Functional groups of bio-lubricants from crude catfish oil (Pangasius hypothalamus)

Bio-lubricants have great potential in the production of lubricating in the future. Several studies have developed animal oils as lubricants, which come from a by-product of fish processing. Fish oil extracted from the material and processed into bio-lubricants reached the highest yield of 94%. This research aimed to study the bio-lubricants functional groups. The research steps extracted crude fish oil as raw material, hydrolysis using HCl catalyst, polymerization using benzoyl peroxide, and polyesterification using ethylene glycol. The extraction process used the wet rendering method with a ratio of catfish waste (viscera) to the water of 1:2 (w/v) at 70 °C for 30 minutes. The best bio-lubricants were analyzed for functional groups using an FT-IR instrument with a wave range of 4000-450 cm−1. The results obtained were the absorption wavelength peak of 3472 cm−1, indicating O-H bonds with the sloping peak and the weak bond. The absorption wave peak of 3006-2852 cm−1 indicated a strong C-H bond (alkane). The absorption wave peaks of 1743 cm−1 indicated the presence of a C=O double bond. The adsorption wave peaks at 1465 cm−1 indicated carbon chain bonds between C-C, while the absorption wave peaks at 1115 and 1174 cm−1 indicated C-O bonds. The three spectral indicated that the ester groups formed in bio-lubricants. In the polymerization reaction, there was no absorption wave of 1600-1500 cm−1 which indicated that all C=C groups had been polymerized by benzoyl peroxide. Meanwhile, a sloping absorption wave of 3472 cm−1 was found in the polyesterification reaction due to the weak O-H bond. The analysis obtained above showed the differences in wave peak between bio-lubricant and crude fish oil as raw material but had the same group shape.

The adsorption of methylene blue on montmorillonite from acid solutions

The adsorption of methylene blue (MB) on montmorillonite from acid solutions has not yet been studied in detail. In this paper the adsorption of this dye on Ca/SAz montmorillonite from 0.32, 0.80 and 1.60 M HCl solutions at ambient temperature and after 2 hours leaching was carefully studied and evaluated. Under the above conditions the MB/SAz intercalates formed are practically insoluble. In contrast to the adsorption of methylene blue on montmorillonite from aqueous solutions, the adsorption from acid solutions consists of two adsorption waves. The intercalated samples from the first and second waves were studied using X-ray powder diffraction (XRD), FTIR, Vis spectroscopy, and scanning electron microscopy (SEM) equipped with a microprobe system. The adsorption of MB in the first wave is attributed to ion exchange of the dye cationic species (MB+, MB22+, H-aggregates, MBH2+ and H+) for the original interlayer cations of montmorillonite. The percentages of MBH2+ and H+ based on total adsorbed MB were estimated for varying HCl concentrations. The second adsorption wave is linked to the precipitation of MB species on the outer MB/SAz surface.

Adsorption Wave of Vanadium Complex with 2,3–Dihydroxybenzaldehyde

The polarographic behavior of the complex formed by V(V) and 2,3–dihydroxybenzaldehyde (2,3–DHBA) in the solution containing acetate buffer (pH 5,2) has been investigated. By means of a.c. polarography, chronovoltammetry and other techniques, it has been shown that the electrode process is complicated by the adsorption of 2,3-DHBA and its vanadium complex. The kinetic and adsorption parameters of the electrode process have been determined: adsorption equilibrium constant B= 1,32⋅105 mol-1⋅dm3, the attraction constant γ = 1,2, the maximum surface concentration Гmax = 9,10⋅10-11 mol⋅ cm-2; the share of the electrode surface occupied by one particle of the adsorbed complex S = 1,81 nm2 and the free adsorption energy ΔG = - 39,1 kJ· mol-1.

Role of the solvent in the oxidative process of a Hg electrode in the presence of thiopyrimidine derivatives

The electrochemical oxidation of a Hg electrode in the presence of thiopyrimidine derivatives has been investigated in a collection of organic solvents using voltammetric and polarographic techniques. Remarkable adsorption phenomena control the electrochemical process, which in all cases gives rise to a Hg(I) complex. The Laviron adsorption model is found to describe well the polarographic adsorption wave. Some correlations between adsorption parameters and solvent properties have also been observed and discussed.Key words: polarography, voltammetry, thiopyrimidine, solvent effect, adsorption.