Application Research Of Carbon Black In Water Treatment

Carbon black is a type of carbon-containing black substance with stable properties,complex matrix,and graphite-like or aromatic ring-like structure.It has the characteristics of odorless,insoluble,non-toxic,large specific surface area,easy to obtain,and low cost.Activated carbon is a common adsorbent for water treatment.However,activated carbon approaches have not been considered feasible for large-scale deployment due to its highly cost and complicated production process.In this paper,commercially available carbon black with a particle size of 2-5 nm is used as a material to study its performance in water treatment,algae removal,coagulation and adsorption.In terms of algae removal performance,the effects of carbon black dosage and pH on algae removal efficiency were investigated.The experimental results show that the acidic and the neutral conditions were more conducive to algae removal.The removal of algae and their extracellular polymers significantly increased with the increasing the amount of carbon black.The algae removal efficiency rate can reach 86% with adding 0.05 g carbon black and pH=5,which is not significantly different from that of activated carbon.In terms of coagulation aid,we investigated the effect of the carbon black dosage,dosage order and pH conditions on the coagulation of low turbid water containing humic acid(HA).The results show that when the carbon black was used as a coagulant,the turbidity of raw water and the removal efficiency of HA were increased by 60% and 42%,respectively,compared with the use of polyaluminum chloride(PAC)alone.Alkaline conditions were more conducive to the reduction of turbidity.When 10 mg of the carbon black was added and pH=9,the turbidity removal rate achieved 91.2%.The order of addition of the carbon black and the PAC has a great influence on the removal of HA.The addition of carbon black before or after PAC addition has a good removal effect on HA,and the simultaneous removal of PAC and carbon black has a poor removal effect on HA.Adding carbon black before or after PAC addition has a good removal effect on HA.The removal effect of the HA by PAC and carbon black at the same time is poor.There is no significant difference between the carbon black and activated carbon in terms of coagulation aid.The triclosan(TCS)and trichloroacetic acid(TCAA)of adsorption performance with the carbon black were explored through static adsorption experiments.We studied the effects of initial concentration,temperature and pH on the adsorption performance of carbon black on organic pollutants.The adsorption process was analyzed by adsorption kinetics,adsorption thermodynamics and adsorption isotherm,and the adsorption mechanism of carbon black.The experimental results show that as the initial concentration of organic pollutants increases,the adsorption capacity of carbon black increases under low temperature and acidic conditions.The maximum adsorption capacity of TCS with initial concentration of 2 mg/L and TCAA with 800 ?g/L can reach 18.65 mg/g and 7.58 mg/g,respectively,compared with the adsorption performance of activated carbon.The adsorption process conforms to the quasi-second adsorption kinetics,the adsorption isotherm conforms to the Freundlich isotherm model,and belongs to the surface adsorption.The thermodynamic analysis result is that the adsorption of organic pollutants by carbon black belong to spontaneous exothermic process.A fixed bed device based on carbon black was established to remove TCS dynamically.The effect of initial concentration,bed height and influent concentration on the removal effect was evaluated.And the penetration curve of the fixed bed was fitted using the model.The experimental results show that as the bed height increases,the inlet flow rate decreases or the initial TCS concentration decreases,the penetration time increases.When the bed height was 4.2 mm,the inlet flow rate was 2 mL/min,and the initial TCS concentration was 0.5 mg/L,the carbon black fixed bed breakthrough time was 14.33 days.BDST model,Thomas model and Yoon-Nelson model could fit the penetration curve well.