Feasibility study to investigate caking in washing powder formulations using a Freeman FT4 powder rheometer

Because of legislation and environmental concerns, washing powder manufacturers have phased out phosphate builders in favour of substitutes such as sodium carbonate. This has meant that the new formulations have a greater tendency towards unwanted agglomeration (caking), based on moisture uptake and migration. This study examines the feasibility of using a Freeman FT4 powder rheometer to examine the effect of moisture migration, using the Basic Flow Energy (BFE) value to compare formulations of sodium carbonate content 27-37% and sodium sulphate content 10-20% by mass after 7 days exposure to 80% relative humidity at 20°C. The results showed that 31% and 33% sodium carbonate formulations were the most resistant to caking, with 27% and 37% being the most susceptible under the test conditions. Using the method of Brockbank et al. (2015), the FT4 was also used to detect the presence of a hard crust; under the test conditions, no hard crust was found. However, the presence of soft caking was detected in the force-height profile, showing a less abrupt transition

Comparing the dynamic flow properties and compaction properties of pharmaceutical powder mixtures

The dynamic flow properties and compaction characteristics of mannitol and mannitol-sodium carbonate mixtures (80/20, 70/30 and 60/40 by mass) were measured using a Freeman FT4 powder rheometer. The results showed that the mixtures containing up to 30% sodium carbonate had better flow properties and improved compaction characteristics when compared with mannitol alone. The study demonstrated the feasibility of combining a more expensive pharmaceutical excipient with a cheaper ingredient, without compromising desired powder characteristics. It may also provide a useful method for assessing the suitability of new formulations for use as direct compression bases, as part of a wider range of powder flow tests

Measuring the flow properties of small powder samples using an avalanche tester

The feasibility of using a small-scale avalanche tester to measure the flow properties of pharmaceutical lactose powders was examined. The modes of behavior observed in larger systems were displayed and showed a clear distinction between angular, free-flowing particles and more spherical particles of similar flow characteristics. Angular Lactohale LH100 particles showed slumping behavior at a rotational frequency of 0.33 Hz that disappeared at higher frequencies. Spherical lactose powder with a similar flow function to LH100 only showed rolling behavior under the same conditions, as did more cohesive powders LH200 and LH300. Further investigation of the LH100 data using fast Fourier analysis showed that the slumping frequency was one tenth of the rotational frequency

Measuring the flow functions of pharmaceutical powders using the Brookfield powder flow tester and Freeman FT4

This study examined the feasibility of combining data from different powder flow testers to determine the flow function characteristics of pharmaceutical powders. The Brookfield PFT and Freeman FT4 can measure flow function over different scales of consolidation load but were found to be most complementary with CRM limestone powder and lactose. The brittle behaviour of Easytab particles at higher loads made obtaining repeatable results with the FT4 challenging. By using the method of Wang et al., where the flow function coefficient ffc is plotted against the dimensionless cohesion C* (measured cohesion Ta divided by the initial compaction I), a plot was formed which could be used to predict the behaviour of other systems, which compared well with previous studies

A feasibility study to investigate caking in washing powder formulations using a Freeman FT4 powder rheometer [Conference paper]

Using conventional powder flow analysis methods to quantify the formation of a crust on the surface layer of a powder formed from moisture ingress is a challenge, as cake formation is not uniform throughout the powder sample. This study examined the feasibility of using a dynamic flow tester to compare the caking tendencies of washing powder formulations. A Freeman FT4 powder rheometer was used to investigate crusting caused by 80% relative humidity in washing powder formulations at room temperature. Formulations of 27%, 31%, 33% and 37% sodium carbonate were exposed for 7 days to high humidity before being tested using a twisted blade powder rheometer. Successive test cycles showed the breakdown of agglomerates caused by caking, with the greatest effect on formulations of 27% and 37%. Visual inspection of these powders indicated a hard caking layer of approximately a third of the depth, beneath which free-flowing powder was present. Variations from weak caking, caused by interparticle liquid bridges, were also detected using this method. The study demonstrates the viability of this methodology for optimising new formulations for caking resistance

The development of oral solid dosage forms using the direct-compression tableting of spray-dried bacteriophages suitable for targeted delivery and controlled release

