Chemical treatment, various, effects

Various physical-chemical treatment processes effectively remove heavy metals from waste-waters. One such treatment is lime precipitation followed by activated-carbon filtration. Activated-carbon filtration may also be preceded by treatment with iron(III) chloride to form an iron(III) hydroxide floe, which is an effective heavy metals scavenger. Similarly, alum, which forms aluminum hydroxide, may be added before activated-carbon filtration. 

The mechanical properties of composites are mainly influenced by the adhesion between matrix and fibers of the composite. As it is known from glass fibers, the adhesion properties could be changed by pretreatments of fibers. So special process, chemical and physical modification methods were developed. Moisture repel-lency, resistance to environmental effects, and, not at least, the mechanical properties are improved by these treatments. Various applications for natural fibers as reinforcement in plastics are encouraged. 

Our intention has been to derive models that can quantify these various effects and thereby build a basis for a quantitative treatment of chemical reactivity. The following simple models that enable calculations to be performed rapidly on large molecules and big data sets have been developed. 

Mineral matter characterization in coal has received considerable attention. Given and Yarzab (1) discussed the problems posed by mineral matter in various coal analyses. Furthermore, mineral matter complicates the chemical treatment of coal. It also has many adverse effects on commercial coal utilization. Coal consumers pay to ship mineral matter, to accommodate its impact on capital equipment and operations, and to dispose of the resultant ash. The impact of coal minerals on utilization motivated Consol s initial interest in mineralogy (2). The results reported here are from a second phase of the FTIR method development, in which extensive improvements were made to the methods. 

We worked with a variety of synthetic silicates and their modifications by various physical or chemical treatments or by various chemical additives. We particularly evaluated many synthetic hydrated calcium silicates, with and without additional treatments. These treatments included various organic and inorganic acid compounds, organic surface-active agents, and inorganic salts. We also studied samples dried to remove free moisture and/or some water of hydration. The modifications were selected to effect favorably the properties of the carriers. 

Figure 4 Effects of chemical treatments on relationships between logarithm of E l 7 and logarithm of tan 6. Dotted lines represent experimental correlations for untreated specimens. Various values of relative increase of matrix rigidity (/ ) and mobility factor (jx) were simulated. (A, A) Experimental values of untreated and treated specimens. (O, ) Theoretical plots for zero mean microfibrillar angle and theoretical plots assuming swelling effect only. See legend to Fig. 2 for treatment abbreviations.

Casting-solution and environmental variables permit far greater control over the ultimate structure and performance of phase inversion membranes than does the modification of a primary gel into a secondary gel by postformation treatments. Because the properties of the primary gel determine to a large extent those of its secondary counterpart, the former should be considered as more fundamental and important in discussing the effects of fabrication parameters such as casting-solution composition, upon performance. Once a primary gel has been formed, it may be utilized as such (particularly for low-pressure applications) or it may be subjected to various physical and/or chemical treatments for conversion into a more pressure-resistant secondary gel. 

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