Open Access Original Research Article

Study of the Adsorption of Nitrogen Compounds for Diesel Fuel Production Using Three Commercial Materials

Pedro M. Vega-Merino, Georgina C. Laredo, Fernando Trejo-Zárraga, J. Jesús Castillo

Chemical Science International Journal, Page 105-121
DOI: 10.9734/ACSJ/2015/13830

The aim of this work was to study the removal of nitrogen (N-) compounds for ultra-low sulfur diesel (ULSD) production purposes by using three commercial materials: selexsorb® CDX (CDX), silica gel (SG), and activated carbon VG-077 (VG-077). The experiments were conducted in three steps: (1) Adsorption of quinoline, indole, or carbazole from model fuels (300wppm in a 1:1g/g n-hexadecane:toluene mixture) in a batch setup; adsorption of N- compounds from straight run gas oil (SRGO): (2) in a batch setup, and (3) in a fixed-bed column (FBC). Langmuir and Freundlich models were considered for modeling the adsorption isotherms of quinoline, indole, carbazole from model fuels and N-compounds from SRGO. Clark and Thomas models were employed for fitting the FBC experimental data. In the batch experiments, the adsorption capacities (qm) for neutral N-compounds were 0.795mmol/g (VG-077), 0.287mmol/g (CDX), and for basic N-compounds were 0.708mmol/g (SG), 0.385mmol/g (CDX), and 0.242mmol/g (VG-077). The goodness of the fit for the Langmuir and Freundlich models strongly depended on the N-compound and the adsorbent when treating model fuels. Treating SRGO, VG-077 presented a higher qm (0.855mmol/g) than the other two materials (0.687mmol/g (SG) and 0.372mmol/g (CDX)), which is understandable because neutral N-compounds represent 75% of nitrogen in this fuel. The Langmuir model was better than the Freundlich model to reproduce the adsorption isotherms properly with SRGO (R2>0.9966). Besides, the pseudo second-order model performed better than the pseudo first-order model to simulate the adsorption rates in almost all cases, although the comparison was not straightforward, because the values depended highly on the N-compound and the material studied. In the FBC experiments, the Clark model agreed better with the experimental data than the Thomas model did. VG-077 achieved the highest N-adsorption (0.38mmol/g vs. 0.18mmol/g (SG) and 0.15mmol/g (CDX)). However, according to the preliminary estimation carried out, a higher adsorption capacity is still required for commercial application of this process.

 

Open Access Original Research Article

Physicochemical Characterization of Water Quality - Lagoa dos Índios in Macapá, Brazil

Josivan S. Costa, Francinaldo S. Braga, Sheylla Susan M. S. Almeida, Ryan S. Ramos, Daímio C. Brito, Alan C. Cunha, Cleydson Breno R. Santos

Chemical Science International Journal, Page 122-134
DOI: 10.9734/ACSJ/2015/11705

Aims: To characterize relevant physicochemical parameters of water quality in an Amazonian tropical lake and compare them with the reference values of the Brazilian Resolution CONAMA 357/2005 and those recommended by the similar US-EPA law. In addition, to correlate statistically the parameters in two different climatic periods.

Study Design: The sampling procedures occurred in five sites of a tropical lagoon (Lagoa dos Índios) in Macapá-Amapá-Brazil. The investigation occurred during the rainy season (November / 2010) and dry season (March / 2011). Seventeen physical and chemical parameters were analyzed according to APHA (1998). The metal ions were determined by atomic absorption spectrometry, with a Shimadzu device (AAS model 6300). The pH was determined in situ with the portable pH-meter, mark ORION, Model 3 STARS THERMO.

Place and Duration of Study/Methodology: The physicochemical analyses were performed at the Laboratory of Chemistry, Sanitation and Environmental Systems Modeling, and the General Laboratory of Analytical Chemistry of the Federal University of Amapá (UNIFAP). The period was from November 2010 to March 2011. Data were analysed using the BioStat 5.0 software to elaborate a Correlation Matrix (Spearman Method and non-parametric test).

Results: Alkalinity presented values ​​outside the EPA standards, unlike hardness, that presented accordingly. The other variables studied ​​could be considered normal when compared to other as the nearby waters of the Amazon River. The results for biochemical oxygen demand (BOD), dissolved aluminum, ammonia nitrogen, total dissolved solids (TDS), nitrate, chloride and turbidity measurement showed in accordance with the reference values ​​of CONAMA and US-EPA. Then a nonparametric test (Kruskal Wallis) showed significant differences in water quality between both seasonal periods as among at the five sampling sites. Kruskal Wallis test showed also significant differences space-seasonal in the water quality. So, the Spearman correlation showed good fitness with some physicochemical parameters: a positive correlation between pH and alkalinity, EC and pH, alkalinity, TDS, and negative correlation between DO and BOD.

