The Modified Biochar Preparation And Adsorption Of Ammonia-nitrogen

Biochar,as adsorbent,with amont surface area and CEC,abundant oxygen functional groups.The BC450,BC550,BC650 were prepared from bagasse at 450 ℃,550 ℃,and 650 ℃.The modified bagasse biochar was treatment with NaOH,HNO₃,and FeCl₃.Use removal rate of ammonia-nitrogen as index,a better modification was selected,and then were use orthogonal test,and the modification on the carbonization properties of bagasse biochar was investigated.To investigate the effect of dosage,temperature,time and pH on the adsorb ammonia-nitrogen by BC and Na-BC,and the adsorption Kinetics and adsorption isotherm characteristics of ammonia-nitrogen.The conclusions were reached:（1）The 450BC、550BC、650BC were modified with NaOH,HN0₃,FeCl₃,the removal rate of ammonia-nitrogen as follow:63.05%、32.78%、22.08%;46.66%、29.02%、20.28%;40.12%、25.69%、18.88%,So NaOH as modifier is better than FeCl₃,HN0₃,choosen the NaOH as modifier,The orthogonal test results is:concentration>time>volume/weight>temperature.the modified condition are:3.0 mol/L,480 min,45 mL/g,25℃.（2）BC and Na-BC,the yield,CEC and acid functional group content,which is reduced when the pyrolysis temperature become higher,and its ash,pH,surface area increased with the temperature higher;And the above parameter values Na-BC are high than BC.The SEM showed that hollow tubular and pore structures were formed on the surface of the raw material of bagasse treated with alkali,while the microscopic morphology of BC showed a flaky structure.BC and Na-BC was mainly composed of hydroxyl,aliphatic,aromatic structures,and surface functional group structure not change.（3）The effects of various factors on the removal rate of ammonia-nitrogen adsorbed by BC and Na-BC were investigated.The results showed that the dosage of BC and Na-BC were 0.7 g.Adsorption equilibrium time respectively are:240 min and 600 min;Optimal pH:9.0.The removal rate of ammonia-nitrogen from BC and Na-BC increased with increasing temperature,indicating that the heat process.Beside,initial concentration become high,the ammonia-nitrogen removal rate is reduced.（4）The adsorption of ammonia-nitrogen by BC and Na-BC was consistent with Langmuir isothermal adsorption model,which was a uniform single molecular layer adsorption.N value of the adsorption degree of Freundlich isotherm,the adsorption ability of BC and Na-BC to ammonia nitrogen is easy to adsorb.（5）The dynamic model of BC and Na-BC is using Lagergren peseudo-second model,a high correlation coefficient,R²>0.99,Lagergren peseudo-second model is described more suitable.It is chemical adsorption.The mechanism of adsorption of ammonia nitrogen involves chemical effects such as shared electron pair or electron transfer.