Removal of arsenic(V) ion from aqueous solutions by lanthanum compounds

1997 ◽  
Vol 35 (7) ◽  
pp. 71-78 ◽  
Author(s):  
Shuzo Tokunaga ◽  
Syed A. Wasay ◽  
Sang-Won Park
Keyword(s):  
Aqueous Solutions ◽  
Adsorption Process ◽  
Lanthanum Carbonate ◽  
Lanthanum Hydroxide ◽  
First Order ◽  
Optimum Ph ◽  
Initial Ph ◽  
Ph Range ◽  
Removal Of Arsenic ◽  
Optimum Ph Range

A new adsorption process for the removal of As(V) ion from aqueous solutions has been studied using lanthanum hydroxide (LH), lanthanum carbonate (LC) and basic lanthanum carbonate (BLC). These La compounds were effective in removing As ion to decrease the concentration down to < 0.001 mM. Dissolution of these La compounds was measured in the pH range of 2 to 12. The dissolution was appreciable at initial pH <4.3, <4.3 and <4.0 for LH, LC and BLC, respectively. Kinetic study showed that the As removal was a first-order reaction in the neutral pH range and the rate constants were in the order of LH > LC > BLC. The As removal was highly pH-dependent. The optimum pH range was 3-8, 4-7 and 2-4 for LH, LC and BLC, respectively. The following two mechanisms are proposed: (i) adsorption by exchange of CO3 and/or OH group with As ions in the neutral to alkaline pH range where La does not dissolve and (ii) precipitation of insoluble lanthanum arsenate, LaAsO4, in the acid pH range.

Removal of Pb(II) from Aqueous Solution Using Composite Filter Material Made of Fly Ash

2010 ◽  
Vol 33 ◽  
pp. 700-703
Author(s):  
Hong Qin Xue ◽  
Xiao Dong Liu ◽  
Zhao Qian Jing ◽  
Chen Zhao
Keyword(s):  
Aqueous Solution ◽  
Fly Ash ◽  
Adsorption Process ◽  
Filter Material ◽  
Adsorption Sites ◽  
Optimum Ph ◽  
Initial Ph ◽  
Composite Filter ◽  
Ph Range ◽  
Optimum Ph Range

Adsorption of Pb(II) on composite filter material mainly made of fly ash was investigated for the removal of Pb(II) from aqueous solution. Batch experiments have been carried out for adsorption of Pb(II) on to this composite filter material. The effects of various parameters influencing the Pb(II) adsorption such as contact time, initial pH, different dosage of adsorbent and temperature have been studied. Results showed that adsorption equilibrium attained within 60 minutes time. Increase in adsorbent dosage led to increase in Pb(II) adsorption due to increased number of adsorption sites. Adsorption process was found to be highly pH dependent, and the optimum pH range for adsorption of Pb(II) was found to be >8.5. The sorption of Pb(II) increased with rise of temperature.

Photoreduction of Cr(VI) in Fe(III)-lactate System

2012 ◽  
Vol 512-515 ◽  
pp. 2317-2320
Author(s):  
Xiang Hua Feng ◽  
Xiao Rong Zheng ◽  
Shi Min Ding
Keyword(s):  
Aqueous Solutions ◽  
Initial Rate ◽  
Photochemical Reduction ◽  
First Order ◽  
Reduction Efficiency ◽  
Optimum Ph ◽  
Initial Ph ◽  
The Law

The photochemical reduction of Cr(VI) in aqueous solutions containing Fe(III)-lactate complex was preliminarily investigated. The effects of initial pH, initial concentrations of Fe (III), lactate and Cr(VI) were studied in detail and the photoreduction mechanism of Cr(VI) was discussed preliminarily. The results indicate that Cr(VI) can be effectively photochemically reduced by Fe(III)-lactate complex, and the optimum pH for photoreduction of Cr(VI) is 3.0. The reduction efficiency of Cr(VI) decreases with increase of the initial concentrations of Cr(VI) over the range of 12.0~48.0 μM. The initial rate of Cr (VI) photoreduction increases with increase of the initial concentrations of Fe (III) or lactate. The photoreduction reaction is accordance with the law of apparent first-order dynamics reaction.

