Removal Of Oil Pollution In Water By Modification Kenaf Stalks

Oil pollution in water seriously affects the ecological environment and human health.How to effectively control oil pollution in water has become a hotspot of current research.Using straw material as an oil absorbent,adsorption and removal of oil pollutants in water are common removal methods,but directly using straw material as an adsorbent has low oil absorption capacity,and modifying straw is a commonly used method to increase the adsorption capacity.This paper selects cheap and easily available kenaf straw as the research object,through physical and chemical pretreatment,surface chemical modification and physical structure modification,two oil-absorbing materials KAPKS and NNRKS are prepared,through SEM,FT-IR,BET and other methods The modified materials were characterized and the effects of different modification conditions on the properties of the materials were studied.At the same time,the material’s oil absorption kinetics,oil retention performance,reuse performance and oil absorption water absorption ratio were measured.The specific research results are as follows:(1)Preparation and properties of surface chemically modified kenaf straw oil-absorbing materialUsing waste kenaf straw as raw material,after physical crushing and sodium hydroxide pretreatment,using potassium permanganate-acetone as an oxidant to modify the functional group on the surface of the straw,a new oil-absorbing material KAPKS was prepared.The characterization results show that the specific surface area and pore volume of KAPKS are 2.2times and 2.1 times that of the unmodified material respectively;some of the hydrophilic hydroxyl groups in the modified straw have undergone functional group changes and are converted to more lipophilic carboxyl groups and aldehyde groups;On the surface of the material,manganese dioxide remains,and the material has a layered hollow network structure.The optimization of the modification conditions showed that the concentration of the oxidant potassium permanganate was 0.4%,the concentration of the solvent acetone solution was 4%,the p H of the potassium permanganate + acetone solution was 2,the modification time was 2h,and the modification temperature was 50℃.The prepared oil spill adsorbent has the best effect,the adsorption capacity for soybean oil is 7.1 g/g,and the adsorption capacity for engine oil is 7.3 g/g,which is 1.8 times of the unmodified material.At 25℃,after the absorbed material dripping soybean oil and engine oil reach equilibrium within 10 min and20min respectively,they can still retain more than 50% of the adsorption capacity and have good oil retention performance;at 25℃,the adsorption After the material is reused for 6 times,the final oil absorption of soybean oil and engine oil can still maintain about 55% and 54.2%,with considerable recyclability;the oil absorption rate of soybean oil and engine oil is 266.7%and 274.8%,4.0 times of the unmodified material,indicating that the material has strong hydrophobic properties.The results of kinetic studies show that at 25℃,KAPKS can quickly adsorb soybean oil and motor oil and finally reach adsorption equilibrium at 1200 min,indicating that the material has a faster adsorption rate.(2)Preparation and properties of kenaf straw oil-absorbing material modified by physical structureUsing waste kenaf straw as raw material,after physical crushing,a new type of oil-absorbing material NNRKS was prepared by physical structure modification of sodium hydroxide-sodium sulfide solution.The characterization results show that the specific surface area and pore volume of NRNKS are 2.1 times and 1.3 times that of unmodified materials respectively;the number of free hydroxyl groups of the modified straw is reduced,most of the lignin and hemicellulose are removed,and there is a strip In flocculent separation,the pores become numerous and dense.The optimization of modification conditions showed that the immersion time was 24 h,the reaction temperature was 60℃,the reaction time was 8h,the sodium hydroxide concentration was 1mol/L,and the sodium sulfide concentration was 0.4mol/L.The adsorption capacity of soybean oil is 6.9 g/g,and the adsorption capacity of engine oil is 7.1 g/g,which is 1.8 times of the unmodified material.At 25℃,after the absorbed material dripping soybean oil and engine oil reach equilibrium within 10 min and 20 min respectively,they can still retain more than 50% of the adsorption capacity and have good oil retention performance;at 25℃,the adsorption After the material is reused for 6 times,the final oil absorption of soybean oil and engine oil can still maintain about 61.2% and 62.1%,with considerable recyclability;the oil absorption rate of soybean oil and engine oil is 230.8%and 233.4%,3.5 times and 3.4 times that of the unmodified material,indicating that the material has strong hydrophobic properties.The results of kinetic studies show that at 25℃,KAPKS can quickly adsorb soybean oil and motor oil and finally reach adsorption equilibrium at 1200 min,indicating that the material has a faster adsorption rate.The above research results show that the oil-absorbing materials KAPKS and NNRKS synthesized by two different methods in this paper have good oil absorption performance and low water absorption,high oil retention rate and reuse performance,fast oil absorption rate,and simple method Low price and easy degradation are potential ideal materials for controlling oil pollutants in water.