Complexation-precipitation interaction

The hydrolysis phenomenon may play a considerable role during the formation of complexes for several reasons. The first one could have been studied in the first section of this chapter. Indeed, the hydrolysis phenomenon induces a competition between the ligand L and the hydroxo ions L for the metallic ion. The second reason results from the fact that hydroxo complexes may precipitate as insoluble hydroxides or oxides. Hence, in this case, a phenomenon of precipitation also occurs, and we can speak of a complexation-precipitation interaction. Of course, all these processes depend on the pH value since the hydroxo ligand and the hydroxo complexes intervene in the complexation phenomenon. 

Complexation—Precipitation Interaction Formation of Insoluble Oxides and Hydroxides... 

In this section, we are interested in the particular case of the interaction of the precipitation of insoluble metal oxides and hydroxides whose metallic ions also form complexes. Within this case, a frequent phenomenon exists the dissolution of an insoluble hydroxide or oxide after adding an excess of precipitating ions. This case is also investigated here. (We shall investigate the treatment of the complexation-precipitation interaction more deeply in Part V of this book.)... 

The driving forces of complex formation were thought to be the geometric compatibility or fit and intermolecular interaction between hosts and guests. It has been reported that many linear polymeric guests could form inclusion complexes with CDs resulting in main-chain pseudopolyrotaxanes. When the polymers were added into the CD solutions and then sonicated, crystalline inclusion complexes precipitated. As the result of X- ray diffraction study, all crystalline inclusion complexes between CDs and polymeric guests are columnar in structure [27,43],... 

In soils and sediments, complexation can increase organic phosphorus stabilization, especially with iron (III) and calcium ions and their minerals (Harrison, 1987 House and Denison, 2002). The interaction with iron (III) was reported to transform a large part of the labile and moderately labile organic phosphorus forms supplied with manure to paddy soils into more resistant organic phosphorus, possibly because inositol phosphates initially bound to calcium or magnesium were transformed into iron-bound compounds (Zhang et aL, 1994). In the presence of calcium, myo-inositol hexakisphosphate can form two soluble calcium complexes with one or two calcium ions (Ca - or Ca2-phytate), but when three calcium ions are involved (Cag-phytate), the complex precipitates at all pH values (Graf, 1983). This enhances the interaction of myo-... 

Acid-base concepts share some features with seemingly different types of interactions complexing, precipitation, and even redox. Comparison of these through theories of Bronsted, Lewis, Usanovich, and Lux-Flood extends our use of the electronic interpretations of... 

A test for detecting the presence of antibodies or antigens in biological fluids. Antibody and antigen solutions are placed in separate wells cut out of an agar plate. Diffusion of the antibody and antigen towards each other occurs and, if there is interaction, the immune complexes precipitate in the form of a line. Thus for instance if C-reactive protein was suspected in a sample of serum, the serum would be placed in the one well and C-reactive protein antiserum in the other. On the other hand if antibodies were suspected in a serum sample, e.g. thyroid autoantibodies. 

Abstract Natural and synthetic polyelectrolytes have acquired notable importance in recent years due to their increasing application in different areas. One of these is downstream process methods which include the recovery, separation, concentration and purification of target enzymes from their natural sources. Polyelectrolytes interact with proteins to form soluble or non-soluble complexes. The interaction is driven by experimental variables of media such as pH, protein isoelectrical value, polyelectrolyte pKa, ionic strength and the presence of salts. The concentration of polyelectrolytes necessary to precipitate a protein completely is of the order of 10 " - 10 % p/v. Precipitation of protein by PE is a novel technique integrating clarification, concentration and initial purification in a single step. This chapter presents some properties of aqueous solutions of natural and synthetic PE as a tool to use them in the protein downstream process. 

The complexes, [Fe(py>4]X2 (X = Br, 1), have been prepared by oxidation of metallic iron with bromine or iodine in methanol. Pyridine is added to the resultant solution and the pyridine complexes precipitated.22 Interaction between metallic zinc or cadmium and an excess of arsenic pentafluoride in liquid sulfur dioxide leads to the formation of solvento-complexes containing two or four SO2 ligands depending on the experimental conditions.23/24 The reactions studied are summarized as follows, Eq.4.4 ... 

Many factors affect the mechanisms and kinetics of sorption and transport processes. For instance, differences in the chemical stmcture and properties, ie, ionizahility, solubiUty in water, vapor pressure, and polarity, between pesticides affect their behavior in the environment through effects on sorption and transport processes. Differences in soil properties, ie, pH and percentage of organic carbon and clay contents, and soil conditions, ie, moisture content and landscape position climatic conditions, ie, temperature, precipitation, and radiation and cultural practices, ie, crop and tillage, can all modify the behavior of the pesticide in soils. Persistence of a pesticide in soil is a consequence of a complex interaction of processes. Because the persistence of a pesticide can govern its availabiUty and efficacy for pest control, as weU as its potential for adverse environmental impacts, knowledge of the basic processes is necessary if the benefits of the pesticide ate to be maximized. 

---