Sorption of Eu(III) at feldspar/water interface: effects of pH, organic matter, counter ions, and temperature

AbstractThe sorption of Eu(III) on potassium feldspar (K-feldspar) was studied under various physicochemical conditions such as pH, temperature, counter ions and organic matter. The results showed that the sorption of Eu(III) on K-feldspar significantly increased with the increase of pH, and high Eu(III) concentration can inhibit such immobility to some extent. The presence of humic acid (HA) can increase the sorption of Eu(III) on K-feldspar in low pH range; while inhibit to a large extent under alkaline conditions. It is very interesting that at pH ~6.5, high ionic strength can promote the sorption of Eu(III) on K-feldspar in the presence of HA. In contrast, Eu(III) sorption was restricted obviously by NaCl in the absence of HA. The sorption procedure was involved with ion exchange and/or outer-sphere complexation as well as inner-sphere complexation. The presence of F

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Differential Effects of pH on the Pore-Forming Properties of Bacillus thuringiensis Insecticidal Crystal Toxins

Applied and Environmental Microbiology ◽

10.1128/aem.67.10.4488-4494.2001 ◽

2001 ◽

Vol 67 (10) ◽

pp. 4488-4494 ◽

Cited By ~ 36

Author(s):

Le Binh Tran ◽

Vincent Vachon ◽

Jean-Louis Schwartz ◽

Raynald Laprade

Keyword(s):

Bacillus Thuringiensis ◽

Brush Border Membrane ◽

Membrane Vesicles ◽

Insect Midgut ◽

Tetramethylammonium Chloride ◽

Effects Of Ph ◽

Alkaline Conditions ◽

Crystal Toxins ◽

Ph Range ◽

Reduced Activity

ABSTRACT The effect of pH on the pore-forming ability of two Bacillus thuringiensis toxins, Cry1Ac and Cry1C, was examined with midgut brush border membrane vesicles isolated from the tobacco hornworm,Manduca sexta, and a light-scattering assay. In the presence of Cry1Ac, membrane permeability remained high over the entire pH range tested (6.5 to 10.5) for KCl and tetramethylammonium chloride, but was much lower at pH 6.5 than at higher pHs for potassium gluconate, sucrose, and raffinose. On the other hand, the Cry1C-induced permeability to all substrates tested was much higher at pH 6.5, 7.5, and 8.5 than at pH 9.5 and 10.5. These results indicate that the pores formed by Cry1Ac are significantly smaller at pH 6.5 than under alkaline conditions, whereas the pore-forming ability of Cry1C decreases sharply above pH 8.5. The reduced activity of Cry1C at high pH correlates well with the fact that its toxicity for M. sexta is considerably weaker than that of Cry1Aa, Cry1Ab, and Cry1Ac. However, Cry1E, despite having a toxicity comparable to that of Cry1C, formed channels as efficiently as the Cry1A toxins at pH 10.5. These results strongly suggest that although pH can influence toxin activity, additional factors also modulate toxin potency in the insect midgut.

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The Removal of CuO Nanoparticles from Water by Conventional Treatment C/F/S: The Effect of pH and Natural Organic Matter

Molecules ◽

10.3390/molecules24050914 ◽

2019 ◽

Vol 24 (5) ◽

pp. 914 ◽

Cited By ~ 2

Author(s):

Rizwan Khan ◽

Muhammad Ali Inam ◽

Du Ri Park ◽

Sarfaraz Khan ◽

Muhammad Akram ◽

...

