Study On The Optimized Preparation Of Carp Charcoal And Its Adsorption To Diesel Oil

Biochar is a substance rich in pore structure obtained by pyrolysis of biomass in different gas environments.Due to its developed pores and specific surface area,biochar has a good adsorption effect on various water pollutants.The current research hotspots of biochar mainly deal with organic matter and heavy metal pollution in water or soil.The crab shells that are discarded are calcined in a tube furnace under anaerobic conditions to prepare crab shell biochar and modified with KOH.Adsorption of diesel oil was studied and the adsorption mechanism was explored,which provided a theoretical basis for the further study of marine biochar adsorbents.The main conclusions are as follows:(1)Using waste crab shell as raw material,use the tube furnace to calcinate biomass carbon at 600°C,700°C,800°C,900°C,and 1000°C,and pass the scanning electron microscope and specific surface area analyzer.The surface microstructure and surface area were analyzed.The results showed that the specific surface area of??the biomass of crab shells calcined at 700°C was the largest(307.265 m2/g),and the pore structure of crab shell biochar at 700°C was obvious and a layered structure appeared.(2)The crab shell biochar calcined at 700°C and the KOH powder were mixed in a mass ratio of 1:3 and calcined in a tube furnace to prepare a modified crab shell biochar.The results showed that the specific surface area of??modified crab charcoal was increased by nearly eight times(2440.955 m2/g),and there were many depressions and cracks on the surface,but there was no major change in chemical composition.(3)Crab shell biochar was added to the diesel waste water and placed in a shaker to oscillate at a frequency of 150 r/min.After adsorption equilibrium was reached,the supernatant was centrifuged at 4000 r/min for 10 min.After the liquid was extracted with petroleum ether,the absorbance was measured by an ultraviolet spectrophotometer.The results showed that the optimum adsorption conditions for the biosorption of diesel by crab shell biochar were:after modification,the dosage was 0.1 g at a temperature of 30°C,and the pH was 7 Adsorption for 4h;Before modification,the dosage was 0.2g at 30°C and 4h at pH 7.(4)The biosorption kinetics of crab shell biochar was studied by comparing the biosorption of diesel biochar with crab shells.It was found that the biosorption kinetics of crab shell biochar after modification were more consistent with the pseudo-second-order kinetics equation,and the fitting coefficient was higher(R~2was 0.993-0.998).The adsorption behavior of diesel on crab shell biochar before and after modification can be described by Langmuir model and Freundlich model.The fitting result of Freundlich equation(R~2is from 0.992 to 0.999)is better than that of Langmuir equation.The adsorption process of biodiesel to diesel is a multi-layer adsorption process.