The interaction of a humic acid with heavy metals

The solubility of a coal humic acid and the sorption of heavy metals (Cu(II), Zn(II), Co(II), and Cd(II)) in the absence and presence of the humic acid were determined as a function of pH and concentration of background electrolyte. The solubility of the humic acid at low electrolyte concentration increases in a 2-step process with increase in pH. About 80% dissolves in the pH region 3–8·5, and the remainder in the region pH >8·5. The sorption of metals occurs at pH values significantly lower than those associated with the formation of insoluble metal hydroxides, with a maximum occurring in the pH region 5·5–7·5, and involves the solid state fraction of the humic acid. At the higher electrolyte concentration, the solubility of the humic acid is again a 2-step process but the increase in acid solution occurs over a relatively narrow pH range (5–6). At high pH, the presence of the humic acid significantly reduces the precipitation of the metals at both low and high salt concentration, probably due to the formation of soluble metal–humate species. There is evidence to suggest that the major functional group of the humic acid with which the metal cations interact is the carboxyl group.

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Interaction of Hg(II) with kaolin-humic acid complexes

Clay Minerals ◽

10.1180/000985543910118 ◽

2004 ◽

Vol 39 (1) ◽

pp. 35-45 ◽

Cited By ~ 18

Author(s):

M. Arias ◽

M.T. Barral ◽

J . Da Silva–Carvalhal ◽

J .C. Mejuto ◽

D. Rubinos

Keyword(s):

Organic Matter ◽

Humic Acid ◽

Dissolved Organic Matter ◽

Equilibrium Concentration ◽

Soluble Complex ◽

Ph Values ◽

Subsurface Waters ◽

Ph Range ◽

Surface And Subsurface Waters ◽

Reduced Risk

AbstractThe adsorption and desorption of Hg(II) by humic acid (HA) previously adsorbed on kaolin was studied. In the range of HA concentration investigated (0.0 –26.9 mg g–1), the Hg(II) adsorption capacity of kaolin at pH 4 is enhanced by the presence of HA. For the complexes with the highest HA concentration and for low Hg(II) initial concentrations, adsorption was lower, i.e. as HA concentration on the complexes increases, Hg(II) equilibrium concentration also increases. This behaviour is due to the increasing presence of dissolved organic matter as the HA concentration on the complexes increases. The dissolved organic matter is able to form a soluble complex with Hg, thus decreasing adsorption. Hg(II) adsorption from a 2.5×10–5 MHg(II) solution was influenced by pH. For kaolin, a pHmax (pH where maximum adsorption occurs) of 4.5 was observed. At pH values >pHmax retention decreased with increasing pH. This same behaviour was observed for the kaolin- HA complex containing the lowest HA concentration (6.6 mg g –1). For the other kaolin-HA complexes there was little effect of pH on Hg(II) adsorption between pH 2.5 and pH 6.5. The presence of HA increased the adsorption of Hg(II) on kaolin all along the pH range studied. Desorption experiments showed that the amount of Hg(II) desorbed was quite low (<1%) for all the HA and Hg(II) concentration range studied, except for the kaolin at acid pH (pH 2.5) where the Hg(II) released was >50% of Hg(II) previously adsorbed. The presence of HA dramatically reduced this percentage of desorption to values of <3%, indicating reduced risk of toxicity problems in surface and subsurface waters. The addition of Cu(II) did not favour any Hg(II) desorption, even though Cu exhibits a strong affinity for organic matter.

