# Kinetics and Thermodynamics of Efficient Phosphorus Removal by a Composite Fiber
## 1 Introduction  
With growing population levels, urbanization and the development of industry and agriculture, a large amount of wastewater is discharged into natural water, resulting in deteriorating water quality and frequent eutrophication [1]. Phosphorus is the minimum limiting factor for eutrophication, and phosphorus removal is the key to preventing eutrophication [2]. Therefore, the development of a cost-effective and widely applicable phosphorus removal material is an important research direction for reducing phosphorus emissions and controlling eutrophication.  
The removal methods of phosphorus from wastewater mainly include biological methods, chemical methods and adsorption methods. The biological phosphorus removal process is complicated and the effluent stability is poor [3]. Although the chemical treatment method has a good treatment effect, the phosphorus removal materials are mostly industrial products, such as lime, aluminum salt, iron salt, ferrous salt and magnesium salt. The high cost of phosphorus removal materials, large amount of sludge and risk of secondary pollution is a major barrier to utilize the chemical method in practical applications [4]. However, the adsorption method is suitable for treating solute contaminants in low-contaminant solution, and has the advantages of high efficiency and low consumption, and at the same time, the purpose of fully utilizing the adsorbent and recovering phosphorus resources can be achieved by desorption [5]. High-efficiency phosphorus removal materials with strong adsorptioncapacity, good chemical stability and low water flow resistance need to be investigated to separate phosphorus from wastewater.  
The traditional adsorbents are mostly granular or powdered (such as granular activated carbon (GAC), powdered activated carbon (PAC), iron oxide and alumina) and it is difficult to separate the solids from the liquid [6]. Researchers have made many improvements, for example, [PERSON] et al. created a ceramic granular adsorbent with fly ash as the main raw material [7]. [PERSON] et al. prepared a Fe\({}_{3}\)O\({}_{4}\)-BC (biochar-supported nano-ferric oxide) composite by chemical coprecipitation method using biochar as a carrier, and applied it to the adsorption and removal of phosphate from wastewater [8]. [PERSON] et al. prepared a functional fiber from chitosan and cotton fiber and used it to remove Cu\({}^{2+}\) and Pb\({}^{2+}\) from aqueous solution. The maximum adsorption capacity of Cu\({}^{2+}\) and Pb\({}^{2+}\) was 95.24 mg/g and 144.93 mg/g, respectively [9]. However, these adsorbent preparation processes are complicated and difficult to apply in large-scale wastewater treatment projects. This paper has developed a new fibrous composite adsorbent with traditional adsorbents as the substrates.  
This study investigated zeolite and two kinds of industrial waste residue (steel slag and fly ash), and prepared zeolite/steel slag/fly ash/basalt (ZSFB) composite fiber. Static adsorption experiments were carried out to investigate the isothermal adsorption characteristics, adsorption kinetics, influencing factors and desorption of ZSFB composite fiber. To simulate the actual flow, a continuous flow fixed-bed dynamic adsorption experiment was conducted to investigate the characteristics of dynamic adsorption and phosphorus removal. The time of breakthrough was set as the reference index to investigate the influence of influent flow rate, filler mass and influent concentration on phosphorus removal. The results can provide guidance for the further development and engineering application of this material.