Influence of pH on the Migration of Various Forms of Metals in the "Bottom Sediments - Water" System under Experimental Conditions

2009 ◽  
Vol 45 (3) ◽  
pp. 92-100 ◽  
Author(s):  
P. N. Linnik ◽  
A. V. Zubko ◽  
I. B. Zubenko ◽  
I. I. Ignatenko ◽  
L. A. Malinovskaya
Keyword(s):  
Bottom Sediments ◽  
Water System ◽  
Experimental Conditions ◽  
Influence Of Ph

Copper Biosorption and Bioprecipitation by Eichhornia spp. and Sulphate Reducing Bacteria

2009 ◽  
Vol 71-73 ◽  
pp. 561-564
Author(s):  
Shailesh R. Dave ◽  
M.S. Damani ◽  
D.R. Tipre
Keyword(s):  
Contact Time ◽  
Copper Removal ◽  
Point Of Zero Charge ◽  
Experimental Conditions ◽  
Element Analysis ◽  
Freundlich Isotherms ◽  
Biomass Influence ◽  
Reducing Bacteria ◽  
Influence Of Ph ◽  
Copper Sorption

Eichhornia spp. biomass collected from Chandola lake, Ahmedabad, Gujarat, India. Point of zero charge of the biomass was pH 7.3. Flask study showed pH 5 and 2 to 3 h contact time as optimum conditions for copper sorption. In 24 h of contact time, as high as 85% of copper was removed from 100 ppm copper containing solution. In first 2 h of the contact time the removal reached to 67.25%. Copper loading capacity of the biomass ranged between 2.85 to 1.0 g per 100 g of biomass. Influence of pH, temperature, nickel and zinc was studied by 24 factorial experiments. Under the experimental conditions pH and interactions between pH-nickel, temperature-pH and temperature-pH-nickel-zinc were found to be significant with 60 to 74.7% copper removal. As high as 95% of sorbed copper was desorbed with 0.1 N HNO3. Langmuir and Freundlich isotherms were also studied. Reactor study showed 90% overall copper removal from 25 L of copper containing waste and sulfatereducing bacteria played a significant role. Treatment of actual waste also showed 61% of copper removal. SEMquant element analysis showed presence of 12.39% w/w of copper in the biomass exposed to the waste, where as only 0.0018% of copper was detected in unexposed biomas

Uptake of Neutral Metal Complexes by a Green Alga: Influence of pH and Humic Substances

2004 ◽  
Vol 57 (10) ◽  
pp. 931 ◽  
Author(s):  
Amiel Boullemant ◽  
Bernard Vigneault ◽  
Claude Fortin ◽  
Peter G. C. Campbell
Keyword(s):  
Humic Acid ◽  
Metal Complex ◽  
Metal Complexes ◽  
Humic Substances ◽  
Low Ph ◽  
Pseudokirchneriella Subcapitata ◽  
Short Term ◽  
Experimental Conditions ◽  
Influence Of Ph ◽  
Neutral Metal

We have examined the influence of pH and a natural humic acid on the short-term uptake (<40 min) of a neutral, lipophilic metal complex by a unicellular freshwater alga, Pseudokirchneriella subcapitata. Cadmium diethyldithiocarbamate ([Cd(DDC)2]0) was used as a model lipophilic metal complex and Suwannee River Humic Acid (SRHA) was chosen as a representative aquatic humic acid (6.5 mg C L−1). Under the experimental conditions virtually all the Cd was expected to be present as the lipophilic complex ([Cd]T = 0.38 nM; [DDC] 1 μM; [Cd2+] <10−15 M; pH 7.0, 6.0, or 5.5). Uptake of [Cd(DDC)2]0 proved to be sensitive to pH changes. It was lower at pH 6.0 and 5.5 than at pH 7.0. To our knowledge, this is the first demonstration of reduced uptake of a lipophilic metal complex at low pH. The presence of SRHA also affected uptake, either by binding the lipophilic complex in solution and reducing its bioavailability (pH 7.0) or by increasing the permeability of the algal membrane (pH 5.5).

scholarly journals Estimation the Sorption Capacity of Chemically Modified Chitosan Toward Cadmium Ion in Wastewater Effluents