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Fluoride sorption by soil components: calcium carbonate, humic acid, manganese dioxide and ailica

Soil Research ◽

10.1071/sr9850429 ◽

1985 ◽

Vol 23 (3) ◽

pp. 429 ◽

Cited By ~ 15

Author(s):

H Farrah ◽

J Slavek ◽

WF Pickering

Keyword(s):

Calcium Carbonate ◽

Humic Acid ◽

Ash Content ◽

Fluoride Ions ◽

Ph Values ◽

Counter Ions ◽

Soil Components ◽

Significant Uptake ◽

Ph Range ◽

Calcium Compounds

The ability of individual soil components to adsorb fluoride ions from dilute solutions (1-12 mg L-1 F-), at different pH values, has been investigated. No significant uptake was detected using substrates such as calcite, hydrous manganese(1v) oxide, cryptomelane, �-MnO2, pyrolusite, silica or silica gel, over the pH range 3-8 (for calcite, 6-9). The sorption of F- by calcite and humic acids at higher solution levels (up to 200 mg L-1) was also examined. Uptake by CaCO3 was observed when [F-] was >7 x 10-4 mol L-1, with the moles retained (pH -8.5) being approximately 1.6[F-]2. The amount of F removed increased on lowering the pH or on adding Ca2+, and it is proposed that the overall reaction is described by the equation CaCO3(S) + 2F- <=>CaF2(S) + CO23-. Two humic acid samples adsorbed increasing amounts of F- as the pH was lowered below 6.5, and increasing amounts of A1 and fluorocomplexes were detected in solution. The amount sorbed (mol kg-', at pH 5.5-6) varied with ash content and equalled either 16[F-]0.64 or 60[F-1. The major interaction appears to be HF attack on aluminosilicates in the ash fraction, with lesser contributions from sorption on calcium compounds and interaction with the counter-ions associated with the humic acid functional groups (e.g. Ca2+, Al3+, Fe3+).

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Sorption of heavy metals by natural biopolymers

Adsorption Science & Technology ◽

10.1177/0263617417703113 ◽

2017 ◽

Vol 35 (7-8) ◽

pp. 595-601 ◽

Cited By ~ 5

Author(s):

Natalya V Efimova ◽

Alla P Krasnopyorova ◽

Galina D Yuhno ◽

Anastasia A Scheglovskaya

Keyword(s):

Functional Group ◽

Ph Value ◽

Kinetic Properties ◽

Hydrolysis Lignin ◽

Second Order Reaction ◽

Equilibrium Solutions ◽

Sorption Equilibrium ◽

Ph Values ◽

Ph Range ◽

Modified Lignin

The sorption properties of modified hydrolysis lignin towards Cu[Formula: see text], Zn[Formula: see text], Ni[Formula: see text], Co[Formula: see text] ions in the pH range from 2 to 8 at temperature of 298.15 K solution are studied. The analysis of kinetic curves of ions sorption on modified lignin at pH 7 shows that sorption equilibrium in heterogenic system ion–metal–sorbent is attained in 30–60 min. Obtained results indicate good equilibrium kinetic properties of sorbent. Supposed that reaction between sorbate and functional group of sorbent are the second-order reaction and they interact between each other in ratio 1:1. The character of the obtained electrokinetic curve suggests that the zeta potential of modified lignin strongly depends on the pH. The dependencies of cations metals sorption coefficients on the pH value of water phase are S-shaped. Maximal extraction of studied cations is observed at pH values of equilibrium solutions close to neutral ones.

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Removal of lead from aqueous solutions by complexation ultrafiltration with chitosan

Water Science & Technology Water Supply ◽

10.2166/ws.2011.001 ◽

2011 ◽

Vol 11 (1) ◽

pp. 1-5 ◽

Cited By ~ 3

Author(s):

Jiahui Shao ◽

Zhangwang Xie ◽

Yiliang He ◽

Guowai Liu

Keyword(s):

