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SYNTHESIS OF POLY- TETRA-p-ALLYLCALIX[4]ARENE TETRA ACETIC ACID ADSORBENT FOR Cr(III) AND Pb(II) METAL IONS
No full textThis paper discusses the preparation, characterization, and the evaluation of adsorption
properties of resin poly-tetra-p-allylcalix[4]arene tetra acetic acid from the p-t-butylphenol. The
synthesized resins were applied as an adsorbent for Cr(III) and Pb(II) metal ions. The
adsorption was conducted in a batch system by investigating the effects of acidity (pH), contact
time and initial concentration of a heavy metal solution. The adsorption of Cr(III) and Pb(II)
metal ions on the resin had the optimum pH rating in region of 4–6 and reached the equilibrium
condition in 40 minutes. The adsorption of Cr(III) and Pb(II) metal ions on the resin follows the
Langmuir isothermal pattern with the linearity constant (R2
) of Cr(III) and Pb(II) adsorption,
whose results were 0.9640 and 0.9716, respectively. The adsorption capacity of Cr(III) and
Pb(II) metal ions is 323.0 µmole/g and 33.4 µmole/g , while the adsorption energy is 30.4
kJ/mole and 39.7 kJ/mole, respectively. Most parameters in batch systems confirm that resin is
a good adsorbent for Cr(III) and Pb(II), though Cr(III) adsorption was more favorable than that
of Pb(II). The outstanding adsorption abilities for Cr(III) and Pb(II) metal ions have exhibited
good prospects for disposal application of polluted water and environmental protection.
Keywords: Adsorption; Metal ions; Poly-tetra-p-allylcalix[4]arene tetra acetic acid; p-t-
butylpheno
Phytoextraction of Cr(VI) from soil using Portulaca oleracea
No full textCr(VI) represents an environmental challenge in both soil and water as it is soluble and bioavailable over a wide range of pH. In previous investigations, Portulaca oleracea (a plant local to the United Arab Emirates (UAE)) demonstrated particular ability for the phytoextraction of Cr(VI) from calcareous soil of the UAE. In this publication, the results of the evaluation of P. oleracea phytoextraction of Cr(VI) from UAE soil at higher concentrations are reported. P. oleracea was exposed to nine different concentrations of Cr(VI) in soil from 0 to 400 mg kg−1. The uptake of Cr(VI) increased as its concentration in soil increased between 50 and 400 mg kg−1, with the most efficient removal in the range from 150 to 200 mg kg−1. The total chromium concentrations exceeded 4600 mg kg−1 in roots and 1400 mg kg−1 in stems, confirming the role of P. oleracea as an effective Cr(VI) accumulator. More than 95% of the accumulated Cr(VI) was reduced to the less toxic Cr(III) within the plant
Protein expression on Cr resistant microorganism using electrophoresis method
No full textAbstrak. Fatmawati U, Suranto, Sajidan. 2009. Ekspresi protein pada mikroorganisme resisten Cr dengan metode elektroforesis.
Nusantara Bioscience 1: 31-37. Krom heksavalen (Cr(VI)) dikenal sebagai logam berat beracun, sehingga perlu direduksi menjadi
Cr(III) yang lebih rendah toksisitasnya. Pseudomonas aeruginosa, Pseudomonas putida, Klebsiella pneumoniae, Pantoea sp. dan
Saccharomyces cerevisiae adalah mikroorganisme resisten dan mampu mereduksi Cr(VI). Tujuan penelitian ini adalah mengetahui
kemampuan mikroorganisme dalam mengurangi Cr(VI) dan mengetahui pola pita protein antara mikroorganisme resisten Cr(VI) dan
mikroorganisme tidak resisten yang diinokulasi pada medium kaldu LB. SDS-PAGE digunakan untuk mengetahui ekspresi protein,
sementara konsentrasi Cr(VI) diidentifikasi dengan metode 1,5 difenilkarbazid. Data kuantitatif dianalisis dengan ANAVA dua faktorial
dilanjutkan dengan uji jarak berganda Duncan pada taraf 1%. Data kualitatif yaitu ekspresi protein dianalisis dengan mobilitas relatif
(Rf). Hasil penelitian menunjukkan bahwa kemampuan mikroorganisme dalam mereduksi Cr(VI) pada konsentrasi awal 0.5 ppm, 1 ppm,
5 ppm dan 10 ppm berbeda-beda, persentase rata-rata kemampuan masing-masing mikroorganisme dalam mereduksi Cr(VI) adalah: P.
putida (65%) > S. cerevisiae (64,45%) > P. aeruginosa (60,73%) > Pantoea sp. (50,22%) > K. pneumoniae (47,82%) > tanpa
mikroorganisme (34,25%). Penambahan mikroorganisme secara nyata mempengaruhi reduksi Cr(VI). SDS-PAGE menunjukkan bahwa
ekspresi protein antara mikroorganisme resisten dan tidak resisten tidak berbeda, tetapi mikroorganisme resisten memiliki lebih banyak
protein (pita protein lebih tebal).
