scholarly journals Unusual Perforations in Phlogopite Crystals from Caldara di Manziana (Italy) Caused by Sulphuric Acid Generated by Microbial Oxidation of H2S Emanations

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 547
Author(s):  
Flavia Pinzari ◽  
Javier Cuadros
Keyword(s):  
Sulphuric Acid ◽  
Crystal Symmetry ◽  
High Humidity ◽  
Mineral Surfaces ◽  
Water Droplets ◽  
Microbial Oxidation ◽  
Acid Attack ◽  
Fe Oxides ◽  
Hexagonal Shape ◽  
Recent Volcanism

Phlogopite flakes strewn on the soil of Caldara di Manziana (Italy) display multiple minute perforations. The site is a caldera linked to recent volcanism (90 ka to 0.8 Ma) with present emanations of CO2 (~150 t d−1) and H2S (~2.55 t d−1). Stereomicroscopy and SEM–EDX observation of the phlogopite crystals shows holes and depressions <200 µm to 2 mm across. They are circular, pseudo-hexagonal, or irregular. Within the depressions, there are deposits of phlogopite alteration products consistent with a sulphuric acid attack, showing loss of Mg and K. Some are thin and homogeneous; others are thick, irregular, and chemically heterogeneous, including plates, flakes, tubes of Fe-beidellite or Fe-bearing halloysite, silica, Fe oxides, and gypsum. Areas of phlogopite surface are also altered. Sulphuric acid is produced from the H2S gas by the mediation of sulphur-oxidizing bacteria. Pseudo-hexagonal perforations are interpreted to result from slow acid attack with dissolution controlled by phlogopite crystal symmetry. Some depressions developed surrounding films of pseudo-hexagonal shape, interpreted as jarosite crystallizing radially outwards from the depressions. This style of acid attack is possibly promoted by local high humidity and precipitation that generate long-lived water droplets and films on mineral surfaces where sulphuric acid is active for prolonged times.

Mist Therapy Reconsidered—Humidified Tents vs. The High Humidity Room, Further Comment

PEDIATRICS ◽  
1969 ◽  
Vol 44 (5) ◽  
pp. 773-774 ◽  
Author(s):  
John C. Griffiths ◽  
Harry Baker
Keyword(s):  
Adverse Effects ◽  
High Humidity ◽  
Water Droplets ◽  
Careful Thought ◽  
Made In

It is gratifying that Avery and her group, in a recent paper, have by careful thought, knowledge of physics, and the alchemy of mathematics helped substantiate some of the statements we made in the paper which dealt with the size of water droplets in relation to the obstructive respiratory ills of childhood. In their report, indicated above, these workers deny the value of a humidified plastic tent (or mist tent) and mention several possible adverse effects when these tents are used.

Using limestone aggregates and different cements for enhancing resistance of concrete to sulphuric acid attack

2005 ◽  
Vol 35 (8) ◽  
pp. 1486-1494 ◽  
Author(s):  
Zhen-Tian Chang ◽  
Xiu-Jiang Song ◽  
Robert Munn ◽  
Marton Marosszeky
Keyword(s):  
Sulphuric Acid ◽  
Acid Attack

scholarly journals Pore Structure Degradation of Different Cement Mortars Exposed to Sulphuric Acid

2019 ◽  
Vol 9 (24) ◽  
pp. 5297 ◽  
Author(s):  
José Ortega ◽  
Victoria García-Vera ◽  
Afonso Solak ◽  
Antonio Tenza-Abril
Keyword(s):  
Compressive Strength ◽  
Sulphuric Acid ◽  
Construction Material ◽  
Zinc Stearate ◽  
Acid Attack ◽  
Structure Degradation ◽  
Refined Microstructure ◽  
Cement Mortars ◽  
Different Types ◽  
Pronounced Reduction