Aqueous Solutions ◽

Electrolyte Concentration ◽

Removal Rate ◽

Background Electrolyte ◽

Transmembrane Pressure ◽

Lead Removal ◽

Dilute Solutions ◽

Step Process ◽

Nacl Concentration ◽

Removal And Recovery

The removal of lead from aqueous dilute solutions by complexation-ultrafiltration with chitosan was studied. Experiments were performed as a function of aqueous pH, chitosan/Pb2+ ratio, and background electrolyte concentration. The value of pH was found to be the most important parameter to effect the lead removal. The lead removal rate reaches the plateau at almost 100% when the chitosan and lead ratio goes more than 4.0 at pH 6.0. With transmembrane pressure (TMP) 0.1 MPa, chitosan/Pb2+ ratio 4 and pH 6, the lead removal rate decreases sharply from 99.2% to 19.5% as the adding NaCl concentration increases from 0 to 500 mmol. The regeneration of the chitosan by acidification using diafiltration technique was further performed. In the end, the effect of regenerated chitosan on the lead removal was evaluated. At the optimum experimental condition of pH 6.0, regenerated chitosan/Pb2+ ratio 4 and TMP 0.10 MPa, the lead removal rate was found to be 96.2%, which is almost the same as that obtained on the original chitosan. The overall results from the two-step process of complexation-UF and decomplexation-UF separation showed that it could be a promising method for lead removal and recovery from aqueous solutions.

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The Malachite Green Biodegradation in Bioreactors on Various pH Domains

Revista de Chimie ◽

10.37358/rc.19.8.7472 ◽

2019 ◽

Vol 70 (8) ◽

pp. 2996-2999

Author(s):

Viorel Gheorghe ◽

Catalina Gabriela Gheorghe ◽

Andreea Bondarev ◽

Vasile Matei ◽

Mihaela Bombos

Keyword(s):

Malachite Green ◽

Contact Time ◽

Dominant Species ◽

Wastewater Treatment Plants ◽

Organic Substances ◽

Biological Degradation ◽

Growth Promoters ◽

Ph Values ◽

Biological Sludge ◽

Ph Range

In the experimental study was studied the malachite green colorant biodegradation in biological sludge with biological activity. The biodegradability tests were carried out in laboratory bioreactors, on aqueous solutions of green malachite contacted with microorganisms in which the dominant species is Paramecium caudatum, in a pH range between 8 and 12, temperatures in the ranges 25-350C, using pH neutralizing substances and biomass growth promoters. The colorant initial concentrations and those obtained after biological degradation depending on the contact time, at certain pH values, were established through UV-Vis spectrometry. The studies have shown the measure of possible biological degradation of some organic substances with extended uses, with largely aromatic structure, resistance to biodegradation of microorganisms, commonly used in wastewater treatment plants.

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Mercury Removal from Wastewater by Steamed Hoof Powder

Water Science & Technology ◽

10.2166/wst.1999.0340 ◽

1999 ◽

Vol 40 (7) ◽

pp. 109-116 ◽

Cited By ~ 4

Author(s):

M. H. Ansari ◽

A. M. Deshkar ◽

P. S. Kelkar ◽

D. M. Dharmadhikari ◽

M. Z. Hasan ◽

...

Keyword(s):

Heavy Metals ◽

Adsorption Capacity ◽

Adsorption Process ◽

Adsorption Equilibrium ◽

Light Metal ◽

Mercury Removal ◽

High Adsorption ◽

Surface Sites ◽

Ph Values ◽

High Adsorption Capacity

Steamed Hoof Powder (SHP), size < 53μ, was observed to have high adsorption capacity for Hg(II) with >95% removal from a solution containing 100 mg/L of Hg(II) with only 0.1% (W/V) concentration of SHP. The SHP has good settling properties and gives clear and odour free effluent. Studies indicate that pH values between 2 and 10 have no effect on the adsorption of Hg(II) on SHP. Light metal ions like Na+, K+, Ca2+ and Mg2+ up to concentrations of 500 mg/L and heavy metals like Cu2+, Zn2+, Cd2+, Co2+, Pb2+, Ni2+, Mn2+, Cr3+, Cr6+, Fe2+ and Fe3+ up to concentrations of 100 mg/L do not interfere with the adsorption process. Anions like sulphate, acetate and phosphate up to concentrations of 200 mg/L do not interfere. Chloride interferes in the adsorption process when Hg(II) concentration is above 9.7 mg/L. The adsorption equilibrium was established within two hours. Studies indicate that adsorption occurs on the surface sites of the adsorbent.

