Study On Preparation,Characterization And Application Of Waste Putty Powder-Hydroxyapatite Composite Material

Construction waste is one of the largest garbage sources in the world.According to statistics,China produces about 2 billion tons of construction waste in a year,occupying 1.4 million mu of land.The hazards of construction waste are also manifold.On the one hand,the piling of construction waste will occupy the land,improve the alkalinity of the land,and affect the property of the land,thus causing serious pollution to the water body and atmosphere environment.On the other hand,due to the lack of effective methods of construction waste,it is often unordered and stacked,which affects the image of the city.At present,how to efficiently dispose and utilize the construction waste has become an important topic in the research direction.Recycling is an important method for efficient disposal and utilization of construction waste.However,at present the construction waste recycling research often focused on recycling of recycled coarse and fine aggregate,there are little research for the powder waste,such as waste putty powder,and lack of innovative ideas.This paper focuses on the high added-value reuse of the waste putty powder,and synthesizes the new putty powder hydroxyapatite composite material by chemical precipitation method.The synthesis mechanism of the compound material of putty powder and hydroxyapatite was analyzed,and the humidifying property and the adsorption capacity of heavy metal ions were tested.Hydroxyapatite is an important component of bones and teeth of human and animals,as well as an important environmental functional material used to control sewage and soil pollution.The hydroxyapatite has better hygroscopicity and can be used as a hygroscopic material because of its special crystal structure and higher than surface,small particle size and high solubility.To waste putty powder and diammonium phosphate（（NH₄）₂HPO₄）as raw material,synthesis putty powder hydroxyapatite composite powder by using chemical precipitation.By using SEM,XRD,BET and EDS microscale characterization instruments,the influence of aging temperature and time on the crystal structure and morphology is studied.Researches show that aging time and temperature significantly influenced the hydroxyapatite crystal type and production,a longer aging time made a better crystallinity of hydroxyapatite.50℃aging temperature is more conducive to the formation of hydroxyapatite. moisture absorption performance of putty powder hydroxyapatite composite powder is tested by using saturated salt solution,the results show that the composite powders of moisture absorption ability is significantly higher than waste putty powder,moisture absorption ability is positively related to the aging time,i.e.the longer aging time,the stronger the ability of moisture absorption.50℃aging temperature is more conducive to the growth of the composite powders hygroscopicity.In addition,the adsorption heavy metal capacity of composite powders is also the focus of this paper.The adsorption performance of Ni²⁺in simulated wastewater was studied by spectrophotometer,and the adsorption mechanism was analyzed.The results showed that the adsorption capacity of Ni²⁺was significantly increased compared with the control group.The higher aging time,the stronger the adsorption capacity of Ni²⁺,and the adsorption capacity of the aging group was stronger than the80degreegroupandtheroomtemperaturegroup.Theadsorptionof nano-hydroxyapatite to metal ions conforms to the kinetics equation of quasi secondary reaction.The experimental data of adsorption Ni²⁺were simulated with the Freundlich isotherm model and the Langmuir isotherm model,and the adsorption of the putty powder hydroxyapatite composite material to Ni²⁺was found to meet the Langmuir isotherm equation.By comparing with other adsorbents,it is found that the putty powder hydroxyapatite composite material has better adsorption capacity for Ni²⁺.