Mmt andα-Fe2O3/Mmt revealled certain adsorption action on chloride in darkness,and the removal rate 27%and 24% respectively.In visible light system of the same other conditions,the concentration of Cl-1 was higher than it was in darkness,which obviously showed that some organic chloride transformed into inorganic chloride,and in the first two hours the concentration of Cl-1 reduced.All of these revealed that photocatalysis and adsorption exsited together in this reaction system.Oxidation character of air played a certian role in the degradation of organic chloride. |
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