Study On Adsorption Performance Of Diatomite Adsorbent For Heavy Metal Ions In Water

In recent years,with the rapid development of industry and the acceleration of urbanization,a large amount of industrial wastewater discharged into water bodies will cause serious heavy metal pollution.In the past few years,my country has achieved certain results in the treatment of heavy metal pollution.However,the hidden dangers of heavy metals in my country are still outstanding.Therefore,on this basis,the country has issued the"Water Pollution Prevention and Control Action Plan"and"About Strengthening"Opinions on the Prevention and Control of Pollution Involving Heavy Metal Industries"and many other documents aim to continue to strengthen the prevention and control of heavy metal pollution.In order to achieve the national emission reduction of heavy metal pollutants and realize the goal of comprehensive utilization of water resources,effective prevention and control of water heavy metal pollution has become an important issue to be solved urgently.In order to remove heavy metal pollutants in water more reasonably and effectively,it is necessary to develop a new type of water heavy metal treatment agent.This experiment starts with the preparation of a new type of diatomite heavy metal adsorbent modified by diatomite;this experiment first adopts a composite modification method of water washing purification-pickling activation-high temperature calcination-calcium modification-pillar modification,and optimization by response surface method A new type of diatomaceous earth adsorbent was prepared,and then the adsorption performance of the diatomaceous earth adsorbent for heavy metals in water was studied,and the characterization experiment,isothermal adsorption,and adsorption kinetic analysis of the diatomaceous earth adsorbent were carried out to explore its Physical and chemical properties and adsorption characteristics.The main results obtained are as follows:（1）The best modification process for preparing diatomite adsorbent is:calcination temperature 350℃～400℃,pickling concentration 15%～20%,acid leaching time 4h～6h,Ca²⁺concentration 4.0%～5.0%,columnar liquid OH^-/Al³⁺molar ratio 2～2.2,Al³⁺The ratio of soil to soil is 8～10mmo L/g.The theoretical prediction values of the removal rate of Cr⁶⁺,Ni²⁺,Cd²⁺,Zn²⁺,Pb²⁺,Cu²⁺in response surface method test are 51.92%,45.51%,69.77%,96.32%,93.45%,99.13%,and the error between the result and the model predicted value are less than2%,and the prediction model has high accuracy.（2）Compared with natural diatomite,the diatomite adsorbent removes surface impurities,strengthens pores,increases the surface roughness and internal space of diatomite,and increases the specific surface area and average pore diameter.Ca CO₃in diatomite The content of Al₂O₃and Al₂O₃increased,indicating that the modification was successful.The adsorption of heavy metal ions in wastewater by diatomite adsorbent conforms to the second-order kinetic equation and Langmuir isotherm adsorption equation,and the adsorption process is a spontaneous endothermic reaction.（3）The optimal conditions for diatomite to adsorb heavy metal ions in industrial wastewater are:the initial concentration is 1.0mg/L,the dosage is 1.0g/L,the reaction time is 8h,and the initial p H is 5.The best conditions for adsorbing heavy metal ions in surface water are:the dosage is 0.4g/L,the reaction time is 4h,and the initial p H is 5.Using the best reaction conditions to treat the actual heavy metal wastewater,the removal rates of Cr⁶⁺,Ni²⁺,Zn²⁺,Cu²⁺are 63.69%,54.81%,97.64%,99.57%;the adsorption capacity is 0.2165mg/g,0.2741mg/g,0.5175,respectively mg/g,0.2390mg/g,the removal effect of actual heavy metal wastewater is good.