• Journal of the Korean Ceramic Society
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• v.27 no.1
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• pp.1-6
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• 1990

Preparation and heavy metal ion adsorption of sumicron hydroxy apatite were studied in this experiment. Submicron HAP was synthesized with Ca(OH)2 solution and H3PO4.Ca(OH)2 solution was made from water-quenching of CaCO3 heated at 1, 00$0^{\circ}C$ and 20%-H3PO4 was dropped into this Ca(OH)2 solution heated at 8$0^{\circ}C$. XRD pattern of prepared powder showed HAP crystal. The average particle size and sahpe of HAP were 0.25${\mu}{\textrm}{m}$ and sphere type. As a adsorbent, 1.0g of the prepared HAP powder in 1 liter of artifical 5ppm heavy matal waste water was sufficient, and more effective at pH7-9.

• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.895-908
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• 2023

Disposal of waste containing heavy metals into the environment is a major threat to human health and can result in toxic or chronic poisoning in aquatic life. In the current study, metal-resistant Raoultella ornithinolytica was isolated from metal-contaminated samples collected from the Tanjaro River, located southwest of Sulaymaniyah, Iraq. R. ornithinolytica was identified by partial amplification of 16S rRNA. The uptake potency of heavy metals was assessed using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and indicated that R. ornithinolytica removed 67, 89, 63.4, 55.6, 56.5, 65, and 61.9% of Cd, Pb, Cr, Ni, Zn, Co, and Fe, respectively. These removal rates were influenced by temperature, pH, and contact time; at 35℃ and pH 5 with a change in the incubation time, the reduction rate improved from 89 to 95% for Pb, from 36.4 to 45% for Cu, and from 55.6 to 64% for Ni. Gene analysis indicated that R. ornithinolytica contained pbrT, chrB, nccA, iroN, and czcA genes, but the pcoD gene was absent. Energy-dispersive X-ray spectroscopy (EDS) images showed evidence of metal ion binding on the cell wall surface with different rates of binding. Transmission electron microscopy (TEM) detected different mechanisms for metal particle localization; cell surface adsorption was the main mechanism for Pb, Zn, and Co uptake, while Cd, Ni, and Fe were accumulated inside the cell. The current study describes, for the first time, the isolation of R. ornithinolytica from metal-contaminated water, which can be used as an eco-friendly biological expedient for the remediation and detoxification of metals from contaminated environments.

• Polymer(Korea)
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• v.31 no.3
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• pp.239-246
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• 2007

The sulfonated ion exchange fibers were synthesized by $Co^{60}\;{\gamma}-ray$ radiation-induced graft copolymerization. Degree of grafting was increased with increasing the total dose. The degree of grafting for POF-g-St/DVB copolymer was 1000%. The ion exchange capacity of sulfonated ion exchange fibers were increased by increasing the degree of sulfonation. Its maximum value was 5.06 meq/g. The ion exchange capacity of sulfonated POF- co-St/DVB ion exchange fiber was higher than that of the sulfonated POF- co-styrene ion exchange fibers. The amount of adsorption for heavy metals were also increased with increase in the degree of grafting of the ion exchange fibers.

• Journal of Environmental Science International
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• v.5 no.2
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• pp.211-220
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• 1996

New thin-and diselena-crown ethers containing two suffer and selenium donor atoms have been prepared. And then, mercury ($Hg^{2+}$) ion-selective electrodes with PVC-plasticizer (STPB) based on some macrocycles as neutral carriers were also made. The electrochemical selectivities for various ions, and the effects for macrocycles, matrix of membranes, ratio of plasticizer to macrowcles, concentration and pH of test solution were investigated on the $Hg^{2+}$ ion-selective electrodes. The 1, 10-diselena-18-crown-6-PVC-STPB (sodium tetraphenylborate) exhibited good linear responses of ${28.2}\pm{0.6}$ decade-1 for $Hg^{2+}$ ion in the conientration ranges of $10^{-2}~10^{-6}$ M $Hg^{2+}$ ion. This electrode exhibited comparatively good selectivities for $Hg^{2+}$ ion in comparison with alkali and alkaline earth metal ions, some heavy metal ions and rare earth metal ion in the range of pH 2.5~6.0. In addition, this electrode was applied as a sensor in the titration of $Hg^{2+}$ ion with $1^-$ ion in water.