2019 ◽  
Vol 35 (2) ◽  
pp. 757-765 ◽  
Author(s):  
Eman A. Alabbad
Keyword(s):  
Kinetic Studies ◽  
Absorption Spectrometry ◽  
Sorption Process ◽  
Experimental Conditions ◽  
Thermodynamic Studies ◽  
Modified Chitosan ◽  
Ion Removal ◽  
Chemically Modified ◽  
Langmuir Isotherm Model ◽  
Influence Of Ph

This study aimed to investigation of Cd(II) ion removal from wastewater using chitosan-vanillin as sorbent I and chitosan-ortho-vanillin as sorbent II under various experimental conditions. The influence of pH, initial Cd(II) ion concentrations and isotherm studies, temperature and thermodynamic studies, adsorbent mass, adsorption time and kinetic studies on the sorption process have been studied using different experiments. The residual ion quantity is estimated through atomic absorption spectrometry. The maximum Cd(II) ion removal is obtained at pH 6 with highest uptake of ions after agitation for 2 hours. Langmuir isotherm model represented the most suitable for the experimental data and the maximum adsorbing capacity was 20.704 mg g-1 and 51.020 mg g-1 for sorbents I and II, respectively. Results of this study suggest that chemisorption is a step of rate-determining and the thermodynamic studies revealed that the nature of uptake sorption process is endothermic and spontaneous.

scholarly journals Behaviour of Sediments in Water Structures

2020 ◽  
Vol 15 (2) ◽  
pp. 69-74
Author(s):  
Natália Junáková ◽  
Jozef Junák
Keyword(s):  
Bottom Sediments ◽  
Water System ◽  
Water Reservoir ◽  
Sorption Process ◽  
Coarse Grained ◽  
Aqueous Environment ◽  
Technical Problems ◽  
Maximum Sorption Capacity ◽  
Small Water ◽  
High Concentrations

AbstractBottom sediments are a natural part of aquatic ecosystems. They are increasingly contributing to the deterioration of watercourses and reservoirs and are an undesirable material that causes various serious environmental and technical problems. The most significant problems include the instability of riverbeds, the transport of chemicals, nutrients and organic compounds, the supply of sediments to water reservoirs. Bottom sediments have the ability to bind to their surface various predominantly harmful substances such as heavy metals, radionuclides, nutrients and organic substances. Such sediments pose a risk to the water system in terms of possible remobilization of pollutants into the water.This paper is focused on the study of behavior of sediments in the Hervartov small water reservoir located in the east of Slovakia and their ability to adsorb phosphorus at the sediment-water interface. The results show that the efficiency of sorption of phosphorus from the aqueous environment by fine and coarse-grained sediments is the highest at the lowest input concentrations of phosphorus in solution, or at low concentrations in surface water above the sediment. At these concentrations, the amount of sorbed phosphorus by fine-grained sediments was up to almost 99%. The coarse-grained sediments sorbed phosphorus at a level of up to 84%. Increasing the concentration of phosphorus in the solution leads to a decrease in the sorption efficiency of the sediment, while at high concentrations of the sorbate, the sorption process is significantly stabilized due to reaching the maximum sorption capacity of bottom sediments.

Caffeine Removal by Adsorption: Kinetics, Equilibrium Thermodynamic and Regeneration Studies

2021 ◽  
Vol 47 (1) ◽  
pp. 95-103
Author(s):  
Ivone Vanessa Jurado Dávila ◽  
Júlia Viola Matzenbacher Hübner ◽  
Keila Guerra Pacheco Nunes ◽  
Liliana Amaral Féris
Keyword(s):  
Adsorption Equilibrium ◽  
Isotherm Models ◽  
Equilibrium Thermodynamic ◽  
Reversible Process ◽  
Experimental Conditions ◽  
First Order ◽  
Equilibrium Data ◽  
Pseudo Second Order ◽  
Adsorption Equilibrium Data ◽  
Influence Of Ph

In this work, it was studied the caffeine removal through the adsorption on granular activated carbon (CAG). The influence of pH, contact time and CAG dosage were analyzed by batch experiments. Adsorption Kinetic was studied using the models of pseudo-first-order and pseudo-second-order. The adsorption equilibrium data was studied with Langmuir, Freundlich, and Redlich-Peterson isotherm models. The process thermodynamic also was studied. It was obtained 88 % of removal under the experimental conditions of natural pH, 60 min of adsorption and 8 g.L-1 of CAG. The kinetic model that showed the best results was the pseudo-secondorder and Langmuir was the isotherm model that best described the adsorption behavior. The thermodynamic parameters obtained showed a spontaneous, endothermic and reversible process. The desorption efficiency also was studied by regenerant solvents. The best results were obtained using a solvent combination of ethyl acetate, ethanol, and water (50:25:25), and it was obtained a caffeine removal of 57 %, achieving 70 % when a new solution is used in each regeneration step.