Acid attack causes the deterioration of construction material surfaces. The objective of this study was to investigate the degradation of different types of cement mortar in terms of variations in pore size distribution obtained by mercury intrusion porosimetry (MIP), mass loss, and compressive strength. The mortars were manufactured with nanosilica, zinc stearate, and an ethyl silicate coating. After curing (28 days), the samples were subjected to acid exposure for 90 days, immersed ina solution (3% w/w) of sulphuric acid (H2SO4). The results indicate that the mortars showed a more refined microstructure, with a higher proportion of smaller pores (<100 nm) compared to the control mortar. The 28-day and 90-day compressive strength variations of mortars were also determined by observing pronounced reduction due to the appearance of expansive compounds responsible for microcracking.

SRPC and modified concretes subjected to severe sulphuric acid attack

1988 ◽  
Vol 40 (144) ◽  
pp. 159-166 ◽  
Author(s):  
N. I. Fattuhi ◽  
B. P. Hughes
Keyword(s):  
Sulphuric Acid ◽  
Acid Attack

scholarly journals Experimental Works on Self-Compacting Concrete By Partial Replacement of Rice Husk Ash with Subjected To Acid Attack

2020 ◽  
Vol 9 (3) ◽  
pp. 664-667
Keyword(s):  
Sulphuric Acid ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Sulphuric Acid Solution ◽  
Partial Replacement ◽  
Acid Attack ◽  
Conventional Concrete ◽  
Concrete Mix ◽  
Normal Water ◽  
Gain Characteristic

The objectives of this work is effect of Rice husk ash (AWM) in self-compaction concrete (SCR) in order to increase in strength and a better bonding between aggregate and cement paste. SCR had an improvement over conventional concrete so that it can be placed easily without vibration or mechanical consolidation. The properties of SCR have been studied in several researches due to its importance and ability to solve the problems of concrete mix. AWM was used to substitute cement in stepped concentration of 0 %, 5%, 10%, 15%, 20% and used to gain characteristic CS of M40 grade concrete mix. It is cured normal water and sulphuric acid solution (H2SO4 ) in for different ages (7days, 28days and 60days) and the strengths were determined. Sulphuric acid used in the percentages of 0%, 1%, 3%, 5%.

Biogenic Sulphuric Acid Attack in Sewage Systems

1988 ◽  
pp. 113-117 ◽  
Author(s):  
Wolfgang Sand ◽  
Eberhard Bock
Keyword(s):  
Sulphuric Acid ◽  
Acid Attack ◽  
Sewage Systems

scholarly journals Discussion: Limestone and siliceous aggregate concretes subjected to sulphuric acid attack

1979 ◽  
Vol 31 (106) ◽  
pp. 46-46
Author(s):  
B. P. Hughes ◽  
J. E. Guest ◽  
Adam Neville
Keyword(s):  
Sulphuric Acid ◽  
Acid Attack

Optimisation of Acid Bioleaching of Metals from Pyrithic Ashes

2013 ◽  
Vol 825 ◽  
pp. 520-523 ◽  
Author(s):  
Elina A. Vestola ◽  
Jarno Mäkinen ◽  
Tero Korhonen ◽  
Raisa Neitola ◽  
Anna H. Kaksonen
Keyword(s):  
Solid Waste ◽  
Sulphuric Acid ◽  
Acid Production ◽  
Stirred Tank ◽  
Acid Attack ◽  
Stirred Tank Reactors ◽  
Shake Flasks ◽  
High Concentrations

Solid waste from sulphuric acid production contains high concentrations of metals that are harmful if released to the environment. The purpose of this study was to evaluate the acid bioleaching of metals from a sample of pyritic ashes, consisting mainly of hematite. Bioleaching was tested in shake flasks and continuously stirred tank reactors (CSTR) inoculated with iron and sulphur oxidising acidophiles. Solubilisation of metals was mainly achieved through acid attack due to the formation of sulphuric acid by sulphur oxidising bacteria.

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