This study addresses the challenge of developing a cheap, patient-friendly alternative to antibiotics using bacteriophages for gastrointestinal applications. It explores the feasibility of manufacturing an enteric solid dosage form containing a salmonella-specific Myoviridae phage, Felix O1, encapsulated in spray-dried trehalose/Eudragit microparticles. The spray-dried powder was further formulated by combining the spray-dried microparticles with magnesium stearate to facilitate the fabrication of tablets using direct compression. The paper presents a comprehensive evaluation of the tablets with measurements of phage viability during tablet fabrication using a range of compression settings and, after tablet disintegration, dissolution and friability. Phage viability measurements were performed using storage stability testing of spray-dried powders and tablets in sealed vials at 4 °C, 20 °C and 30 °C and under different humidity conditions of 0%, 50% and 65% RH. The recommended compression force range was found to be 10–15 kN for a standard 10 mm diameter tablet. The storage of tablets at 4 °C/0% RH was found to be the most favourable condition resulting in a ~1 log loss in titre over a six-month storage period. Storage at higher temperatures and samples exposed to high levels of humidity resulted in a significant loss in phage viability. The paper highlights challenges in developing phage formulations suitable for direct-compression tableting, which afford the phages protection when exposed to temperatures and humidity levels that do not require a cold supply chain.</p

Characterization of municipal solid waste residues for hydrothermal liquefaction into liquid transportation fuels

This paper presents and evaluates a new method for characterising municipal solid waste residues for assessing the performance of thermochemical conversion technologies to produce fuels. The method combines information from three complementary analytical techniques to estimate the quantity of key organic waste fractions and was demonstrated using two commercial waste residues: ‘BRDF’ and ‘Floc’ produced from the mechanical processing of domestic waste. Cellulose content (mostly paper and textiles) is estimated using acid hydrolysis, while thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) are combined to determine the plastics (LDPE and PET) and non-volatile fractions such as lignin of the wastes. High mass balance closures were achieved for both residues, although the nature of the non-volatile fraction was difficult to verify. Hydrothermal liquefaction (HTL) of cellulose rich BRDF (34.0% cellulose) produced much higher biooil yields than Floc (26.8% and 12.2%, respectively), with a cellulose content of only 22.4%. In both cases, most of the plastic and non-volatile waste fractions partitioned into the solid HTL product, representing a potential method for separating the plastic fractions from other waste components. Importantly, this combined waste characterization method can be used for characterization of any municipal waste residue using acid hydrolysis, TGA and FTIR data, providing accurate information about feedstock composition. It enables comparison between different waste valorisation studies of complex waste residues

Valorisation of hydrothermal liquefaction aqueous phase: Process modelling to quantify net energy recovery [Abstract]

Valorisation of hydrothermal liquefaction aqueous phase: Process modelling to quantify net energy recovery [Abstract]</p

Treatment of dark humic water using photocatalytic advanced oxidation (PAO) processes under visible and UV light

The aim of the study was to investigate the application of photocatalytic advanced oxidation (PAO) for the treatment of water contaminated with dark humic material from fynbos biome plants, which cannot be treated by conventional methods. The study used a fynbos species (Aspalathus linearis) to create a model wastewater that was compared with a brew made from black tea (Camellia sinensis). Two photocatalysts (TiO2 and ZnO) and three light sources (natural, halogen light, and UV light) were tested, with and without hydrogen peroxide. The treatment of the two teas by only photolysis was observed to be minimal. The study found that natural sunlight was not effective, but a combination of ZnO and halogen lamp exhibited the best performance, with a 60% degradation in 20 min under solar irradiation. The optimum catalyst concentration was identified as 10 g/L for both photocatalysts. The influence of some process parameters showed that a combination of an optimum dose of 5 mM H2O2 and solar radiation improved the performance of TiO2 from 16 to 47%. The photocatalytic reaction data were fitted to the pseudo first and second-order kinetic models in order to exploit the kinetic process of the photo-destruction reaction. The kinetic fits showed that the degradation reaction better adhered to the second-order kinetic model when only ZnO and solar radiation were applied, regardless of the tea type employed. The application of PAO in this novel and cost-effective way has potential for the abatement of contaminated water to potable water. The use of heterojunction photocatalysts could be explored in future research to further improve the process. </p

Effect of lithium chloride additive on forward osmosis membranes performance

The research efforts on the development of ideal forward osmosis membranes with high water flux and low reverse salt flux have been devoted in the recent years. In this study, thin film composite polyamide forward osmosis membranes were prepared. The porous polysulfone (PSU), polyphenylsulfone (PPSU), and polyethersulfone (PESU) substrates used in this study were prepared by the phase inversion process, and the active rejection layer was prepared by interfacial polymerization. All the membranes showed highly asymmetric porous structures with a top dense upper layers and finger-like porous substrates with macro voids in the bottom layer. The addition of 3% lithium chloride (LiCl) to the membrane substrates resulted in an increase in both the water flux and reverse salt flux. PSU and PESU showed the highest water flux when the active layer faced the feed solution (AL-FS), while the largest water flux was obtained when the active layer faced the draw solution (AL-DS). For all the membranes, the water flux under the AL-DS orientation was higher than that under the AL-FS orientation