Application of response surface methodology in process parameters optimization for phenol mineralization using Fentons peroxidation

摘要

Adverse?effect?of?the?highly?biorecalcitrant?compound?phenol?to?the?environment?iswell?established?and?its?concentrations?in?industrial?effluents?vary?greatly?from?2.8 to 6,800?mg/l?depending?on?the?source.?Fenton?process?effectively?mineralises?to CO2and H2O?but?reported?works?consumed?more?reagents?and?require?longer?reactiontimes.?Due?to?the?strong?interaction?between?the?several?predictor?variables?in?theFenton?oxidation,?response?surface?methodology?was?used?to?optimise?themineralization?treatment.?Efficient, faster and economical operating conditions for phenol removal were explored by investigating four parameters?namely theconcentration?ratio?of?hydrogen?peroxide?to?phenol?-?((H2O2):(Phenol)),?mass??ratioof?hydrogen?peroxide?to?ferrous?ions -?((H2O2):(Fe2+)),?initial?phenol?concentration - ([Phenol]o)?and?reaction?time - (tr).?The?optimal TOC % reduction obtained were 35 and 88% for initial phenol concentrations of 100 and 5 mg/l, respectively. Reaction conditions?corresponding to this phenol?mineralization?a reaction time of 20 min atratios?of?6?and?15?for?[H2O2]:[Phenol]?and [H2O2]:[Fe2+], respectively.?For mineralisation at 52.5 mg/l phenol concentration, the optimal conditions were 20 min, ratios 10 and 15 for the reaction time, [H2O2]:[Phenol]?and [H2O2]:[Fe2+], respectively.?The soluble?iron content of the analysed supernatant?was found to be below the 15?mg/l?(the maximum?limit allowable for?total?iron?discharges?required?bycommon?regulative?subscribed).?This?indicated?that,?the?Fenton?reagents?wereutilised?during?the?peroxidation?reaction?evident?from?the?almost?near?consumptionof?all?Fe2+?introduced?in?about?85%?of?the?samples,?thus,?negating?the?need?forimmobilising?the?Fe2+?catalyst?or?its removal by?post?treatment.?The work proves that the optimized Fenton process can be potentially used for treatment of any phenol containing wastewater.