Encapsulation solid materials

Beck (4) received a patent in which he advocated the use of sucrose and hydrolyzed cereal solids as the encapsulation matrix materials. The hydrolyzed cereal solids were defined as having a DE below 20, typically 10 to 15 being preferred. This... 

Binder In site remediation and waste treatment, binders refer to cement, clays, or other cohesive solid materials that encapsulate and immobilize solid and even liquid wastes. Binders are key components in waste solidification/stabilization. 

Solidification refers to techniques that encapsulate the waste, forming a solid material, and does not necessarily involve a chemical interaction between the contaminants and the solidifying additives. The product of solidification, often known as the waste form, may be a monolithic block, a clay-like material, a granular particulate, or some other physical form commonly considered solid. Solidification as applied to fine waste particles, typically 2 mm or less, is termed microencapsulation and that which applies to a large block or container of wastes is termed macroencapsulation [29]. 

Not only solid particles can be built up by using hydrogel as shell material, but also capsules. Over the past two decades, the encapsulation of materials has become an extensive area of research activity owing to their utilization as submicrome-... 

Encapsulation is a process in which tiny particles or droplets are covered by a coating [36-43]. Its role is either to isolate the active ingredient or to control the rate by which it leaves the capsule. As examples for the first case, one can mention the isolation of vitamins from oxygen or of a reactive core from chemical attack, and for the second case, the control of the rate of release of drugs or pesticides. Numerous encapsulation techniques have been suggested. Most of the encapsulations of the active solid materials have been carried out for solids larger than 1 pm. 

In general, spray dried flavourings can be considered small capsules of an active volatile and/or tasting ingredient which is embedded in a matrix material. The spray dried capsules are almost spherical particles, each containing a high number of oil-globules or solid particles. Most liquid or solid materials can be encapsulated, whether they are hydrophobic or hydrophilic. 

A complete thermodynamic description of a material under pressure requires knowledge of the (thermal) equation of state (EOS), for example, in the form F = V (p,T) or p = p (p,T), for the specific material, where V is usually the specific volume (the volume per unit mass) or the molar volume and p is the specific density p=l/F. For a rigid cylinder with a fixed amount of a sample enclosed by the piston, the relative change in volume V(p,T)IVo is directly related to the movement of the piston if deformations of the piston and cylinder, and leakage and friction, can be neglected. For pressures below 1 GPa and moderate temperatures these techniques are well developed for liquids and gases. However, for higher pressures and variable temperatures the encapsulation of the sample and the deformation of the pressure vessel need special attention. The state of the art for encapsulated solids corresponds to a precision of only 500 p.p.m. (parts per million) in V/Vq or 3 per... 

Type m enclosures are encapsulations, for example an electronic circuit encapsulated in solid epoxy resin or fire-resistance solid material. There are very few examples in electrical power equipment used in the oil industry. 

UX refers to the level at which sohds are decontaminated to the point that agent concentration in the headspace above the encapsulated solid does not exceed the health-based, 8-hour, time-weighted average limit for worker exposure. The level for mustard agent is 3.0 mg/m in air. Materials classified as 3X may be handled by qualified plant workers using appropriate procedures but are not releasable to the environment or for general public reuse. In specific cases in which approval has been granted, a 3X material may be shipped to an approved hazardous waste treatment facility for disposal in a landfill or for further treatment. 

Polymer coacervation can occur in either aqueous or organic liquids. Coacervation in aqueous liquids and the related processes are mainly used to encapsulate water-immiscible liquids or water-insoluble solid particles. On the other hand, coacervation in organic liquids, or sometimes called phase separation in organic liquids, is used to encapsulate core materials that are not miscible or soluble in the organic liquids. It may be induced by the addition of a nonsolvent to the polymer solution or by the addition of an incompatible polymer based on polymer-polymer incompatibility. This chapter will only discuss the coacervation in aqueous liquids. 

Through the process of encapsulation, solid or liquid active ingredients are homogeneously embedded into a carrier material, producing a stable product with defined characteristics (Figure 21.3). 

Some formally square four-coordinate structures are also fiuxional.Rearrangement of metal clusters and carbonyls which are bound to them have also been studied extensively.DNMR is not limited to solutions and can also be studied in solid materials. DNMR has also been observed with supramolecular complexes.Calixarene complexes based on Ir(l) and Rh(l) complexes also show dynamic motions associated with encapsulation of other molecules. " Although not an organometaiiic, a study of ring inversion in Fe(lll) porphyrins provides a particularly well-documented discussion of the methodologies that can be applied to DNMR. ... 

The most important class of solid-state enzyme mimics is based on zeolites. Zeolites are solid materials composed of Si04 or AIO4 tetrahedra linked at their corners, affording a three-dimensional network with small pores of molecular dimensions. They possess a unique feature of a strictly uniform pore diameter. In particular, zeolites with encapsulated metal complexes are used as inimics of cytochrome P-450.An efficient enzyme mimic was obtained by encapsulating an iron phthalocyanine complex into crystals of zeolite Y, which were, in turn, embedded into a polydimethylsiloxane membrane acting as a mimic of the phospholipid membrane.With t-butylhydroperoxide as the oxidant, the system hydroxyl-ates alkanes at room temperature with rates comparable to those for the enzyme. It shows similar selectivity (preference oxidation of tertiary C-H bonds) and a large kinetic isotope effect of nine. 

---