A.K. Mohd Omar

Removal of dyes and industrial dye wastes by magnesium chloride

Magnesium chloride, as compared to alum and polyaluminium chloride (PAC) is a less commonly used coagulant in the field of wastewater treatment, with a cost in between alum and PAC. It has been used in this study as a coagulant to investigate the eAectiveness in the chemical precipitation method for the removal of colouring matters. The colour concentration of dye solutions was measured by visible spectrophotometry. Parameters such as the eAect of pH, the eAect of coagulant and coagulant aid dosages and the eAect of diAerent coagulants have been studied. The results show that MgCl2 is capable of removing more than 90% of the colouring material at a pH of 11 and a dose of 4 g MgCl2/l of dye solution. MgCl2 is shown to be more eAective in removing reactive dye than alum and PAC in terms of settling time and amount of alkalinity required. Optimal operating conditions such as pH value, coagulant dose and eAect of polyelectrolyte have been determined. Wastewaters of a dyeing and printing mill on diAerent days have been treated by MgCl2 aqueous solution in bench scale. The treatment of the industrial waste has shown a reduction of 88% in COD and 95% of suspended solids. # 1999 Elsevier Science Ltd. All rights reserved

Clinical solid waste management practices and its impact on human health and environment--A review.

The management of clinical solid waste (CSW) continues to be a major challenge, particularly, in most healthcare facilities of the developing world. Poor conduct and inappropriate disposal methods exercised during handling and disposal of CSW is increasing significant health hazards and environmental pollution due to the infectious nature of the waste. This article summarises a literature review into existing CSW management practices in the healthcare centers. The information gathered in this paper has been derived from the desk study of open literature survey. Numerous researches have been conducted on the management of CSW. Although, significant steps have been taken on matters related to safe handling and disposal of the clinical waste, but improper management practice is evident from the point of initial collection to the final disposal. In most cases, the main reasons of the mismanagement of CSW are the lack of appropriate legislation, lack of specialized clinical staffs, lack of awareness and effective control. Furthermore, most of the healthcare centers of the developing world have faced financial difficulties and therefore looking for cost effective disposal methods of clinical waste. This paper emphasizes to continue the recycle-reuse program of CSW materials after sterilization by using supercritical fluid carbon dioxide (SF-CO2) sterilization technology at the point of initial collection. Emphasis is on the priority to inactivate the infectious micro-organisms in CSW. In that case, waste would not pose any threat to healthcare workers. The recycling-reuse program would be carried out successfully with the non-specialized clinical staffs. Therefore, the adoption of SF-CO2 sterilization technology in management of clinical solid waste can reduce exposure to infectious waste, decrease labor, lower costs, and yield better compliance with regulatory. Thus healthcare facilities can both save money and provide a safe environment for patients, healthcare staffs and clinical staffs.

Mango (Mangifera indica L.) by-products and their valuable components: a review.

The large amount of waste produced by the food industries causes serious environmental problems and also results in economic losses if not utilized effectively. Different research reports have revealed that food industry by-products can be good sources of potentially valuable bioactive compounds. As such, the mango juice industry uses only the edible portions of the mangoes, and a considerable amount of peels and seeds are discarded as industrial waste. These mango by-products come from the tropical or subtropical fruit processing industries. Mango by-products, especially seeds and peels, are considered to be cheap sources of valuable food and nutraceutical ingredients. The main uses of natural food ingredients derived from mango by-products are presented and discussed, and the mainstream sectors of application for these by-products, such as in the food, pharmaceutical, nutraceutical and cosmetic industries, are highlighted.

Simple fractionation through the supercritical carbon dioxide extraction of palm kernel oil

Abstract Supercritical carbon dioxide (SC-CO 2 ) in the pressure range 20.7–48.3 MPa (3000–7000 psi) and temperatures between 40 and 80°C was used as a solvent in the extraction of palm kernel oil (PKO). At 20.7 and 27.6 MPa, the solubility of PKO in SC-CO 2 decreased with temperature. However, at higher pressures of 34.5, 41.4 and 48.3 MPa, the solubility increased with temperature. The composition of the oil extracted varied with time. Earlier fractions were rich in short-chain triglicerides, while the later fractions were rich in longer chain triglicerides and unsaturated triglicerides. However, at higher pressures, the fractionation effect diminished and the oil could be considered as a single component. At 48.3 MPa and 80°C, the solubility of PKO in SC-CO 2 of about 20% was relatively high compared with that of soybean oil of about 3%.