Conclusion: We concluded that the Spearman correlation matrix describes reasonably well the behavior of the heterogeneous quality of the Lagoa dos Índios to the different sampling sites, both in the dry season and in the rainy season. The water quality is yet within legal standards expected to CONAMA Resolution 357/2005 and EPA-USA. However, there is evidence of imbalances of some parameters of water quality resulting from likely effects of urban pollution on the water quality of the lagoon.

 

Open Access Original Research Article

Determination of Heavy Metals in Fish (Clarias gariepinus) Organs from Asaba Major Markets, Delta State, Nigeria

Kelle Henrietta Ijeoma, Ngbede Esther Onyoche, Oguezi Veronica Uju, Ibekwe Fidelis Chukwuene

Chemical Science International Journal, Page 135-147
DOI: 10.9734/ACSJ/2015/11968

Aim: To determine and compare the bioaccumulation of selected heavy metals- zinc, lead, cadmium, copper, mercury, and cobalt in organs of Clarias gariepinus obtained from fish sellers in the three major markets in Asaba.

Place and Duration of Study: Department of Chemistry Education Laboratory, Federal College of Education (Technical), Asaba between June and August 2013.

Methodology: Catfish, Clarias gariepinus sold commercially, were bought in replicates from three major markets in Asaba. The samples were dissected and the various organs dried separately at 110ºC to constant weight. The ground samples were digested with aqua regia solution and the heavy metals concentrations determined by AAS machine.

Results: The result revealed that the gills contained the highest total concentration (11.363 ppm)representing 27.70% of the detected heavy metals followed by the liver (11.267 ppm) representing 27.46% followed by the heart (10.303 ppm) representing 25.11% while the muscle had the lowest concentration (8.095) representing 19.73%. The difference in the bioaccumulation in the various organs however, did not differ significantly (P = 0.990). The overall accumulation pattern for the three markets was: Ogbeogonogo - Zn > Hg > Cu >Pb> Cd > Co; Cable - Zn > Cu > Hg >Pb> Co > Cd; and Abraka - Zn > Cu > Hg > Cd > Co >Pb. Zn mean concentration differs significantly (P =.000) from those of other metals. Mean concentrations of Pb, Cd, and Co were significantly the same but differ from those of Cu and Hg whose mean concentrations were statistically the same. The total concentrations in ppm of Zn (35.995, 32.336, and 36.292); Cu (1.587, 4.189, and 3.496) and Co (0.016, 0.070, and 0.088) in the three markets were below the permissible limits of 150 ppm, 10 ppm, and 0.15 – 1.0 ppm respectively stipulated by FAO/WHO. Also, the concentrations of Pb, 0.139 in Cable and 0.000 in Abraka; and Cd, 0.042 in Ogbeogonogo and 0.031 in Cable were below the permissible limits 0.5 ppm for Pb and 0.05 ppm for Cd. However, the concentrations in ppm of Pb, 0.949 in Ogbeogonogo, Cd, 0.673 in Abraka, and Hg in all three markets were above the permissible limits of 0.5 ppm, 0.05 ppm and 0.5 ppm in fish and food substances.

Conclusion: The consumption of Clarias gariepinus sold in these markets poses serious health threat to humans especially pregnant women.

Open Access Original Research Article

Characterization and Elastic study on Zinc Sulphide Nanofluid Doped with Neodymium

George Varughese, T. Lincy, S. Sincy, K. T. Usha

Chemical Science International Journal, Page 148-155
DOI: 10.9734/ACSJ/2015/13534

Among the Semiconductor nanoparticle ZnS as an important II-VI semiconductor has been researched extensively because of the broad spectrum of potential application such as catalysis, cathode ray tube (CRT), field emission display (FED) phosphors for a long time. It can be used for electroluminescent devices and photodiodes. Zinc sulphide doped with Neodymium (ZnS: Nd) quantum dots have various applications in electronics, nonlinear optical devices and optical computers. ZnS: Nd nanomaterials with an average particle size of 21-25 nm are synthesized by the reaction of zinc acetate and hydrogen sulphide by chemical route technique. XRD, SEM, FTIR and EDS characterize the samples. The percentage of doping material in the crystal is confirmed from the EDS spectra. The average crystal size of the prepared ZnS nanopowder is determined by XRD. Ultrasonic velocity through doped and undoped sample is measured and compressibility is computed. The compressibility is found to be increased. Also variation of compressibility of ZnS: Nd nanofluid with various grain size have been carried out and found that compressibility increases with decrease of particle size.

