**3.3 Effect of contact time and amount of adsorbent**

In the process of solid-liquid adsorption, it is convenient to know the necessary contact time between the adsorbent and the adsorbate to achieve a maximum interaction between both and get removed as much metal ions as possible. **Figures 4**–**6** show the adsorption curves of each metal ion, where it is observed that about 10 h after the start of the process, the adsorption speed is high and that after this time the rate of removal of the ions. It decays, probably, because the sites where the capture of the ions is carried out are saturated, and therefore the balance is reached regardless of the concentration of absorber that has been used. This type of behavior is common among various adsorbent materials [37]. Also, it is observed that the adsorption capacity of the adsorbent material decreases significantly with the


#### **Table 4.**

*Equilibrium parameters of adsorption models at different temperatures for Cu ions.*


**101**

of metals [1, 26, 28, 29].

*The Use of Industrial Waste for the Bioremediation of Water Used in Industrial Processes*

*Behavior of the removal of Ni ions at different temperatures and concentrations of adsorbent: (a) 15, (b) 30* 

*Behavior of the removal of Co ions at different temperatures and concentrations of adsorbent: (a) 15, (b) 30* 

increase in the concentration of absorbent independent of the temperature at which the removal process is carried out, so that the adsorption potential of the Ni ions decreases from 25.8 to 7.78 mg/g at 15°C, while at 30 and 45°C, it decreases from 20.6 to 7.78 and 20.6 to 8.6 mg/g, respectively. In the case of Co ions, the adsorption capacity decreases from 28.4 to 10.4 mg/g, from 31.04 to 11.97 mg/g, and from 31.04 to 10.4 mg/g at 15, 30, and 45°C, respectively. Finally, in the case of Cu ions, the decrease in the adsorption capacity at 15, 30, and 45°C was 49.9–11.0, 56.8–12.4, and 61.2–12 mg/g, respectively. This type of behavior is observed in the adsorption

*Behavior of the removal of Cu ions at different temperatures and concentrations of adsorbent: (a) 15, (b) 30* 

In the aqueous solutions with the three metal ions present, a behavior similar to that observed in the solutions prepared with a single metal compound was observed; however, the time necessary to reach equilibrium was around 5 h, and the adsorption capacity of the ions in solution was also significantly decreased by increasing the concentration of sorbent in the solution. The adsorption capacity achieved (**Figure 7**), for Ni ions, was from 32.4 to 6.2 mg/g, for Co ions from 41.9 to 10 mg/g, and for Cu ions from 59.9 to 12.1 mg/g at 45°C, which indicates that

*DOI: http://dx.doi.org/10.5772/intechopen.86803*

**Figure 4.**

**Figure 5.**

**Figure 6.**

*and (c) 45°C.*

*and (c) 45°C.*

*and (c) 45°C.*

#### **Table 5.**

*Thermodynamic parameters for the equilibrium adsorption process of Ni, Co, and Cu ions.*

*The Use of Industrial Waste for the Bioremediation of Water Used in Industrial Processes DOI: http://dx.doi.org/10.5772/intechopen.86803*

#### **Figure 4.**

*Water Chemistry*

**SIPS**

**Redlich-Peterson**

**Langmuir**

**Freundlich**

**Temkin**

**Table 4.**

**Models Parameters**

*KS* 1.396 × 10<sup>−</sup><sup>5</sup> ND 0.2080 *qm* 41.4493 41.3266 *nS* 2.3971 1.1676 R2 0.9980 0.9200

*KR* 0.2036 ND 9.9421 *aR* 0.0013 0.2322 β 1.0 1.0 R2 0.9632 0.9170

*KL* 0.0013 ND 0.2322 *qm* 154.8825 42.8164 R2 0.9632 0.9170 *RL* 0.435–0.885 0.004–0.041

*KF* 0.2914 ND 14.5249 *n* 1.1274 4.7001 R2 0.9548 0.7741

*A* 2.9527 × 10<sup>−</sup><sup>8</sup> ND 10.1004 *B* 4.5983 6.7337 R2 0.5789 0.8472

**15°C 30°C 45°C**

**100**

**Table 5.**

**Metal T (K) -Δ***G* **(kJ/mol) Δ***H* **(kJ/mol) Δ***S* **(kJ/mol K)** Ni 288.15 18.52 69.63 308.53

Co 288.15 24.15 13.39 130.08

Cu 288.15 20.20 131.74 572.27

*Thermodynamic parameters for the equilibrium adsorption process of Ni, Co, and Cu ions.*

