Experimental Study of the Segregation Tendency of Minor Ingredients in the Formulated Bulk Particulate Products

Segregation, the separation of particles during handling, transportation and storage of powders, is a phenomenon that nearly all industrial sectors dealing with powders encounter. A good example is detergent industry where segregation of the formulated powder mixtures and in particular the minor components such as enzyme granules could have significant economic as well as health and safety impacts. Most industrial processes aim to achieve a homogenous mixture as the inhomogeneities caused by segregation could contribute to significant effects on the economics of production. In this research, a broad literature review on segregation of powders was carried out to understand the main segregation mechanisms and popular measurement techniques for the segregation evaluation. The literature review revealed that despite considerable reported research on particle segregation, there is a lack of in-depth work on the evaluation of segregation mechanisms and minimization of minor ingredients (less than 2 wt %), particularly in multicomponent powder mixtures during processes such as heap formation and vibration. In addition, robust measurement methods for quantifying the segregation of such ingredients must be investigated. The aim of this research project is to investigate the segregation of the main constituents of laundry detergent powders (Blown Powder (BP), Tetraacetylethylenediamine (TAED) and enzyme granules). Specific attention is given to the segregation analysis of the minor ingredient enzyme granules as it is highly prone to segregate during heap formation and vibration. For the evaluation of the segregation propensity of minor ingredient, image processing technique is simple but it lacks the assessment of segregation in the mixture of powders with similar particle colours. On the other hand, differentiation of particles with similar colour could be achieved using spectroscopic techniques. In this work, two interesting areas of research are investigated: firstly, reliable measurement of the component fractions particularly for low level ingredients using both image processing and Near-Infrared spectroscopy technique is explored and secondly, segregation reduction approaches (by particle surface coating and modification) for the low-content level ingredient in the mixture of laundry detergent powders are examined. The results have demonstrated that powder segregation analysis of the components can be successfully achieved using the proposed Near-Infrared spectroscopy instrument. In addition, different spectral pre-processing (to remove the effect of varying physical properties of the components) have been compared and the optimum spectral treatment technique is introduced for the accurate quantification of minor ingredient. Study of the segregation of powder mixture during heap formation and vibration (representing the conditions encountered during box filling and transportation) has shown that enzyme granules are prone to extensive segregation towards the centre of the heap due to their higher density and the push-away effect as compared to other components. Segregation of enzyme granules in the ternary powder mixtures was shown to be reduced noticeably by applying a thin layer of a sticky liquid on the granules, due to the interlocking effect arising from the surface coverage of enzyme granules by fine particles. Optimum coating level has been found for this purpose to reduce the segregation of enzyme granules without compromising the flowability of the materials. Segregation of enzyme granules is further evaluated by modifying their surface properties to analyse its effects on density driven segregation. Granulation technique has been used for modifying the structural properties of enzyme granules. It is shown that surface modification of dense enzyme granules could hinder the push-away effect

Analysis of Minor Component Segregation in Ternary Powder Mixtures

In many powder handling operations, inhomogeneity in powder mixtures caused by segregation could have significant adverse impact on the quality as well as economics of the production. Segregation of a minor component of a highly active substance could have serious deleterious effects, an example is the segregation of enzyme granules in detergent powders. In this study, the effects of particle properties and bulk cohesion on the segregation tendency of minor component are analysed. The minor component is made sticky while not adversely affecting the flowability of samples. The segregation extent is evaluated using image processing of the photographic records taken from the front face of the heap after the pouring process. The optimum average sieve cut size of components for which segregation could be reduced is reported. It is also shown that the extent of segregation is significantly reduced by applying a thin layer of liquid to the surfaces of minor component, promoting an ordered mixture

Mechanically Induced Amorphization of Diaqua-bis(Omeprazolate)-Magnesium Dihydrate

The influence of milling diaqua-bis(omeprazolate)-magnesium dihydrate (DABOMD), an active pharmaceutical ingredient (API), was investigated. DABOMD was processed in a planetary ball mill at different milling times, from 1 to 300 min. The milling process resulted in a prominent comminution (size reduction) and amorphization of the API. DABOMD amorphization was identified with various characterization techniques including thermogravimetric analysis, differential scanning calorimetry, powder X-ray diffraction, and attenuated total reflection-Fourier transform infrared spectroscopy. The solid–solid crystalline to amorphous phase transformation is driven by compression, shear stresses, and heat generated in the planetary ball mill. This leads to distortion and breakage of hydrogen bonds, release of water molecules from the crystalline lattice of DABOMD and the accumulation of defects, and eventually a collapse of the crystalline order. Model fitting of the kinetics of comminution and the amorphization of DABOMD revealed a series of events: a rapid comminution at the start of milling driven by crystal cleavage of DABOMD, followed by partial amorphization, which is driven by rapid water diffusion, and subsequently, a slow steady comminution and amorphization

Synthesis of Stable Iron Oxide Nanoparticle Dispersions in High Ionic Medi

A novel one-pot method was developed in this work to synthesize and disperse nanoparticles in a binary base fluid. As an example, stable magnetite iron oxide (Fe3O4) dispersions, i.e., nanofluids, were produced in a high ionic media of binary lithium bromide-water using a microemulsion-mediated method. The effects of temperature and precursor concentration on morphology and size distribution of produced nanoparticles were evaluated. An effective steric repulsion force was provided by the surface functionalization of nanoparticles during the phase transfer, supported by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The formed nanoparticles exhibited a superior stability against agglomeration in the presence of high concentrations of lithium bromide, i.e., from 20 to 50 wt.%, which make them good candidates for a range of novel applications

A review of current techniques for the evaluation of powder mixing

Blending a mixture of powders to a homogeneous system is a crucial step in many manufacturing processes. To achieve a high quality of the end product, powder mixtures should be made with high content uniformity. For instance, producing uniform tablets depends on the homogeneous dispersion of active pharmaceutical ingredient (API), often in low level quantities, into excipients. To control the uniformity of a powder mixture, the first required step is to estimate the powder content information during blending. There are several powder homogeneity evaluation techniques which differ in accuracy, fundamental basis, cost and operating conditions. In this article, emerging techniques for the analysis of powder content and powder blend uniformity, are explained and compared. The advantages and drawbacks of all the techniques are reviewed to help the readers to select the appropriate equipment for the powder mixing evaluation. In addition, the paper highlights the recent innovative on-line measurement techniques used for the non-invasive evaluation of the mixing performance

Nanoparticle Formation in Stable Microemulsions for Enhanced Oil Recovery Application

Magnetic iron oxide and titanium dioxide nanoparticles (NPs) have been synthesized inside stable oil-in-water microemulsions in harsh environment of high temperature-high salinity (HT-HS). Screening of anionic–nonionic mixture of commercial surfactants was carried out to identify the appropriate compositions for the production of stable microemulsions in harsh environment. The effects of salinity and NPs formation on interfacial tension and rheological properties of microemulsions were evaluated and compared with other studies. It was found that oil-in-water microemulsions exhibit a non-Newtonian behavior in the absence of NPs, while the surfactant solutions show Newtonian behavior. The shear-thinning characteristic of microemulsions was improved and the interfacial tension between microemulsions and oil phase was increased after generation of NPs. A set of flooding experiments were accomplished using a microfluidic device to assess the efficiency of enhanced oil recovery on the pore scale in the absence and presence of NPs. The flooding tests confirmed the improvement of oil recovery efficiency after the formation of NPs inside the microemulsions. The oil displacement of API flooding was equal to 69.8% and the maximum oil displacement of 76.9% was observed after the injection of microemulsion containing iron oxide NPs