scholarly journals Strength of Humic Acid Aggregates: Effects of Divalent Cations and Solution pH

ACS Omega ◽  
2019 ◽  
Vol 4 (5) ◽  
pp. 8559-8567 ◽  
Author(s):  
Azizul Hakim ◽  
Tomoharu Suzuki ◽  
Motoyoshi Kobayashi
Keyword(s):  
Humic Acid ◽  
Divalent Cations ◽  
Solution Ph

scholarly journals Rapid Degradation of Carbon Tetrachloride by Microscale Ag/Fe Bimetallic Particles

2021 ◽  
Vol 18 (4) ◽  
pp. 2124
Author(s):  
Xueqiang Zhu ◽  
Lai Zhou ◽  
Yuncong Li ◽  
Baoping Han ◽  
Qiyan Feng
Keyword(s):  
Humic Acid ◽  
Catalytic Reduction ◽  
Direct Reduction ◽  
Cost Effective ◽  
Degradation Efficiency ◽  
Pseudo First Order Reaction ◽  
Solution Ph ◽  
Reaction Stage ◽  
Bimetallic Particles ◽  
Slow Reaction

Cost-effective zero valent iron (ZVI)-based bimetallic particles are a novel and promising technology for contaminant removal. The objective of this study was to evaluate the effectiveness of CCl4 removal from aqueous solution using microscale Ag/Fe bimetallic particles which were prepared by depositing Ag on millimeter-scale sponge ZVI particles. Kinetics of CCl4 degradation, the effect of Ag loading, the Ag/Fe dosage, initial solution pH, and humic acid on degradation efficiency were investigated. Ag deposited on ZVI promoted the CCl4 degradation efficiency and rate. The CCl4 degradation resulted from the indirect catalytic reduction of absorbed atomic hydrogen and the direct reduction on the ZVI surface. The CCl4 degradation by Ag/Fe particles was divided into slow reaction stage and accelerated reaction stage, and both stages were in accordance with the pseudo-first-order reaction kinetics. The degradation rate of CCl4 in the accelerated reaction stage was 2.29–5.57-fold faster than that in the slow reaction stage. The maximum degradation efficiency was obtained for 0.2 wt.% Ag loading. The degradation efficiency increased with increasing Ag/Fe dosage. The optimal pH for CCl4 degradation by Ag/Fe was about 6. The presence of humic acid had an adverse effect on CCl4 removal.

Coagulation of humic acid by ferric chloride in saline (marine) water conditions

2003 ◽  
Vol 47 (1) ◽  
pp. 41-48 ◽  
Author(s):  
J. Duan ◽  
N.J.D. Graham ◽  
F. Wilson
Keyword(s):  
Humic Acid ◽  
Zeta Potential ◽  
Membrane Filtration ◽  
Metal Salt ◽  
Substantial Effect ◽  
Precipitation Process ◽  
Solution Ph ◽  
Floc Size ◽  
Coagulant Dosage ◽  
Co Precipitation

The coagulation of a model seawater-humic acid solution with a hydrolysis metal salt (FeCl3) has been studied by monitoring floc size, solution pH, and zeta potential. The kinetic features of the orthokinetic coagulation have been demonstrated in relation to coagulant dosages, solution pH and zeta potential. Humic acid removal and floc charge reduction increased with coagulant dosage. Adjusting the solution pH prior to coagulation had a substantial effect on the treatment performance. By pH adjustment to pH 6, the greatest humic acid removal (by coagulation and subsequent membrane filtration) and the largest floc size was achieved at a FeCl3 dosage of 200 mmol l−1. It is believed that the coagulation is characterised by competition between OH- ions and humic acid for ferric ions in the co-precipitation process. In acidic pH, where the concentration of OH- ions is low, humic acid molecules may compete more favourably for bonding sites in the co-precipitation, which leads to a more compact precipitation and a higher overall humic acid removal.

Comparison of Coal Ash and Activated Carbon for Removal of Humic Acid from Aqueous Solution

2013 ◽  
Vol 864-867 ◽  
pp. 1509-1512
Author(s):  
Xue Mei Zhang ◽  
Yan Zhang ◽  
Di Fan
Keyword(s):  
Aqueous Solution ◽  
Humic Acid ◽  
Activated Carbons ◽  
Removal Rate ◽  
Coal Ash ◽  
Cost Effective ◽  
Solution Ph ◽  
Adsorption Behaviors ◽  
Calcium Loading ◽  
Working Solution

