# Wastewater Treatment by Polymeric Microspheres: A Review
## 2 Synthetic Polymer
The degradation process followed pseudo-first-order (PFO) kinetics. In order to check the effectiveness of photocatalysis, membranes with photoactive microspheres were linked to conducting composite nanofiber. Inspired by multiscale structures of taro leaf, as shown in Figure 3, a biomimetic nanofibrous membrane composed of BiOBr microspheres anchored on electroconductive SiO\({}_{2}\)/PANI core-shell nanofiber was fabricated to solve issues of prevailing oil separation membranes that suffer oil fouling issues [32]. The membrane shows great superhydrophilicity, underwater superoleophobicity, and low oil adhesion due to the surface multiscale structures and hydrophilic matrix. The matrix displays high permeation flux of 6140 L/m\({}^{2}\) h, and high separation efficiency at total organic carbon content below 5 mg/L, which can be ascribed to the properties of biomimetic structure (which are the submicron pore size, high porosity, and good channel  
Figure 2: Schematic illustrating the adsorption mechanisms of CD-GAM for dyes and organic micropollutant (Reproduced with permission from [PERSON] et al. [26], Copyright 2021, Elsevier Ltd.). obtained microsphere showed enhanced organic removal in the slaughter wastewater from its synergic effect of adsorption and biodegradation. Poly(ethylene glycol dimethacrylate-n-vinyl imidazole) (poly(EGMDA-VIM)) microspheres were fabricated for the removal of phenol from an aqueous solution [34]. The microsphere was synthesized via suspension polymerization and characterized by various analysis techniques. The microsphere had high specific surface area of 304.4 m\({}^{2}\)/g. The adsorption followed the PSO kinetic model and the Freundlich isotherm model, and it was an exothermic and spontaneous process. The maximum adsorption capacity for phenol was 34.7441 mg/g at 25 \({}^{\circ}\)C and neutral pH from the Langmuir model. Poly(EGMDA-VIM) microsphere was easily regenerated by using 0.01 M NaOH solution and could be reused for five cycles with maintained adsorption capacity. To improve adsorption properties, carbon can be incorporated into the polymer matrix. Phenolic resin-based microfiltration carbon membranes (MFCMs) were prepared by incorporating polyacrylamide-based microspheres to effectively separate the emulsion of oil and water [35]. The TGA result confirmed that incorporating polyacrylamide (PAN) improved the thermal degradation property of precursor, and that the PAN amount should exceed 25%. With increased PAN, the average macropores of resultant MFCMs decrease, mesopores and micropores were reduced, and the microstructure was densified. The pore size distributions were measured via nitrogen adsorption analyzer. PAN microsphere incorporation improved emulsified oil-water separated performance and was stable for over 240 min. The oil-water separation is dependent on early-stage adsorption and size exclusion at steady state. The obtained MFCMs containing 35% PAN microsphere achieved 93.6% oil removal, along with the permeation flux of 251.1 kg/m\({}^{2}\)h under the feed oil concentration of 50 mg/L, transmembrane pressure at 0.03 MPa, and feed flow rate at 6 mL/min. As feed oil concentration or trans-membrane pressure increased, the permeation flux increased. Divinylbenzene (DVB) and polystyrene (PS)-based polymers are often used as adsorbents for heavy metal ions and dyes. A porous (Styrene-divinylbenzene)/CuNi bimetallic nanocomposite microsphere (P(St-DVB)/CuNi BNC) was fabricated as an adsorbent for heavy metals in drinking water treatment [36]. It was prepared via oil-in-water emulsion polymerization of styrene and divinylbenzene while CuNi bimetallic NPs existed. SEM image showed that the average diameter of the nanocomposite is about 112 \(\upmu\)m. TEM imaging showed that the nanocomposite is entrapped in a spherical shape. The adsorption efficiencies of Pb\({}^{2+}\), Cd\({}^{2+}\), Mn\({}^{2+}\), and Zn\({}^{2+}\) ions from synthetic water were evaluated via batch study. The removal efficiency increased as contact time and adsorbent mass increased