Speciation of Chromium in Water Samples with Homogeneous Liquid-Liquid Extraction and Determination by Flame Atomic Absorption Spectrometry

Abkenar, Shiva Dehghan,Hosseini, Morteza,Dahaghin, Zohreh,Salavati-Niasari, Masoud,Jamali, Mohammad Reza Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.10

A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III) reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion ($TBA^+$)-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a $100\;{\mu}L$ micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9.5, [ligand] = $1.0{\times}10^{-4}\;M$, [$TBA^+$] = $2.0{\times}10^{-2}\;M$, [$CHCl_3$] = $100.0\;{\mu}L$ and [$ClO_4$] = $2.0{\times}10{-2}\;M$, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.

ENERGENT: An Energy-Efficient UAV-Assisted Fog-IoT Framework for Disaster Management

Shirin Abkenar, Forough,Iranmanesh, Saeid,Bouguettaya, Athman,Raad, Raad,Jamalipour, Abbas 한국통신학회 2022 Journal of communications and networks Vol.24 No.6

In this paper, we propose ENergy-efficient disastERmanaGmENT (ENERGENT) as a novel framework for disastermanagement in the unmanned aerial vehicle (UAV)-assisted Fog-Internet of things (IoT) networks. ENERGENT optimizes theenergy consumption of the terminal nodes (TNs), as well asthe UAVs, using three proposed algorithms. The first algorithmoptimally adjusts the 3D placement of the UAVs such that thesenodes consume the minimum energy to reach the desired clusterof the TNs. Besides, the transmit power and the transmissionrate of the TNs are set in a way that their energy consumptionis minimized and the outage probability requirements are metin the network. In the second algorithm, we propose an optimaltask offloading scheme where tasks are offloaded to the UAVsin order to meet the network delay constraints. Finally, thethird algorithm takes advantage of wireless power transfer totransfer energy to the TNs when their remaining energy degradesa predefined threshold. This scheme guarantees a minimumthroughput for all TNs within a cluster by which the totalnetwork throughput is maximized. Simulation results revealthat ENERGENT outperforms the existing methods in terms ofoptimized network energy consumption, delay, and throughput.

Speciation of Chromium in Water Samples with Homogeneous Liquid-Liquid Extraction and Determination by Flame Atomic Absorption Spectrometry

Shiva Dehghan Abkenar,Morteza Hosseini,Zohreh Dahaghin,Masoud Salavati-Niasari,Mohammad Reza Jamali 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.10

A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III)reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion (TBA+)-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a 100 μL micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9.5, [ligand] = 1.0 × 10‒4 M, [TBA+] = 2.0 × 10‒2 M, [CHCl3] = 100.0 μL and [ClO4‒] = 2.0 × 10‒2 M, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.

Determination of Trace Amounts of Lead and Copper in Water Samples by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

Shemirani, Farzaneh,Abkenar, Shiva Dehghan,Khatouni, Asieh Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.8

The need for highly reliable methods for the determination of trace metals is recognized in analytical chemistry and environmental science. A method based on the cloud-point extraction (CPE) technique for the trace analysis of Pb and Cu in water samples is described in this study. The analytes in the initial aqueous solution are complexed with pyrogallol, and 0.1%(w/v) Triton X-114 is added as surfactant. Following phase separation at $50^{\circ}C$, based on the cloud point of the mixture and dilution of the surfactant-rich phase with acidified methanolic solution, the enriched analytes are determined by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions, the enrichment factors of Pb and Cu were found to be 72 and 85, respectively. Under optimum conditions, the preconcentration of 60 mL of samples in the presence of 0.1%(w/v) Triton X-114 permitted the detection of 0.4 ${\mu}gL^{?1}$ of Pb and 0.05 ${\mu}gL^{?1}$ of Cu. The proposed method was applied successfully to the determination of Pb and Cu in water samples.

Determination of Trace Amounts of Lead and Copper in Water Samples by Flame Atomic Absorption Spectrometry after Cloud Point Extraction

Farzaneh Shemirani*,Shiva Dehghan Abkenar,Asieh Khatouni 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.8

Comparison of Frequencies in Order to Estimate of Tree Species Diversity in Caspian Forests of Iran

Mehrdad Mirzaei,Atefeh Karimiyan Bahnemiry,Kambiz Taheri Abkenar 강원대학교 산림과학연구소 2019 Journal of Forest Science Vol.35 No.1

Species diversity is one of the most important indices that used to evaluate the sustainability of forest communities. In the present study, three variables including number of individuals (frequency of species), basal area and volume of tree species were compared to estimate tree species diversity in broadleaves forests of Iran. Based on systematic random design, 30 plots (circle plot, 1000 m2) was selected. Type of species, number of species, DBH and height of trees were measured. Simpson (1-D), Hill (N2), Shannon-Wiener (H’), Mc Arthur (N1), Smith-Wilson (Evar) and Margalef (R1) indices used to estimate tree species diversity. Species diversity was calculated in each plot. ANOVA test showed that there was a significant difference between of three variables used for estimation of species diversity. Number of trees variable has more precision than basal area and volume variables to estimate of species diversity. But Duncan test revealed that there were significant difference between of basal area and volume variables with number of trees. Therefore, basal area and volume variables were selected as more suitable variables in order to estimate of biodiversity indices in northern forests of Iran.

Comparison of Frequencies in Order to Estimate of Tree Species Diversity in Caspian Forests of Iran

Mirzaei, Mehrdad,Bahnemiry, Atefeh Karimiyan,Abkenar, Kambiz Taheri Institute of Forest Science 2019 Journal of Forest Science Vol.35 No.1

Species diversity is one of the most important indices that used to evaluate the sustainability of forest communities. In the present study, three variables including number of individuals (frequency of species), basal area and volume of tree species were compared to estimate tree species diversity in broadleaves forests of Iran. Based on systematic random design, 30 plots (circle plot, $1000m^2$) was selected. Type of species, number of species, DBH and height of trees were measured. Simpson (1-D), Hill ($N_2$), Shannon-Wiener (H'), Mc Arthur ($N_1$), Smith-Wilson ($E_{var}$) and Margalef ($R_1$) indices used to estimate tree species diversity. Species diversity was calculated in each plot. ANOVA test showed that there was a significant difference between of three variables used for estimation of species diversity. Number of trees variable has more precision than basal area and volume variables to estimate of species diversity. But Duncan test revealed that there were significant difference between of basal area and volume variables with number of trees. Therefore, basal area and volume variables were selected as more suitable variables in order to estimate of biodiversity indices in northern forests of Iran.