This paper presents the adsorption behaviors of humic acid (HA) on coal ashes and powdered activated carbons (PACs). A bituminous coal, with or without calcium-loading, was used as a feedstock for coal ash preparation. The working solution of HA with a concentration of 20 mg/L was used in all adsorption tests. The results showed that calcium-enriched coal ash (CECA) gave rise to the removal rate of HA as high as 84.05%, much higher than those of raw coal ash (RCA) and PACs. The impacts of solution pH and adsorbent dosage on HA adsorption capacity were also investigated. It was found that lower pH facilitated to the removal of HA from aqueous solution by means of CECA, and the optimal CECA dosage was about 1.0g/L at pH 7.00. The data obtained in this study suggested that calcium-enriched coal ash could be useful and cost-effective in the treatment of wastewaters containing HA-like organic macro-molecules.

scholarly journals Effect of Water Chemistry on Antimony Removal by Chemical Coagulation: Implications of ζ-Potential and Size of Precipitates

2019 ◽  
Vol 20 (12) ◽  
pp. 2945 ◽  
Author(s):  
Muhammad Ali Inam ◽  
Rizwan Khan ◽  
Muhammad Akram ◽  
Sarfaraz Khan ◽  
Ick Tae Yeom
Keyword(s):  
Water Chemistry ◽  
Divalent Cations ◽  
Chemical Properties ◽  
Point Of Zero Charge ◽  
Hydrodynamic Diameter ◽  
Alkaline Ph ◽  
Solution Ph ◽  
Ζ Potential ◽  
Wide Group ◽  
Co Precipitation

The process of coagulation and precipitation affect the fate and mobility of antimony (Sb) species in drinking water. Moreover, the solubility and physico-chemical properties of the precipitates may be affected by the media chemistry. Accordingly, the present study aimed to investigate the removal of Sb(III, V) species by ferric chloride coagulation under various water chemistry influences with a particular focus on the role of the properties of the precipitates. The results indicated that the amount of Sb(III) removed increased with increasing solution pH, showing the insignificant effects of the hydrodynamic diameter (HDD) and ζ-potential of the precipitates. However, no Sb(V) removal occurred at alkaline pH values, while a highly negative ζ-potential and the complete dissolution of precipitates were observed in the aqueous solution. The solution pH was also useful in determining the dominant coagulation mechanisms, such as co-precipitation and adsorption. The Fe solubility substantially affects the Sb removal at a certain pH range, while the HDD of the precipitates plays an insignificant role in Sb removal. The presence of divalent cations brings the ζ-potential of the precipitates close to point of zero charge (pzc), thus enhancing the Sb(V) removal at alkaline pH conditions. Pronounced adverse effects of humic acid were observed on Sb removal, ζ-potential and HDD of the precipitates. In general, this study may provide critical information to a wide group of researchers dealing with environmental protection from heavy metal pollution.

Effects of Porous Medium Geochemical Heterogeneity and Divalent Cations on the Transport of Humic Acid

2016 ◽  
Vol 5 (2) ◽  
pp. 165-172
Author(s):  
R. Ait Akbour ◽  
J. Douch ◽  
A. Jada ◽  
H. Ouachtak ◽  
A. Ait Addi ◽  
...  
Keyword(s):  
Porous Medium ◽  
Humic Acid ◽  
Divalent Cations ◽  
Geochemical Heterogeneity

scholarly journals Chemical properties of the divalent cation binding site on potassium channels.

1992 ◽  
Vol 100 (2) ◽  
pp. 181-193 ◽  
Author(s):  
S Spires ◽  
T Begenisich
Keyword(s):  
Potassium Channels ◽  
Binding Site ◽  
Divalent Cation ◽  
Divalent Cations ◽  
Chemical Properties ◽  
Cation Binding ◽  
Solution Ph ◽  
Electrophysiological Properties ◽  
Cation Binding Site ◽  
Voltage Gated Ion Channels

The actions of divalent cations on voltage-gated ion channels suggest that these cations bind to specific sites and directly influence gating kinetics. We have examined some chemical properties of the external divalent cation binding sites on neuronal potassium channels. Patch clamp techniques were used to measure the electrophysiological properties of these channels and Zn ions were used to probe the divalent cation binding site. The channel activation kinetics were greatly (three- to fourfold) slowed by low (2-5 mM) concentrations of Zn; deactivation kinetics were only slightly affected. These effects of Zn were inhibited by low solution pH in a manner consistent with competition between Zn and H ions for a single site. The apparent inhibitory pK for this site was near 7.2. Treatment of the neurons with specific amino acid reagents implicated amino, but no histidyl or sulfhydryl, residues in divalent cation binding.

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