| Phenol contamination and heavy metal pollution are the more serious and common types of environmental pollution.P-nitrophenol?PNP?is a typical representative of phenolic organic compounds which has a wide range of sources.PNP enters environment through the use of pesticides,leather manufacturing,diesel exhaust,etc.Copper?Cu?is a typical industrial heavy metal,and its main source is mining and industrial wastewater discharge.Both PNP and Cu have caused more serious pollution to the environment.The detection rate of PNP in the Huaihe River system in Jiangsu Province is as high as 100%,and the average detection concentration is as high as 5ug·L-1.The detection concentration of PNP in the Qiantang River system in Zhejiang Province is 4.5ug·L-1.After testing and risk assessment,Poyang Lake has been contaminated by Cu mainly into the lake,and heavy metal Cu has the highest content in surface sediments.At present,many studies have shown that biochar can be widely used as an adsorbent to remove contaminants.In this study,corn stover,used as raw material,is produced into biochar,at 300°C and 600°C,which are marked as CC300 and CC600 respectively.The CC300and CC600 were characterized by elemental analysis,specific surface area and pore size distribution analysis,electron microscopy?SEM?and infrared spectroscopy?FTIR?.The adsorption kinetics,adsorption isotherms of PNP on biochar were studied by batch adsorption experiments.The effects of temperature,pH and dosage of biochar on the adsorption process were investigated.The adsorption of PNP and Cu?II?by biochar in the dual system was also investigated.The effect of biochar on the retention behavior of PNP by soil was studied by soil column experiments.The main conclusions obtained are as follows:?1?The ash content,yield,elemental composition and specific surface area of biochar depend on pyrolysis temperature.The higher the pyrolysis temperature is,the higher the biochar ash content is,the lower the yield,O/C and H/C are,the higher the BET specific surface area and the t-pLot micropore volume are.The electron microscopic scanning and infrared spectroscopy showed that the corn stover biochar mainly had irregular strip structure,and its surface microporous structure and surface functional groups were very rich.?2?The adsorption amount of PNP by CC300 and CC600 increased with the increase of adsorption time,and finally reached equilibrium.The adsorption curve accorded with quasi-secondary kinetic model;the adsorption amount of PNP by CC300 and CC600 increased with the equilibrium concentration.The increase and finally reach equilibrium,the adsorption isotherm accords with the Langmuir-Freundlich equation and the Temkin equation;the adsorption amount of PNP by CC300 and CC600 decreases with the increase of solution pH and biochar dosage.?3?The adsorption amount of Cu?II?by CC300 and CC600 increases with the increase of pH,the increase of time and the increase of equilibrium concentration,and finally reaches equilibrium.The adsorption isotherm conforms to the Langmuir-Freundlich equation and the Temkin equation.In the dual system where PNP and Cu?II?coexist,when the initial PNP solution is less than 200mg·L-1,Cu?II?has no obvious effect on the adsorption amount of PNP;when the initial concentration of PNP is higher than 200mg·L-1,Cu?II?The adsorption of PNP by CC600 was obviously inhibited,and the adsorption of PNP by CC300 was promoted.PNP completely promoted the adsorption of Cu?II?by CC300 and CC600.?4?With the increase of biochar addition,the tailing phenomenon of the breakthrough curve is more obvious,and the rejection rate increases;as the concentration of PNP injection increases,the penetration time becomes shorter;the pH of the injection solution penetrates.The curve has little effect;the addition of biochar can significantly enhance the soil's ability to retain PNP and slow down the elution of PNP. |
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