## 5 Mitigation of Pharmaceutical Pollutants by Nanomaterials
### Biochar-Based Adsorbents
#### 5.1.5 Electrospun-Based Adsorbents  
The electrospinningning process dates to the 1930s. [PERSON] received a patent for an electrospinningning apparatus in 1934 [117], and for the first time suggested the synthesis of polymer nanofibers by electrostatic force [118]. It is regarded as one of the most frequent and successful procedures for producing nanofibers. Many materials have been electrospun into ultrafine fibers with diameters ranging from a few nanometres to a few microns, including natural and synthetic polymers, ceramics, metal oxides, and so on [119]. More than 200 different polymers have been electrospun into nanofibers, according to reports [120]. Various electrospinningning techniques have been invented for many generations. These consist primarily of a high-voltage power source, a spinning solution storage and supply system, a spinneret, and a receiving device [119]. There are several elements that influence the electrospinningning process, including spinning solution properties (such as polymer molecular weight, concentration, viscosity, and conductivity of the spinning solution, solvent volatility, etc. ), spinning parameters (such as spinning voltage, receiving distance, solution extrusion speed, and so on), and environmental parameters (such as humidity and temperature) [121]. With the fast growth and rising maturity of the electrospinningning technology in recent years, an increasing number of organic polymers and inorganic materials have been elec  
Figure 8: Desorption of pharmaceuticals after 2 h sorption step on SBA-15 (in 1 mM phosphate buffer, pH 7 and 9, ionic strength 0.01 M KCl, 25 \({}^{\circ}\)C, reaction time 12 h) adapted with permission from [115]. trospun into nanofibrous membranes as adsorbents for the removal of pharmaceuticals in water [59]. It has been reported that some natural polymers have a high adsorption affinity for heavy metals and dyes and may be immediately electrospun into membranes for the adsorptive removal of these pollutants from water [62]. However, very few studies on its ability to adsorb pharmaceutical contaminants have been conducted. Most natural polymers have weak spin ability or mechanical qualities and, therefore, they are generally combined with other synthetic polymers to create composites of electrospun nanofibrous membranes (ENFMs). More researchers are turning to ordinary synthetic polymers with good spin ability and mechanical strength as raw spinning materials, then functionalizing the surface of the resulting ENFMs to improve their adsorption performance or introducing other inorganic compounds with excellent adsorption performance for blend electrospinningning [59]. ENFMs are classified into three types based on their material composition and properties: organic polymer ENFMs, organic/inorganic composite ENFMs, and inorganic ENFMs [119]. The distinct physicochemical properties of nanomaterials ranging from noble metal-based nanostructures to transition metal oxide nanomaterials, carbon-based nanomaterials, carbon nanotubes, and graphene and/or graphene oxide nanomaterials, as well as their novel nanocomposites and nanoconjugates, have revealed a plethora of new opportunities for sensing and the catalytic degradation of various pollutants of high environmental concern in aqueous environment [119]. The molecular structure of lignin nanofibers has been suggested as solution to remove emerging contaminants such as pharmaceuticals from wastewater [122]. The developed material had a large surface area, increasing its ability to adsorb pharmaceutical contaminants at the surface. The optimal adsorption ratio was 50:50 AL:PVA, which resulted in a maximum adsorption capacity of 29 mg/g, representing approximately 38 % of contaminants adsorbed by the nanofibers [122]. The adsorption capacity through time is shown in Figure 9. The optimum conditions were obtained after 4 h of thermal treatment at 180 \({}^{\circ}\)C followed by a 120-min chemical treatment (citrate buffer solution 0.5 M, pH 4.5).