scholarly journals Isothermal and Kinetic Studies of Biosorption of Low Concentration Cr(III) from Aqueous Solution by 4 Microbial Biosorbents

Author(s):  
Rui Wang ◽  
Ming Zhong ◽  
Wei Li ◽  
Yangwu Chen ◽  
Zhouliang Tan ◽  
...  
1982 ◽  
Vol 35 (7) ◽  
pp. 1357 ◽  
Author(s):  
TJ Broxton

The hydrolysis of 2-acetyloxybenzoic acid in the pH range 6-12 has been studied in the presence of micelles of cetyltrimethylammonium bromide (ctab) and cetylpyridinium chloride (cpc). In the plateau region (pH 6-8) the hydrolysis is inhibited by the presence of micelles, while in the region where the normal BAC2 hydrolysis (pH > 9) occurs the reaction is catalysed by micelles of ctab and cpc. The mechanism of hydrolysis in the plateau region is shown to involve general base catalysis by the adjacent ionized carboxy group both in the presence and absence of micelles. This reaction is inhibited in the presence of micelles because the substrate molecules are solubilized into the micelle and water is less available in this environment than in normal aqueous solution.


1992 ◽  
Vol 18 (1) ◽  
pp. 43-51 ◽  
Author(s):  
KAORU CHIBA ◽  
MASANAO TAKAHASHI ◽  
NOBUMASA HAYASE ◽  
SHIGETAKA AKUTSU ◽  
SHUNICHI INAGAKI

2021 ◽  
Vol 12 (2) ◽  
pp. 2022-2040

Almond shell (AS) is a low-cost adsorbent used in this study for the removal of methylene blue (MB), crystal violet (CV), and Congo red (CR) from an aqueous solution in single and mixture binary systems. The low-cost adsorbent was characterized by FTIR and SEM analysis. The effects of AS dose, contact time, initial dye concentration, pH, and temperature on MB, CV, and CR adsorption were studied in a single system. In a binary system, the MB, CV, and CR were removed from the mixture of MB+CR, CV+MB, and CV+CR with a percentage in volume ranging from 0 to 100 % in MB and CV, and CR. Kinetic studies showed rapid sorption following a second-order kinetic model with of contact time of 10 min. The modulation of adsorption isotherms showed that retention follows the Langmuir model. The thermodynamic parameters proved that the MB, CV, and CR adsorption process was feasible, spontaneous, and exothermic. The synergy adsorption between dyes in a binary mixture of MB+CR and CV+CR, while the competition adsorption between dyes in a binary mixture of MB+ CV.


Author(s):  
I. O. Ekwere ◽  
M. Horsfall ◽  
J. O. E. Otaigbe

The photocatalytic reduction of Cu (II), Pb (II), Cd (II) and Cr (VI) ions in aqueous solution has been investigated. The photocatalyst utilized was nano titanium dioxide, composed of 80% anatase and 20% rutile; the UV light source was a 15 W UV bulb with a wavelength of 254 nm. The results obtained indicated a reduction efficiency order as follows; Cr6+ > Cu2+ > Pb2+ > Cd2+. It was observed that these results correlate with the respective reduction potentials of the metal ions. The effect of pH on the photocatalytic reduction of the metal ions was also carried out and results obtained indicated that with the exception of Cr (VI) ions, higher percentage removal of metal ions from their aqueous solution was recorded at alkaline pH than at acidic pH. This was attributed to an extensive formation of precipitate by the metal ions at alkaline pH. Kinetic studies revealed that the removal of metal ions from their solutions largely followed the pseudo- first-order kinetics. Therefore, the results of this study will be useful in metal ion removal from industrial waste water using photocatalytic process.


2005 ◽  
Vol 23 (4) ◽  
pp. 335-346 ◽  
Author(s):  
Yue Sun ◽  
Jin-Long Chen ◽  
Ai-Min Li ◽  
Fu-Qiang Liu ◽  
Quan-Xing Zhang

The adsorption of phenol from aqueous solution onto the hypercrosslinked polymeric adsorbent NDA-100 and its dimethylamine aminated derivatives AH-1, AH-2 and AH-3, the commercial resin Amberlite XAD-4 and the weakly basic anion-exchange resin D301 was compared. Of the tested polymers, the aminated hypercrosslinked resins had the highest adsorption capacities. The empirical Freundlich equation was successfully employed to describe the adsorption process. The specific surface area and the micropore structure of the adsorbent together with the tertiary amino group on the matrix affected the adsorption performance towards phenol. Furthermore, these factors also influenced the thermodynamic properties. Kinetic studies demonstrated that the presence of the tertiary amino group on the polymer matrix decreased the adsorption rate and increased the apparent activation energy of the adsorption process.


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