scholarly journals Effect of Acidithiobacillus ferrooxidans on Humic-Acid Passivation Layer on Pyrite Surface

Minerals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 422 ◽  
Author(s):  
Hongying Yang ◽  
Wenjie Luo ◽  
Ying Gao
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Pyrite Oxidation ◽  
Passivation Layer ◽  
Pyrite Surface ◽  
Force Microscopy ◽  
Atomic Force ◽  
Leaching Experiments ◽  
Bacterial Adsorption ◽  
Number Of Bacteria

The effect of Acidithiobacillus ferrooxidans on the humic-acid passivation layer on pyrite surfaces was studied by atomic-force microscopy, leaching experiments, and adsorption experiments. Atomic-force-microscopy results showed that humic-acid was adsorbed onto the pyrite surface. The bacteria grew and reproduced on the humic-acid layer. Leaching experiments showed that the humic-acid passivation layer prevented the oxidation of pyrite by Fe3+ under aseptic conditions. Bacteria destroyed the humic-acid layer, promoted pyrite oxidation, and increased the oxidation of pyrite from 1.64% to 67.9%. Bacterial adsorption experiments showed that the humic-acid passivation layer decreased the speed of bacterial adsorption on the pyrite surface but had no effect on the number of bacteria adsorbed on the pyrite surface. The maximum number of bacteria adsorbed by pyrite with and without the humic-acid layer was 4.17 × 1010 cells∙mL−1 and 4.4 × 1010 cells∙mL−1, respectively. Extracellular polymeric stratum layer of bacteria cultured at different concentrations of humic-acid was extracted and analyzed. This layer could destroy the humic-acid layer and promote pyrite oxidation.

scholarly journals Study of a Model Humic Acid-type Polymer by Fluorescence Spectroscopy and Atomic Force Microscopy

2012 ◽  
Vol 03 (07) ◽  
pp. 478-484
Author(s):  
Marcilene Ferrari Barriquello ◽  
Fábio de Lima Leite ◽  
Daiana Kotra Deda ◽  
Sérgio da Costa Saab ◽  
Nelson Consolin-Filho ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Fluorescence Spectroscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Acid Type

Probing molecular interactions between humic acid and surface-grafted polyacrylamide using quartz crystal microbalance with dissipation and atomic force microscopy: implications for environmental remediation

2018 ◽  
Vol 15 (6) ◽  
pp. 336 ◽  
Author(s):  
Omar Maan ◽  
Jun Huang ◽  
Hongbo Zeng ◽  
Qingye Lu
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Quartz Crystal Microbalance ◽  
Molecular Interactions ◽  
Environmental Remediation ◽  
Quartz Crystal ◽  
Major Constituent ◽  
Environmental Behaviour ◽  
Force Microscopy ◽  
Atomic Force

Environmental contextPolyacrylamide and its derivatives may enter the natural environment as a consequence of their wide use in various industrial applications. This study demonstrates the application of a quartz crystal microbalance and atomic force microscopy to study the molecular interactions between polyacrylamides and humic acids under various solution chemistries. The knowledge obtained can be used to understand and predict the environmental behaviour of polyacrylamides. AbstractA fundamental understanding of the environmental behaviour of polyacrylamide (PAM) is of importance for guiding environmental remediation. We create a framework for understanding the molecular interactions between PAM and a major constituent present in all natural waters and soil, humic acid (HA), using a quartz crystal microbalance with dissipation (QCM-D) and an atomic force microscope (AFM). A thin film of PAM was grafted on a silica surface silanised with 3-(trimethoxysilyl)propyl methacrylate and the resulting surface was characterised by X-ray photoelectron spectroscopy for the chemical bonds and composition, secondary ion mass spectrometry for the composition and molecular weight, water contact angle measurements for the hydrophilicity, AFM for the morphology, and ellipsometry for the thickness. Surface-grafted PAM was used to study its interactions with HA in aqueous solutions at different pH (2, 7, and 10) and NaCl salt concentrations (1, 10, and 100 mM, within the range of salt concentrations of fresh water) using QCM-D. QCM-D measurements showed that compared with bare silica, the adsorption of HA by PAM-coated silica was greatly reduced at all pHs and salt concentrations, and the adsorption of HA on PAM-coated silica depended on the solution chemistry including solution pH and salt concentration. Hydrogen bonding between PAM and HA is the major driving force for HA to adsorb on PAM. AFM force measurements showed that adhesion between PAM and HA was observed only at acidic conditions. The knowledge obtained from this study will benefit the prediction of the environmental behaviour of PAMs under different conditions in natural/engineered environments and provide guidance for the design of remediation technologies for water and soil.

scholarly journals AFM Study of Pyrite Oxidation and Xanthate Adsorption in the Presence of Seawater Salts

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1177 ◽  
Author(s):  
Álvaro Paredes ◽  
Sergio M. Acuña ◽  
Pedro G. Toledo
Keyword(s):  
Atomic Force Microscopy ◽  
Experimental Evidence ◽  
Fresh Water ◽  
Surface Reactions ◽  
Pyrite Oxidation ◽  
Mining Industry ◽  
Sulfide Minerals ◽  
Force Microscopy ◽  
Atomic Force

The effect of seawater ions presents a great challenge to theories about mechanisms of pyrite oxidation, collector adsorption, and surface reactions. As the use of seawater is key to the sustainability of the mining industry in regions without fresh water, there is a need to study the surfaces of minerals and products that are formed in the presence of seawater salts. In this study, atomic force microscopy (AFM) was used to analyze the topography of pyrite surfaces subjected to treatments, including oxidation and exposure to xanthate and solutions of seawater salts and xanthate, at pH 8.5. Topographic details were related to surface products. The results showed that xanthate was adsorbed without hindrance on oxide-free pyrite which validated one well-known model. The results also showed that pyrite oxidized forming a structure of interconnected pillars and that xanthate was adsorbed on the top and skirt of these pillars; the experimental evidence on the increase in the height and width of these pillars validated another well-known model. In the presence of seawater salts, the cations covered the surface of the pyrite, suppressing collector adsorption regardless of the dose. The results are expected to help in decisions about the flotation of sulfide minerals in water with limited metallurgical quality.

Adsorption of Humic Acid onto Carbonaceous Surfaces: Atomic Force Microscopy Study

2011 ◽  
Vol 17 (6) ◽  
pp. 1015-1021 ◽  
Author(s):  
Zhiguo Liu ◽  
Yuangang Zu ◽  
Ronghua Meng ◽  
Zhimin Xing ◽  
Shengnan Tan ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Humic Acid ◽  
Pyrolytic Graphite ◽  
Microscopy Study ◽  
Molecular Structures ◽  
Spherical Particles ◽  
Adsorption Characteristic ◽  
Force Microscopy ◽  
Rigid Particles ◽  
Atomic Force

AbstractThe adsorption of humic acid (HA) onto highly ordered pyrolytic graphite (HOPG) surfaces at different concentrations has been studied by atomic force microscopy. When HA concentration was increased from 10 to 1,000 mg/L, HA can sequentially form spherical particles, layered structures, and connected blocks on HOPG surfaces. The findings of the layer structures and small amount of fine chains have been verified and discussed. When HA was acidified by addition of acetic acid, it changed into small rigid particles. These results indicated that HA can be considered as supramolecular associations of self-assembling heterogeneous and relatively small molecules, and a small amount of polymers. The present results are important for understanding HA molecular structures and their adsorption characteristic on carbonaceous surfaces.

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