THE TRYPSIN CATALYZED HYDROLYSIS OF p-NITROPHENYL ACETATE

1959 ◽  
Vol 37 (4) ◽  
pp. 751-759 ◽  
Author(s):  
James A. Stewart ◽  
Ludovic Ouellet
Keyword(s):  
Active Site ◽  
Initial Rate ◽  
Competitive Inhibition ◽  
Early Stage ◽  
Stopped Flow ◽  
Hydrogen Ions ◽  
Experimental Conditions ◽  
Influence Of Ph ◽  
Kinetics Of ◽  
Hydrolysis Of

The hydrolysis of p-nitrophenyl acetate (NPA) by trypsin has been investigated in the early stage of the reaction using stopped-flow techniques. The influence of pH on the initial rate suggests competitive inhibition of the active site of the enzyme by hydrogen ions. The dissociation constant of the enzyme obtained from the kinetics of this reaction (pK = 6.9) indicates possible catalysis by an ammo group or an imidazole group of the enzyme. Lysine methyl ester as an analogue of the enzyme catalyzes the hydrolysis of NPA under similar experimental conditions. The results are described in terms of an assumed mechanism and the nature of the catalytic site is discussed.

scholarly journals Hydrochemistry of sediment pore water in the Bratsk reservoir (Baikal region, Russia)

2020 ◽  
Author(s):  
Vera Poletaeva ◽  
Elvira Tirskikh ◽  
Mikhail Pastukhov
Keyword(s):  
Pore Water ◽  
Bottom Sediments ◽  
Ionic Composition ◽  
Water System ◽  
Water Reservoir ◽  
Water Area ◽  
Pore Waters ◽  
Overlying Water ◽  
The Difference ◽  
Bratsk Reservoir

Abstract This study was aimed at identifying the processes responsible for the major ion composition of pore water from the bottom sediments of the Bratsk water reservoir, which is a part of the largest freshwater Baikal-Angara water system. The pore water ionic composition varies both along the sediment depth profile and across the water area. In pore water, the difference between the highest and lowest values is remarkably large: 5.1 times for K+, 13 times for Mg2+, 16 times for HCO3-, 20 times for Ca2+, 23 times for Na+, 80 times for SO42-, 105 times for Cl-. Such a variability suggests that the dominant factors, influencing pore water chemistry, depend on the location. At the first stages of the sedimentation process, the chemistry of the pore water in the Bratsk reservoir is dependent on HCO3-Ca of the overlying water. Later on, due to the interaction with the sedimentary terrigenous material, they changed to SO4, SO4-HCO3, HCO3-SO4, HCO3-Cl-SO4-water types with exchangeable cations, mainly Ca. Some of pore waters may have a complex genesis associated with subaqueous groundwater discharge. The change in the redox potential observed in the pore water is the indicator of early-diagenetic transformations taking place in bottom sediments.

Gas holdup and kLa in perforated-plate bubble columns in the presence of solid particles

1985 ◽  
Vol 50 (1) ◽  
pp. 48-60 ◽  
Author(s):  
Jan Kratochvíl ◽  
Kurt Winkler ◽  
Jindřich Zahradník
Keyword(s):  
Solid Phase ◽  
Bubble Column ◽  
Average Particle Size ◽  
Perforated Plate ◽  
Water System ◽  
Gas Holdup ◽  
Solid Particles ◽  
Average Particle ◽  
Experimental Conditions ◽  
Negative Effect

The effect of solid particles on values of volumetric liquid-side mass transfer coefficient, kLa, and gas holdup, εG, was determined in a bubble column 0.14 m in diameter within the range of solid phase concentration cS = 0-10% (mass). Experiments were carried out in air-water system at zero liquid flow rate, glass spheres of average diameters 24, 36, 50, 102, 142, 190, and 280 μm and fine Zn0 powder (average particle size 2.3 μm) were used as a solid phase. Perforated plate with holes diameter 1.6 mm and free plate area 0.2% was used for gas distribution, superficial gas velocities ranged between 0.036 and 0.215 m/s. Only negative effect of the gas holdup and kLa was observed in the whole range of experimental conditions, this effect being most pronounced in the region of small particle sizes (dS ⪬ 36 μm).

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