Removal of Methyl Red from Aqueous Solution by Adsorption onto Mg-Al HTLc

2013 ◽  
Vol 750-752 ◽  
pp. 1426-1429
Author(s):  
Yun Bo Zang
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Contact Time ◽  
Adsorption Process ◽  
Bulk Solution ◽  
Methyl Red ◽  
Initial Ph ◽  
Pseudo Second Order ◽  
Ph Range ◽  
Percent Removal

In this study, removal of Methyl Red from aqueous solutions by synthetic Mg-Al-HTlc was investigated as a function of contact time, pH and temperature. It is found that HTlc could reduced Methyl Red concentration effectively. The kinetic process which reached equilibrium at about 2h can be fitted by pseudo-second order kinetics. The percent removal of MR by the HTlc was dependent on the initial pH of bulk solution. There was no much changes in amount of adsorption in the initial pH range of 6-8, while it reached maxium at about of 9. The adsorption process was endothermic.

scholarly journals Haem disorder in modified myoglobins. Effect of reconstitution procedures

1983 ◽  
Vol 215 (1) ◽  
pp. 117-122 ◽  
Author(s):  
M B Ahmad ◽  
J R Kincaid
Keyword(s):  
Selective Oxidation ◽  
High Spin ◽  
Chromatographic Purification ◽  
Optimum Ph ◽  
Ph Range ◽  
Optimum Ph Range

Apomyoglobin was reconstituted with deuterohaem derivatives under various conditions. The fraction of disordered component, which is characterized by a 180 degree rotation of the haem group, for the various preparations was determined by n.m.r. spectroscopy. By using the procedures described, it was shown that the fraction of disordered component is minimized if the reconstitution is carried out with high-spin ferric haem derivatives within an experimentally determined optimum pH range of 8-9.5. Use of low-spin derivatives in either the ferrous or ferric forms leads to substantial increases in the fraction of disordered form. Attempted removal of the disordered form by selective oxidation and chromatographic purification was not effective.

CHARACTERISTICS OF FOUR RHIZOBIOPHAGES ACTIVE AGAINST RHIZOBIUM MELILOTI

1957 ◽  
Vol 3 (4) ◽  
pp. 651-668 ◽  
Author(s):  
D. T. Parker ◽  
O. N. Allen
Keyword(s):  
Rhizobium Meliloti ◽  
The Other ◽  
Cross Reactions ◽  
Thermal Death ◽  
Optimum Ph ◽  
Ph Range ◽  
Optimum Ph Range ◽  
Standard Techniques

Four phage isolates for strains of Rhizobium meliloti were obtained from sewage and held soil and purified by standard techniques. Plaque sizes ranged from 1.0 to 4.0 mm. The titers of these phages remained unchanged after 24 months' storage at 0° and 4 °C. None of the phages lysed all of the 38 strains of R. meliloti tested, although 29 of these strains were lysed by one of the phages. Of 292 other strains of rhizobia isolated from 108 species of 50 leguminous genera, one of the phages lysed six strains, another, five strains, while the other two phages did not lyse any. None of the phages lysed any of the 40 strains of Agrobaderium and Chromobaderium species tested. Inactivation rates of the four phages by their homologous antisera were linear up to 90% inactivation. Cross-reactions with heterologous antisera showed weak serological relationships between some of the phages. The latent periods of growth ranged from 80 to 90 minutes to 170–180 minutes. Burst sizes of rhizobia infected by the four phages ranged from 80 to 317 particles per bacterium after an adsorption period of 60 minutes at 30 °C. The optimum pH range was 6.4–7.8. Thermal death points in broth were 51 °C, 53 °C, 61 °C, and 70 °C, respectively, for the four phages.

scholarly journals The subcellular distribution of triphosphoinositide phosphomonoesterase in guinea-pig brain

