| Dye wastewater contains a variety of refractory organic matter,and COD is high,high color,high toxicity,is a difficult to treat industrial wastewater.crystalline violet is a basic dye,its coloring ability is strong,printing and dyeing wastewater often have the residue of crystalline violet dye.Treatment of printing and dyeing wastewater often with adsorption method,on the one hand adsorption can reduce the content of crystalline violet in wastewater,but also can greatly reduce the color.In recent years,walnut shell as the representative of agricultural and forestry waste due to its superior adsorption performance,as the raw material of activated carbon,which walnut shell abrasive particles with high carbon content has a broad application prospect.In this study,using zinc chloride as the main activator and nitric acid as the auxiliary activator,walnut shell abrasive particles were modified,and microwave heating was used to prepare walnut shell abrasive grains microwave carbon(WGMC).Through discussion of the single variables affect the performance of adsorption,from the adsorbent particle size,the dipping condition,microwave condition and the impact of repetition,etc.,get WGMC best preparation conditions for:walnut shell abrasive granule(WG)particle size 0.2 0.4 mm,zinc chloride volume fraction of 40%,2%nitric acid volume fraction,agent than 3:1,dipping time of 24 h,507 w microwave power,microwave time 8 min,modified microwave carbon(WGMC)before and after the carbonized walnut shell quality ratio is 55.56%,the adsorption of100 mg/L of crystal violet adsorption capacity of 1.643 mg/g.WGMC and WG were characterized and analyzed.SEM analysis showed that WGMC produced more microporous structures than WG.The XRD figure showed that the characteristic peak of cellulose crystal disappeared,and the characteristic peak of graphite crystal was shown.According to the FTIR diagram,the types of functional groups obtained from WGMC did not change much,but there were still many unsaturated bonds and oxygen-containing functional groups,which provided active sites for adsorption.Characterization analysis WG and WGMC.WG specific surface area are0.5207m~2/gand micropore specific surface area are0m~2/g,with an average pore diameter of 17.6685nm.WGMC specific surface area are8.2459m~2/gand micropore specific surface area are6.6863m~2/g,with an average pore diameter of2.8620nm.Langmuir adsorption isotherm model fitting,R~2(28)0.9892.Freundlich adsorption isotherm model fitting,R~2(28)0.9943.Pseudo-first-order kinetic model fitting,R~2(28)0.931.Pseudo-second-order kinetic model fitting,R~2(28)0.9936,q_e(28)1.535mg/g.In the static adsorption experiment,when the initial concentration was fixed and the dosage of WGMC increased from 0.4 to 1.2g,the removal rate gradually increased and reached adsorption saturation at 0.8g,at which time the removal rate was close to100%and the adsorption capacity decreased from 3.369mg/g to 1.650mg/g.When the initial concentration was 60mg/L,with the increase of WGMC dosage,the removal rate increased from 26.65%to 96.88%.When WGMC was 0.4g,the removal rate reached equilibrium,but the adsorption capacity reached the maximum of 1.722mg/g at 0.2g.Under the same condition,the removal rate increased with the increasing of WGMC dosage.When the dosage of WGMC is constant,the removal rate gradually decreases with the increase of the initial concentration,and the adsorption capacity gradually increases to a certain level and remains unchanged.At this point,WGMC reaches adsorption saturation,and this value is the maximum adsorption capacity of the dosage of WGMC.At the initial stage of adsorption,the reaction occurs rapidly,and with the increase of time,the reaction rate gradually slows down.When the concentration in the solution does not change,the reaction is balanced,and the reaction equilibrium time in this experiment is 6h.Acid environment is conducive to adsorption,and the optimal p H of this experiment is 3.0.Salt ions in actual wastewater do not affect the adsorption effect.WGMC was regenerated by microwave406W radiation for 5min.When the regeneration times reached three times,the regeneration rate did not change much,and WGMC could be reused.With initial concentration,additive quantity,p H,reaction to balance time,the design of four factors and four levels orthogonal experiment to optimize the static adsorption,after absorption solution concentration,with removal rate and adsorption capacity of judging index,choose the optimal combination group three,finally according to the three optimal combination,pick out the best reaction point of this study are as follows:the initial concentration of 300 mg/L,WGMC dosing quantity0.6 g,p H=3.0,the reaction time of 6 h,the removal rate of 81.52%,the adsorption capacity of 4.891 mg/g.In the dynamic experiment,the influence of column height,flow rate,initial concentration and p H on the adsorption process was obtained.The optimal adsorption conditions for dynamic experiment were column height of 50cm,flow rate of10m L/min,initial concentration of 250mg/L and p H=3.0. |
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