# Spouted-Bed Gasification of Flame Retardant Textiles as a Potential Non-Conventional Biomass
## 4 General Discussion
Table 2 shows a moderate variation in gas components evolved from gasification of flame retardant cotton and after the removal of flame retardant substrates with Fenton's reaction. With a manual fluidification of flame retardant cotton textile pellets, initiated by feeding wood pellets to attain the gasification temperature this perhaps led to irregular gas composition. Beds of the spouted bed gasifiers are made up of fine particles, where produced gas instead ascend through predefined spout in the center, goes through whole bed in a big bubble form [26]. Which is known as slugging and generally cause instability in spouted beds but can be refined with fountain alterations [53]. The irregular gas evolution outcomes with mass flow rate are obvious in Figure 6. However, thermal valorization by gasification of flame retardant textile products is achievable under standard and controlled conditions. Nevertheless, the average reactor temperature (annulus) for flame retardant cotton after removal of flame retardant substrate is higher, posing improved combustion/gasification. The cotton textile treated with organophosphorus flame retardant has lower decomposition temperatures because of the catalyzed dehydations by phosphorus acid on cellulose [54]. This occurrence leads to the incomplete combustion of cellulose materials with organophosphorus substrates. Low gasification temperature, which is due to organophosphorus substrate of flame retardant has phosphorus and nitrogen active elements, affects pyrolysis reactions of cellulose while burning. After the removal of flame-retardant substrate from cotton, the gasification temperature increased. The flame retardant substrate decomposes and generates phosphoric acid, later it polymerizes to polyphosphoric acids at lower temperatures. The acids catalyze the hydroxyl groups of cellulose to dehydrate and carbonize, limiting the pyrolysis reactions [46]. So the production of water, carbon dioxide and other residues increases. At the same time, the production of combustible fragments particularly ketone, aldehyde, ether and ester is reduced. It also affects the mass to energy conversion, as flame retardant has the tendency to lower the decomposition temperature of substrate, favoring carbonization instead de-polymerization of the macromolecules, ultimately results in greater char yield. It is required fewer volatile materials for gas phase combustion [23]. The removal or degradation \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Cotton Pellets**} & \multirow{2}{*}{
\begin{tabular}{c} **Flow Rate** \\ **(g/min)** \\ \end{tabular} } & \multicolumn{3}{c}{**Temperature (\({}^{\circ}\)C)**} & \multicolumn{3}{c}{**Gas Composition \% (t/v)**} \\ \cline{3-8}  & & **Annulus** & **Fountain** & **CH\({}_{4}\)** & **CO** & **CO\({}_{2}\)** & **H\({}_{2}\)** \\ \hline Flame retardant & 150 & 750 & 983 & 1.8 & 12.2 & 15.8 & 1.8 \\ After flame retardant & 150 & 781 & 1064 & 0.8 & 12.1 & 15.33 & 1.85 \\ substrate removal & & & & & & & \\ \hline \hline \end{tabular} The values were calculated under the conditions of: silica sand (2 L), fluidization with air at 17 Nm\({}^{3}\)/h and bed inert material.  
\end{table} 
Table 2: Averaged gas composition values evolved from the gasification. of flame retardant substrate from cellulose alters the pyrolytic properties, reverting to its original cellulosic properties. The conversion of material or biomass by fractional oxidation into a gas composition, consisting of CH\({}_{4}\), H\({}_{2}\), CO and CO in gasification also requires oxidants, which can be either stream, air, O\({}_{2}\), and CO\({}_{2}\) or their mixtures sometimes. The oxidant type is considered as a main parameter in gas composition. Air is the mostly used as a gasifying agent for its zero cost. Steam is also preferred for its advantages as H\({}_{2}\) content in produced syngas and increased heating value [55].