Open Access Short Research Article

Synthesis and Characterization of Caprolactam- based Ionic Liquids as Green Solvents

Rania A. Naiyl, Fredrick O. Kengara, Kirimi H. Kiriamiti, Yousif A. Ragab

Asian Journal of Applied Chemistry Research, Page 74-87
DOI: 10.9734/ajacr/2021/v8i430201

Aims: To synthesize and characterize six caprolactam-based ionic liquids (CPILs) by combination of caprolactam with different organic and inorganic Brønsted acids that can be utilized for lipid extraction from microalgae.

Study design:  Experimental design include quantitative and qualitative.

Place and duration of study: The study was done at Department of Chemistry & Biochemistry, School of Sciences and Aerospace Studies, Moi University (Kenya) between November 2020 and May 2021.

Methodology: Six CPILs were prepared through a  simple neutralization reaction between Caprolactam and Brønsted acids such as Hydrochloric acid (HCl), Methane sulphonic acid (CH3SO3H), Trifluoromethanesulphonic acid (CF3SO3H), Acetic acid (CH3CO2H), Trifluoroacetic acid (CF3CO2H), and Sulfuric acid (H2SO4). The first three acids were used in the synthesis of CPILs for the first time. The chemical structures of the synthesized CPILs were characterized by Fourier transform infrared and Raman spectroscopy. The densities and viscosities were measured at 20 oC using the weight (pycnometer) and capillary viscometer (Oswald) methods, respectively.

Results: All the CPILs were insoluble in hexane and had high miscibility with water and methanol. Fourier transform infrared and Raman spectra of the CPILs were compared with that of free Caprolactam. The characteristic absorption bands of the synthesized compounds showed a big shift in position and/or intensity (compared to caprolactam), indicating the formation of the CPILs. The results showed that both the density and viscosity increased with the molecular weight of the anion - except in Caprolactamium hydrogen sulphate (CPSA)- which could be due to the strong interactions between the cation and anion resulting from the dimerization between hydrogen sulphate anions.  

Conclusion: The hydrophilic nature of the CPILs indicated by high miscibility with polar solvents (water and methanol) indicates that they are suitable for the dissolution of cellulose of microalgae cell wall and thus could result in high lipid extraction efficiency. Further studies should therefore utilize the synthesized CPILs in lipid extraction from microalgae.

Open Access Original Research Article

Point Zero Charge Determination and Fluoride Adsorption on Natural Red Ash (Metal Oxide)

Lejalem Abeble Dagnaw, Dessie Almaw Cherie

Asian Journal of Applied Chemistry Research, Page 1-6
DOI: 10.9734/ajacr/2021/v8i430196

The PZC is essential parameter for the characterization of certain materials used for the treatment of organic or inorganic wastes in the environment, particularly from waste water and industrial sludge. Potentiometric titration and batch experimentation method was used to determine PZC value and type of adsorption isotherm behavior observed.  Red ash is the natural metal oxides collected from the rift valley of Ethiopia which have PZC values of 3.35 for 0.5g, 1g and 1.5g adsorbent dose studied. On the adsorbent surface, monolayer and homogeneous adsorption process of fluoride observed. Therefore, based on the interest of the researcher and the adjustment of the pH of red ash solution might used for the treatment of ionic wastes.

Open Access Original Research Article

Treatment of Wastewaters from the Olive Mill Industry Wastewaters by Sonication Process at Different Conditions

Rukiye Oztekin, Delia Teresa Sponza

Asian Journal of Applied Chemistry Research, Page 7-53
DOI: 10.9734/ajacr/2021/v8i430197

In this study, the effects of increasing sonication time (60 min, 120 and 150 min), increasing temperatures (25oC, 30oC and 60oC), different Dissolved Oxygen (DO) concentrations (2 mg/l, 4 mg/l, 6 and 10 mg/l), different N2(g) sparging (15 and 30 min) and H2O2 concentrations (100 mg/l, 500 and 2000 mg/l) was investigated on Olive Mill Industry wastewaters (OMI ww) by sonication process. The maximum removal efficiencies were 60.91% CODdis, 59.28% TOC, 49.70% color, 58.25% total phenol, 63.27% total aromatic amines (TAAs), 37.51% total fatty acids (TFAs), at 25oC and 150 min, respectively. The maximum removal yields were 66.83% CODdis, 65.92% TOC, 83.77% color, 61.24% total phenol, 70.52% TAAs, 48.84% TFAs, at 60oC and 150 min, respectively. The maximum removal efficiencies were 88.73% CODdis, 93.79% color, 91.38% total phenol, 91.58% TAAs, 74.44% TFAs, at DO=10 mg/l, at 60oC and 150 min, respectively. The maximum removal efficiencies were 84.51% CODdis, 91.88% color, 78.98% total phenol, 74.56% TAAs, 80.18% TFAs, at 30 min N2(g) sparging, at 60oC and 150 min, respectively. The maximum removal yields were 91.13% CODdis, 93.59% color, 93.65% total phenol, 83.68% TAAs, 90.30% TFAs, at 2000 mg/l H2O2, at 60oC and 150 min, respectively. Sonication at 35 kHz proved to be a viable tool for the effective removal of COD, TOC, color, total phenol, TAAs and TFAs from OMI ww, providing a cost-effective alternative for destroying and detoxifying the refractory compounds in OMI ww.