1972 ◽  
Vol 128 (3) ◽  
pp. 579-586 ◽  
Author(s):  
A. Sheltawy ◽  
M. Brammer ◽  
D. Borrill
Keyword(s):  
Guinea Pig ◽  
Subcellular Fractions ◽  
Assay System ◽  
Acid Phosphatases ◽  
Alkaline Phosphatases ◽  
Pig Brain ◽  
Optimum Ph ◽  
Ph Range ◽  
Guinea Pig Brain ◽  
Optimum Ph Range

1. Some properties of the triphosphoinositide phosphomonoesterase from the homogenates of guinea-pig brain were studied. The enzyme has an optimum pH range 6.7–7.3, is stimulated with KCl at a concentration of 0.1m, and under these conditions has Km1.43×10-4m. 2. A factor from the ‘pH5 supernatant’ of guinea-pig brain stimulates the enzyme activity over and above the stimulation produced by KCl. Subcellular fractions of guinea-pig brain varied in their response to the ‘pH5 supernatant’. Maximum stimulation was observed with the P1 fraction, containing myelin and nuclei. 3. An assay system for the enzyme was developed that contained optimum concentrations of both KCl and the ‘pH5 supernatant’. Acid phosphatases were inhibited by NaF, but, in contrast with previous work, no EDTA was added to the assay system to inhibit the alkaline phosphatases. This reagent inhibited the triphosphoinositide phosphomonoesterase. It was estimated that the remaining fraction of non-specific phosphatases can account for only 14% of the observed triphosphoinositide phosphomonoesterase activity. 4. Subcellular fractions of guinea-pig brain were characterized by electron microscopy and subcellular markers. The triphosphoinositide phosphomonoesterase exhibited a distribution between the fractions similar to that of 5′-nucleotidase, but different from that of alkaline phosphatase.

Coagulation/flocculation of dye-containing solutions using polyaluminium chloride and alum

2009 ◽  
Vol 59 (7) ◽  
pp. 1343-1351 ◽  
Author(s):  
M. Hasani Zonoozi ◽  
M. R. Alavi Moghaddam ◽  
M. Arami
Keyword(s):  
Dye Removal ◽  
Coagulant Dosage ◽  
Optimum Ph ◽  
Ph Range ◽  
Influence Of Ph ◽  
Acid Blue ◽  
Ph Variations ◽  
Optimum Ph Range ◽  
Low Dosage ◽  
Polyaluminium Chloride

This study aims to compare the performance of Polyaluminium Chloride (PAC) and alum as coagulants to remove a specific type of dye (Acid Blue 292 (AB292)) from dye-containing solution. For this purpose, the influence of pH, coagulant dosage, coagulant aids (kaolinite and bentonite), and initial dye concentration on dye removal efficiency were examined. According to the results, removal of AB292 was absolutely dependent on the pH variations. The maximum dye removal occurred when pH was 7 and 5 for PAC and alum, respectively. Both coagulants efficiently removed the dye (about 85%) with a relatively low dosage (40 mg/l) in their optimum pH range. By adding kaolinite as a coagulant aid, the removal efficiencies tended to increase, especially for lower dosages of PAC and alum. With the increase of initial dye concentration, PAC and alum represented different behaviors. In the case of PAC, Q (the amount of the removed dye per unit mass of coagulant) increased at first and reached to a maximum value, 2.1 mg dye/mg PAC, and then decreased rapidly. While for alum, Q steadily increased with the increase of dye concentration and reached to 2.8 mg dye/mg alum. No reduction of Q occurred for alum with the increase of dye concentration in the range of 25–250 mg/l.

Photocatalytic mineralisation of perchloroethylene using titanium dioxide

1995 ◽  
Vol 31 (9) ◽  
pp. 47-54 ◽  
Author(s):  
Hani Gupta ◽  
Shuzo Tanaka
Keyword(s):  
Titanium Dioxide ◽  
Lag Time ◽  
Order Reaction ◽  
Co2 Production ◽  
First Order ◽  
Tio2 Particles ◽  
Initial Ph ◽  
Wide Ph Range ◽  
Catalyst Dosage ◽  
Ph Range

