Study On Foam Separation Of Surfactants And Metal Ions From Wastewater

Foam separation is a new practical separation method. In this dissertation, thefoam separation of metal ions and surfactants from the simulated waste solutions wasstudied. Through single factor experiments and orthogonal experiments, the effects ofvarious operation parameters such as air flow rate, solution concentration, solutionvolume, pH value of solution, strength of metal ionic, experimental device, etc. on theenrichment and recovery ratio were investigated.Through a series of experiments, the best recovery ratio for sodium stearate canreach73.2%, and the corresponding operating conditions were: initial concentrationof sodium stearate1.4mmol/L, solution volume500mL, air flow rate0.3m3/h,separation time4min. The best recovery ratio for sodium laurate can reach85.32%,and the corresponding operating conditions were: initial concentration of sodiumlaurate0.65×10-2mol/L, pH value of solution8, solution volume500mL, air flowrate0.3m3/h, separation time4min.The best recovery ratio for Ni²⁺could reach75.62%, and the correspondingoperating conditions were: initial concentration of sodium stearate1.6mmol/L,concentration of Ni²⁺7mg/L, solution volume750mL, pH value of solution9.Combined with damping sheets, sodium laurate was used to separate Cu²⁺. Throughsingle factor experiments, the best recovery ratio for Cu²⁺could reach73.2%. Itsenrichment ratio which reached12.6was obviously higher than the effect by singleseparation tower, and the corresponding operating conditions were: initialconcentration of sodium laurate0.8cmc, solution volume1000mL, separation time12min, air flow rate0.2m3/h. Combined with circumfluence pipe, sodium lauratewas used to separate Ni²⁺. The best recovery ratio for Ni²⁺could reach98.1%, andthe corresponding operating conditions were: initial concentration of sodium laurate0.8cmc, solution volume1000mL, pH value of solution10, air flow rate0.4m3/h,concentration of Ni²⁺7mg/L.Surfactants are classified chemically according to their hydrophilicgroup asanionic, cationic, nonionic, or amphoteric. In this dissertation, anionic, cationic andnonionic surfactants were used to separate Cu²⁺in simulated wastewater. Theappropriate separation conditions for Cu²⁺were: initial concentration of SDBS0.5 cmc, concentration of Cu²⁺3mg/L, pH value of solution8, the best recovery ratio forCu²⁺could reach90.96%. Trapping agent could influence the recovery ratio andenrichment ratio for Cu²⁺in wastewater too. Considering trapping agent, theappropriate separation conditions for Cu²⁺were obtained. The best recovery ratio forCu²⁺could reach89.72%, and the corresponding operating conditions were: SDBSwithout scavenger, pH value of solution8. Because of the ion-ion action betweenSDBS and Cu²⁺, their selectivity and increasing rate of concentration were betterthan other separation methods.