Study On Degradation Behavior Of Phenolic Pollutants In Coal Chemical Industry Wastewater By Humic Acid Based Carbon Materials Activated Persulfate

Coal gasification work is an important strategic support for national energy security and an important way to achieve clean and efficient utilization of coal resources in China.However,in the process of coal processing and production,a large amount of refractory organic wastewater is generated,and after pre-treatment and biochemical treatment,it still contains many toxic and harmful substances.Therefore,achieving efficient and rapid deep treatment of coal chemical wastewater is an urgent technical challenge in China.The advanced oxidation process represented by persulfate（PMS）has the advantages of short reaction time,strong universality and complete oxidative degradation.In this regard,the common phenolic compounds in wastewater are selected as the target pollutants,and humic acid in lignite is used as the carbon source to prepare cheap,efficient and stable carbon materials for rapid activation of persulfate through non-metallic and metal doping modification.The main research contents are as follows:（1）Nitrogen doped carbon materials（NC-Ts）were prepared by high-temperature carbonization using humic acid as carbon source and urea synthesized carbon nitride（C₃N₄）as nitrogen source.The effects of carbonization temperature on the morphology,structure,and composition of materials were investigated,and the performance of activated PMS prepared at different temperatures for phenol degradation was compared.Among them,NC-800 has the strongest ability to activate PMS.When its dosage is0.15 g/L and PMS concentration is 1.5 mmol/L,the phenol removal rate of 50 mg/L within 60 minutes is 99.62%.This system has strong anti-interference ability and can still achieve efficient removal of phenol（removal rate greater than 99%）in the presence of a wide p H range（p H=1-9）,high concentration of inorganic salt ions,and natural organic matter.（2）The mechanism of phenol removal by PMS activated by NC-800 was explored.Quenching experiments and electron paramagnetic resonance spectroscopy showed that there were three active substances in the system:hydroxyl radical（·OH）,sulfate radical(SO₄^·-)and superoxide radical(O₂^·-);The electrochemical test structure indicates the existence of electron transfer pathways present in the system,and the combination of free radicals and non free radical pathways dominated by electron transfer promotes the degradation of phenol.Meanwhile,the NC-800/PMS system has good degradation effects on various phenolic pollutants,and its reaction rate is positively correlated with the hydrophobicity of the pollutants.Selective oxidation removal can be achieved based on the different hydrophobicity of organic pollutants.（3）On the basis of NC-800,iron element was further introduced to prepare iron nitrogen co doped carbon material Fe NC-800.Compared with NC-800,the addition of iron increased the specific surface area and graphitization degree of the material.Under the same reaction conditions,the rate constant of phenol degradation in the system increased from 0.1214 min^-1 to 0.1491 min^-1,and the stability was greatly improved.After three cycles,the phenol removal rate of the material increased from 45.25%to80.00%,but its anti-interference ability was slightly inferior to NC-800.The main active substances in the Fe NC-800/PMS system include·OH,SO₄^·-,O₂^·-,and singlet oxygen（¹O₂）,which together promote the degradation of phenol.This paper has 48 figures,17 tables,and 134 references.