Keyword(s):

Organic Matter ◽

Natural Organic Matter ◽

Colloidal Stability ◽

Copper Oxide Nanoparticles ◽

Engineered Nanoparticles ◽

Cuo Nps ◽

Effects Of Ph ◽

Alkaline Conditions ◽

Ft Ir ◽

The Fourier Transform

The increased use of engineered nanoparticles (ENPs), such as copper oxide nanoparticles (CuO NPs), in commercial products and applications raises concern regarding their possible release into freshwater sources. Therefore, their removal from water is important to eliminate adverse environmental and human health effects. In this study, the effects of pH and natural organic matter (NOM), i.e., humic acid (HA) and salicylic acid (SA) on the removal of CuO NPs by coagulation/flocculation/sedimentation (C/F/S) were evaluated. The results indicated that pH significantly affects the coagulation efficiency, where 10–60% CuO NPs removal was achieved under extreme acidic/alkaline conditions. However, at neutral pH, removal of up to 90% was observed with a lower ferric chloride (FC) dosage (0.2 mM). The coagulation efficiency and mechanism were strongly affected by the type of Fe species present in the aqueous phase, which is mainly controlled by pH. Higher concentrations of both HA and SA decrease the CuO NPs agglomeration rate, and thereby improve the colloidal stability due to the NOM molecules adsorbed onto the NPs surface. The presence of hydrophobic HA needs a higher FC dosage of 0.5–0.8 mM than a dosage of hydrophilic SA of 0.25–0.35 mM, to obtain a similar CuO coagulation efficiency. Moreover, higher removals of dissolved organic carbon (DOC) and UV254 were observed more in hydrophobic NOM than in hydrophilic. The results of the Fourier transform infrared (FT-IR) analysis of FC composite flocs confirm that the charge neutralization and enmeshment of coagulant might be a possible removal mechanism. The findings of the current study may provide critical information in the prediction of the fate, mobility, and removal of CuO NPs during C/F/S in water treatment.

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Effect of calcium, pH and nitrogen on the growth and chemical composition of some tropical and temperate pasture legumes. I. Nodulation and growth

Australian Journal of Agricultural Research ◽

10.1071/ar9760611 ◽

1976 ◽

Vol 27 (5) ◽

pp. 611 ◽

Cited By ~ 68

Author(s):

CS Andrew

Keyword(s):

Dry Matter ◽

Calcium Sulphate ◽

Low Ph ◽

Root Weight ◽

Calcium Treatment ◽

Pasture Legumes ◽

Low Calcium ◽

High Calcium ◽

Effects Of Ph ◽

Ph Range

The effects of a factorial combination of calcium (0.125, 2.0 mM calcium sulphate), pH (4.0, 4.5, 5.0, 6.0) and nitrogen (nil, 2.0mM ammonium nitrate) on the nodulation and growth of some tropical and temperate pasture legumes were determined. Macroptilium lathyroides and Lotononis bainesii were unaffected by low pH and low calcium (100% of plants nodulated at all treatments). In Stylosanthes humilis, Trifoliurn semipilosum, and T. rueppellianum reduced nodulation occurred only at pH 4.0. Desmodium uncinatum and Trifolium repens were sensitive to low pH, and nodulation was markedly reduced at pH 4.0 and below 5.0 respectively. Medicago sativa, M. truncatula, M. scutellata, and Glycine wightii were extremely sensitive, maximum nodulation occurring only at pH 6-0 and 2 . 0 mM calcium. Furthermore, the dry matter yields of plants that nodulated under inferior treatments were less than those of plants nodulated under optimum treatments. Nodulation and growth were strongly controlled by pH, and although interactions occurred with calcium treatment, these were primarily in the intermediate pH range. Dry matter yields of nodulated plants of S. humilis and L. bainesii were greater at the low calcium sulphate treatment (0.125mM) than at thc high treatment (2.0mM). The remaining legumes gave varying positive responses to the high calcium treatment. Root weight ratios of nodulated plants were decreased by the higher treatments, the minimum occurring at those treatments producing the highest dry matter. In the presence of applied nitrogen (no nodulation), the effects of pH and calcium on dry matter were small, but the trends were similar to those for nodulation and dry matter production of the nodulated plants in the Rhizobium series. Root weight ratios of plants in the nitrogen series were equal to or less than those for the maximum-yielding plants in the nodulation series. It is considered that both nodulation and subsequent plant growth are dominated by the hydrogen ion effect, and that the beneficial effect of calcium operates within certain pH limits. pH had little effect on plants that were well supplied with nitrogen.

