Process Study On Pretreatment Of Dye Wastewater By Liquid/liquid Extraction

With the increasing use of reactive dyes in the textile industry in recent y-ears,reactive dye wastewater has become one of the sources of pollution th at threaten the safety of water environment in our country.Reactive dye wast ew-ater is recognized as the most one of difficult wastewater now with the c harac-teristics of high chroma,high toxicity and complex composition.The re cent st-udies have shown that ordinary physic-chemical and biochemical meth ods and other traditional methods are difficult to degrade the reactive dye wa stewater ef-fectively,reactive dye wastewater degradation and decolorization pr oblems to b-e solved.Due to its high efficiency and high selectivity,liquid-li quid extractio-n has been widely studied in recent years.But nowadays,dye wastewater is c-onfined to extraction process of single-component extractant,There are few re-ports on the extraction of dye wastewater with multi-compo nent complex extrac-tant.In this paper,the reactive red K-7B dye was extracted from simulated wa st-ewater by TOA-P204 extractant.The selection of complexing agent and dil uen-t was confirmed by screening.The proportion of complexing agent comp onent-s and component concentration parameters were optimized,and the opti mal rat-io of extractant was determined.The FT-IR analysis was carried out o n the opt-imal proportioning compound extractant and series of complex extra ctants.The synergistic mechanism between the components and the component s of the mi-xture was studied.The extraction thermodynamic model was esta blished to inv-estigate the spontaneousity of the extraction process at room te mperature.The effects of initial dye concentration,phrase ratio(A/O),pH,temp erature,extraction time,stirring rate on the decolorization rate of wastewater,t he ionic strength o-f the extraction process was tested;different types and co ncentrations of eluen-t,phrase ratio(O/A),the temperature of the extractant de sorption rate The effects of multiple cycles of regenerated composite extractan t on decolorization wer-e investigated.The experimental results show that the optimum ratio of TOA/P204/SK =18:12:70 is best extraction ratio of TOA and P204,and the synergistic coeffic ie-nt between TO A and P204 extracting reactive K-7B was 8.0,showing good sy-nergistic effect,FT-IR analysis confirmed that P204 can promote the proto nate-on process of TOA and improve the extraction rate during the extraction proc-ess.The entropy change,enthalpy change and Gibbs free energy change of ext-raction process at 298.15K are-25.443kJ/mol,1.936kJ/mol and-8.109 kJ/mol,r-espectively.It indicates that the reaction is a spontaneous exothermic reaction at room temperature and the temperature increase is not conducive t o the extra-ction reaction.The best decolorization rate and distribution ratio o f dye were 86.7%and 32.46 under the optimal extraction conditions of pH=3.0,temperatur-e 25?,extraction time 10 min and stirring speed 500r/min.15%NaOH solut-eion was used as desorbent,the desorption rate was 94.2%unde r the optimum desorption conditions of phrase ratio(O/A)= 4:1 and temperatu re of 25?.Re-cycled on the extraction of decolorization performance has litt le effect,with g-ood recycling performance.