| With the rapid development of economy and technology in the past 40 years,the heavy metal pollution(Pb,As,Hg,Cd,Ni,Cu,etc.)caused by human production and life has continued to increase.A large number of heavy metal-containing wastewater residues caused by human activities have been Discharged into the geochemical environment,these heavy metal pollutants enter the atmosphere,soil,and watershed through atmospheric deposition,etc.,are absorbed and enriched by plants,and pass through the food chain,which ultimately causes great harm to the ecological environment and human health.At present,there are five main treatment technologies for heavy metals: physical and chemical repair,biological repair,ecological repair and joint repair.The most commonly used control technology is mainly the adsorption method in physical and chemical repair.The adsorption method can target a certain treatment.Heavy metals are economical and have a significant removal effect.Currently,they are most commonly used to treat heavy metal pollutants in water.Biochar is an adsorbent material with low development cost and high adsorption capacity.It is easy to prepare,has a large specific surface area,and is rich in various functional groups.Therefore,it has been widely used to remove heavy metal pollutants in water.However,biochar as an adsorption material also has shortcomings.The adsorption capacity of a single biochar is poor,and it is difficult to separate the biochar solid from the water body after the adsorption is completed.These problems restrict the development of biochar.In this paper,waste corn stover is used as biochar raw material,and the carbonized corn stover is fully mixed with nano-hydroxyapatite by dipping method to prepare biochar-loaded nano-hydroxyapatite composite material(hereinafter referred to as HBC).Select the HBC with the best effect of absorbing heavy metals through the optimization experiment,and combine with the single factor experiment to study the adsorption dose of the aqueous solution,the pH of the aqueous solution,the initial concentration of heavy metal pollutants,interfering ions,etc.The effect of physical effects.The adsorption kinetic model and the isothermal adsorption model were used to study the adsorption behavior of the composite materials to heavy metal ions in the aqueous solution.Finally,the adsorption experiments of HBC on multiple heavy metal ions were studied by comparing the single pollution and the composite pollution experiments.The main research content and results are as follows:(1)Under the same conditions,the adsorption capacity of HBC to zinc,lead and chromium ions is higher than that of biochar 0.5%HBC The adsorption rate of zincion,lead ion and chromium ion in aqueous solution is the highest.(2)At 298 K,308k,318 k,0.5% The maximum adsorption capacity of HBC for lead ions is 272.63mg/g,285.31mg/g,298.54mg/g,0.5% The adsorption process of lead ion by HBC is spontaneous,endothermic and sustainable,and the adsorption rate is controlled by the chemical adsorption process,0.5% The process of adsorption of lead by HBC accords with Langmuir Isotherm model and quasi second order dynamic equation.(3)With the increase of the dosage and pH value of the adsorbent,0.5%HBC The adsorption rate of zinc ion,lead ion and chromium ion also increased,0.5%HBC The optimal amount of adsorbent for zinc,lead and chromium is 0.1g,0.02 g and0.08 g The optimal pH values were 6,7 and 6,respectively.With the increase of the concentration of zinc,lead and chromium in aqueous solution,0.5%HBC When the concentration of zinc,lead and chromium in the solution is 5mg / L 0.5%HBC Its adsorption rate is the highest.(4)The interference ion has obvious influence on the equilibrium concentration of zinc ion and chromium ion,but has little influence on the equilibrium concentration of lead ion.The influence of calcium ion on the equilibrium concentration of zinc ion and chromium ion is significantly greater than that of sodium ion and potassium ion,and the greater the interference ion concentration is,the stronger the influence on zinc ion and chromium ion is.(5)Through the comparison of single and compound pollution experiments,it is found that: under the reaction condition of compound pollution,0.5% The removal efficiency of HBC to lead ion in aqueous solution is the best,the removal rate is more than 90%,but the removal rates of zinc and chromium ion are decreased to some extent. |
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