The Efficacy And Mechanism Of Bioflocculant In Adsorbing Sulfonamides In Wastewater

Sulfonamides are one of the important sources of antibiotic pollution in livestock and poultry wastewater,threatening the ecological environment and human health,it has become a hot spot in recent years about how to effective remove sulfonamides from water.The conventional treatment method is inefficient and easy to produce secondary pollution,the treatment of sulfonamides with bioflocculant can overcome this limitation.In order to separate the adsorbed pollutant from the water,Magnetic bioflocculant for the treatment of sulfonylamine antibiotics was developed.In order to improve the selectivity and universality of substrates used by magnetic bioflocculants in the treatment of sulfonylamine antibiotics contamination,the efficacy and mechanism of magnetic bioflocculant in the treatment of four different kinds of sulfonamides which includes sulfadiazine(SDZ),sulfamerazine(SM1),sulfamethazine(SM2),sulfamethoxazole(SMX)were investigated,provides theoretical guidance and technical support for the treatment of sulfonamides in wastewater.Researches show that under the condition of p H values at 4,900 mg/L of bioflocculants,100 min of adsorption time,and 0.8 mg/L of initial SDZ concentration,the adsorption efficiency reaches the highest at 57.88%;under the condition of p H values at 4,500 mg/L of bioflocculants,120 min of adsorption time,and 1.0 mg/L of initial SM1 concentration,the adsorption efficiency reaches the highest at 63.45%;under the condition of p H values at 4,900 mg/L of bioflocculants,100 min of adsorption time,and 1.0 mg/L of initial SM2 concentration,the adsorption efficiency reaches the highest at 63.39%;under the condition of p H values at 4,700 mg/L of bioflocculants,120 min of adsorption time,and 0.8 mg/L of initial SMX concentration,the adsorption efficiency reaches the highest at 73.80%.The removal efficiency of bioflocculants on different sulfonylamine antibiotics in water was SMX>SM1>SM2>SDZ from high to low,this is related to the difference in its structure and physical and chemical properties.The adsorption processes of SMX,SM1,SM2 and SDZ of bioflocculants can be fitted by quasi-second-order kinetic models Langmuir ? Freundlich ?Dubinin-Radush Lkevich,as well as the pseudo-second order kinetics model.There are both single-layer adsorption and multi-layer adsorption in the process of adsorption,and the mechanism is complex.The characterization of SEM?FTIR?Zeta potential and 3D-EEM shows that the porous,multi-adsorbent site structure is tightly packed with sulfonamides after bioflocculant adsorbed SMX?SM1?SM2?SDZ.Tryptophan and tyrosine play major roles in the composition,and hydroxyl groups are the main functional groups in the adsorption process.The main adsorption process is chemical adsorption,both hydrophilic and hydrophobic adsorption sites play a role.Magnetic powder was prepared by coprecipitation,magnetic bioflocculant was synthesized by cross-linking magnetic powder with bioflocculant,are used to treat sulfonamides in wastewater.Under the condition of p H values at 5,350 mg of magnetic bioflocculants,70 min of adsorption time,and 0.6 mg/L of initial SDZ concentration,the adsorption efficiency reaches the highest at 63.94%;under the condition of p H values at 5,200 mg of magnetic bioflocculants,60 min of adsorption time,and 0.8 mg/L of initial SM1 concentration,the adsorption efficiency reaches the highest at 76.23%;under the condition of p H values at 5,400 mg of magnetic bioflocculants,50 min of adsorption time,and 0.6 mg/L of initial SM2 concentration,the adsorption efficiency reaches the highest at 69.83%;under the condition of p H values at 5,250 mg of magnetic bioflocculants,80 min of adsorption time,and 0.6 mg/L of initial SMX concentration,the adsorption efficiency reaches the highest at 89.14%.The removal efficiency of magnetic bioflocculants on different sulfonylamine antibiotics in water was SMX>SM1>SM2>SDZ from high to low,as same as the order of the adsorption efficiency of bioflocculant,but the adsorption efficiency was improved obviously.The results show that magnetic bioflocculant can not only separate pollutants from water,but also improve adsorption efficiency.The results of thermodynamic analysis and kinetic analysis of adsorption of sulfonylamine antibiotics by magnetic bioflocculant were consistent with those of microbial flocculant.three thermodynamic adsorption isotherm models and pseudo-second order kinetics model can be used to simulate the adsorption process.Multi-adsorbent site structure is tightly packed after magnetic bioflocculant adsorbed SMX?SM1?SM2?SDZ,both hydrophilic and hydrophobic adsorption sites play a role.Different from bioflocculant,both the hydroxyl and carboxyl groups of magnetic bioflocculants play important roles.Further analysis of adsorption mechanism by XRD indicates that the increase of adsorption sites may be one of the reasons for the better adsorption efficiency of magnetic microbial flocculants.