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Studies of the relationship between the catalytic activity and binding of non-substrate ligands by the glutathione S-transferases

Biochemical Journal ◽

10.1042/bj2170179 ◽

1984 ◽

Vol 217 (1) ◽

pp. 179-185 ◽

Cited By ~ 53

Author(s):

T D Boyer ◽

D A Vessey ◽

C Holcomb ◽

N Saley

Keyword(s):

Indocyanine Green ◽

Bile Acids ◽

Low Ph ◽

Glutathione S Transferase ◽

Effects Of Ph ◽

Glutathione S Transferases ◽

Ph Range ◽

The Individual ◽

Induced Changes ◽

The Relationship

The dimeric enzyme glutathione S-transferase B is composed of two dissimilar subunits, referred to as Ya and Yc. Transferase B (YaYc) and two other transferases that are homodimers of the individual Ya and Yc subunits were purified from rat liver. Inhibition of these three enzymes by Indocyanine Green, biliverdin and several bile acids was investigated at different values of pH (range 6.0-8.0). Indocyanine Green, biliverdin and chenodeoxycholate were found to be effective inhibitors of transferases YaYc and YcYc at low (pH 6.0) but not high (pH 8.0) values of pH. Between these extremes of pH intermediate degrees of inhibition were observed. Cholate and taurochenodeoxycholate, however, were ineffective inhibitors of transferase YcYc at all values of pH. The observed differences in bile acids appeared to be due, in part, to differences in their state of ionization. In contrast with the above results, transferase YaYa was inhibited by at least 80% by the non-substrate ligands at all values of pH. These effects of pH on the three transferases could not be accounted for by pH-induced changes in the enzyme's affinity for the inhibitor. Thus those glutathione S-transferases that contain the Yc subunit are able to act simultaneously as both enzymes and binding proteins. In addition to enzyme structure, the state of ionization of the non-substrate ligands may also influence whether the transferases can perform both functions simultaneously.

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The Competitive Adsorption of Chromate and Sulfate on Ni-Substituted Magnetite Surfaces: An ATR-FTIR Study

Minerals ◽

10.3390/min11010088 ◽

2021 ◽

Vol 11 (1) ◽

pp. 88

Author(s):

Xiaoju Lin ◽

Gaoling Wei ◽

Xiaoliang Liang ◽

Jing Liu ◽

Lingya Ma ◽

...

Keyword(s):

Competitive Adsorption ◽

Chemical Properties ◽

Outer Sphere ◽

Mineral Surfaces ◽

Similar Chemical ◽

Adsorption Affinity ◽

Individual Adsorption ◽

Alkaline Conditions ◽

Ph Range

With similar chemical properties and geometrical configurations, sulfate and chromate display interesting competitive adsorption on mineral surfaces. Although such issues have been investigated on several Fe (hydr)oxide surfaces, e.g., ferrihydrite, goethite and hematite, the competitive adsorption on magnetite surfaces and the constraint mechanism have seldom been studied. This impedes the understanding of the transfer and fate of chromate and sulfate on magnetite surfaces, as magnetite is not only a useful adsorbent but also an efficient reductant to decrease the mobility and toxicity of chromium. In the present study, the geometries of the competitive adsorption of chromate and sulfate on Ni-substituted magnetite surfaces over a pH range of 4–9 were investigated using in situ attenuated total reflectance Fourier transform infrared spectroscopy and two-dimensional correlation analysis. In individual adsorption, nonprotonated monodentate mononuclear (NMM) complexes dominated chromate adsorption, accompanied by a few bidentate binuclear (BB) complexes. For sulfate, NMM complexes and outer-sphere (OS) species predominated under acidic and neutral–alkaline conditions, respectively. The above variation in adsorption configuration resulted in the different adsorption competitiveness between chromate and sulfate at different pH values. Specifically, the NMM complexes of chromate were substituted by NMM sulfate complexes under acidic conditions and vice versa. However, under neutral and alkaline conditions, the OS species of sulfate scarcely affected the adsorption of chromate. The adsorption affinity of chromate and sulfate on Ni-substituted magnetite increased in the following order: OS complex (sulfate) < NMM complexes (chromate) < NMM complexes (sulfate).

