Preparation Of Porous Silica Microspheres And Their Application In Dye Adsorption

Over the years,the treatment of dye wastewater has become an important topic in the water treatment industry.Among many dye wastewater treatment methods,the adsorption method is favored by water treatment researchers because of its various advantages,such as simple operation,high efficiency,and low cost.Nano-porous silica（SiO₂）materials are often used as adsorbents in the field of dye wastewater treatment owing to their high specific surface area and strong adsorption capacity.In this paper,SiO₂microspheres with controllable particle size,high specific surface area,and high pore volume were fabricated by a hydrothermal method,and their adsorption performance of Rhodamine B dye was explored systematically.what’s more,to address daily household laundry problems,like that dark-colored and light-colored clothes can’t be mixed and that dyes will drop resulting in dye wastewater during the washing process,an idea of performing laundry anti-cross-dyeing color absorption sheets by combining porous SiO₂microspheres and woven base materials was proposed.The adsorption performance of the dye-adsorbing sheets on dyes in the laundry wastewater was explored.The theoretical and practical basis on the treatment of dye wastewater by adsorption methods will be provided by the research results of this study.The research contents of this article are summarized in three aspects as follow:（1）Ethyl orthosilicate（TEOS）was selected as the silicon source,cetyltrimethylammonium bromide（CTAB）as a template,and the alcohol as a auxiliary.The nano-porous SiO₂microspheres with controllable particle sizes and good monodispersity were synthesized by the hydrothermal method.The influence of the amount of raw materials,pre-reaction time and stirring speed on the particle size and morphology of SiO₂microspheres were explored.The surface morphology,structure composition,specific surface area,pore volume,Zeta potential of porous SiO₂microspheres and other performance were systematically characterized.（2）The prepared nano-scale porous SiO₂microspheres were utilized as adsorbents to research their adsorption properties of Rhodamine B.The adsorption mechanism of the porous SiO₂microspheres to Rhodamine B dye was researched,the adsorption conditions of the porous SiO₂microspheres were optimized,and the reusable performance of the porous SiO₂microsphere adsorbent was explored through calcination.（3）The anti-cation dye and anti-cross-dyeing laundry color absorption sheets were prepared by loading a non-woven fabric with nano-porous SiO₂microspheres.Optimized the preparation conditions of the color absorption sheets,and analyzed their adsorption performance for Rhodamine B dye.Then compared the adsorption performance with other commercially available color absorption sheets.Porous SiO₂microspheres were directly decorated on the color absorption sheet in the market which can only adsorb anionic dyes to prepare a color absorption sheet that can prevent both cationic and anionic dyes from cross-dyeing.This color absorption sheet was used for the treatment of laundry wastewater which contained Rhodamine B dyes and reactive blue dyes simultaneously,and the adsorption effects on different types of dyes were explored.The research results showed that:（1）Nano-scale porous SiO₂microspheres with controllable particle size and good monodispersity could be prepared by the hydrothermal method through adjusting the synthesis reaction parameters.The amount of TEOS,CTAB and the type of alcohol auxiliary templating agent directly affected the average particle size of the microspheres,while the pre-reaction time and stirring speed exerted less influence.With the amount of TEOS,CTAB,and the carbon chain length of the alcohol auxiliary templating increasing,the average particle size of the microspheres decreased.The prepared porous SiO₂microspheres were uniform in size,good in sphericity.And they hold a typical wrinkle-shaped pore structure emitting from the center of the circle,and had a large specific surface area and a negative charge on the surface.（2）Porous SiO₂microspheres with different particle sizes were served as adsorbents and applied to the adsorption of Rhodamine B dye.It was found that porous SiO₂microspheres with an average particle size of 530 nm had the best adsorption effect on Rhodamine B.When the amount of porous SiO₂microspheres increased from 0.01 g to 0.05 g,the removal rate of 50 m L Rhodamine B dye with a concentration of 10 mg/L by the microspheres increased from 71%to 99%.When the initial p H value of the dye solution was 8,the removal effect of porous SiO₂microspheres on rhodamine B was optimal.The adsorption capacity gradually increased with time increasing,finally reached the adsorption equilibrium and then tended to be flat.With the increase of the initial concentration of the dye,the adsorption capacity of porous SiO₂adsorbent gradually increased,and it reached 109 mg/g when the initial concentration was 50 mg/L.The adsorption kinetics showed that it accorded with the quasi-two-level kinetic model and the adsorption isotherm coincided with the Langmuir model,indicating that the adsorption of porous SiO₂microspheres to Rhodamine B was a single-layer homogeneous adsorption on the surface.The saturated adsorption capacity q_mwas calculated to be 138.89 mg/g.The porous SiO₂microspheres with adsorbed dyes were calcined to remove the dyes.After 10 cycles,the microspheres still had good adsorption performance.（3）The porous SiO₂microspheres were decorated on a blended non-woven fabric with a viscose content of 70%and a polyester content of 30%to prepare an anti-cross-dyeing color absorption sheet.It was found that the removal effect on Rhodamine B dye was obvious,but the reactive blue dye had almost no removal effect,which was attributed to that the negative charged surface of SiO₂microspheres would repel anionic dyes.The porous SiO₂microspheres were directly decorated on a commercially available color absorption sheet that could only absorb anionic dyes to prepare a color absorption sheet that could prevent cationic and anionic dyes from cross-dyeing.It was found that when the concentration of the SiO₂microsphere dispersion was 1.6 g/L,and the ultrasonic loading time was 2 h,the absorption performance of the color absorption sheet was good.The SiO₂microspheres were evenly distributed on the substrate,and the binding fastness to the substrate was strong.It could remove cationic Rhodamine B dye and anionic reactive blue dyes in a laundry environment with detergents.