Azo-dye Adsorption Of Active Carbon, Charcoal, Modified Sludge

In this paper,the active carbon sorbent,charcoal sorbent,two different modified sludge sorbent were used for treating dye wastewater,the strcture of the four soebents was characterized by Scanning Electron Microscope and infrared spectroscopy,tested for granularity distributing and ZETA potenlial,the thermal stability was mensurated by differental thermal analysis apparatus The results show that:(1) Four kinds of sorbents have abundant pores.The results from DSC indicate that four absorbents have thermal stability,The order of the thermal stability of the four adsorbents are as follows:modified sludge B＞active carbon＞modified sludge A＞charcoal;the results form FTIR indicate that the functional groups which in the sorbents are simpleness,association-OH,C=O,C=C,C-O-C and C-C.(2) The adsorption time,the adsorption temprature,the salinity to adsorb have certain influence to the adsorption effects.(3) The equilibrium time in normal temperature of the four adsorbents are as follows:24h,1h,24h,48h.The order of the capability of the four adsorbents for direct scarlet was as follows:active carbon＞modified sludge B＞modified sludge A＞charcoal,the corresponding elimination rate in room temperature was 82.3%,70.5%, 42.7%,40.4%.(4) The adsorption process all fit the Langmuir and the Freundich isothermmodel exellently.For active carbon,modified sludge A and modified sludge B,the increase of temperatur does favor the adsorption process,while charcoal is in the other way round. when the temperatur is 25,the maximum adsorption capacities of active carbon,charcoal,modified sludge A and modified sludge B are 357.14mg·g-1,31.847 mg·g-1,97.087 mg·g-1,142.86 mg·g-1,respectively.(5) For active carbon the existence of salinity has certain stimulation effect to adsorption,and has inhibitory effect for the other three.(6) According to the influence of the temperature to the adsorption,the change of apparent Gibbs free energy,the enthalpy as well as the entropy of four kinds of adsorbents to direct scarlet are calculated.The results indicated that the adsorption processes of four kinds adsorbents are spontaneous.Active carbon,the adsorption process of modified sludge A and modified sludge B are endothermic and entropy increased process,while charcoal is exothermic and entropy reduced reaction. (7) The influence of adsorption time to the adsorption shows that the adsorption process of all the adsorbents conform to the second-order model.(8) The modified sludge as a inexpensive absorbent may disposal the priting waste water effectively.