 

Open Access Original Research Article

Tissues Accumulation of Heavy Metals by Maize (Zea maize L.) Cultivated on Soil Collected from Selected Dumpsites in Ekiti State, Nigeria

E. E. Awokunmi, O. S. Adefemi, S. S. Asaolu

Chemical Science International Journal, Page 156-162
DOI: 10.9734/ACSJ/2015/9262

Aims: The study examined the levels of heavy metals in tissues of maize (Zea mays L.), cultivated on four selected dumpsites in Ekiti State, Nigeria; with a view to discouraging constant cultivation of abandoned dumpsites.

Study Design: It is an analytical study.

Place and Duration of Study: The study was carried out in 2012 on selected dumpsites located in Ekiti State, Nigeria.

Methodology: Representative soil samples collected from four dumpsites located in Ekiti State were analyzed for pH, organic matter and heavy metals, prior to plant cultivation. After maturity, heavy metals concentrations were determined in various sections of plant, using flame absorption spectrophotometer. All determinations were carried out in triplicates using standard analytical procedures. The results obtained were subjected to statistical analyses.

Results: The results showed that these dumpsites were grossly polluted  with heavy metals when compared with control sites in the range: Cd (21.9-138.0), Co (11.1-60.8), Cr (9.0-29.8), Cu (7.0-18.0), Fe (125.0-752.0), Pb (35.0-60.0), Mn (11.0-47.1), Ni (15.0-29.8), Sn (3.5-9.6) and Zn (63.0-80.2), all in mg/kg. Moderate values of soil pH and organic matter content revealed that maize could thrive well on mentioned dumpsites. However, the plant accumulated elevated concentrations of heavy metals in their shoot, when compared with the root, with Cr and Pb having higher concentration range of 101-104 mg/kg and 109.9-158.2 mg/kg respectively in its shoot at all dumpsites investigated.  

Conclusion: Therefore, cultivation of arable crops on dumpsites should be discouraged as constant environmental monitoring is imperative.

 

Open Access Original Research Article

A Sequential Injection Analysis Method for the Determination of Glyphosate and Aminomethylphosphonic Acid in Water Samples

Britta Jahnke, Carsten Frank, José F. Fernández, Bernd Niemeyer

Chemical Science International Journal, Page 163-173
DOI: 10.9734/ACSJ/2015/13089

A conventional laboratory method for the determination of glyphosate and its degradation product aminomethylphosphonic acid (AMPA) is high performance liquid chromatography (HPLC) followed by post column derivatization with o-phthaldialdehyde (OPA). However, AMPA is partly decomposed in the process causing a deviation in the AMPA detection or even making a simultaneous detection of glyphosate and AMPA with the described postcolumn procedure impossible. We used a compact sequential injection analysis system and optimized the process conditions for both analytes independently from each other. The process conditions were adjusted to the different chemical characteristics of AMPA (primary amine) and glyphosate (secondary amine), which needs to be oxidized to a primary amine prior to the derivatization. An ion exchange column was included in the system to eliminate amines interfering with the method. Limits of detection of 16 and 9 µg L-1 for glyphosate and AMPA, respectively are similar to those achieved with HPLC methods reported in literature, but compared to conventional HPLC methods only small amounts of reagents are consumed.

Open Access Original Research Article

Water Quality Characteristics of Floodwater from ABA Metropolis, Nigeria

E. C. Ogoko, D. Emeziem, I. Osu Charles

Chemical Science International Journal, Page 174-184
DOI: 10.9734/ACSJ/2015/12649

Aims: To report the extent of contamination of floodwater by physicochemical parameters (total suspended solids, total dissolved solid, chemical oxygen demand, biochemical oxygen demand, dissolved oxygen, electrical conductivity, nitrate, nitrite, chloride and sulphate  and heavy metals (Zn, Cu, Pb, Hg, As and Cd).

Study Design: Triplicate floodwater samples collected from ten different sample points in Aba metropolis, Abia State, in the month of July, 2012 were analyzed for physicochemical parameters and heavy metal concentrations.

Place and Duration of Study: The study was carried out at Temple-Gate polytechnic Aba and the analysis was conducted at the Industrial and Analytical Chemistry Laboratory of University of Port Harcourt, River’s State, Nigeria at mid July, 2012.

Methodology: Nitrate, nitrite and sulphate were quantitatively determined by spectrophotometric method while chloride was determined by titrimetric method. Heavy metals in water were determined by atomic absorption spectrophotometry while BODs, COD, DO, TDS, TSS, pH, turbidity and Hardness of water were determined by standard methods.

Results: Results indicated a wide variation in the concentrations of different physicochemical parameters and those of heavy metals at various study sites. Correlation coefficient analysis of data showed statistically significant positive correlation between the following two pairs of parameters: Electrical conductivity and total dissolved solid; Sulphate and hydrogen ion concentration; And nitrates and sulphate. Others are cadmium and chemical oxygen demand; Mercury and cadmium as well as arsenic and hydrogen ion concentration. However, significant negative associations were observed between arsenic and copper; Cadmium and total dissolved solid; And lastly nitrate and chemical oxygen demand. Furthermore, highly significant positive relationship was observed between lead and dissolved oxygen while highly significant negative association occurred between sulphate and chemical oxygen demand. Among the metals determined, Cu had the highest concentration while Hg had the lowest concentration.  

