Catalytic Degradation Of Dye Wastewater By Fe-Cu Supported Biochar In Collaboration With H₂O₂

Textile printing and dyeing wastewater has the characteristics of complex composition,large discharge volume,strong toxicity,and high treatment cost.Discharge that fails to meet the standards will cause greater risks to the environment.Advanced oxidation technology can effectively degrade this type of wastewater.In this paper,semi-coke（BC）was used as raw material to synthesize iron-copper-doped carbon matrix composites by bioleaching-pyrolysis method,combined with heterogeneous Fenton technology to treat dyes such as methyl orange（MO）and methylene blue（MB）.The catalytic degradation of wastewater was studied,and the main results are as follows（1）Iron-copper doped biochar（Fe/Cu-BBC）was prepared successfully by the bioleach reaction involving thiobacter ferrooxidans,in which the iron content was up to 167.1mg/g,and the leaching bacteria showed a certain tolerance to Cu ions（0.01～0.2mol/L）.Combined with the characterization analysis,the metal loading mechanism was revealed:Fe is crystallized by jarosite（KFe₃[SO]₂（OH）₆）on the surface and pores of the semi-coke,while Cu is doped in the lattice structure of KFe₃[SO]₂（OH）₆.Biochar was modified by pyrolysis to synthesize a composite material（Fe Cu-PBC）,and the degradation efficiency of MO was the best when the pyrolysis atmosphere was CO2,the temperature was 1000°C,and the residence time was 10min,the decolorization effect of Fe Cu-PBC（99.54%）was much higher than that of Fe Cu-BBC（12.64%）and BC（18.36%）.（2）The materials prepared under different iron-copper molar ratios are mainly in the form of Fe₅Cu O₈ and have good degradation effect on MO.The degradation rate of 2Fe3Cu-PBC（k=0.062）is the fastest and higher than that of Fe-PBC（k=0.028）.The doping of copper promoted the degradation of MO,and the k value was positively correlated with the content of copper in the material（R²=0.9714）.When the dosage is 0.1g/L,H₂O₂ is 20mmol/L,p H=3,the decolorization rate of Fe Cu-PBC for 300mg/L MO and 4g/L RR can reach 100%.In addition to azo dyes,the decolorization rates of Fe Cu-PBC to anthraquinone dyes（MB）and triphenylmethane dyes（CV）can also reach 95.77%and 63.52%.The mineralization ability and stability of Fe Cu-PBC were investigated through TOC removal rate and reuse experiments.After 5 cycles of degradation,the decolorization rates of MB and MO only decreased by 7%and 13.4%,TOC removal rates of MO and MB were 68.4%and 63.2%,respectively.（3）Radical quenching experiment and EPR characterization analysis,it is proved that hydroxyl radicals（·OH）are the main active species in the catalytic reaction,and the surface·OH produced by the catalyst’s heterogeneous catalysis plays a leading role.After the reaction,the proportion of Fe²⁺in Fe Cu-PBC increased and the proportion of Cu²⁺decreased,which indicated that iron and copper were the active centers of the catalyst reaction,and the synergistic effect between iron and copper also promoted the degradation of pollutants.In addition,the electron transfer between biochar and metal accelerates the redox cycle of Fe²⁺/Fe³⁺and Cu⁺/Cu²⁺and improves the activity of the catalyst.Combined with GC-MS mass spectrogram analysis,it is concluded that under the degradation of Fe Cu-PBC,the dimethyl,sulfonic acid groups and azo bonds in the molecular structure are broken,causing decolorization,and other intermediate products form small molecules under the attack of·OH The carboxylic acid is directly converted into CO₂,H₂O and other non-toxic substances.