Research On The Preparation Of Activated Carbon/Iron Oxide Composite And Adsorption Properties For Dye Wastewater

Activated carbons have been widely employed in wastewater treatment field. However,the applications are limited by difficulties encountered in separation and regenerationprocesses. In this paper, we prepared magnetic activated carbon composites by chemicalco-precipitation method which combined the magnetism of iron oxides with the highadsorption feature of activated carbon. The fabrication conditions of activated carbon/ironoxide composites were optimized using orthogonal experiment method. SEM, XRD, BET,VSM and FT-IR were used to characterize the obtained magnetic composite material, Theirperformance for methyl orange(MO) and acid orange Ⅱ(AO7) removal by adsorption wasalso evaluated.The characterization results proved that the iron oxide loaded on activated carbonuniformly with the size of11.65nm, BET specific surface area was up to666.72m2/g,microporous accounts for the majority, there is also a certain amount of mesopore and fewmacroporous, the pore size and pore volume of micropore is0.819nm and0.215cm3/g，（3.945nm and0.5282cm3/g for mespore, respectively). The saturation magnetization ofactivated carbon/iron oxide measured in room temperature is22.34emug-1, small coercivefield and remnant magnetization implied uniform and small size of iron oxide loaded onactivated carbon. The magnetic activated carbon can be rapidly separated from the solutionunder a magnetic field in three minutes and the sedimentation effects is well. The magneticcomposites can easily recovered from solution by applying a external magnetic field andhave a good magnetic stability characteristic, the recovery can up to91%.The activated carbon/iron oxide was used as sorbents for the removal of MO and AO7,the results showed that adsorption rate can be attained99.1%and96.7%with the initialconcentration (200mg/L). The dye solution can be efficiently removed with the wide rangeof initial pH from3to11, indicating the magnetic composite has broad pH adaptability. Theisothermal adsorption behavior of MO and AO7could be simulated by Langmuir andFreundlich models. The adsorption process of MO and AO7on the activated carbon/ironoxide is spontaneous and adsorption is exothermic reaction, increasing temperatures isdetrimental to the adsorption. The adsorption kinetic can simulated by pseudo-first-order,pseudo-second-order and Elovich models, the result indicated pseudo-second-order modelsis the best adsorption model. The adsorption kinetic was mainly controlled by internal diffusion procedure.The magnetic composites can be easily regenerated by sodiumhydroxide solution.The magnetic composite exhibited good magnetic separation characteristics andmagnetic energy is relatively stable. The existence of iron oxides particles has little effect onadsorption property of the activated carbon/iron oxides which has a good recyclingperformance. These are fully embodies the advantages of magnetic modified activatedcarbon have potential application prospect in water pollution treatment.