Sdudy On The Adsorption Removal Of As(Ⅲ) From Water Using Iron And Manganese Modified Materials

In allusion to the problem of the contamination of arsenic growing in groundwater, prepared iron oxide modified filter media and manganese oxides modified filter media and characterized its surface properties; Studaied of the effect of adsorption As(Ⅲ),the kinetics of removal of As(Ⅲ), the effect of pH and coexisting ions using modified materials; The regeneration of the modified materials were studied and the modification mechanism and the modified materials adsorption of As(Ⅲ)process were discussed. The main conclusions are as follows:(1) Prepared iron oxide modified filter media using iron salt solution evaporation, the iron oxide content of surface is 5.604mgFe/g, the anti-acid-base propertie and adhesion strength are perfect; The determination of the isoelectric point is about 8.25; Respectively, using activated carbon and quartz sand as the carrier prepared manganese oxide modified materials, the former attached to the surface of the amount of manganese oxide and the adhesion strength are better than the latter; The effect of removal of As(Ⅲ) changed little beforeand after the Quartz sand modified by manganese oxides, but modified activated carbon filter was significantly improved.(2)When the initial As(Ⅲ) concentration is 0.5mg/Land volume is 100ml, the best dosage of iron oxides modified filter media is 2.5g and for manganese oxide modified activated carbon filter is 1.0g. The kinetics of removal of As(Ⅲ) are in line with Lagergren adsorption kinetic model II and the adsorption isotherm Langmuir isotherm can be used to describefor the two modified materials, but the adsorption rate of manganese oxide modified filter media was faster.(3) The rate of removal of As(Ⅲ) is higher than 85% using iron oxide modified filter media, when pH in the range of 4.0 to 8.0; For the manganese oxide modified activated carbon filter media.When pH <7.7, the adsorption of As(Ⅲ) changed little with the increasing of pH; When pH> 7.7, with the increased of pH, the removal rate of As (Ⅲ) decreased rapidly. The presence of phosphate and sulfate, had inhibited the removal of As (Ⅲ)for the two modified materials, but the inhibitory effect of phosphate sulfate is smaller than the sulphate. (4) Selecting of 0.1mol/L of NaOH to regenerated of iron oxide modified filter media, regeneration ratewas high and regeneration speed was rapid; The removal rate of As (Ⅲ) reach to 90.8% with freshly iron oxide modified filter media, regeneration times has little effect on removal of As(Ⅲ); Column experiments show that: the filtration rate should be controlled at 6m/h below; The greater of water hardness, the lower rateof removal of As(Ⅲ); Using 0.1mol/L of NaOH solution to regenerated the adsorption column, after regenerated, the effects of adsorption of As(Ⅲ) were reduced, but the number of regeneration has little effect for therenoval of As(Ⅲ).(5) Manganese oxide modified activated carbon filter media had considerable removal efficiency of As(Ⅲ) and As(V), but in addition to As(Ⅲ), a large number of manganese dissolved in the solution, subject to As(V), a small amount of manganese dissolved. This indicated that, existed redox in As(Ⅲ) adsorption system.When remove of As (Ⅲ),there will be the release of Mn²⁺.(6) By comparing the two modified materials obtained that:iron oxide modified filter media canremoval of As(Ⅲ) effectly, and will not cause secondary pollution, no pre-oxidation and can be reused after regeneration, saving the economy cost, suitable for various types of arsenic in drinking water purification; Manganese oxide modified activated carbon filter had high cost, and in the process of adsorption of As(Ⅲ) had manganese dissolved, Using the filter to remove of As(Ⅲ), should be oxidated to As (V) firstly, When removal ofwith the media,the effect of removal of As(V) is perfect, adsorption rate was fast.