Conclusion: The values obtained for the anions and heavy metals were higher than the tolerance limits for aesthetic and inland surface water quality, indicating pollution of the sample areas.

 

Open Access Original Research Article

Kinetics and Mechanism of Malachite Green Oxidation by Hypochlorite Ion in Aqueous Acidic Medium

S. O. Idris, A. Tanimu, J. F. Iyun, Y. Mohammed

Chemical Science International Journal, Page 185-193
DOI: 10.9734/ACSJ/2015/12705

The kinetic investigations of the redox reaction between malachite green, MG+, and hypochlorite ion, ClO, were carried out in aqueous HClO4 medium at [H+] = 1x10–3 mol dm–3, µ = 0.1 mol dm–3, T =  25±1°C. The reaction showed a stoichiometry  of  1:2, which conforms to the equation:

            MG+  +  2ClO  Products

Kinetic data revealed a first order dependence on both [MG+] and [ClO-] giving a second order overall. The second order rate law for the reaction conforms to the equation:

            −d[MG+]/dt   =   k2[MG+][ClO-]

where k2 = 115.55± 1.21 dm3 mol-1 s–1

Reaction rate increased with increase in [H+]. Changes in ionic strength and dielectric constant of the reaction medium did not alter the reaction rate. Addition of anions at different concentrations also did not affect reaction rate.  The absence of spectroscopic evidence of intermediate complex formation suggests that the reaction proceeds through the outersphere mechanism. This suggestion is further reinforced by kinetic evidence from the Michaelis-Menten plot. A plausible mechanism based on these observations is proposed.

 

Open Access Original Research Article

Removal of Toxic Metal Ions in Water by Photocatalytic Method

E. T. Wahyuni, N. H. Aprilita, H. Hatimah, A. M. Wulandari, M. Mudasir

Chemical Science International Journal, Page 194-201
DOI: 10.9734/ACSJ/2015/13807

Aims: To study the photocatalytic method for decreasing the concentration of Cu(II),  Cd(II), Cr(VI), and Pb(II) in the solutions.

Study Design: The photocatalytical process was proceeded for single solutions containing respective Cu(II), Cd(II), Cr(VI), and Pb(II) ions. Reaction time, photocatalyst dose, and solution pH were optimized. The influence of Cr(VI), Cd(II) and Pb(II) ions on the Cu(II) removal was also evaluated.

Place and Duration of Study: Laboratory of Analytical Chemistry, Chemistry Department, Gadjah Mada University, Indonesia. June 2013 – January 2014.

Methodology: Photocatalytic process was carried out by  irradiating  100 ml of  4 single solutions containing 10 mg/L of Cu(II),  Cd(II), Cr(VI) and Pb(II) added with TiO2 with UV lamp having 290-390 nm of the wavelength, for certain time. The same procedure was also taken place with variation of  photocatalyst dose (10, 25, 50, 75, and 100 mg for 100 ml solution), irradiation time (1, 3, 5, 10, 25, 50, and 75 h), and solution pH (1, 3, 5, 7, 9, and 13), and for 3 solutions containing Cu(II), that was added  with Cd(II), Cr(VI), and Pb(II) respectively.  The concentrations of Cu(II),  Cd(II) and Pb(II) ions in the solutions were measured by AA Spectrophotometer  and by spectrophotometer UV-Visible for Cr(VI) ion.

Results: The maximum effectiveness of the photocatalytic  process can be obtained by using 50 mg of TiO2, in 24 h and at pH 5, that can take  Cu(II), Cr(VI), Cd(II) and Pb(II) out from the solutions as high as 45.56%, 77.72%, 15.23%, and 40.32%, by photocatalytic reduction, adsorption on TiO2 and photocatalytic oxidation, respectively. The presence of Cr(VI) and Cd(II) can decrease Cu(II) photo reduction from  45.36% into 15.24% and into 40.53%, meanwhile Pb(II)  improves the photo reduction from 45.56 into 58.76% for low Pb(II) concentration.

Conclusion: The concentration of the toxic Cu(II) and Cr(VI), Cd(II), and Pb(II) ions can be successfully decreased by photocatalytic process through different mechanisms. The removal of the metal ions was controlled by photocatalyst dose, irradiation time, and solution pH. The presence of Cr(VI) and Cd(II) can inhibit Cu(II) photoreduction due to the competition,  meanwhile  Pb(II) with low concentration promotes Cu(II) photoreduction by synergic effect.