Combined Production Of Gypsum Retarder And Activated Carbon From Waste Penicillin Mycelium

Waste penicillin mycelium?WPM?is a solid waste from the fermentation process of penicillin in pharmaceutical industry,which will result in air pollution and threaten the environment.High ignition point materials and nitrogenous materials of WPM were removed by producing mixed amino acids retarder.The residue was used for preparation of activated carbon.Compared to the traditional treatment process of WPM,this approach reduces secondary pollution and abuse of antibiotics,realizing deep utilization of waste penicillin mycelium.Fist,we treated WPM by microwave hydrolysis in alkali condition to produce mixed amino acids,which can be used for gypsum retarder.Based on single factor experiment,four factors were selected for orthogonal experiment:alkali concentration,solid-liquid ratio,treatment time and temperature.The optimal results for the hydrolysis process were obtained:alkali concentration 0.04 mol/L,solid-liquid ratio 1:4,reaction time 10 min,and at 85?.The amino acid type nitrogen content in the product was 1.8021 g/L,meanwhile,the initial setting time of gypsum reached 245min.Compared to commonly used gypsum retarder?citric acid,sodium citrate,STPP?,mixed amino acid retarder not only has excellent retarding effect on building gypsum,but also has less strength loss for the gypsum paste because of good synergistic effect in-between.Second,chemical composition of the product was analyzed using high speed amino acid analyzer.The retarding mechanism for building gypsum was investigated by means of FT-IR and SEM.The results show that the retarder contains amino acids such as lysine,tyrosine,and cysteine,etc.The amino and carboxyl group in the retarder chelate with calcium ion,forming mixed amino acids/small peptides complexes,which delay dissolution,hydration and crystallization of gypsum crystals,thereby prolonging the setting time of gypsum paste.In order to utilize the filter residue,microporous/mesoporous activated carbon were prepared from residue by zinc chloride activation.Based single factor experiment,response surface method?Box-Behnken?was used to optimize the process of activated carbon preparation.The optimal conditions for microporous activated carbon?Mic-AC?are obtained:activation time 1 h,activation temperature 425?,ZnCl₂ concentration 20%and impregnation ratio 1:3.85.The iodine number of the prepared Mic-AC is 884.76 mg/g.As for the preparation of mesoporous activated carbon?Mes-AC?,the optimal conditions are:activation time 2 h,activation temperature 600?,ZnCl₂ concentration 30%and impregnation ratio 1:4.The methylene adsorption of the prepared Mes-AC is 448.65 mg/g.The characterization and pore structure of the activated carbon from residue were studied using nitrogen physisorption,SEM and FI-IR.The results show that Mic-AC possesses excellent microporous structure with BET surface area of 255.94 m²/g,total pore volume of 0.19 cm³/g and average pore size of 1.83 nm,and the Mic-AC is alveolate on the surface.The Mes-AC prepared possesses excellent mesoporous structure with BET surface area of 904.91 m²/g,total pore volume of 0.53 cm³/g and average pore size of 3.15nm,and the Mes-AC with the surface of cotton-like structure.The surface of the activated carbon contains some oxygen-containing functional groups such as carbonyl,carboxyl,hydroxyl and lactones.