Study On The Modification Technology Of Activated Carbon Fiber And The Application For Cu(?)

Cu(?)is a common harmful pollutant,which is usually discharged from electroplating,metallurgy,refining,printing and fertilizer industries.Excessive intake of Cu(?)may lead to liver injury and acute human poisoning.The most promising purification process in the field of low concentration Cu(?)purification is adsorption process,and activated carbon fiber felts(ACFFs)are the adsorbents with high adsorption performance for specific adsorbate with low concentration.However,the research on the modification process of activated carbon fiber'for Cu(?)adsorbate needs to be further improved,especially ACFFs with high adsorption capacity and recyclable for the low-concentration Cu(?)to be developed.In order to develop the modification process of activated carbon fiber with high Cu(?)adsorption performance,this paper aims to improve the Cu(?)adsorption performance and regeneration performance of activated carbon fiber.Design,develop and optimize of ACFFs modification process and regeneration process based on the evaluation criteria of adsorption performance of modified ACFFs and regenerated ACFFs.It has certain guiding significance for the development of ACFFs with high Cu(?)adsorption and regeneration properties,functional modification of porous materials,regeneration process,enrichment and recovery of precious metals,etc.In this paper,ACFFs modification process mainly uses nitric acid oxidation process,ultrasound-assisted nitric acid oxidation process,microwave-assisted nitric acid oxidation process and sonication-assisted reactivation process.The maximum adsorption value Qmax of modified ACFFs can be increased to 3.11 times,3.64 times.4.55 times and 5.42 times of ACFF0,respectively.In the oxidation process,the microwave-assisted nitric acid oxidation process has the best effect on the Cu(II)adsorption performance of ACFFs.The Cu(II)adsorption value of the modified sample is Q(Nm-ACFF)=23.13)mg/g.The effect of Cu(?)adsorption value is best when 15 wt%KOH used as activator and activation temperature set at 1023 K in sonication-assisted reactivation process,the Cu(II)adsorption value Q(ACFF-K15)=27.55 mg/g.Sonication-assisted KOH reactivation process was used to reactivate ACFFs for 1-4 times.After the third reactivation,the adsorption value of Cu(II)reached the maximum Q(ACFF-K15-3)=35.24 mg/g,which was 6.94 times of ACFF0.The effect of pH of Cu(?)solution on the adsorption of ACFFs is significant.When the pH was adjusted to 6.5,the Cu(II)adsorption values of ACFF0,No-ACFF,NM-ACFF and Ns-ACFF increased significantly,reaching 32.59 mg/g,34.41 mg/g,39.07 mg/g and 37.59 mg/g,respectively.When the pH is adjusted to 7.5 or above,the precipitation of Cu(?)solution is formed after adsorption by ACFFs,but the purifying rate of Cu(?)can reach 96.58%.Therefore,this paper presents a method of purifying wastewater containing Cu(?)by combining chemical sedimentation technology with adsorption technology:the combined purification process of Nm-ACFFs adsorption after the wastewater containing Cu(?)is fully stationary at pH=7.5 and filtered to remove precipitation.In this paper,the regeneration process of Cu(II)-adsorbed ACFFs was studied by low-temperature-pickling process and sonication-assisted pickling process.Among them,the regeneration process of low-temperature-pickling not only achieved efficient desorption and regeneration of Cu(II)-adsorbed ACFFs,but also further improved the Cu(II)adsorption performance of ACFFs after regeneration.Taking ACFF0 as an example,the regeneration process of low-temperature-pickling can increase the regenerated ACFFO to 8.3 times of that before regeneration at the optimum concentration of 15 wt%pickling solution.ACFFs regenerated by low-temperature-pickling method could still maintain a high Cu(?)adsorption capacity after being regenerated by 1-5 times,and the Cu(?)adsorption value of ACFFs roughly increased with the increase of regeneration times in the range of 1-5 regeneration times.