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Ideal pH for the adsorption of metal ions Cr6+, Ni2+, Pb2+ in aqueous solution with different adsorbent materials

Open Agriculture ◽

10.1515/opag-2021-0225 ◽

2021 ◽

Vol 6 (1) ◽

pp. 115-123

Author(s):

Luísa P. Cruz-Lopes ◽

Morgana Macena ◽

Bruno Esteves ◽

Raquel P. F. Guiné

Keyword(s):

Heavy Metals ◽

Metal Ions ◽

Walnut Shell ◽

Lead Adsorption ◽

Viable Solution ◽

Chestnut Shell ◽

Adsorption Processes ◽

Irreversible Effects ◽

Optimal Values ◽

Ph Range

Abstract Industrialization increases the number of heavy metals released into the environment. Lead (Pb2+), nickel (Ni2+) and chromium (Cr6+) are among these toxic metals and cause irreversible effects on ecosystems and human health due to their bio-accumulative potential. The decontamination through adsorption processes using lignocellulosic wastes from agricultural and/or forestry processes is a viable solution. Hence, this work aimed at studying the effect of pH on the biosorption of the metal ions using four different by-product materials: walnut shell, chestnut shell, pinewood and burnt pinewood. These experiments were conducted with solutions of the three heavy metals in which the adsorbents were immersed to measure the rate of adsorption. A range of pH values from 3.0 to 7.5 was used in the experiments, and the concentrations were determined by atomic absorption. The results showed different behaviour of the biosorbent materials when applied to the different metals. The lead adsorption had an ideal pH in the range of 5.5–7.5 when the walnut shell was used as an adsorbent, corresponding to values of adsorption greater than 90%, but for the other materials, maximum adsorption occurred for a pH of 7.5. For the adsorption of chromium, the pH was very heterogeneous with all adsorbents, with optimal values of pH varying from 3.0 (for chestnut shell) to 6.5 (for walnut shell and wood). For nickel, the best pH range was around pH 5, with different values according to the lignocellulosic material used. These results indicate that the tested biosorbents have the potential to decontaminate wastewater in variable extensions and that by controlling the pH of the solution; a more efficient removal of the heavy metals can be achieved.

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Performance of Photocatalytic Microfiltration with Hollow Fiber Membrane

Materials Science Forum ◽

10.4028/www.scientific.net/msf.544-545.95 ◽

2007 ◽

Vol 544-545 ◽

pp. 95-98 ◽

Cited By ~ 8

Author(s):

Jong Tae Jung ◽

Jong Oh Kim ◽

Won Youl Choi

Keyword(s):

Heavy Metals ◽

Humic Acid ◽

Rate Constant ◽

Hollow Fiber ◽

Reaction Rate ◽

Hollow Fiber Membrane ◽

Membrane Surface ◽

Reaction Rate Constant ◽

Operational Parameters ◽

Tio2 Particles

The purpose of this study is to investigate the effect of the operational parameters of the UV intensity and TiO2 dosage for the removal of humic acid and heavy metals. It also evaluated the applicability of hollow fiber microfiltration for the separation of TiO2 particles in photocatalytic microfiltration systems. TiO2 powder P-25 Degussa and hollow fiber microfiltration with a 0.4 μm nominal pore size were used for experiments. Under the conditions of pH 7 and a TiO2 dosage 0.3 g/L, the reaction rate constant (k) for humic acid and heavy metals increased with an increase of the UV intensity in each process. For the UV/TiO2/MF process, the reaction rate constant (k) for humic acid and Cu, with the exception of Cr in a low range of UV intensity, was higher compared to that of UV/TiO2 due to the adsorption of the membrane surface. The reaction rate constant (k) increased as the TiO2 dosage increased in the range of 0.1~0.3 g/L. However it decreased for a concentration over 0.3 g/L of TiO2. For the UV/TiO2/MF process, TiO2 particles could be effectively separated from treated water via membrane rejection. The average removal efficiency for humic acid and heavy metals during the operational time was over 90 %. Therefore, photocatalysis with a membrane is believed to be a viable process for humic acid and heavy metals removal.

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