**3.5 SEM studies**

SEM images of grafted pine magnetite composite with acrylamide are shown in **Figure 5(a)** and **(b)**. The observation showed changes in morphology of the GACA

**Figure 5.**

**163**

*(a) SEM image of the GACA, (b) SEM image of the GACA and (c) elemental analysis from SEM-EDX.*

*Characterization of Grafted Acrylamide onto Pine Magnetite Composite for the Removal…*

*DOI: http://dx.doi.org/10.5772/intechopen.92114*

*Characterization of Grafted Acrylamide onto Pine Magnetite Composite for the Removal… DOI: http://dx.doi.org/10.5772/intechopen.92114*

**3.4 TEM studies**

*(a) TEM image and (b) size distribution of GACA.*

**Figure 4.**

**Figure 3.**

*TGA and DTA curves for GACA.*

*Waste in Textile and Leather Sectors*

**3.5 SEM studies**

**162**

The TEM image in **Figure 4(a)** shows the appearance of the typical images of grafted pine magnetic composite with acrylamide. The supporting information showed spherical nano-particles as attributed to the shape and the incorporation of the magnetic nanoparticles in the polymer matrix. **Figure 4(b)** shows the size

SEM images of grafted pine magnetite composite with acrylamide are shown in **Figure 5(a)** and **(b)**. The observation showed changes in morphology of the GACA

distribution of the pine magnetite particles with a peak at 12 nm.

because of the graft copolymerization process and incorporation iron oxide magnetite. Supporting information showed the granular smooth surface. Roughness of the surface increased after modification, better matrix coherence was achieved after incorporation of the iron oxide magnetite nanoparticles. All the observations confirmed that grafting pine magnetite composite with acrylamide allows better compatibility. The presence of the Fe peak in the EDX of the nanocomposite showed successful incorporation of iron oxide composite in the polymer matrix **Figure 5(c)**. dye adsorption because it does not only change the surface charge of an adsorbent,

*Characterization of Grafted Acrylamide onto Pine Magnetite Composite for the Removal…*

Changes in the point of zero charge values within the sample can be attributed by the difference in types and amounts of surface functional groups present on the surface of the adsorbent. pHpzc is observed when modification on the suitability of the synthesized materials is determined. It is known to be the pH at which the amount of positive charges on a biosorbent surface equals the amount of the negative charge, i.e., the pH at which the biosorbent surface has net electrical neutrality [21, 22]. Methylene blue is a cationic dye and can easily form positively charged species over a wide pH range. The pHpzc of pine magnetite composite was found to be 8.56 and grafted pine magnetite with acrylamide was found to be 6.2. The decrease in the pHpzc is attributed to the modification of the surface area.

The adsorption experiments were carried out using batch equilibration techniques. Various methylene blue (MB) solutions with different pH range, initial concentrations and mass dosage were prepared by diluting 1000 mg/dm<sup>3</sup>

rium experiments, to determine the adsorption capacity of pine magnetite composite were conducted using 250 cm<sup>3</sup> bottles. 0.1 g of PMC and 100 cm<sup>3</sup> of the MB solution were added and shaken for 2 h at 26°C. Thereafter, absorbance was determined using UV-VIS spectrophotometer at the wavelength corresponding to the maximum absorbance (*λ*max = 665 nm) as determined from the plot. This wavelength was used for measuring the absorbance of residual concentration of MB. pH of the solution was adjusted using 0.1 M HCl and 0.1 M NaOH. **Figure 6** showed the effect of pH on the adsorption of MB. An increase in pH showed an increase in percentage removal. When the pH was 2.0 and 4.0, the removal rate of MB was 99.4 and 99.5%, respectively. This indicated that the lower adsorption of MB at acidic pH was due to the presence of excess H<sup>+</sup> ions. The influence of low pH to MB adsorption was that H<sup>+</sup> ions could occupy the binding sites; this was not favorable for the adsorption of MB. Furthermore, MB possessed positive surface charges and could be repulsed by H+ ions to prevent MB adsorption onto grafted pine magnetic

. Equilib-

but it also reflects the molecular structure of the dye.

*DOI: http://dx.doi.org/10.5772/intechopen.92114*

**3.8 Adsorption studies**

*3.8.1 Effect of solution pH*

composite.

**Figure 6.**

**165**

*Effect of pH on the adsorption of MB.*

#### **3.6 BET (surface area) analyses**

A surface property of an adsorbent describes the effect of modification on the surface area of the adsorbent. **Table 1** shows comparison of the effect of modification on the surface area of the materials. The pure pine magnetite nanoparticles showed a surface area of 113.60 m<sup>2</sup> /g, pore volume of 0.6321 cm<sup>3</sup> /g and pore size of 25.86 nm. On the other hand, the NaOH treated pine had a surface area of 2.25 m<sup>2</sup> /g, pore volume of 0.0177 cm<sup>3</sup> /g and pore size of 10.17 nm. Pine magnetite composite exhibited surface area of 54.80 m<sup>2</sup> /g, pore volume of 0.1522 cm3 /g and pore size of 23.10 nm. Grafted acrylamide reflected the surface area of 57.77 m<sup>2</sup> /g, pore volume of 0.1591 cm<sup>3</sup> /g and pore size of 17.33 nm. The higher surface area was due to the pine cone structure which was found to be important for the improvement of mass diffusion and adsorptive capacity. An increase in surface area, pore volume and pore size confirmed that GACA can adsorb MB more efficiently than the PMC. The distinct pore structure size enables fast transportation of particles.