303.15 25.56 318.15 27.62

*Equilibrium parameters of adsorption models at different temperatures for Cu ions.*

303.15 25.91 318.15 28.07

303.15 ND 318.15 36.02

*Behavior of the removal of Ni ions at different temperatures and concentrations of adsorbent: (a) 15, (b) 30 and (c) 45°C.*

#### **Figure 5.**

*Behavior of the removal of Co ions at different temperatures and concentrations of adsorbent: (a) 15, (b) 30 and (c) 45°C.*

#### **Figure 6.**

*Behavior of the removal of Cu ions at different temperatures and concentrations of adsorbent: (a) 15, (b) 30 and (c) 45°C.*

increase in the concentration of absorbent independent of the temperature at which the removal process is carried out, so that the adsorption potential of the Ni ions decreases from 25.8 to 7.78 mg/g at 15°C, while at 30 and 45°C, it decreases from 20.6 to 7.78 and 20.6 to 8.6 mg/g, respectively. In the case of Co ions, the adsorption capacity decreases from 28.4 to 10.4 mg/g, from 31.04 to 11.97 mg/g, and from 31.04 to 10.4 mg/g at 15, 30, and 45°C, respectively. Finally, in the case of Cu ions, the decrease in the adsorption capacity at 15, 30, and 45°C was 49.9–11.0, 56.8–12.4, and 61.2–12 mg/g, respectively. This type of behavior is observed in the adsorption of metals [1, 26, 28, 29].

In the aqueous solutions with the three metal ions present, a behavior similar to that observed in the solutions prepared with a single metal compound was observed; however, the time necessary to reach equilibrium was around 5 h, and the adsorption capacity of the ions in solution was also significantly decreased by increasing the concentration of sorbent in the solution. The adsorption capacity achieved (**Figure 7**), for Ni ions, was from 32.4 to 6.2 mg/g, for Co ions from 41.9 to 10 mg/g, and for Cu ions from 59.9 to 12.1 mg/g at 45°C, which indicates that

**Figure 7.**

*Behavior of the different metallic ions of Ni, Co, and Cu found in the solution at 45°C.*

it is not necessary to saturate the solution with nDCPD to achieve greater metal uptake [32–34]. On the other hand, in the analysis of the Co-Cu binary solution, a behavior similar to the previous cases was observed, achieving a greater adsorption capacity with less amount of absorbent, so that at a temperature of 45°C (**Figure 8**), for Co ions, it was possible to adsorb 32–9.9 mg/g and for Cu ions from 57 to 11.8 mg/g.

In the removal of ions in solutions, it was observed that the percentage of removal increases with the increase in the amount of nDCPD used, achieving removal percentages close to 100% for Cu ions and 95% for Co ions; however, for Ni about 70% removal was only achieved (**Figure 9**), suggesting that sites available for nickel capture are quickly saturated due to the large amount of chromium in the effluent. The changes caused by the variation of the temperature depend on the metal ion, since the maximum removal of the Ni ions is between 15 and 30°C, while for the Cu and Co ions, it is given at 30°C. Similar observations have been reported in adsorption studies conducted with other biomaterials [29, 38]. The selectivity shown in the present study was the following: Cu > Co > Ni, with percentages of removal in solutions composed of the three ions of 96% (Cu), 83% (Co), and 59% (Ni). Additionally, in **Figure 10**, it is observed that in the solutions composed only by Co or Cu, the time necessary to reach the equilibrium decreases considerably; in addition, the selectivity is maintained toward the removal of Cu compared to the Co, having a percentage of removal of 95–79%, respectively. Finally, the changes caused by the variation of the temperature depend on the metal ion, since the maximum removal of the Ni ions is between 15 and 30°C, while for the Cu and Co ions, it was at 30°C (**Figure 11**).

#### **3.4 Kinetic study**

To understand the process of removal of the different metal ions in aqueous solution, as well as the relationship that occurs between the metals and the interaction of the metal ions with the adsorbent material, the data obtained in the experimentation was evaluated at different temperatures and with different concentrations of adsorbents with the adsorption models that are concentrated in **Table 6** [6]. The kinetic parameters calculated with the different models (**Table 1**), were used to adjust the experimental adsorption values obtained for the three metal ions with the different concentrations of adsorbent and temperatures utilized, by using SigmaPlot software (Version 11®). Based on the obtained values, it is distinguished that the models that present the best adjustments to the obtained data are pseudo first order, Elovich and pseudo-second order, so it can be inferred that the removal mechanism is due to the ions being adsorbed in one or two sites on the surface that is heterogeneous since each site has different adsorption energy

**103**

**Figure 10.**

problems of mass transfer.

