Determination of formation constants of molybdophosphates in strong acid solutions

1982 ◽  
Vol 54 (6) ◽  
pp. 879-884 ◽  
Author(s):  
C. C. Kircher ◽  
S. R. Crouch
Keyword(s):  
Strong Acid ◽  
Formation Constants ◽  
Acid Solutions

Spectrophotometric study of the reaction of alizarin green series dyes with uranyl ions in the presence of cationoid surfactants

1985 ◽  
Vol 50 (3) ◽  
pp. 611-620 ◽  
Author(s):  
Jiří Šimek ◽  
Nguyen Truong Son ◽  
Eduard Ružička
Keyword(s):  
Photometric Determination ◽  
Spectrophotometric Study ◽  
Formation Constants ◽  
Ternary Complexes ◽  
Acid Solutions ◽  
Uranyl Ions ◽  
Cetylpyridinium Bromide ◽  
Weakly Acid ◽  
Coordination Properties

The coordination properties of alizarin green series dyes with uranyl ions were studied in the presence of cationoid surfactants (cetylpyridinium bromide, carbethoxypentadecyltrimethylammonium bromide). Ternary complexes of the composition UO2L2S2, UO2L2S4, UO2L2S6, and UO2L3S9, where L is dye and S is surfactant, are formed in weakly acid solutions. The formation constants of the complexes were established and a procedure was worked out for the direct photometric determination of uranium.

scholarly journals A Simple and Accurate Approach for Determining the VFA Concentration in Anaerobic Digestion Liquors, Relying on Two Titration Points and an External Inorganic Carbon Analysis

2021 ◽  
Vol 5 (2) ◽  
pp. 15
Author(s):  
Paz Nativ ◽  
Yonatan Gräber ◽  
Yaron Aviezer ◽  
Ori Lahav
Keyword(s):  
Partial Pressure ◽  
Volatile Fatty Acids ◽  
Inorganic Carbon ◽  
Strong Acid ◽  
Direct Analysis ◽  
Anaerobic Digesters ◽  
Acid Titration ◽  
Partial Pressure Of Co2 ◽  
Ph Range

A new analytic approach is presented for determining the total volatile fatty acids (VFAT) concentration in anaerobic digesters. The approach relies on external determination of the inorganic carbon concentration (CT) in the analyzed solution, along with two strong-acid titration points. The CT concentration can be determined by either a direct analysis (e.g., by using a TOC device) or by estimating it from the recorded partial pressure of CO2(g) in the biogas (often a routine analysis in anaerobic digesters). The titration is carried out to pH 5.25 and then to pH 4.25. The two titration results are plugged into an alkalinity-mass-based equation and then the two terms are subtracted from each other to yield an equation in which VFAT is the sole unknown (since CT is known and the effect of the total orthophosphate and ammonia concentrations is shown to be small at this pH range). The development of the algorithm and its verification on four anaerobic reactor liquors is presented, on both the raw water and on acetic acid-spiked samples. The results show the method to be both accurate (up to 2.5% of the expected value for VFAT/Alkalinity >0.2) and repetitive when the total orthophosphate and ammonia concentrations are known, and fairly accurate (±5% for VFAT >5 mM) when these are completely neglected. PHREEQC-assisted computation of CT from the knowledge of the partial pressure of CO2(g) in the biogas (and pH, EC and temperature in the liquor) resulted in a very good estimation of the CT value (±3%), indicating that this technique is adequate for the purpose of determining VFAT for alarming operators in case of process deterioration and imminent failure.

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