Soils acetic adds

The effect of ammonia as a complexing agent to enhance the efficiency of electrochemical remediation was evaluated by Vereda-Alonso et al. (2007). Laboratory-scale experiments on copper-spiked kaolin were carried out to explore if metal precipitation could be prohibited at neutral and alkaline pH. Ammonia was added at the anode compartment and migrated into the soil as ammonium by electromigration. Tvo set of experiments were performed (a) using ammonia solution as anolyte and sodium nitrate as catholyte, and (b) combining the ammonia enhancement with the addition of acetic add into the cathode (weak-acid enhancement). The results indicate that metal recovery with only ammonia was less than 40%, while the combination of ammonia and add enhancements achieved a copper recovery of more than 90%. 

Step 1 To an appropriate centrifuge tube add 1-g (0.001-g) of air-dry, sieved soil and 40 mL of acetic acid. The mixture is shaken overnight, centrifuged, and the supernate separated from the residue for analysis. 

Procedure (extraction). Transfer 2.5 g air-dry soil, 2 mm mesh size, into a 250 ml polypropylene screw-cap centrifuge bottle/tube and add 100 ml acetic acid - 8-hydroxyquinoline reagent. Cap the tube and shake overnight (17 h) on a reciprocating shaker, at approximately 275 strokes of 25 mm length per minute at a constant temperature (20°C). Centrifuge for 15 min at 2800 rpm and remove an aliquot for the determination of acid extractable inorganic phosphorus (a). 

Soil extract (20 g). Extract with 40 mL of acetonitrile/water (80 20). Acidify extract with acetic acid (1/100 with DI water), add 25 mL of acid to 5 mL of extract for a total of 30 mL. Atrazine, propazine, and simazine. 

Transfer without loss 10 g of air dry soil sample accurately weighed in a 250 ml beaker and add 50 ml of neutral normal ammonium acetate solution. 

Wash the recidue left on the filter paper with 60% alcohol to remove excess ammonium acetate. To ensure this add a pinch of solid NH Cl to the recidue on the filter paper and wash with alcohol till the filtrate is free from chloride (as tested with silver nitrate solution, the filtrate is perfectly clear when free from chloride). If the washing is to be interrupted such as for the night, attach a rubber tube to the tail of the fimnel and pinch it tight with a clip when there is solution above the level of soil in the filter paper, i.e. in no case the soil should dry otherwise loss of ammonia may occur. 

The hydrated components (C-S-H, portlandite, sulfoaluminates) in the cement matrix of concrete are in equilibrium with the pore liquid that is characterized by a high pH, due to the presence of OH (balanced by Na and K ). When concrete comes into contact with acid solutions, these compounds may dissolve at a rate that depends on the permeability of the concrete, the concentration and the type of acid. In soil with acidic ground water, the rate of refreshing is important Acids that can attack concrete are sulfuric acid, hydrochloric acid, nitric acid, organic acids such as acetic acid and humic adds and solutions of CO2. The rate of attack on the cement matrix depends on the solubility of the salts that are formed... 

Aliphatic mono- and dicarboxylic acids (such as acetic acid and oxalic acid, respectively), oxocarboxyhc adds (such as pyruvic acid), hydroxycarboxylic acids (citric, tartaric, malic and lactic adds) and numerous aromatic acids (such as benzoic add) are normal constituents of plant and animal foods. They form salts with metal ions and their anions also have the properties of ligands. Carboxylic adds are the major binding partners of metals in fruits and some vegetables. They also contribute significantly to the binding of minerals (metal ions) by humic substances in soils and sediments. 

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