Kata kunci: logam berat Cr, mikroorganisme, protein, elektroforesis
CR-Cross
No full textCR-Cross: A Novel Approach for Cross Domain Coral Recognitions with Reject Options</p
Effects of the alloy composition on phase constitution and properties of laser deposited Ni-Cr-B-Si coatings
No full textThree Ni-Cr-B-Si hardfacing alloy powders with different Cr contents and Si to B ratios were deposited at cladding speeds of 5-40 mm/s on steel substrate using laser beam and the alloy composition-phase formation-properties relationships in the deposits were studied using several experimental techniques. Two general groups of compositions could be defined in this alloy system; the high-alloy grades characterized by numerous Cr boride precipitates, a low Si/B ratio and substantial Ni-B-Si eutectics, and the low-alloy grades with very little Cr boride precipitates, a high Si/B ratio and limited amounts of interdendritic eutectics. The findings confirmed that phase formation of Ni-Cr-B-Si laser deposited coatings primarily depends on the Cr content and Si/B ratio with the former controlling the amount of Cr-rich precipitates and the latter influencing the nature of the eutectic structures. In addition, it is shown that both Cr-rich precipitates and eutectic structures contribute to the functional properties of the coatings such as hardness and cracking susceptibility. The correlation between phase constitutions produced by different compositions and the hardness/cracking tendency is established and discussed.
Carburisation of ferritic Fe–Cr alloys by low carbon activity gases
No full textModel Fe–Cr alloys were exposed to Ar–CO2–H2O gas mixtures at 650 and 800 °C. At equilibrium, these atmospheres are oxidising to the alloys, but decarburising (aC ≈ 10−15 to 10−13). In addition to developing external oxide scales, however, the alloys also carburised. Carbon supersaturation at the scale/alloy interface relative to the gas reflects local equilibrium: a low oxygen potential corresponds to a high pCO/pCO2 ratio, and hence to a high carbon activity. Interfacial carbon activities calculated on the basis of scale–alloy equilibrium are shown to be in good agreement with measured carburisation rates and precipitate volume fractions, providing support for the validity of the thermodynamic model
Micro-abrasion–corrosion of a Co–Cr/UHMWPE couple in Ringer's solution : an approach to construction of mechanism and synergism maps for application to bio-implants
No full textIn studies of tribo-corrosion, the degradation of bio-materials has become of increasing research interest in recent years. This is because, in many cases, the interactions of the tribological and corrosion component in biological environments are not well understood. Moreover, the wide range of variables involved in the tribo-corrosion process, and the variety of materials used in such conditions, means that there are few systematic studies where materials and operating conditions are optimized. In the total replacement of hip joints, the Co-Cr/UHMWPE couple has been used widely. However, the application of any replacement joint for biological conditions will depend on many factors including the activity of the patient and the overall load imposed on the artificial joint. This means evaluation of the tribo-corrosion behaviour over a multi parameter space is important in order to assess the degradation possible for many patient/activity and body mass categories.In this work, the performance of a Co-Cr/UHMWPE couple was evaluated in Ringer's solution in a tribological situation where micron size particles particles were entrained in the contact - micro-abrasion-corrosion. The effects of applied load and potential were investigated in the study. Micro-abrasion-corrosion maps were constructed for the material indicating the mechanism of degradation, the extent of wastage and of synergy/antagonism involved in the tribo-corrosion interaction
Electrodeposition and characterization of Fe-Cr-P amorphous alloys from trivalent chromium sulfate electrolyte
No full textFe-Cr-P amorphous alloys were electrodeposited in a trivalent chromium sulfate electrolyte containing glycine as complexing agent. The effects of bath composition and electrodeposition parameters such as current density, bath pH and plating time on the structure, morphology
and composition of the amorphous Fe-Cr-P deposits were investigated. The optimum bath composition and electrodeposition parameters were obtained using glycine as complexing agents. It showed that glycine is a suitable complexing agent to get good quality of Fe-Cr-P amorphous
alloys by trivalent chromium electrodeposition. The obtained Fe Cr P deposits were characterized by means of SEM, EDS, XRD as well as XPS techniques. It was observed that the chromium content in the deposits increased with increasing the cathodic current density. When current density
exceeds specific value, the chromium content in the deposit would decrease. SEM results show that fine-grain, smooth and compact Fe-Cr-P alloy deposits were obtained. Results of EDS and XPS indicate that the deposited alloys contain chromium, iron, phosphorus, nitrogen, oxygen and carbon. The XRD pattern reveals that the Fe-Cr-P alloy deposit has amorphous structure. These results may be of some practical and theoretical significance for further improving chromium alloy electrodeposition process.Fe-Cr-P amorphous alloys were electrodeposited in a trivalent chromium sulfate electrolyte containing glycine as complexing agent. The effects of bath composition and electrodeposition parameters such as current density, bath pH and plating time on the structure, morphology
and composition of the amorphous Fe-Cr-P deposits were investigated. The optimum bath composition and electrodeposition parameters were obtained using glycine as complexing agents. It showed that glycine is a suitable complexing agent to get good quality of Fe-Cr-P amorphous
alloys by trivalent chromium electrodeposition. The obtained Fe Cr P deposits were characterized by means of SEM, EDS, XRD as well as XPS techniques. It was observed that the chromium content in the deposits increased with increasing the cathodic current density. When current density
exceeds specific value, the chromium content in the deposit would decrease. SEM results show that fine-grain, smooth and compact Fe-Cr-P alloy deposits were obtained. Results of EDS and XPS indicate that the deposited alloys contain chromium, iron, phosphorus, nitrogen, oxygen and carbon. The XRD pattern reveals that the Fe-Cr-P alloy deposit has amorphous structure. These results may be of some practical and theoretical significance for further improving chromium alloy electrodeposition process
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