Hard cocoa butter replacers from mango seed fat and palm stearin

The blending effects of mango seed fat (MSF), extracted using supercritical fluid, and palm stearin (PS) to formulate hard cocoa butter replacers (CBRs), were investigated. The triglycerides (TG), thermal properties and solid fat content (SFC) of the formulated blends were determined using different chromatographic and thermal techniques. All the blends had three main TGs; namely, 1,3-dipalmitoyl-2-oleoylglycerol (POP) (8.6-17.7%), 1-palmitoyl-2-oleoyl-3-stearoyl-glycerol (POS) (12.6-19.6%), and 1,3-distearoyl-2-oleoyl-glycerol (SOS) (37.2-31.4%), with SOS being the major component. The melting peak temperatures gradually increased and shifted towards higher temperatures with PS. The crystallization onset temperatures increased, while the offset decreased with PS. The SFC did not drop to 0% at 37.5°C, which was shifted to 0% at and above 40°C for some blends. The studies revealed that CBRs could be prepared by blending MSF and PS, and they could be utilised by chocolate manufacturers in tropical countries.

Rice Husk Ash as Fillers in Polypropylene: A Preliminary Study

Abstract Burnt rice husk ash yields two types of fillers namely black rice husk ash (BRHA) and white rice husk ash (WRHA). These ashes were incorporated into polypropylene using a Brabender thermoplastics mixer. Torques at various filler loadings were investigated. For both types of ashes, the mixing torques increase with filler contents; the increase being more prominent in the BRHA. Polypropylene composites of different filler loadings were compounded using a twin screw extruder and test specimens were injection molded. Thermogravimetry analysis showed a good agreement between analyzed and actual filler content The composites were found to have a good filler distribution by the same technique. Flexural modulus and density showed an increase whereas tensile strength, elongation at break and impact strength decreased with increasing filler content. Poor adhesion between polymer and filler was indicated by SEM studies.

Density measurement of rice husk ash filler particles in polypropylene composites

Abstract A simple and accurate method for determination of filler material density is described. Rice husk ash (RHA) which consists predominantly of silica serves as a filler in polypropylene. The filler density was determined from first principles using a pyknometer. The filler was compounded in polypropylene and the densities of the composites were measured using an electronic densimeter. The measured composite densities agree very closely with theoretical values calculated based on the measured density of the filler material.

STUDY OF RHEOLOGICAL PROFILE ANALYSIS RELATED TO TEXTURE FOR MIXTURES OF SAGO-WHEAT GEL

ABSTRACT Starch gels containing mixtures of sago+wheat of different protein content at different levels of sago substitutes were prepared as follows: sago+high protein wheat (HPW), sago+medium protein wheat (MPW) and sago+slow protein wheat (LPW). The rheological profile analysis (RPA) related to texture was carried out for sago-wheat mixtures at different percentages of sago substitutions of 10,15, 20, 30, 40 and 50% of sago. The hardnes for control sago gel increased gradually with the increment of concentration of gel and the value tends to be higher than control wheat gels at 20% concentration. The gel becomes too hard for control sago when the concentration exceeded 30%. In RPA study, gel did not exhibit any significant differences in hardness, cohesiveness and adhesiveness with sago portion in HPW, MPW and LPW flour mixtures at different percentages. In retrogradation study, the hardness was found to decrease in comparison to the values for fresh samples.

Stress Relaxation Test for Sago–Wheat Mixtures Gel

Abstract Viscoelastic properties of sago starch and wheat flour, and sago–wheat flour mixtures at different percentages of sago substitution were studied. Swelling characteristics of high protein wheat (HPW), medium protein wheat (MPW) and low protein wheat (LPW) flour, and sago starch were determined at various temperatures (55°–95°C). Both sago and wheat starch granules started to swell from 55°C and reached a maximum at 75°C. Flour gels containing mixture of sago + wheat of different protein content at different levels of sago substitutions were prepared as follows: sago + HPW, sago + MPW, and sago + LPW flours. Stress relaxation (SR) test for control sago and control wheat flours and sago–wheat mixtures were carried out at different percentages of sago substitutions from 10 to 50%. For control flours the value of asymptotic residue modulus, E A for HPW and MPW was rapidly increased with the increase of the gel concentration up to 30% but it decreased at 20%. For LPW it decreased at 20 and 25%, and increased at 30%. At higher percentage of sago in the mixture, E A value does not show uniform consistence pattern. It was found to increase rapidly at 50% of sago portion for all types of wheat flour.

Rice Husk Ash (RHA)-Based Silica as Filler in Polypropylene Composite: Effect of Peroxide-Containing Silane on the Rheological Behavior

The effect of incorporating silica filler derived from rice husk ash (RHA) on the rheological properties of polypropylene was studied using a Bra bender slit capillary die. The melt shear stress and viscosity increased with filler content. The filler was treated with a silane-based coupling agent. The silane used was Prosil 2020, a proprietary silane coupling agent containing the peroxide bis(t-butyl peroxy)di-isopropyl benzene. The peroxide induces β- scission of the polypropylene molecular chains reducing the shear stress and viscosity. Hence the filler and the coupling agent (peroxide concentration) have opposing effect on the rheology of the composites melt. For high filler content melt, the peroxide effect is more prominent, lowering the overall stress and vis cosity. At higher shear rate, the effect of filler concentration is more dominant. Mixing torque and melt flow index studies support the rheology measurements by the slit die technique.