A Study On The Adsorption Of Anionic Dye And Micro-molecular Organics By Cationic Agents Modified Zeolite

The adsorption for anionic pollutant on natural zeolite is restricted due to itsnegative surface charge; cationic surfactant removes pollutants from aqueouseffluents by flocculation, but it is difficult to separate the product from wastewater;polyethyleneimine show strongly positive charge, however, its adsorption effect foranion is not satisfactory because its soft and vulnerability. Based on above materials,the fundamental adsorption behaviors of naphthol green B (NGB) and2,4-dichlorophenol(2,4-DCP) on natural zeolite modified by CPC (CZ) wereinvestigated in batch systems. Similarity, the adsorption of reactive redX-3B(RR-X-3B) on zeolite modified by polyethyleneimine(PEI-Z) were also studied.For adsorption of NGB on CZ, when pH was above8, adsorption capacitydecreased; increasing ion strength contributed to adsorption. The sorption isothermsclosely followed Freundlich, Henry and Koble-Corrigan modes. As to kinetic,pseudo-second order, Elovich and Double constant modes can describe accurately theadsorption process, suggesting that chemisorption and ion exchange may exist inadsorption process.In order to make full use of materials, the CZ loaded NGB (CZ-NGB) wereapplied in secondary adsorption as a new adsorbent for a cationic dye methyleneblue (MB). Higher pH and lower ion strength contributed to adsorption process. Afterfitting of several isotherm models, the Redlich-Pererson and Koble-Corrigan wereconfirmed to be optimum equation to depict the adsorption behaviors. The adsorptionkinetics was in agreement with Intraparticle diffusion and Double constant equations.It indicated that adsorption process was not homogeneous. The heterogeneousadsorption, electrostatic attraction, hydrophobic effect and Van der Waals’ force wereinvolved in adsorption mechanism.In order to promote adsorption capacity of2,4-DCP on zeolite by clearingchannel, zeolite was modified by CPC and NaCl(CZ-NaCl). As a result, theadsorption capacity of2,4-DCP on CZ-NaCl was better than CZ. The adsorption capacity obviously decreased at higher pH. The effect of ion strength was negligible.Langmuir and Koble-Corrigan models could fit the adsorption curves successfully atlower temperature. The adsorption kinetics was in agreement with Intraparticlediffusion and Double constant modes. The adsorption was endothermic and entropyincreasing. Different pH determined different adsorption mechanism.For adsorption of RR-X-3B on PEI-Z, the adsorption capacity was higher whenpH was below7. Increasing ion strength increased slightly adsorption capacity.Koble-Corrigan model and pseudo-order model were confirmed to be optimumequation to depict the adsorption process. Adsorption was endothermic and the valueof activation energy show chemisorption was included in adsorption process.Hydrogen bond and electrostatic attraction were involved in adsorption mechanism.