Understanding Sorption Onto Mineral Surfaces: Terminology and Mechanisms, Quizzes of Engineering

Download Understanding Sorption Onto Mineral Surfaces: Terminology and Mechanisms and more Quizzes Engineering in PDF only on Docsity! TERM 1 What natural surface are available for sorption? DEFINITION 1 1. metal oxides2. clay minerals3. organic matter TERM 2 Name characteristics of mineral surfaces DEFINITION 2 Metal surfaces are...1. polar2. nearly all charged TERM 3 Mathematically and physically, what is the point of zero charge DEFINITION 3 Mathematically: (pKa1 + pKa2)/2Physically: the pH at which the mineral surface charge is zero TERM 4 If pH < pHpzc, then the surface is... DEFINITION 4 Positively chargedAlternatively, if the pH > pHpzc then the surface is negatively charged TERM 5 When might sorption onto mineral surface occur? DEFINITION 5 If there is little OM in the systemi.e. Kmin dominates for Foc < 0.001 TERM 6 What is Kmin, including units? DEFINITION 6 Kmin (L/m^2) = Cmin (mol/m^2) / Cwater (mol/L) TERM 7 What is Kd, including units? DEFINITION 7 Kd (L/kg) = [Cmin (mol/m^2) * A (m^2/kg)] / Cwater (mol/L) = Kmin*AKd = [Cs] / [Cw] TERM 8 Is sorption onto mineral surfaces Langmuir or linear? DEFINITION 8 Langmuir tends to be observed for polar and/or charged organicsNon-polar organics, may hit Cw,sat before site saturation occurs TERM 9 When is the Langmuir model important? DEFINITION 9 For systems with low organic carbon contentand systems with high concentrations (of compound of interest?) TERM 10 Two major mechanisms of sorption onto mineral surfaces DEFINITION 10 1. "hydrophobic" sorption to bare mineral surfaces2. Specific interactions (e.g. ion exchange, specific complexation) TERM 21 Metal and ligands strongly adsorb via which complexation type? DEFINITION 21 Surface complexes strongly adsorb ions, specifically metals and ligands TERM 22 Cations and anions weakly adsorb via which complexation type? DEFINITION 22 beta (outer sphere) complexes weakly adsorb ions TERM 23 Explain diffuse surfaces complexation DEFINITION 23 Ions are bound to the surface by electrostatic attractionWeaker than beta complexation TERM 24 Which surface complexation most strongly adsorbs? DEFINITION 24 Surface complexes because covalent bonds are formed in the inner sphere TERM 25 What is the surface charge balance equation? DEFINITION 25 Sigma 0 + Sigma B = -Sigma d TERM 26 What is the main way we measure surface charge? DEFINITION 26 By measuring the zeta potential TERM 27 What are 4 types of chemical reactions at the surface? DEFINITION 27 1. Proton exchange2. ion exchange3. metal (cation) complexation4. ligand (anion) complexation TERM 28 Is metals adsorption typically Langmuir or Freundlich adsorption? DEFINITION 28 Langmiur TERM 29 What do cations compete with for adsorption? DEFINITION 29 H+ TERM 30 What is pH edge? DEFINITION 30 The pH at which the fraction of metal adsorbed drops off (for cations, opposite for anions) TERM 31 What do anions compete with for adsorption? DEFINITION 31 OH- TERM 32 Why do we use the "bag of fat" approach? DEFINITION 32 To simulate biological lipid tissue TERM 33 When is the bag of fat approach not appropriate DEFINITION 33 if the compound's Kow > 6 TERM 34 When may partitioning into proteins be important? DEFINITION 34 If protein content is high and lipid content is low, typically not the caseThis is a weak partition TERM 35 In words, what is the Bioconcentration Factor (BCF) DEFINITION 35 whole organism accumulation from dissolved phase of the dominant single medium (i.e. water)Usually for aqueous organisms TERM 46 What is the equation for the biomagnification factor? DEFINITION 46 BMF = Corganism / Cdiet = BAForganism / BAFdietBiomagnification occurs when BMF > 1 TERM 47 What is bioavailability? DEFINITION 47 used to qualitatively compare the relative availability of a chemical to an organism or a biological processThe fraction of total ambient metal than an organism will actually take up TERM 48 Define BCF DEFINITION 48 BCF typically denotes the concentration ratio achieved in an organism if uptake occurs only through one route (i.e. the aqueous route? TERM 49 Define BAF DEFINITION 49 Typically considers all uptake routes, including food TERM 50 How is BMF used? DEFINITION 50 BMF is used to relate the concentration of compound in a predator to the concentration in its prey TERM 51 How is BSAF used? DEFINITION 51 BSAF is used to relate the concentration in a sediment or soil-dwelling organism to the concentration in the sediment or soil TERM 52 What chemical property affects how plants uptake contaminants? DEFINITION 52 Kow TERM 53 Why are charged compounds of interest? DEFINITION 53 Many emerging contaminants are charged at environmental pHs TERM 54 Why does compound speciation matter in this context? DEFINITION 54 Neutral forms and ionic forms behave differently.For example, aspirin can only be absorbed in its neutral form TERM 55 Does an aromatic compound have a higher or lower pKa? DEFINITION 55 Lower TERM 56 What are the "endings" of the alcohol, carboxyl, thiol, and amine functional groups? I.e different classes of charged organics DEFINITION 56 Alcohol: R - OHCarboxyl: R - COOHThiol: R - SHAmines: R - NH3+ TERM 57 What chemical property of these functional groups might affect their pKa? DEFINITION 57 Whether it is aromatic or aliphatic may affects its pKa TERM 58 When are amines positively charged? DEFINITION 58 When pH is below the pKa TERM 59 What are Zwitterions? DEFINITION 59 Molecules that have positive and negative surface charges at the same time TERM 60 If a compound is charged (i.e. ionized) its solubility will...? DEFINITION 60 Increase TERM 71 Bioaccumulation DEFINITION 71 The accumulation of metals in an organism's tissues TERM 72 Define LC50 DEFINITION 72 The toxicant concentration which is lethal to 50% of the test organisms TERM 73 LA50 DEFINITION 73 The amount of toxicant accumulated in/on the tissue, which is lethal to 50% of the test organisms TERM 74 What is biotransformation? DEFINITION 74 When a dissolved metal is volatilized or mineralized or chelated metals TERM 75 What happens to dissolved metals when pH increases? DEFINITION 75 Metal hydroxides formMetals sorb TERM 76 How does hardness affect toxicity? DEFINITION 76 Increased hardness decreases toxicity TERM 77 How does metal toxicity change with particulate matter? DEFINITION 77 Increasing PM decreases metal toxicity TERM 78 What is the Biotic Ligand Model DEFINITION 78 A computational approach to estimate toxicity TERM 79 Biotic Ligand Model: What factors determine how much metal can bind to a biotic ligand? DEFINITION 79 Concentration, complexation, competition (hardness, pH) TERM 80 For humic and fulvic acids, how does metal binding ability change with pH? DEFINITION 80 Metal binding ability increases with increasing pH