| The dying site is a kind of special polluted site.Due to the abnormal colors of the soil and groundwater,such as reddism,black,etc.,in the plot,the phenomenon of serious pollution appears in the sense.Naphthalene sulfonate dye intermediates such as amino-G-acid(7-amino1,3-naphthalene disulfonate)and K-acid(7-amino-1,3,5-naphthalene trisulfonic acid)are the characteristic pollutants in the dye chemical industry site.Such pollutants have not received much attention in the investigation,and the behavior law in soil and the treatment technology are still unclear.Therefore,this study was conducted to investigate the distribution characteristics of naphthalene sulfonic acids and other pollutants in a typical dyeing site in Jiaxing,Zhejiang Province.The distribution characteristics of naphthalene sulfonic acid dyes in soil were clarified and the adsorption and migration rules of naphthalene sulfonic acid in soil were revealed.On this basis,the oxidation of naphthalene sulfonic acids in soil by persulfate was investigated,and the optimal combination of four influencing factors(initial PMS concentration,initial ZVI concentration,solution pH and temperature)was obtained.The main conclusions of this paper were as follows:(1)The concentrations of heavy metals and organic matter in soil were all lower than the screening values of the second type of land in "Soil environmental quality—Risk control standard for soil contamination of development land"(GB 36600-2018).As,benzene and 1,2dichloroethane at only 3 points in groundwater did not meet the Class Ⅲ standards in "Standard for groundwater quality"(GB/T 14848-2017),and the rest meet the standards.Amino G acid and K acid,as characteristic pollutants of the dye chemical site,were detected in both soil and groundwater by the self-established method.The contents of amino G acid and K acid in soil were respectively 0.11～97.69 mg·kg-1 and 0.14～15.50 mg·kg-1,respectively.The contents of amino G acid and K acid in groundwater were respectively 0.10～124.80 mg·L-1 and 0.11-6.70 mg·L-1.The distribution of the two kinds of naphthalene sulfonic acid was mainly concentrated in the the middle and lower soil layers and the groundwater,and the average concentration of amino G acid was much higher than that of K acid while the distribution range of K acid was wider than that of amino G acid.The results of ECOSAR calculation showed that the ChV of amino G acid and K acid to Daphnia were significant,which were 5.028 mg·L-1 and 12.096 mg·L-1,respectively,and the former was more toxic to aquatic organisms than the latter.(2)The adsorption of amino G acid and K acid in soil was weak,but the migration effect was strong.Soil adsorption tests showed that under the condition of 1:10 solid-liquid ratio and 2 mg·L-1 initial concentration,the adsorption rates of amino G acid and K acid were 10.99%and 6.072%,respectively.The adsorption kinetics of amino G acid and K acid conformed to a pseudo-second-order kinetic model with correlation coefficients greater than 0.99.At the solidliquid ratio of 1:10 and initial concentrations ranging from 2 to 100 mg·L-1,the maximum adsorption amounts of amino G acid and K acid were 9.675 mg·kg-1 and 7.660 mg·kg-1,respectively,and their adsorption isotherms were in accordance with the Langmuir model with correlation coefficients greater than 0.99.On the basis of adsorption tests,soil column migration experiments were carried out.The kinetic dispersion coefficient was 0.09391 cm2·h-1 and the adsorption distribution coefficients of amino G acid and K acid were respectively 0.1679 cm3·g1 and 0.1067 cm3·g-1.The penetration time were 21 h and 19 h which were slightly longer than that of the tracer Cl-(16 h).Hydrus-1D simulation showed that the penetration processes of amino G acid and K acid were in line with the linear equilibrium CDE migration model.Under the condition of longitudinal dispersion of 0.2095 cm and saturation permeability of 1.467 cm·h1,the mean migration rates of the two were 9.52 mm·h-1 and 10.53 mm·h-1,respectively.(3)Amino G acid with high concentration and relatively high toxicity to aquatic organisms in the dyeing site was selected as the target pollutant for research.The results of peroxymonosulfate oxidation experiments in mud system showed that initial PMS concentration,the initial pH and the temperature of the reaction system could had more significantly effects on the degradation of amino G acid,while the concentration of ZVI had weaker effect.Based on the above results,when the initial concentration of amino G acid in mud system was 1000 mg·kg-1,the optimized process combination was for initial PMS concentration of 8107.88 mg·kg-1,initial ZVI concentration of O,initial solution pH of 4 and system temperature of 45℃.Notably,the degradation rate of naphthalene sulfonic acid reached 98.34%after 2 h under optimal conditions.The results showed that peroxymonosulfate had good oxidation effect on amino G acid in mud system... |
PDF Full Text Request