## 3 Polymer Nanocomposites as Adsorbent
### Polymer Nanocomposites as Adsorbent for Separation of Gases  
Thin film processes have been utilized for reducing harmful gases from fossil fuel and natural gas. Organic matrix is the main thin film material used for reducing harmful gases because of its low-cost, mechanical properties, and permeability; however, selectivity restricts their desirable applications for industrial processes [171]. Hence, adsorption has become one of the prospective ways of solving the shortcomings of thin film composites [172]. The literature has shown that adsorbents synthesized from agarian debris have been widely utilized owing to their outstanding performances and are inexpensive [173]. However, there is little information on polymer nanocomposites as adsorbent for separation of gases; nonetheless, there are other promising adsorbents for gaseous separation. The separation of gas using solvent/sorbents is dependent on gas affinity, in the direction of a precise sorbent like solid porous materials--activated carbon, zeolites, alumina, silica gels or a solvent, for example, methanolamine. The pressure swing adsorption method is the most illustrative technology. In this method, separation of gases ensues when the gaseous mixture makes contact with the sorbent/solvent, with further subjection to pressure. The gas that has maximum affinity for the adsorbent will be confined while the other gases move across the system (Figure 5). The restoration of the vessel is done by taking it back to air pressure or via upsurge in the temperature, by discharging the confined gas. The key benefits of this method are the high purity of the separated gas; however, a shortcoming is the high energy needed for running the system, particularly for the regeneration of the vessel [174]. Hence, for the continuous increase in the necessity for more effectual energy-saving, adsorbents that possess well channeled structures and tunable surface properties must be synthesized. Metal-organic frameworks made from metal-containing nodes linked by organic bridges are considered a new kind of porous materials that will meet the need for more efficient, energy-saving adsorbents for gas separation [175]. When evaluating metal-organic frameworks for gas adsorption and separation, the capacity of adsorption is a vital factor that should be considered [176]. Based on the large surface areas, amendable pore sizes, and satisfactory thermal stability they possess, they are prospective materials as adsorbents for gas separations. Figure 5: Illustration of the pressure swing adsorption technique. The technology works under pressure by using the adsorbent’s differences in gas adsorption rate to separate some gases from a gaseous mixture (Adapted from Ref. [174]). [PERSON] et al. [177] reported a microporous metal-organic structure with appropriate pore spaces favourably to absorb additional acetylene than ethylene whereas the functional amine groups on the pore surfaces put in force their inter-activities with acetylene molecules, further resulting in maximum performance. It was proposed that this material could be employed in industries for acetylene removal from ethylene/acetylene mixtures. [PERSON] et al. [178] synthesized a quartz like metal-organic structure having a one-dimensional network for hydrocarbon separation. A substantial quantity of acetylene and the uptake capacities of CO\({}_{2}\) and moderately high selectivities for the natural gases separation at surrounding condition were attained. [PERSON] et al. [179] synthesized novel metal-organic framework-505@graphite oxide composites made of a copper-based metal-organic structure and graphite oxide through a solvothermal technique for effectual separation of CO\({}_{2}\)/CH\({}_{4}\) and CO\({}_{2}\)/N\({}_{2}\). The selectivities of these gases were assessed based on model adsorbed solution theory. Metal-organic framework-505@graphite oxide demonstrated a rise in upsurge of CO\({}_{2}\) uptake of 3.94 mmol'g at 298 K and 100 kPa, possessing an upsurge of 37.3% when compared to the parent metal-organic framework-505.