Study On Catalytic Degradation Of Organic Pollutants In Water By Tourmaline

Tourmaline is a kind of natural borosilicate mineral with ring structure,and its general structure formula is Na R₃Al₆[Si₆O₁₈]（BO₃）₃（OH）₄,in which Na,OH^-and R sites can be occupied by different ions,and there are rich species in nature.Because of the unique structure and composition characteristics of calcium carbide gas,it has a variety of properties such as thermoelectric,piezoelectric,infrared radiation,negative ion release and so on.In recent years,due to the characteristics of wide distribution,low cost and environmental friendliness,as well as rich transition metal catalytic sites of tourmaline,attention has been paid to the removal and purification of pollutants in water by tourmaline at home and abroad.Advanced oxidation technologies（such as ozonation,persulfate oxidation,H₂O₂/HCO₃^-oxidation,etc.）are commonly used and effective technologies for degradation of organic pollutants in water.Its main principle is to generate highly active species（such as·OH、O₂·^-、SO₄^-·、¹O₂,etc.）in water through catalytic activation strategy to drive the degradation and mineralization of organic pollutants.At present,catalytic materials used to construct advanced oxidation technology are mainly synthesized by artificial synthesis,which have many problems such as high preparation cost,difficult macro quantization production and unknown environmental safety compatibility.In view of the demand characteristics of advanced oxidation technology for catalytic materials,as well as the existing shortcomings of synthetic catalytic materials,this paper is based on tourmaline as a natural mineral material with unique structure,composition and catalytic properties.The effect,rule and mechanism of catalytic activation of persulfate and H₂O₂/HCO₃^-degradation of organic pollutants in water by different kinds of tourmaline are systematically studied.The main contents and conclusions are as follows:The degradation of tetracycline in water by persulfate catalyzed by high iron tourmaline（High-Fe TM）,low iron tourmaline（Low-Fe TM）,magnesium tourmaline（Mg-TM）and lithium tourmaline（Li-TM）were systematically studied.Of the four tourmalines,two iron tourmalines showed high catalytic activity,and their coupling with persulfate degraded 90%of tetracycline in water within 150 min（initial tetracycline concentration:300 ppm）.The two kinds of iron tourmalines have different mechanisms of catalytic activation of persulfate to degrade tetracycline in water:High-Fe TM react with persulfate to produce SO₄^-·and·OH as active species to drive tetracycline degradation.Low-Fe TM reacts with persulfate through Fe active site on its surface to produce ¹O₂ as active species,driving tetracycline degradation reaction.Due to the difference in the mechanism of catalytic activation of tetracycline in water by persulfate between the two kinds of iron tourmaline,High-Fe TM has better catalytic stability than Low-Fe TM.The effect,regularity and mechanism of catalytic activation of H₂O₂/HCO₃^-by High-Fe TM,Low-Fe TM,Mg-TM and Li-TM to degrade organic dyes（Rhodamine B,methyl orange and methylene blue）in water were systematically studied.Among the four kinds of tourmaline,High-Fe TM shows the best catalytic performance.Taking Rhodamine B（Rh B）degradation as an example,the High-Fe TM/H₂O₂/HCO₃^-system can degrade more than 90%Rhodamine B within 20 min.The stability of High-Fe TM in catalytic activation of H₂O₂/HCO₃^-to degrade three dyes in water is different:Its catalytic performance in Rhodamine B and methylene blue（MB）system decreases gradually with the number of reactions,but its catalytic performance in methyl orange（MO）system increases with the number of reactions.The catalytic activation of H₂O₂/HCO₃^-to degrade the three dyes in water by High-Fe TM is also different.In Rhodamine B system,the coupling of high iron tourmaline with H₂O₂/HCO₃^-produces·OH and O₂·^-,which drives the degradation reaction.In the methylene blue and methyl orange systems,the coupling of High-Fe TM with H₂O₂/HCO₃^-produces ¹O₂,which drives the degradation reaction.·OH,O₂·^-and ¹O₂ are mainly produced by Fe active sites of high iron tourmaline,iron ions dissolved out and reactions with H₂O₂/HCO₃^-.In this paper,the study on the catalytic activation of persulfate and H₂O₂/HCO₃^-degradation of organic pollutants in water by different kinds of tourmaline as well as future application in a wide range of target pollutant degradation,actual water treatment scenarios in-depth exploration can provide valuable experimental and theoretical reference for the development of related technologies of tourmaline water purification environment,and also provide useful method inspiration for the environmental application of related natural mineral materials.