Preparation And Application Of Attapulgite Based Wastewater Treatment Agent

Clean water is not only necessary for the existence of life but also vital to the environment.In recent years,the high mobility,toxicity,non-biodegradability,and destructiveness of heavy metal ions and dyes in natural aquatic ecosystems have attracted widespread attention.Heavy metal ions and dyes produced during manufacturing,transportation,and domestic waste pollution,even if their concentration is very low,can cause serious damage to the human kidney,reproductive system,nervous system,and liver.Therefore,how to treat dye wastewater and heavy metal polluted wastewater with high efficiency,environmental protection,and low cost has become a hot topic for many researchers.Attapulgite,also known as palygorskite,is a natural one-dimensional nano-shaped water-bearing magnesium-rich aluminosilicate clay mineral,which belongs to the sepiolite group in mineralogy.The single rod crystal of attapulgite has a diameter of about 20-70 nm and a length of 0.5-5μm.Attapulgite has abundant reserves in nature.Due to its regular and fine structure,it has a porous channel morphology and a large specific surface area.Compared with other sewage treatment agents,attapulgite has the characteristics of large surface area and high adsorption capacity.At the same time,it has the advantages of wide sources and low price.Therefore,it is widely used in industries such as grease decolorization,dye wastewater,and heavy metal pollution wastewater.Due to the physical and chemical structure of natural attapulgite,it is easy to self-aggregate or agglomerate with other impurities,resulting in a decrease in its specific surface area and blockage of the pore structure,which will ultimately affect its adsorption and decolorization performance.Therefore,the adsorption effect of untreated attapulgite raw ore is not very ideal.In recent years,the preparation of high-performance,easy-to-handle,and recyclable attapulgite-based composite materials has become a research hotspot.At present,most studies reported in the literature mainly focus on the preparation of adsorption materials,adsorption thermodynamics,and adsorption kinetics.There are few reports on the theoretical calculation of the adsorption process.This paper used attapulgite as the base material to prepare high-performance attapulgite-based sewage treatment agents through modification and compounding methods.At the same time,the first-principles theoretical calculations were used to investigate the possible removal of pollutants in the sewage treatment process.The design of the experimental part of this paper is from shallow to deep,starting with amino-modified attapulgite（M-ATP）as the adsorbent,and on this basis,loading carbon nitride to prepare the attapulgite/graphite phase carbon nitride adsorption material（M-ATP/g-C₃N₄）.Finally,to achieve the purpose of recycling the adsorbent,the Cu²⁺adsorbed M-ATP/g-C₃N₄ was further thermal regenerated to prepare a copper-doped M-ATP/g-C₃N₄composite material（Cu@M-ATP/g-C₃N₄）.The research content and experimental results of this paper are as follows:1.Firstly,the attapulgite was modified with 3-aminopropyltriethoxysilane（KH-550）to prepare the M-ATP adsorbent,which was used to selectively adsorb mixed heavy metal wastewater(Pb²⁺and Cu²⁺).The experimental results presented that:M-ATP exhibits a good adsorption performance for both Pb²⁺and Cu²⁺.At 298.15 K,pH=6,the maximum adsorption capacity of M-ATP for Pb²⁺and Cu²⁺is 53.58 mg/g and 28.86 mg/g in the binary heavy metal ion solution,respectively,which indicates that M-ATP is easier to adsorb Pb²⁺,and the density functional theory calculation results also demonstrated that Pb is more easily adsorbed by M-ATP.2.The research content of the second chapter is based on the first part of the experiment.The prepared M-ATP was used to synthesis M-ATP/g-C₃N₄ composite material,and the M-ATP/g-C₃N₄ composite material was used to remove heavy metal pollutants in sewage.The experimental results exhibit that:compared with pure g-C₃N₄,the MATP/g-C₃N₄composite shows a better adsorption effect on Pb²⁺and Cu²⁺.At the same time,the calculation results of density functional theory also show that Pb²⁺is easier to be absorbed by M-ATP/g-C₃N₄ composite material.3.This part of the research is based on the second part of the experiment.To reuse the M-ATP@g-C₃N₄ composite material adsorbing Cu²⁺,the Cu@M-ATP/g-C₃N₄ composite material was prepared through the thermal regeneration process.Compared with pure g-C₃N₄,the Cu@MATP/g-C₃N₄ composite material has a better photocatalytic degradation effect on methylene blue dye.Theoretical calculation results revealed that after loading copper,the bandgap of Cu@M-ATP/g-C₃N₄ is reduced,which is more conducive to the excitation and separation of photogenerated electrons.