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Material Cycle in

he EnvironmentAdvanced ChemistryWednesday 17 April 2013

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Aim of class:

Understanding the concept ofbiogeochemical cycle in the environment

and the impact towards civil engineering

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What does it consist of?

Define compartments

Define Environment

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What does it consist of?

How does it work?

How does it regulate itself?

Define Environment

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Interaction in the environment:Every material is involved in a cycle inside the different compartments

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Interaction in the environment

Abiotic Compartments:

Atmosphere

HydrosphereLithosphere/Geospher

e

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Interaction in the environment

Biotic Compartments:

Anthrosphere

Ecosphere

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Something is then exchanged within

the different com artments

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Every materialis involved in a cycle inside the different

compartments

What kind of material? (hint: chemistry class)

What is exchanged?

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Abiotic Elements:

Crustal Abundance Source: CRC Handbook of Chemistry and Physics

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Biotic Elements:

Human bod abundance Source: Wikiipedia

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Exchange of biotic-relevant

element throughtout all the

compartments

Material cycle in the

environment

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What do theyhave in

common?

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Destruction dueto acidity (H+)

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Sulfur cycle in the

environment

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Sulfur vs Acidity

Impact of sulfur for

buildings

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SO2 + OH HSO3

HSO3 + O2 SO3 + HO2

SO3 + H2O

H2SO4

or direct transformation to sulfate ions

SO2 + O2 (dissolved) + H2O2 H+ + SO42-

Impact of sulfate Impact of acidity

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Sulfur vs Acidity

Impact of sulfate

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CaCO3+ H2OCa2+ +

CO32- Ca2+ + SO42-CaSO4

(more soluble)

CaCO3 solubility 0,0013 g/100 mlCaSO4 solubility 0,21 g/100 ml

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Formation of ettringiteSO4

2-+ Ca(OH)2CaSO4.2H2O

(Gypsum) + 2OH-

C3A + H2O + CaSO4.2H2O

C6AS

3H

32(Ettringite)

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Ettringite causes microcracks and

gives access of other pollutants and

oxygen to reinforcement steel2Fe(s) + O2(g)+ 2H2O(l) 2Fe2+ + 4OH-(aq)4Fe2+ + O2+ (4+n) H2O 2Fe2O3.nH2O + 8H

+

f

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Sulfur vs Acidity

Impact of acidity

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CaCO3+ H2OCa2+ +

CO32- Ca2+ + SO42-CaSO4

(more soluble)

CaCO3 solubility 0,0013 g/100 mlCaSO4 solubility 0,21 g/100 ml

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Destruction of Zinc CoatingZn+H20ZnOH +H+ + CO2 + H2O

ZnCO3 (insoluble)

in low pH ZnCO3 becomes soluble

exposing the iron underneath

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Destruction due to acidity (H+)Higher availability of Al and other metals

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