Preparation Of Potato Straw Activated Carbon And Study On Its Adsorption Removal Of Typical Antibiotics In Water

Antibiotics are a type of new organic pollutants that are bioaccumulative,biologically active,and difficult to biodegrade.Antibiotics are frequently used in production and life,and continue to enter the environment through various channels.In recent years,the detection frequency and detection concentration in water,soil,and other environmental media have been increasing.Antibiotics have"fake"persistence and induce a large number of drug-resistant pathogens in the environment,causing serious harm to human health and ecological environment security.Activated carbon is a kind of porous material with many advantages such as low relative density,large specific surface area,high mechanical strength,acid and alkali resistance,well-developed pore structure,etc,which has been widely used in environmental pollution control,electrochemical and catalytic reactions.Activated carbon as adsorbent is one of the best choices for removing antibiotics in water.However,activated carbon is expensive and difficult to recycle.The adsorption rate and adsorption capacity need to be improved.This paper addresses the issue of antibiotic contamination in water bodies.In this paper,the agricultural waste,potato stalk,was used as the raw material.Carbonization and chemical activation methods ofzinc chloride were used to optimize the preparation conditions and methods.In combination with characterization methods and preliminary adsorption experiments,the best activated carbon materials were prepared and screened.On this basis,the adsorption performance of the selected activated carbon for typical antibiotics ultrapure water distribution and actual sewage was systematically investigated.The main findings are as follows:?1?After screening and optimization,the optimal preparation conditions were mass ratio of zinc chloride to potato straw of 2:1,temperature of 600°C,and calcination for 1 h.Potato straw activated carbon?PAC?was prepared under optimal conditions was mainly mesoporous,with a high specific surface area and pore volume of 1237.61 m²/g and 0.9930 cm³/g,respectively.The nitrogen adsorption-desorption isotherm conformed to the?40?-type isotherm.PAC was mainly amorphous structure.The surface of PAC contained hydroxyl,carboxyl,and other oxygen-containing functional groups.Compared with unactivated activated carbon?PW?,PAC had significant changes in surface functional groups.This was due to the increased volatilization of organic matter in the potato straw biomass after addition of zinc chloride.?2?Sulfamethazine?SMZ?,sulfamethoxazole?SMX?,ciprofloxacin?CIP?and norfloxacin?NOR?were representative antibiotic contaminants.Under ultrapure water distribution conditions,the maximum saturated adsorption capacities of PAC to SMZ,SMX,CIP and NOR at 25°Cwere98.94 mg/g,91.70 mg/g,103.34 mg/g and 103.34 mg/g,respectively.Compared with sulfa antibiotics,PAC had better adsorption properties for fluoroquinolones.The adsorption process of PAC on four antibiotics met the pseudo-second-order kinetics and Sips model.Adsorption thermodynamic studies showed that adsorption was a spontaneous and endothermic process dominated by physical adsorption.The addition of NaCl and CaCl₂ promoted the adsorption of NOR and CIP by PAC,and had little effect on the adsorption of SMZ by PAC.CaCl₂ inhibited the adsorption of SMX by PAC.Humic acid?HA?had less effect on the adsorption of fluoroquinolones antibiotics by PAC in water and had inhibitory effect on PAC removal of sulfa antibiotics.Antibiotics were more easily removed by PAC adsorption under acidic conditions.?3?By changing the PAC dosage,reaction time,initial concentration of antibiotics,temperature and pH value,etc.,the effect of environmental conditions on the removal of antibiotics by PAC adsorption in domestic sewage was studied.Under the same conditions,there were significant differences in adsorption removal of different antibiotics with PAC dosage and adsorption equilibrium time.For SMZ,when the PAC dosage was 40 mg,the equilibration time was 420 min and the removal rate was 95.4%.For SMX,when the PAC dosage was 120 mg,the equilibration time was 30 min and the removal rate was 96.3%.For CIP and NOR,when the PAC dosage was 25 mg,the equilibration time was 120 min and the removal rate was 96.0%and 97.5%,respectively.For SMZ,SMX,CIP and NOR,when the solution pH value was 3,the removal rates were 98.9%,98.7%,99.6%and 99.8%,respectively.PAC still had good adsorption performance in strongly acidic solution.And in the pH range of 3.0 to 9.0,PAC could adsorb and remove the antibiotics in the actual sewage.PAC had obvious removal effect on dissolved organic matter?DOM?in domestic sewage.After adsorption,the fluorescence intensity of DOM in the water was significantly reduced.