Luiza-Postai et al 2016a - Revision history

Scipediacontent: Scipediacontent moved page Draft Content 900806651 to Luiza-Postai et al 2016a

2017-04-12T07:52:49Z

Scipediacontent moved page Draft Content 900806651 to Luiza-Postai et al 2016a

Scipediacontent at 07:49, 12 April 2017

2017-04-12T07:49:51Z

Scipediacontent at 07:48, 12 April 2017

2017-04-12T07:48:42Z

Scipediacontent at 07:48, 12 April 2017

2017-04-12T07:48:07Z

Scipediacontent: Created page with "==Abstract== Removal of the cationic dyes rhodamine B (RhB) and methylene blue (MB) by waste seeds ''Aleurites moluccana'' (WAM) was studied in a batch system. The adsorbent..."

2017-04-12T07:38:37Z

Created page with "==Abstract== Removal of the cationic dyes rhodamine B (RhB) and methylene blue (MB) by waste seeds ''Aleurites moluccana'' (WAM) was studied in a batch system. The adsorbent..."

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 On the other hand, when the solution pH was higher than 5.84, the adsorbent surface was likely to have a net negative charge that favored cationic dye adsorption. This behavior can be observed for the results of the adsorption capacity of anionic dye CR, [[#t0005|Table 1]], which is well below those for cationic dyes.
-The adsorption of cationic dyes is favored when the pH is higher than pH<sub>PCZ</sub>, due to the presence of functional groups such as
+The adsorption of cationic dyes is favored when the pH is higher than pH<sub>PCZ</sub>, due to the presence of functional groups such as &mdash;NH<sub>2</sub>&mdash;<sup>+</sup> and S<sup>+</sup> in the different classes of dyes. The reduction of MB adsorption capacity with decreasing pH was also reported by Vieira et al. [[#b0010|[2]]], employing the residue as adsorbent and Macauba due to the decreased amount of negative charge on the adsorbent.
-[[Image:draft_Content_900806651-sbnd|center|px|single bond]]
 NH<sub>2</sub>
-[[Image:draft_Content_900806651-sbnd|center|px|single bond]]
 <sup>+</sup> and S<sup>+</sup> in the different classes of dyes. The reduction of MB adsorption capacity with decreasing pH was also reported by Vieira et al. [[#b0010|[2]]], employing the residue as adsorbent and Macauba due to the decreased amount of negative charge on the adsorbent.
 The results indicate that the main mechanism of adsorption is the electrostatic interaction between the surface of the adsorbent negative and the positive parts of the dye molecule.

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 |}
-[[#f0010|Fig. 2]] also shows the FTIR spectra of WAM after RhB or MB adsorption. The spectra show new peaks, which are absent from the spectrum of the WAM Peaks at 1647 cm<sup>−1</sup> and 1655 cm<sup>−1</sup> corresponding to the stretching vibration of (C
+[[#f0010|Fig. 2]] also shows the FTIR spectra of WAM after RhB or MB adsorption. The spectra show new peaks, which are absent from the spectrum of the WAM Peaks at 1647 cm<sup>−1</sup> and 1655 cm<sup>−1</sup> corresponding to the stretching vibration of (C═C) bonds, and the peaks found at 1537 cm<sup>−1</sup> and 1542 cm<sup>−1</sup> confirm the presence of aromatic bonds of (C═C) in both dyes. However, in the spectra after adsorption of both dyes, the peaks of the WAM were predominant, due to the small amount of dye adsorbed.
-[[Image:draft_Content_900806651-dbnd|center|px|double bond; length as m-dash]]
-C) bonds, and the peaks found at 1537 cm<sup>−1</sup> and 1542 cm<sup>−1</sup> confirm the presence of aromatic bonds of (C
-[[Image:draft_Content_900806651-dbnd|center|px|double bond; length as m-dash]]
-C) in both dyes. However, in the spectra after adsorption of both dyes, the peaks of the WAM were predominant, due to the small amount of dye adsorbed.
 Thermogravimetric analysis (TGA) of the WAM was performed before and after the adsorption process, in order to investigate the thermal characteristics of the adsorbent, and TGA is shown in [[#f0015|Fig. 3]](A), which shows that at approximately 150 °C, there was a small loss of weight due to elimination of moisture retained in the material. Another mass loss starts at approximately 250 °C, caused by the thermal degradation of cellulose and hemicellulose. At 400 °C it is observed that the WAN before the adsorption process had greater weight loss than compared with the material after the adsorption process, which can be attributed to decomposition of the dye. The final weight loss occurs at about 450 °C, and may be attributed to the degradation of lignin, which has a much higher thermal stability than either cellulose or hemicellulose polymers.

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 The functional groups present on the surface chemistry of WAM were characterized through the Boehm, showing a prevalence of acidic sites, particularly phenol (46.06 mg/g), lactones (1.8 mg/g), and carboxylic acid (9 mg/g) compared with the basic functional group (5.6 mg/g). The higher amount of acid sites shows that the surface is rich in OH groups, which results in greater ability to adsorption cationic dyes [[#b0135|[27]]].
-The infrared spectrum of the WAM waste was performed before and after the adsorption process, [[#f0010|Fig. 2]]. The presence of peaks at 1743 cm<sup>−1</sup> represented the carbonyl (
+The infrared spectrum of the WAM waste was performed before and after the adsorption process, [[#f0010|Fig. 2]]. The presence of peaks at 1743 cm<sup>−1</sup> represented the carbonyl (&mdash;C═O) stretching vibration present in WAM. The peaks observed at 1675 cm<sup>−1</sup> are of strong stretching vibrations of (&mdash;C═O). The bands at 1035 cm<sup>−1</sup> (C&mdash;O) can be assigned to esters. These peaks are attributed to the carbonyl of the long-chain acids and esters that still remained in the residue after the extraction of oil. A peak at 1450 cm<sup>−1</sup> indicates the presence of a (&mdash;CH) group. A peak at 1240 cm<sup>−1</sup> was assigned to CH═CH stretching, and small peaks ranging from 1100 to 1000 cm<sup>−1</sup> were assigned to C(&mdash;O stretching [[#b0140|[28]]].
-[[Image:draft_Content_900806651-sbnd|center|px|single bond]]
-−
-[[Image:draft_Content_900806651-dbnd|center|px|double bond; length as m-dash]]
-O) stretching vibration present in WAM. The peaks observed at 1675 cm<sup>−1</sup> are of strong stretching vibrations of (
-[[Image:draft_Content_900806651-sbnd|center|px|single bond]]
-−
-[[Image:draft_Content_900806651-dbnd|center|px|double bond; length as m-dash]]
-O). The bands at 1035 cm<sup>−1</sup> (C
-[[Image:draft_Content_900806651-sbnd|center|px|single bond]]
 O) can be assigned to esters. These peaks are attributed to the carbonyl of the long-chain acids and esters that still remained in the residue after the extraction of oil. A peak at 1450 cm<sup>−1</sup> indicates the presence of a (
-[[Image:draft_Content_900806651-sbnd|center|px|single bond]]
-CH) group. A peak at 1240 cm<sup>−1</sup> was assigned to CH
-[[Image:draft_Content_900806651-dbnd|center|px|double bond; length as m-dash]]
-CH stretching, and small peaks ranging from 1100 to 1000 cm<sup>−1</sup> were assigned to C
-[[Image:draft_Content_900806651-sbnd|center|px|single bond]]
 O stretching [[#b0140|[28]]].
 <span id='f0010'></span>

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