Preparation Of Modified Biochar And Its Adsorption Performance For Organic Pollutants In Wate

The problem of water pollution has become one of the great challenges faced by countries all over the world,especially the problems such as antibiotic-based and dye-based contaminated wastewater.Therefore fast and effective removal of antibiotics and dyes from water is an urgent matter,and among the various techniques to reduce the concentration of pollutants in water,adsorption technology is used for low concentrations.Carbon materials are widely used because of their unique surface properties and high adsorption capacity.In this study,industrial waste sugarcane bagasse and agricultural waste oak leaves were used as carbon sources to prepare porous carbon materials,and potassium hydroxide(KOH)modification was used to increase the specific surface area and the number of surface functional groups of biochar,which in turn improved the adsorption capacity of organic pollutants.The main contents and results of the research are as follows:1.Bagasse Porous Carbon(BPC)was prepared by a two-step method using industrial waste bagasse as the carbon source and KOH as the activator for the removal of methylene blue(MB)and tetracycline(TC)from wastewater.The adsorption effect of BPC prepared by different activation temperature,activation time and activator addition on MB was investigated by single-factor method,and the best preparation process of BPC was screened.The preparation conditions were:the activation temperature was 700℃,the activation time was 2 h,and the mass ratio of KOH to charcoal was 3:1(BPCK700,2,3:1);the adsorption capacity of bagasse-based porous charcoal(BPCK700,2,3:1)on MB and TC under the conditions of adsorption time,adsorbent dosage,initial concentration of solution and pH value were systematically investigated by the controlled variables method.2.The related adsorption mechanisms were analyzed and discussed by SEM,BET,XRD,Raman,FTIR,zeta potential and other characterization means.The results showed that BPCK700,2,3:1 had good adsorption effect on both MB and TC,and the adsorption time was close to the adsorption equilibrium at 120 min.For MB adsorption,the dosage was 0.4 g/L with an initial for concentration of 100 mg/L,and for TC adsorption the dosage was 0.3 g/L with an initial concentration of 50 mg/L in TC solution,and the pH value>5 had good The adsorption kinetics was fitted and found to be in accordance with the proposed secondary kinetic model;the Langmuir isotherm could better describe the adsorption process of BPCK700,2,3:1 for MB and TC.By characterizing the morphological structure of BPCK700,2,3:1,the surface pore structure of BPCK700,2,3:1 is very rich with irregular porous structure,and the surface contains oxygen-containing functional groups such as carboxyl groups and hydroxyl groups,and has good regeneration ability.3.Oak leaf-based porous carbon OPCK700,2,3:1 was prepared by one-step carbonization method using natural agricultural waste oak leaves as raw material.The raw material was pretreated with KOH,oven dried,and obtained porous carbon(OPCK700,2,3:1)by one-step carbonization using a tube furnace.The results showed that:compared with BPC700,2,3:1,the adsorption capacity of OPCK700,2,3:1 was stronger for MB and TC;the systematic analysis of the adsorption behavior was in accordance with the Langmuir isotherm model and the proposed secondary kinetic model;after five regenerations,the adsorption rate could still reach more than 85%,indicating that the porous carbon material prepared from oak leaves was more stable.The characterization analysis of OPCK700,2,3:1 showed that the specific surface area of OPCK700,2,3:1 was 2036.0417 m2/g,which had a high specific surface area and pore volume,and the surface pores were more abundant,and the average pore size was 2.0395 nm,which was a carbon material with mesoporous structure and good surface graphitization and abundant surface functional groups.The one-step preparation of porous carbon reduces the production cost and makes the preparation of porous carbon more simple and convenient.From the above experiments,it can be concluded that the adsorption process belongs to physisorption and chemisorption,and the adsorption mechanism mainly contains pore filling,hydrogen bonding interaction,π-π electron donor interaction and electrostatic interaction.