• Advances in environmental research
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• v.7 no.1
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• pp.53-71
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• 2018

Waste glass disposal causes environmental problems in the cities. To find a suitable green environmental solution for this problem low cost adsorbent in this study was prepared from waste glass. An effective new green adsorbent was synthesized by hydrothermal treatment of waste glass (WG), followed by acidic activation of its surface by HCl (WGP). The prepared adsorbent was characterized by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), and BET surface measurement. The developed adsorbent was used for the removal of heavy metals (Cd, Cu, Fe, Pb and Zn) from well water. Batch experiments were conducted to test the ability of the prepared adsorbent for the removal of Cd, Cu, Fe, Pb and Zn from well water. The experiments of the heavy metals adsorption by adsorbent (WGP) were performed at different metal ion concentrations, solution pH, adsorbent dosage and contact time. The Langmuir and Freundlich adsorption isotherms and kinetic models were used to verify the adsorption performance. The results indicated high removal efficiencies (99-100%) for all the studied heavy metals at pH 7 at constant contact time of 2 h. The data obtained from adsorption isotherms of metal ions at different time fitted well to linear form of the Langmuir sorption equation, and pseudo-second-order kinetic model. Application of the resulted conditions on well water demonstrated that the modified waste glass adsorbent successfully adsorbed heavy metals (Cd, Cu, Fe, Pb and Zn) from well water.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.411-417
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• 1999

The interfacial chemical behavior, lattice exchange and dissolution, of $FeS_{(S)}$ as one of the important sulfide minerals was studied. Emphases were made on the surface characterization of hydrous $FeS_{(S)}$, the lattice exchange of Cu(II) and $FeS_{(S)}$, and its effect on the dissolution of $FeS_{(S)}$, and also affect some organic ligands on that of both Cu(II) and $FeS_{(S)}$. Cu(II) which has lower sulfide solubility in water than $FeS_{(S)}$ undergoes the lattice exchange reaction when Cu(II) ion contacts $FeS_{(S)}$ in the aqueous phase. For heavy metals which have higher sulfide solubilities in water than $FeS_{(S)}$, these metal ions were adsorbed on the surface of $FeS_{(S)}$. Such a reaction was interpreted by the solid solution formation theory. Phthalic acid(a weak chelate agent) and EDTA(a strong chelate agent) were used to demonstrate the effect of organic lignads on the lattice exchange reaction between Cu(II) and $FeS_{(S)}$. The $pH_{zpc}$ of $FeS_{(S)}$ is 7 and the effect of ionic strength is not showed. It can be expected that phthalic acid has little effect on the lattice exchange reaction between Cu(II) and $FeS_{(S)}$. whereas EDTA has very decreased the removal of Cu(II) and $FeS_{(S)}$. This study shows that stability of sulfide sediments was predicted by its solubility. The pH control of the alkaline-neutralization process to treat heavy metal in wastewater treatment process did not needed. Thereby, it was regarded as an optimal process which could apply to examine a long term stability of marshland closely in the treatment of heavy metal in wastewater released from a disussed mine.

• Economic and Environmental Geology
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• v.28 no.3
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• pp.231-241
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• 1995

It is well known that hydroxyapatite [$Ca_{10}(PO_4)_6(OH)_2$] have an exchangeability for various heavy metal ions in aqueous solution. To evalute the feasibility of employing the synthetic hydroxyapatites as an eliminatable exchanger for environmentally noxious caions in waste water, the adsorption properties, the removal capacities and the selectivity of the apatites for various cations were investigated in more detailed. The heavy metal cations have been exchanged in calcium part of hydroxyapatite. The order of the degree of amount exchanged of the investigated cations is $Pb^{2+}>Cd^{2+}>Zn^{2+}>Ba^{2+}$. The molar ratios between released $Cd^{2+}$ ions and remeved divalent metal cations in the reacted solution with hydroxyapatite are roughly close to an integer 1.0, suggesting that an ion-exchange reaction could have played a major role in the removal of heavy metals rather then an adsorption effect. The exchangeability of the hydroxyapatite powder of Ca/P molar ratio 1.67, which have specipic surface area of $104.5m^2g^{-1}$, appeared to be better then $237.6{\mu}g$ per g for $Pb^{2+}$ ions. The removal capacity of the heavy metal ions varies directly as particle size of hydroxyapatites. All evidences obtained indicate that the synthesized hydroxyapatite powders by precipitation reaction method can be employed as an effective cation exchanger for eliminating noxious ions in waste water even in some improvemental.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.46-55
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• 1999

