# Utilization of Polymeric Materials toward Sustainable Biodiesel Industry: A Recent Review
## 3 Polymeric Catalysts
### Waste Derived Polymeric Catalysts  
They are polymeric wastes utilized and modified to synthesize useful forms of polymeric materials with the purpose of catalyzing triglycerides transesterification and FFA esterification. [PERSON] et al. (2018) synthesized D50w2 catalyst from polystyrene cross-linked divinylbenzene and sulfonated with -SO3H. It was employed on palmitic acid to yield 76.8% biodiesel under optimized conditions. Similarly, oleic acid was esterified by the acidic polymeric catalyst D5081 and yielded 97% biodiesel. This acidic polymeric catalyst was utilized from waste hyper-cross-linked polystyrene and improved with sulfonic group. The reusability efficiency reached 92% after the fourth cycle ([PERSON] et al., 2018). Low conversion efficiency was observed with partially sulfonated polystyrene polymeric acidic catalyst PSS. Only 53.4% of the oleic acid was barely converted to biodiesel in the first run. Additionally, the efficiency was reduced till 35.1% in the third cycle ([PERSON] et al., 2018). In contrast, the conversion efficiency reached 100% with polystyrene-supported fluoroalkyl superacid sPS-S. Moreover, the reusability efficiency remains considerable till the tenth cycle where it reached 88% once it was employed on Dodecanoic acid (Dodecanoic acid, 1986). MSA-Pani catalyst was synthesized from methanosulfonic, modified polyaniline, and organo-sulfonic acidic groups. The acidic composite revealed efficiency 92% to covert Ricinoleic acid into biodiesel ([PERSON] et al., 2018). p-toluenesulfonic acid-functionalized polyaniline was utilized to synthesize the acidic polymeric catalyst _p_-TSA-PANI. This catalyst proves good efficiency and reusability possibility where it employed on waste cooking oil and yield biodiesel 97.1% in the first run and 94.3% at the tenth cycle ([PERSON] et al., 2018). Recently, waste scraped tires were utilized to synthesize heterogeneous polymeric solid acidic catalyst TPC-SO3H. This catalyst was prepared by carbonization of waste polymer tires. Then, it was sulfonated with strong H2 SO4 to obtain the novel catalyst. TPC-SO3H was employed on chicken fats which featured with high content of FFA. Even though, the heterogenous polymeric catalyst proves high conversion efficiency 98.8% in the first run and 92.5% in the third cycle. However, the conversion efficiency declines till 48% in the seventh cycle ([PERSON] et al., 2018). Table 6 explores the conversion and reusability efficiencies for some waste derived polymeric catalysts. Evaluation of the three groups of polymeric catalysts for biodiesel production have been carried out as depicted in Figure 5. The evaluation was conducted based on six items, synthesis simplicity, catalytic activity, reusability possibility, safe reactants, ecofriendly and biodegradability, and economic costs. Chemically synthesized polymeric catalysts have excellent catalytic activity. However, other aspects remain concerning since they contain toxic reactants that may constitute a medium hazard for the personnel and environment. Moreover, the complexity of chemical synthesis makes the chemosynthetic polymeric catalysts unpreferable. In contrast, the naturally derived polymeric catalysts feature simplicity in preparation, biodegradability, and affordable economic costs. Similarly, the waste derived polymeric catalysts are low-cost materials utilized for biodiesel catalysis. Beside the