## 3 Results and Discussion
### Characteristics of the Amine Immobilized GMA-g-NWF and IRP
#### 3.2.3 Water Absorptive Capacity Analysis
[36] discussed the effect of the covalent index in their study, and they found out that Pb has a larger covalent index of 6.41 than Cu (2.64), which resulted in Pb having stronger interaction to the nitrogen and oxygen atoms to form complexes than Cu. This explained the reason of reduction in adsorption capacity towards Cu as aliphatic amines chain grows greater. Figure 5: Expected speciation distribution of copper (10 mg/L) as a function of pH in nitric acid. However, all the IRP samples had shown a different trend from amine immobilized GMA-\(g\)-NWF on adsorption capacity with time. The EDA-IRP sample had shown ascending trend with time for adsorption capacity of Cu ion. The adsorption capacity increases from 1.82 to 50.41 mg/g while the adsorption time increases from 15 to 480 min, respectively. Although the adsorption reaches the maximum allocated time of 480 min, the adsorption capacity of the EDA-IRP sample still did not show any sign for saturation. The EDA-IRP samples initially exhibit a slower adsorption rate. Since the adsorbent did not reach saturation, it is anticipated that there are more available active sites for Cu, which leads to higher Cu ion intake capacity. Due to the slow adsorption rate, the IRP does not reach a plateau as consequences of insufficient contact time between the solute and the adsorbent. The three-dimensional network formed through cross-linked imprinted polymeric material enables specific sites for designated ions which gives higher adsorption capacity at a slower adsorption rate [37]. A similar trend was attained for DETA-IRP, TETA-IRP, and TEPA-IRP samples as well. Meanwhile, IRP samples also illustrated a descending trend for adsorption capacity with aliphatic amines chain growth. The adsorption capacity towards Cu ion reduces with the trend of EDA-IRP \(<\) DETA-IRP \(<\) TETA-IRP \(<\) TETA-IRP. The size of aliphatic amine plays a major role in the adsorption performance of both amines immobilized GMA-\(g\)-NWF and IRP samples. Figure 6: The adsorption capacity of Cu versus time by amine immobilized GMA-\(g\)-NWF and IRP samples at experimental condition of initial Cu/Pb concentration: 10 mg/L, adsorbent dose: 0.02 g, temperature: 30 \({}^{\circ}\)C, amine density: 2.0-2.2 mmol/g\({}^{\text{-ad}}\), stirring speed: 200 rpm and adsorbate volume: 100 mL. .3.2 Selectivity of Amine Immobilized GMA-\(g\)-NWF and IRP Samples in Binary Metal Species System  
Both amines immobilized GMA-\(g\)-NWF, and IRP samples were subjected to selectivity experiment in binary metals system which consists of both Cu and leads ions. The main aim of the study is to investigate the selectively of the prepared polymeric material which enacted with the ion recognition technique in terms of several different aliphatic amines. The experimental conditions of the amine functionalization process were predetermined to attain AD approximately 2.0-2.2 mmol/g\({}^{-\text{ad}}\) as a standardized condition when to apply for the selectivity experiment. The selectivity of both amines immobilized GMA-\(g\)-NWF and IRP samples towards Cu ions were measured against time, as shown in Figure 7. The selectivity of EDA-GMA-\(g\)-NWF towards Cu ion increases slightly for at the beginning of 60 min, then, the adsorption capacity reaches a plateau. However, the selectivity attained for EDA-GMA-\(g\)-NWF was only around 1.12. DETA-GMA-\(g\)-NWF, TETA-GMA-\(g\)-NWF, and TETA-GMA-\(g\)-NWF samples, were also exhibited a similar trend. Therefore, all the amine immobilized GMA-\(g\)-NWF had shown insignificant selectivity towards Cu ion. It can be concluded that EDA-GMA-\(g\)-NWF, DETA-GMA-\(g\)-NWF, TETA-GMA-\(g\)-NWF, and TETA-GMA-\(g\)-NWF samples possess good adsorption capacity for Cu ions in a single metal ion system and own very poor selectivity towards Cu ion in the binary metal system. However, the EDA-IRP sample exhibited excellent selectivity towards Cu ion in the binary metal system. The selectivity of EDA-IRP increases from 44% to 113% while the adsorption time increases from 15 to 480 min, respectively.