Open Access Original Research Article

Antioxidants Capacity, Phenolic and Oxalate Content from Two Varieties of Solanum melongena at Different Maturity Stages

A. Mohd Zulkhairi, M. N. Siti Aisyah, M. Razali, G. Nur Syafini, M. B. Umikalsum, A. Aimi Athirah, M. Y. Nur Daliana, H. Rosali

Asian Journal of Applied Chemistry Research, Page 54-63
DOI: 10.9734/ajacr/2021/v8i430198

Aims: To investigate the antioxidant activities, total phenolic and oxalate contents in two varieties of eggplant (Solanum melongena) (terung telunjuk (TT) and terung rapuh (TR)) at different maturity stages.

Study design: Each sample was extracted three times (n=3) for the antioxidant activities, total phenolic and oxalates content. All the data were analysed by using ANOVA and Tukey Pairwise tests.

Place and duration of study: Malaysian Agricultural Research and Development Institute (MARDI), between December 2019 and October 2020.

Methodology: Two varieties of eggplant (TT and TR) were cultivated and the samples were tagged and the fruits were harvested according to their maturity stages (stage 1 – stage 4). Samples were freeze dried and extracted to evaluate the antioxidant activities as well as the total phenolic and oxalate contents.

Results: Total phenolic contents (TPC) in TR were lower from stage 1 to stage 3 but high at over mature stage (stage 4) meanwhile TPC in TT increased upon maturity. The DPPH assay from the fruit extracts of TT in all maturity stages showed a stronger antioxidant activity as compared to TR, in which fruit of TT from stage 3 was double in antioxidant activity as compared to TR. The FRAP assay of both eggplants showed extracts of TT having a higher ferric reduction power in all stages as compared to TR. Meanwhile, both eggplant varieties showed different total, soluble and insoluble oxalate contents in all maturity indices. TT had the highest total oxalate content at stage 1 as compared to TR while the soluble oxalate content increased in TR in all maturity stages. The highest percentage of soluble oxalate content was observed in TR at stage 4 with 95.5%. Conclusion: Phytochemical findings from these eggplant varieties showed their potentials to improve livelihood and public health. More comprehensive studies on the bioactive compounds, structural elucidation and pharmacological evaluation are to be conducted to understand the possible effects of these phytochemical results.

Open Access Original Research Article

Thermodynamic and Adsorption Study of the Corrosion Inhibition of Mild Steel by Aframomum chrysanthum Extract in 0.1 M Hydrochloric Acid Solution

Omotola M. Fayomi, Habibat F. Chahul, David C. Ike, Gloria I. Ndukwe, Ikpum M. Phoebe

Asian Journal of Applied Chemistry Research, Page 64-73
DOI: 10.9734/ajacr/2021/v8i430200

The study reports the corrosion inhibition activity of methanol extract of Aframomum chrysanthum on mild steel in 0.1 M HCl, using gravimetry analysis. The weight loss of the mild steels was observed to increase with increasing immersion time. The inhibition efficiency (%IE) was also observed to have increased with increasing concentrations of the inhibitor but decreases with increasing immersion time. The effect of temperature change on the inhibition efficiency was also studied and it was observed that for every increase in temperature there was a corresponding increase in weight loss and decreased in the %IE. The highest values of %IE; 46.66, 56.66, 60.0, 80.0 & 93.33 was observed at temperature 303 K for 0.2, 0.4, 0.6, 0.8 & 1.0 g/L respectively. Activation energy (Ea) values and the enthalpy values reviews that the adsorption process followed a physisorption’s mechanism. Change in enthalpy (ΔH) and entropy change (ΔS) of the reaction was positive indicating the endothermic nature and the spontaneity of the reaction. Three adsorption isotherms were tried on the inhibition process and only the Temkin isotherm gave the best fit with R2 value of 0.903, describing the best adsorption mechanism. The adsorption equilibrium constants K­ads were positive, indicating the feasibility of the adsorption of the inhibitor to the metal surface. Gibb’s Free Energy change of adsorption, ΔGads are negative indicating that the adsorption of the extract of Aframomum chrysanthum on mild steel surface is spontaneous. The values of ΔGads shows physisorption mechanism. All confirming that Aframomumm chrysanthum extract is a good corrosion inhibitor on mild steel in 0.1 M HCl.