Study On Separation And Purification Of Wood Vinegar And Its Inhibition On Bacteria In Water

Wood vinegar(Pyroligneous acid)is a dark brown acidic aqueous solution produced by high-temperature pyrolysis of biomass such as wood and straw,and whose main components are organic acids and phenolic compounds.Wood vinegar exhibits significant antioxidant and antimicrobial activity,so it can be used as an antioxidant and antimicrobial agent in medicine,food and water treatment and other fields.However,the harmful substances such as wood tar and phenol contained in wood vinegar are easy to have adverse effects on the environment and organisms.How to reduce the harm of wood vinegar to the environment and organisms is one of the key issues that need to be solved urgently in the marketization and industrialization of wood vinegar.This paper proposed a new method to remove harmful substances in the wood vinegar,and then used the wood vinegar prepared by this method to modify the activated carbon to investigate the inhibitory ability of the modified activated carbon on the bacteria in the water.Firstly,a new method for the separation and purification of phenols in wood vinegar was proposed.The wood vinegar was pretreated by salting out,the precipitate was removed by centrifugation,and the supernatant was extracted with organic solvents.The experiment investigated the influence of the type of solvent,the concentration of sodium chloride,the speed of centrifugation and the time of centrifugation on the extraction efficiency of phenolic substances,and the influence of the concentration of sodium chloride on the content of wood tar and the percentage of phenol peak area was explored.At the same time,the DPPH free radical scavenging experiment was used to determine the antioxidant capacity of the extracted phenolic substances.The results showed that the concentration of sodium chloride was 1.25/4(g/m L,salt/water),and the extraction efficieney of phenolic substances was the best with ethyl acetate as the extraction solvent and centrifuged at 4000 r/min for 5 min while extracting phenolic substances in wood vinegar.Compared with other extraction methods,this method was not only simple to operate,but also can recover the solvent and salt used in the experiment,while reducing the content of wood tar and the percentage of phenol peak area.In addition,when the antioxidant activity of the extracted phenols was measured,it was found that the antioxidant activity of wood vinegar was related to the content of phenolic compounds.Secondly,the optimal conditions for modified activated carbon with wood vinegar were investigated.The inhibitory effect of modified activated carbon on Klebsiella pneumoniae,Acinetobacter baumannii,Pseudomonas aeruginosa,Methicillin-sensitive Staphylococcus aureus,Methicillin-resistant Staphylococcus aureus,Enterococcus faecalis and Standard Staphylococcus aureus was also determined.Using Standard Staphylococcus aureus as a representative of water pollutants,a fixed bed experiment was carried out to explore the effects of the quality of the modified activated carbon,flow rate and initial concentration on the performance of the fixed bed.Finally,the morphology of the modified activated carbon was characterized.The results indicated that 20 m L salted-out wood vinegar,5g of activated carbon dosage,2 h and 80 ℃ of water bath were preferred for activated carbon modification with WV.The surface of the modified activated carbon adsorbed the organic matter of the wood vinegar,and whose pore size was larger than that of the activated carbon.When performing a fixed bed experiment on Staphylococcus aureus,the performance of the fixed bed increases with the increase of in the quality of activated carbon,the decrease of the initial concentration,and the decrease of the flow rate.