The Study On Utilization Technology Of Wastewater From Acid Pickling Electrolysis

In the steel industry,hydrochloric acid?HCl?has been widely used as a effective surface cleaning agent,so resulting in a large number of annual hydrochloric acid pickling electroplating waste was discharged,the main component is a high concentration of Fe²⁺and free acid.The main features of the waste water are high acidity and concentration,if not properly handled,not only endanger the ecological environment and human health,but also cause a lot of waste of resources.The hydrochloric acid pickling wastewater has become the main environmental problems of the steel industry.To achieve rational utilization of electroplating wastewater,therefore,this paper uses hydrochloric acid pickling electroplating wastewater as a raw material to research the development the green process by negative pressure evaporation method to separate ferrous sulfate and hydrochloric acid and the preparation of polymer polymerization of ferric chloride and porous iron oxide material.The following research work has been investigated in this work:1.To detect the ions concentration of hydrochloric acid pickling electroplating wastewater in a electroplating wastewater treatment plant in Baoding,Hebei Province.The results showed that the main components were Fe²⁺,Cl^-,H⁺,and the concentrations were3.39,8.458 and 0.955 mol/L,respectively.2.According to negative pressure evaporation method and different iron salt solubility,the simulated titanium white waste acid?20%H₂SO₄?was added to hydrochloric acid pickling electroplating wastewater.The HCl and ferrous sulfate in the waste liquid were obtained by evaporation and low temperature crystallization.The results show that the pressure is controlled at 11.3 kPa,vacuum distillation is carried out.When the solution reaches saturation,it is cooled to room temperature and crystallized at-20?for low temperature to obtain FeSO₄·7H₂O crystal.After four cycles,the recovery rate of iron ions in the waste liquid reached 90.64%,and the recovery rate of hydrochloric acid was about69.53%.3.In this paper,hydrochloric acid pickling electroplating wastewater as raw material,the inorganic polymer flocculant was synthesized through adjusting basicity value with HCl and NaOH.The flocculant was used in the treatment of humic acid simulated water under different pH and basicity value conditions.The measurement of UV absorption at 254 nm(UV₂₅₄)might provide a possible solution,and the optimum experimental conditions for humic acid flocculation were obtained.The results show that the oxidation rate of Fe²⁺reaches 98.5%when the H2O2 dose is was 11.4mL during the pretreatment.In the process of oxidation,iron ions were spontaneously hydrolyzed to form polymerized ferric chloride,the basicity value was 0.277,UV₂₅₄ removal rate reaching 98%when PFC dose was15mg/L under pH 5.0.PFC achieve the best coagulation performance and meet the water treatment discharge standards.4.In this paper the synthesis of porous iron oxide materials was synthesis by hard template method.The porous iron oxide was synthesized using Fe?NO₃?₃ and FeCl₃ as iron source and KIT-6 as structural guide agent by impregnation method.The materials was used to treat the simulated methyl orange dye wastewater under different temperature,catalyst dosage and pH conditions.The results show that Fe?NO3?3-Fe and FeCl3-Fe are pure phase?-Fe₂O₃ materials with surface area of 147 m²/g and 49 m²/g,respectively.The appearance is irregular and massive.In batches addition of FeCl3 has not significant effect on the specific surface area of FeCl3-Fe.Two kinds of catalysts under the optimal conditions,methyl orange can be completely decolorized during 2-4 minutes.The stability and adsorption properties of Fe?NO3?3-Fe were investigated.The results showed that the decolorization rate of methyl orange was more than 95%after ten cycles,but the adsorption performance for CrO₄^2-was poor.