Study On The Adsorption Of Organic Pollutants From The Aqueous Solution By Modified Pyrolytic Carbon

In this research, pyrolytic char (PC) treated with NaOH (NaOH-AC) andNH4H2PO4-microwave irradiation (PMAC) were used as adsorbent to remove thecontaminant (4-chlorinephenol,4-CP;4-nitrophenol,4-NP;2,4-dichlorophenol,2,4-DCP;4-chloro-2,5-dimethoxynitrobenzene, CDNP) from aqueous solution. Thecharacterization of NaOH-AC and PMAC and PC were analyzed. The main resultsare as follows：Characterization results showed that the the point of zero charge reduced for bothNaOH-AC and PMAC. The results of titration indicated that acidic functional groupsincreased while the basic functional group decreased. SEM results manifested that themodified pyrolytic carbon surface was rough and loose, which could be indicated thatthe surface area was higner.The study on the batch adsorption of4-CP and4-NP onto NaOH-AC has beencarried out．It was found that the pH value was important to the adsorption, the opticalpH was2~8and3for4-CP and4-NP, respectively. The influence of salinity andtemperature was small for both4-CP and4-NP.The Freundlich isotherm was found torepresent the sorption equlibrium data of4-CP and4-NP well. In addition,Koble-Corrigan and Redlich-Peterson can be employed to describe the adsorption of4-NP. The kinetic of adsorption was found to confirm to the pseudo-second-orderequation and Elovich equation. Desorption and regeneration reuse was best with4-CP-loaded,4-NP-loaded adsorbents being exposed to NaOH and75%ethanol.Desorption kinetics was fitted with the pseudo-second-order equation model．Thethermodynamic study indicated that the adsorption of4-CP and4-NP were notspontaneous and endothermic．In the mixed system, the competitive adsorption between4-CP and4-NP onNaOH-AC was studied. The equilibrium time had no impact on the condition of competitive adsorption. The adsorption capacity was little smaller in the mixedsystem than that in single system, and it was serious for4-CP.The study on the batch adsorption of2,4-DCP and CDNP onto PMAC has beencarried out．The influence of pH to2,4-DCP was similar to4-CP. However, theadsorption of CDNP was hardly affected by pH. The presence of salt was adverse toadsorption. The Equilibrium data of2,4-DCP and CDNP was best described byFreundlich model. The Elovich equation was best o fit the adsorption kinetic processof2,4-DCP while the pseudo-second-order equation was best fitted the adsorptionprocess of CDNP.2,4-DCP-loaded and CDNP-loaded adsorbents could beregenerated using sodium hydroxide solution and ethanol. Thermodynamicparameters suggested adsorption of2,4-DCP be spontaneous, endothermic whileadsorption of CDNP be spontaneous, exothermal in nature．...