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Decolorisation of natural organic matter by Phanerochaete chrysosporium: the effect of environmental conditions

Water Science & Technology Water Supply ◽

10.2166/ws.2004.0075 ◽

2004 ◽

Vol 4 (4) ◽

pp. 175-182 ◽

Cited By ~ 2

Author(s):

K. Rojek ◽

F.A. Roddick ◽

A. Parkinson

Keyword(s):

Organic Matter ◽

Ionic Strength ◽

Natural Organic Matter ◽

Phanerochaete Chrysosporium ◽

Fungal Growth ◽

Low Ph ◽

Colour Removal ◽

Humic Material ◽

Carbon And Nitrogen ◽

Carbon And Nitrogen Content

Phanerochaete chrysosporium was shown to rapidly decolorise a solution of natural organic matter (NOM). The effect of various parameters such as carbon and nitrogen content, pH, ionic strength, NOM concentration and addition of Mn2+ on the colour removal process was investigated. The rapid decolorisation was related to fungal growth and biosorption rather than biodegradation as neither carbon nor nitrogen limitation, nor Mn2+ addition, triggered the decolorisation process. Low pH (pH 3) and increased ionic strength (up to 50 g L‒1 added NaCl) led to greater specific removal (NOM/unit biomass), probably due to increased electrostatic bonding between the humic material and the biomass. Adsorption of NOM with viable and inactivated (autoclaved or by sodium azide) fungal pellets occurred within 24 hours and the colour removal depended on the viability, method of inactivation and pH. Colour removal by viable pellets was higher under the same conditions, and this, combined with desorption data, confirmed that fungal metabolic activity was important in the decolorisation process. Overall, removals of up to 40–50% NOM from solution were obtained. Of this, removal by adsorption was estimated as 60–70%, half of which was physicochemical, the other half metabolically-dependent biosorption and bioaccumulation. The remainder was considered to be removed by biodegradation, although some of this may be ascribed to bioaccumulation and metabolically-dependent biosorption.

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Efficient Preconcentration of Cu2+, Zn2+ and Fe3+ with an Agarose-Schiff Base Sorbent

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20070908 ◽

2007 ◽

Vol 72 (7) ◽

pp. 908-916 ◽

Cited By ~ 3

Author(s):

Payman Hashemi ◽

Hatam Hassanvand ◽

Hossain Naeimi

Keyword(s):

Schiff Base ◽

Metal Ions ◽

Metal Ion ◽

Good Accuracy ◽

Kinetic Studies ◽

Sample Volume ◽

Effects Of Ph ◽

Glass Column ◽

High Concentrations ◽

Ph Range

Sorption and preconcentration of Cu2+, Zn2+ and Fe3+ on a salen-type Schiff base, 2,2'- [ethane-1,2-diylbis(nitrilomethylidyne)]bis(2-methylphenol), chemically immobilized on a highly crosslinked agarose support, were studied. Kinetic studies showed higher sorption rates of Cu2+ and Fe3+ in comparison with Zn2+. Half-times (t1/2) of 31, 106 and 58 s were obtained for sorption of Cu2+, Zn2+ and Fe3+ by the sorbent, respectively. Effects of pH, eluent concentration and volume, ionic strength, buffer concentration, sample volume and interferences on the recovery of the metal ions were investigated. A 5-ml portion of 0.4 M HCl solution was sufficient for quantitative elution of the metal ions from 0.5 ml of the sorbent packed in a 6.5 mm i.d. glass column. Quantitative recoveries were obtained in a pH range 5.5-6.5 for all the analytes. The volumes to be concentrated exceeding 500 ml, ionic strengths as high as 0.5 mol l-1, and acetate buffer concentrations up to 0.3 mol l-1 for Zn2+ and 0.4 mol l-1 for Cu2+ and Fe3+ did not have any significant effect on the recoveries. The system tolerated relatively high concentrations of diverse ions. Preconcentration factors up to 100 and detection limits of 0.31, 0.16 and 1.73 μg l-1 were obtained for Cu2+, Zn2+ and Fe3+, respectively, for their determination by a flame AAS instrument. The method was successfully applied to the metal ion determinations in several river water samples with good accuracy.

