Research On The Comparison Of Photodegradation For Nonylphenol With Radicals And Elimination For Nonylphenol On The Absorbents

Nonylphenol(NP) is a kind of persistent organic pollutants with strong endocrinedisrupting properties. It has been widely found in aquatic environment、soil andsuspended substance and can poison the organisms when it has been exposed toenvironment. In this paper, NP was studied as target compounds to research onphotodegradation for NP with H2O2and Fe(III) which was photosensitive materials.The mechanism of photodegradation for NP was discussed. The degradation of NPwith radicals under empty-illumination was also studied. The degradation rate of NPwith radicals was compared to adsorption behavior of two different kind ofadsorbents for NP. The aim of this paper was to find scientific and reasonable avenuefor degradation of NP. The major conclusions of this paper was as following:(1) The influence of photodegradation for NP with H2O2and H2O2-Fe(III) wasresearched under simulated illumination. The effect of degradation rate for NP withthe distance of illumination and concentration of NP、H2O2and Fe(III) was discussedby detecting the residues of NP in aqueous solutions.The mechanism ofphotodegradtion for NP in analogous Fenton system was also discussed.The resultsdemonstrated that the degradation rate of NP under direct photolysis was very low,the influence of illumination distance and NP concentration for photodegradation rateof nonylphenol was not significant.With the increase of concentration of H2O2, thedegradation rate of NP raised. The degradation rate of NP reached70.5%from55.7%when the concentration of H2O2raised to1.0mmol/L from0.1mmol/L. However,there is no obvious proportional relationship between the concentration of H2O2anddegradation rate of NP. Fe(III) has the synergistic effect to the degradation of NP inH2O2system. With the increase of the concentration of Fe(III) in H2O2aqueous, thedegradation rate of NP raised. The photodegradation kinetic was tested with thefirst-order reaction model, it showed that the effect of photodegradation for NP couldbe well described by first-order reaction model. The main photodegradation productwas phenol in analogous Fenton system by detecting the intermediate products.(2) The influence of degradation for NP in Fenton system was researched underempty-illumination. The effect of degradation rate for NP with pH and concentration of NP and Fe(III) and content of H2O2was discussed by detecting the residues of NPin aqueous solutions. The results demonstrated that the degradation rate of NP waseffected with pH of solutions significantly. The best pH for degradation of NP is3to4. The degradation rate of NP was poor when the concentration of Fe(III) and contentof H2O2was too overtoop or lower. The best degradation rate of10mg/L NP was67%in best Fenton system. The degradation of NP was attributed to hydroxylradicals while using salicylic acid as molecular probes to catch hydroxyl radicals andproducts was detected by spectrophotometric.(3)Two different kinds of adsorbents, macroporous resins(XAD-4) and activatedcarbon (GAC), were used to study the sorption behavior for NP. The effect ofelimination rate of NP was tested by detecting the residues of NP in aqueoussolutions. The difference between elimination of adsorption for NP and degradationof NP with radicals was analyzed. The results showed that two adsorbents had highadsorption capacities for NP. The adsorption capacity of NP on the XAD-4washigher than that on the GAC. The study on the isothermal adsorption of twoadsorbents for NP showed that with the increase of temperature, the adsorptioncapacity of NP on XAD-4raised, and the adsorption capacity of NP on GAC was notaffected by temperature obviously.The sorption behavior of two adsorbents for NPcould be better described in Langmuir adsorption model than in Frendlich adsorptionmodel, and the correlation coefficients exceeded0.99, they were also monolayeradsorption. The adsorption kinetics were tested with the pseudo-first-order,second-order and pseudo-second-order reaction model, it showed that the adsorptionprocess of two adsorbents for NP could be well described by pseudo-second-orderreaction model, and the correlation coefficients exceeded0.99. The effect ofelimination of NP with XAD-4was significant, and the elimination rate of0.5gXAD-4for10mg/L NP can reach72%, but the elimination rate of same quality ofGAC for NP was lower. However, the elimination rate was lower than degradationwith radicals for NP.