*The Use of Industrial Waste for the Bioremediation of Water Used in Industrial Processes*

*Behavior of the different metal ions of Co and Cu found in the solution at 45°C.*

*Removal of the different metals in aqueous solution at 15, 30, and 45°C.*

*Removal of Cu, Co, and Ni ions that are in the same solution at 45°C.*

[1, 4, 5]. Similarly, it can be noticed that the models that do not adequately describe the process of metal removal in nDCPD are those that are related to the mass transfer both external and internal, independent of the temperature, the concentration of the adsorbent material, and the presence of another metal ion in the same solution; so it can be inferred that the removal process of these metals does not present

*DOI: http://dx.doi.org/10.5772/intechopen.86803*

**Figure 8.**

**Figure 9.**

*The Use of Industrial Waste for the Bioremediation of Water Used in Industrial Processes DOI: http://dx.doi.org/10.5772/intechopen.86803*

**Figure 8.** *Behavior of the different metal ions of Co and Cu found in the solution at 45°C.*

**Figure 9.**

*Water Chemistry*

57 to 11.8 mg/g.

**Figure 7.**

ions, it was at 30°C (**Figure 11**).

**3.4 Kinetic study**

it is not necessary to saturate the solution with nDCPD to achieve greater metal uptake [32–34]. On the other hand, in the analysis of the Co-Cu binary solution, a behavior similar to the previous cases was observed, achieving a greater adsorption capacity with less amount of absorbent, so that at a temperature of 45°C (**Figure 8**), for Co ions, it was possible to adsorb 32–9.9 mg/g and for Cu ions from

*Behavior of the different metallic ions of Ni, Co, and Cu found in the solution at 45°C.*

In the removal of ions in solutions, it was observed that the percentage of removal increases with the increase in the amount of nDCPD used, achieving removal percentages close to 100% for Cu ions and 95% for Co ions; however, for Ni about 70% removal was only achieved (**Figure 9**), suggesting that sites available for nickel capture are quickly saturated due to the large amount of chromium in the effluent. The changes caused by the variation of the temperature depend on the metal ion, since the maximum removal of the Ni ions is between 15 and 30°C, while for the Cu and Co ions, it is given at 30°C. Similar observations have been reported in adsorption studies conducted with other biomaterials [29, 38]. The selectivity shown in the present study was the following: Cu > Co > Ni, with percentages of removal in solutions composed of the three ions of 96% (Cu), 83% (Co), and 59% (Ni). Additionally, in **Figure 10**, it is observed that in the solutions composed only by Co or Cu, the time necessary to reach the equilibrium decreases considerably; in addition, the selectivity is maintained toward the removal of Cu compared to the Co, having a percentage of removal of 95–79%, respectively. Finally, the changes caused by the variation of the temperature depend on the metal ion, since the maximum removal of the Ni ions is between 15 and 30°C, while for the Cu and Co

To understand the process of removal of the different metal ions in aqueous solution, as well as the relationship that occurs between the metals and the interaction of the metal ions with the adsorbent material, the data obtained in the experimentation was evaluated at different temperatures and with different concentrations of adsorbents with the adsorption models that are concentrated in **Table 6** [6]. The kinetic parameters calculated with the different models

(**Table 1**), were used to adjust the experimental adsorption values obtained for the three metal ions with the different concentrations of adsorbent and temperatures utilized, by using SigmaPlot software (Version 11®). Based on the obtained values, it is distinguished that the models that present the best adjustments to the obtained data are pseudo first order, Elovich and pseudo-second order, so it can be inferred that the removal mechanism is due to the ions being adsorbed in one or two sites on the surface that is heterogeneous since each site has different adsorption energy

**102**

*Removal of the different metals in aqueous solution at 15, 30, and 45°C.*

**Figure 10.** *Removal of Cu, Co, and Ni ions that are in the same solution at 45°C.*

[1, 4, 5]. Similarly, it can be noticed that the models that do not adequately describe the process of metal removal in nDCPD are those that are related to the mass transfer both external and internal, independent of the temperature, the concentration of the adsorbent material, and the presence of another metal ion in the same solution; so it can be inferred that the removal process of these metals does not present problems of mass transfer.

#### **Figure 11.**

*Removal of Cu and Co ions in the aqueous solution at 45°C.*


#### **Table 6.**

*Adsorption isotherm models used for the analysis of experimental data.*
