Hazardous material

phase
state of matter solid liquid or gas
surface
that atomic layer of a sample which, if were placed in a vacuum it is tha layer in contact with the vacuum, “outermost atomic layer.”
Interface
the boundary between two phases; where two surfaces come together
adsorption
the separation of a compound or individual species and its subsequent deposition at the interface
absorption
accumulation that goes into a particle (e.g. diffusion into crystal lattice, absorption into micropores within a structure
Desorption
opposite of adsorption; species or compound is released
sorbent
phase to which the species or compound is sorbed. soil sludges, activated carbon
sorbate
species or compound in the liquid phase which sorbs to solid phase (water)
3 classes of sorption
chemical, electrostatic, physical
intermolecular forces
hydrogen bonding and Van der Waals forces- weak bonding
4 types of dipole interactions
dipole moments, dipole-dipole interactions, dipole induced, instantaneous dipole
total porosity
fraction/percent soil volume occupied by pore space. important with regard to groundwater transport retardation and mass transfer. 30 to 50%
effective porosity
does not include space of dead end pores; used to calculate groundwater velocity based on darcy’s law.
soil organic matter
humic and non humic material
humic material
humis polymers formed by microbiual activity.
nonhumic material
do to presence of of living organism; amino acids carbohydrates, fats etc
three factors of humus
humin- insoluble at high pH
humic acids- soluble in acid and insoluble at high pH
Fulvic acid- soluble at both hihg and low pH
Freundlich
assumes sorption continues as sorbate increases in aqueous phase
langmuir
based upon assumption that sorbate accumulates in a single monolayer on sorbent
most common quantifying sorption
empirical studies followed by best-fit analysis of sorption isotherm equation
Eh
difference in potential between Pt electrode and standard hydrogen hydrogen electrode (mV)
pE
negative log of free aqueous electron activity
volatilization from soils
i)desorb
ii)diffuse from soil water to soil air
iii) diffuse to ambient atmosphere
important soil variables
sorption
soil water content
diffusion
temperature
wind and atmospheric turbulence
R for volatilization
8.21 x 10^-5 m3xatm/ mol x K
abiotic
hydrolysis, oxidation-reduction, photolysis
biotic contaminants
organic contaminants metabolized
microorganisms use contaminant
Effective porosity
Does not include space of dead-end pores, Used to calculate groundwater velocity based on Darcy’s Law
Freundlich isotherm
Assumes sorption continues as [sorbate] increases in aqueous phase. Mass of material sorbed is proportional to aqueous phase concentration at low [sorbate] and decreases as sorbate accumulates on sorbent surface (C5-1-S40) (Slide 41 has equations)
Intake dose
Isotherm
Isotherm Quantitative empirical mathematical expression to describe sorption. Plot of extent to which sorption occurs at successively higher concentration of sorbate at constant temperature. Representation of material sorbed (mass sorbate/mass sorbent) as function of equilibrium sorbate concentration. Langmuir and Freundlich isotherms
Langmuir isotherm
Based upon assumption that sorbate accumulates in a single monolayer on sorbent. As [sorbate] increases in liquid phase, proportionately more sorbent surface is covered until complete saturatio
Chemisorption
Stronger, more permanent bond in relation to physical sorption. Same characteristics as a true chemical bond. High enthalpy of sorption results in being favored by high temperatures
Fulvic acids
soluble at both high and low pH C135H182O95N5S2 (C5-1-S34)
Genotoxicity
Dipole moment
shifts in electron density within molecules that produce partial separation of charges
Dipole?dipole interactions
polar molecules interact with other polar molecules (C5-1-S14)
Dipole?induced dipole interactions
polar molecules interact with non-polar molecules (C5-1-S14)
Humic acids
soluble in acid and insoluble at high pH C187H186O89N9S (C5-1-S34)
Instantaneous dipole?induced dipole interactions fluctuating
fluctuating electron cloud results in short-term dipole moments (C5-1-S14)
Ion exchange
Displacement of charged species on a solid surface by another species that has a higher affinity for the same site
Surface
“That atomic layer of a sample which, if the sample were placed in a vacuum, is the layer ‘in contact’ with the vacuum; the outermost atomic layer of a sample.” (IUPAC) (C5-1-S3)
Bulk density
Density of soil in place (kg/m3), Not compacted or disturbed, Silts and clays have lower ?B than sands and gravels (C5-1-27)
Cation exchange capacity
Measure of surface density of exchange sites, Quantity of cations sorbed per mass of soil (expressed as meq per 100 g), Higher clay content ~ higher CEC, Higher organic content ~ higher CEC (
Fugacity
Molecule’s tendency or driving force to leave its environment or phase it is in (C5-1-S7)
Humin
insoluble at high pH
Humus
Thermodynamically stable. Originates from plant, animal and microbial biomass carbon. Three fractions: Humin/Humic Acids/Fulvic acids. Strongly sorbed to inorganic fraction (secondary iron minerals). Mineral organic complex. Primary sorbent in soils
Partitioning
Describes the tendency of a contaminant to exist at equilibrium between phases (C5-1-S4)
Phase
state of matter; solid, liquid, or gas
Physical sorption
Probably most important for sorption of organic contaminants to soils, subsurface strata and granular activated carbon. Intermolecular forces – hydrogen bounding and Van der Waals forces – cause weak bonding. Four types of dipole interactions
Porosity
Fraction/percent of soil volume occupied by pore space, Important with regard to groundwater transport, retardation, and mass transfer
Primary minerals
Small pieces of parent material (i.e., rocks), More resistant to weathering, Examples: quartz (SiO2), feldspar
Secondary minerals
Formed through chemical transformations (weathering), Clays Kaolinite (Si4Al4O10[OH]8), Smectite (Mx[Si,Al]8[Al,Fe,Mg]4O20[OH]4), Metal oxides (primarily Fe and Mn) (C5-1-S27)
Soil organic matter
Two categories: Humic materials: humus; polymers formed by microbial activity. Nonhumic materials: due to presence of living organisms; amino acids, carbohydrates, fats, etc. (C5-1-S35) Often measured as organic carbon. SOM = 1.724SOC , SOC decreases exponentially with soil depth. Surface: 1-5% SOC, > 1-m depth: <0.1% SOC. Significant influence on sorption of organic and inorganic hazardous materials
Volumetric water content
Fraction of soil pores filled with water, 100% in saturated soils, Typically 5-50% in surface soils, but can approach saturation. Used to estimate pore water velocity in unsaturated zone