This study compared the adsorption characteristics of heavy metal ions by crab shell, treated crab shell with 2N-HCl, treated crab shell with 4%-NaOH, chitin and chitosan.Using crushed crab shell, the heavy metal ions removal rates of $Cd^{2+}$ and $Zn^{2+}$ were about 70-80% in 45minutes, but the removal rates of $Cu^{2+}$, $Cr^{6+}$ and $Pb^{2+}$ was less than 10%, 10% and 30%, respectively. For the by-products crab shell by 2N-HCl treatment, it was shown that the removal rates of $Cu^{2+}$ and $Pb^{2+}$ were about 70-80% in 45minutes reaction. But, some problems were observed, that the contained protein in crab shell was changed into gel in the mixing solution after a few hours. For the by-products of crab shell by 4%-NaOH treatment, the removal rates of Pb and Zn were about 90% in 45 minutes, and those of capacity of chitin and chitosan powder was better than those of the other by-products. The more adding to the adsorbent dosages increased the removal rates, and the adsorption reaction was rapidly occurred in a few minute. Using 1.0 wt% chitin powder, the heavy metal removal rates were ordered $Cu^{2+}$(94%) > $Zn^{2+}$(89%) > $Cd^{2+}$(88%) > $Pb^{2+}$(77%) > $Cr^{6+}$(58%) in 45 minutes. Using 1.0 wt% chitosan powder, the heavy metal removal rates were ordered $Cu^{2+}$(99%) > $Pb^{2+}$(96%) > $Cd^{2+}$(79%) > $Zn^{2+}$(71%) > $Cr${6+}$(46%) in 45minutes. The degree of degree of deacetylation by prepared chitosan was 91%.The Freundlich adsorption isotherm of $Cu^{2+}$, $Cd^{2+}$ and $Zn^{2+}$, when it was applied to 1.0 wt% chitosan powder in minutes, can be acceptable very strictly. The equation constant (1/n) for $Cu^{2+}$, $Cd^{2+}$ and $Zn^{2+}$ were 0.54 0.41 and 0.23 respectively.

• Journal of Environmental Science International
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• v.2 no.1
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• pp.61-72
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• 1993

Result of this study indicate that two criteria must be met in order to have effective macrocycle-mediated transport in these emulsionsystem. First, one must effective extraction of the post transition metals, $Cd^{2+}$. $Pb^{2+}$ and $Hg^{2+}$ , into toluene membrane. The effectiveness of this extraction is greatest if log K values for the metal-macrocycle interaction is large. Second, the ratio of the log K values for the metal ion-receiving phase to the metal ion-macrocycle interaction must be large enough to ensure quantitative stripping of the metal ion at the toluene phase interface. Control of the first step can be obtained by appropriate selection of macrocycle donor atom, substituents, and cavity radius. The second step can be controlled by selecting the proper complexing agent for inclusion in the receiving phase. The order of the transport, when using the several $A^-$ species such as $SCN^-$, $1^-$, $Br^-$ and $Cl^-$ is the order of the changing degree of solvation for $A^-$ and the transport of the metals is also affected by the control of concentration for receiving species because of solubility-differences. In this study, we can seperate each single metal ion from the mixture of $Cd^{2+}$, $Pb^{2+}$, and $Hg^{2+}$ ions by using the toluene membranes controlled by optimized conditions. Transport of the single metal is also very good, and alkaline and alkaline earth metals as interferences ions did not affect the seperation of the metals in this macrocycle-liquid membrances but transition metal ions were partially affected as interferences for the post transition metal ions.

• Archives of Pharmacal Research
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• v.16 no.1
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• pp.78-81
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• 1993

Solution equilibria of the thmary systems $UO_2(II)$, La(III), Ce(III)-N-(2-acetamido)-iminodiacetic acid and dicarboxylic amino acids are studied potentiometrically. The formation of 1:1:1 mixed ligand complexes are inferred from the potentiometric titration curves. The formation constants of the different binary and thmary complexes in such system are evaluated at t=$24\pm{0.1}^\circ{C}\;and\;\mu=0.1\;mol\;dm^{-3}(kNO_3)$. It is deduced that the temary complex is more stable than the corresponding binary amino acid anion complex. Moreover, the order og stability of the binary or temary complexes in terms of nature of amino acid and metal ion is investigated and discussed.