The photocatalytic mineralisation of perchloroethylene (PCE) is demonstrated mainly in terms of CO2 formation to investigate the effects of various factors such as dissolved oxygen (DO), titanium dioxide semiconductor (TiO2) catalyst dosage, PCE concentration and pH on PCE photocatalysis. PCE was rapidly adsorbed onto the TiO2 particles followed by its gradual degradation, and CO2 production started after a short lag time that corresponded to the adsorption phase. The rate of CO2 formation increased with increasing DO, TiO2 dosage and PCE concentration. There was no significant effect of initial pH on the CO2 production rate over a wide pH range. The dependence of the CO2 formation on PCE concentration was found to obey the Langmuir-Hinshelwood model. No intermediates were detected during PCE degradation and PCE degradation followed a first-order reaction.

Adsorption Behavior and Thermodynamic Characteristics of p,p’- DDT on Expanded Graphite

2011 ◽  
Vol 287-290 ◽  
pp. 1653-1658 ◽  
Author(s):  
You Ya Zhou ◽  
Zeng Guang Yan ◽  
Kinam Kim
Keyword(s):  
Aqueous Solutions ◽  
Adsorption Process ◽  
Adsorption Equilibrium ◽  
Thermodynamic Characteristics ◽  
Expanded Graphite ◽  
Freundlich Isotherm ◽  
Type Ii ◽  
Efficient Removal ◽  
First Order ◽  
Water And Wastewater

The adsorption of p,p’-DDT onto expanded graphite (EG) in aqueous solutions was investigated under varying conditions of p,p’-DDT concentrations, adsorbent doses, pH, and contact time. The removal efficiency of p,p’-DDT from the aqueous solutions remained constant in a range of pH 2 to 10, and the thermodynamic data followed the type II adsorption isotherm characterized by a spontaneous process. At lower concentrations, adsorption equilibrium of p,p’-DDT onto EG was fitted to Freundlich isotherm. Dynamic modeling of the adsorption showed that the first order reversible kinetic model was held for the adsorption process within the range of experimental concentration. It was suggested that expanded graphite can be used for efficient removal of p,p’-DDT from water and wastewater.

Optimization of multiple parameters of coking wastewater (CWW): catalytic thermolysis (CT) at high pressure reactor (HPR)

2020 ◽  
Vol 18 (4) ◽  
Author(s):  
Vibha Verma ◽  
Parmesh Kumar Chaudhari ◽  
Bidyut Mazumdar
Keyword(s):  
High Pressure ◽  
Adsorption Process ◽  
Treatment Time ◽  
Mass Loading ◽  
Initial Value ◽  
First Order ◽  
Multiple Parameters ◽  
Second Stage ◽  
Initial Ph ◽  
Central Composite

AbstractPresent study deals with the treatment of coking waste water (CWW) for the reduction of pollutants COD, phenol and cyanide using catalytic thermolysis (CT). For screening of catalyst and optimization of pH the CT was performed at 100 °C, pH = 3–11 using catalyst mass loading Cw = 3 g/L. In this study Cu (NO3)2 gave best performance. Further, CT was carried out using Cu (NO3)2 catalyst in high pressure reactor (HPR). The investigated parameters range were initial pH (pHi) = 3–11, Cw = 1–5 g/L, temperature (T) = 100–160 °C and treatment time (tR) = 6 h. The maximum percentage reduction for COD, phenol and cyanide were 83.33, 80.57 and 97.61%, respectively at pH = 9, Cw = 4 g/L, T = 140 °C and tR = 6 h. The CT did not give complete reduction of pollutant; therefore it was further treated using adsorption process as second stage treatment. The initial value of COD = 610 mg/L, phenol = 70.58 mg/L and cyanide = 0.45 mg/L were further reduced to 98.85, 100.00 and 55.55%, respectively, when adsorption process was performed at pH = 9, adsorbents dose Aw = 4 g/L, tR = 2 h. The response surface methodology (RSM) was performed through central composite design (CCD) for the designing of experiments and optimization of both the process. The kinetics studies of CT at HPR showed first order with respect to COD and phenol, and 0.24–0.608 order with respect to CW.

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