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Common Loon, Gavia immer, Breeding Success in Relation to Lake pH and Lake Size Over 25 Years

The Canadian Field-Naturalist ◽

10.22621/cfn.v123i2.693 ◽

2009 ◽

Vol 123 (2) ◽

pp. 146 ◽

Cited By ~ 5

Author(s):

Robert Alvo

Keyword(s):

Breeding Success ◽

Low Ph ◽

Single Pair ◽

Gavia Immer ◽

Common Loon ◽

Sulphur Deposition ◽

Acidic Lakes ◽

Ph Range ◽

Lake Size ◽

Critical Ph

I monitored Common Loon (Gavia immer) breeding success in relation to lake pH (range 4.0–8.5) between 1982 and 2007 on 38 single-pair lakes (5–88 ha) in the Sudbury, Ontario, area. No chicks fledged on lakes with pH < 4.4. Chicks fledged on lakes with slightly higher pH only if the lakes were relatively large. Acidic lakes became less acidic as sulphur dioxide emissions from the Sudbury smelters and sulphur deposition from other long-range sources decreased. Two lakes initially too acidic to support successful loon reproduction eventually had successful reproduction. One loon pair used two large acidic lakes (combined area 140 ha) connected by shallow rapids, and one of the adults made extremely long dives (average = 99 s) while foraging for the chicks. One chick died on that lake after apparently ingesting a very large food item; the lack of smaller items was attributed to the lake’s acidity. My results suggest that a shortage of food for chicks is the main reason why low pH reduces breeding success. I suggest that, for lakes without high levels of dissolved organic carbon (DOC), the critical pH for loon breeding success is approximately 4.3, and the suboptimal pH is approximately 4.4–6.0.

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The effects of pH on force and stiffness development in mouse muscles

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y87-280 ◽

1987 ◽

Vol 65 (8) ◽

pp. 1798-1801 ◽

Cited By ~ 3

Author(s):

J. M. Renaud ◽

R. B. Stein ◽

T. Gordon

Keyword(s):

High Frequency ◽

Small Amplitude ◽

Force Production ◽

Muscle Length ◽

Low Ph ◽

Muscle Stiffness ◽

Average Force ◽

Cross Bridge ◽

Effects Of Ph ◽

Cross Bridges

Changes in force and stiffness during contractions of mouse extensor digitorum longus and soleus muscles were measured over a range of extracellular pH from 6.4 to 7.4. Muscle stiffness was measured using small amplitude (<0.1% of muscle length), high frequency (1.5 kHz) oscillations in length. Twitch force was not significantly affected by changes in pH, but the peak force during repetitive stimulation (2, 3, and 20 pulses) was decreased significantly as the pH was reduced. Changes in muscle stiffness with pH were in the same direction, but smaller in extent. If the number of attached cross-bridges in the muscle can be determined from the measurement of small amplitude, high frequency muscle stiffness, then these findings suggest that (a) the number of cross-bridges between thick and thin filaments declines in low pH and (b) the average force per cross-bridge also declines in low pH. The decline in force per cross-bridge could arise from a reduction in the ability of cross-bridges to generate force during their state of active force production and (or) in an increased percentage of bonds in a low force, "rigor" state.

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