Foam-mat Drying of Papaya (Carica Papaya L.) using Glycerol monostearate as Foaming Agent

The study was carried out to production of papaya powder using glycerol mono-stearate as foaming agent under foam-mat drying technique. Foaming, drying, reconstitution, quality and sensory attributes of dried papaya powder were investigated. Foams were prepared from papaya pulp by adding different concentration of glycerol monostearate (1, 2, 3 and 4% w/w) at whipping time of 5, 10 and 15 min. The foam expansion was significantly influenced by pulp concentration and levels of the foaming agent at 1% level. The maximum stable foam formation was 90% at 3% glycerol monostearate with 9°Brix pulp concentration and whipping time of 10 min. The resulting foams were dried at air temperatures of 60, 65 and 70°C with foam thickness of 2, 4, 6 and 8 mm in a batch type cabinet dryer under air flow rate of 2.25 m3/min. Lower drying temperature and higher foam thickness resulted in longer drying time. Biochemical and sensory properties of fresh papaya fruit and reconstituted juice from foam-mat dried papaya powder were determined. Biochemical analysis results showed a significant (P?0.05) reduction in ascorbic acid, ?-carotene and total sugars in the foamed papaya dried product at higher foam thickness (6 and 8 mm) and temperature (65 and 70°C due to destruction at higher drying temperature and increasing time. There was no significant change in other biochemical constituents such as pH and acidity. The sensory attributes of papaya powder juice were significantly (P?0.01) influenced by drying temperature and was compared with fresh papaya juice. The papaya powder obtained from the foam thickness of 4 mm and dried at 60°C was found to be optimum to produce the foam-mat dried papaya powder. Keywords: papaya pulp, glycerol monostearate, whipping, foam expansion, foam thickness, drying, moisture conten

Prospects of Grouper Culture in India

The "Groupers" of the genus Epinephelus are excellent marine food fishes in the Indo Pacific and Carribean regions and have assumed importance for commercial culture in recent year

Adsorptive removal of heavy metals from water using sodium titanate nanofibres loaded onto GAC in fixed-bed columns

© 2015 Elsevier B.V. Heavy metals are serious pollutants in aquatic environments. A study was undertaken to remove Cu, Cd, Ni, Pb and Zn individually (single metal system) and together (mixed metals system) from water by adsorption onto a sodium titanate nanofibrous material. Langmuir adsorption capacities (mg/g) at 10-3M NaNO3 ionic strength in the single metal system were 60, 83, 115 and 149 for Ni, Zn, Cu, and Cd, respectively, at pH 6.5 and 250 for Pb at pH 4.0. In the mixed metals system they decreased at high metals concentrations. In column experiments with 4% titanate material and 96% granular activated carbon (w/w) mixture at pH 5.0, the metals breakthrough times and adsorption capacities (for both single and mixed metals systems) decreased in the order Pb>Cd, Cu>Zn>Ni within 266 bed volumes. The amounts adsorbed were up to 82 times higher depending on the metal in the granular activated carbon+titanate column than in the granular activated carbon column. The study showed that the titanate material has high potential for removing heavy metals from polluted water when used with granular activated carbon at a very low proportion in fixed-bed columns

Effects of humic acid and suspended solids on the removal of heavy metals from water by adsorption onto granular activated carbon

© 2015 by the authors; licensee MDPI, Basel, Switzerland. Heavy metals constitute some of the most dangerous pollutants of water, as they are toxic to humans, animals, and aquatic organisms. These metals are considered to be of major public health concern and, therefore, need to be removed. Adsorption is a common physico-chemical process used to remove heavy metals. Dissolved organic carbon (DOC) and suspended solids (SS) are associated pollutants in water systems that can interact with heavy metals during the treatment process. The interactions of DOC and SS during the removal of heavy metals by granular activated carbon were investigated in batch and fixed-bed column experiments. Batch adsorption studies indicated that Langmuir adsorption maxima for Pb, Cu, Zn, Cd, and Ni at pH 6.5 were 11.9, 11.8, 3.3, 2.0, and 1.8 mg/g, respectively. With the addition of humic acid (HA) (DOC representative), they were 7.5, 3.7, 3.2, 1.6, and 2.5 mg/g, respectively. In the column experiment, no breakthrough (complete removal) was obtained for Pb and Cu, but adding HA provided a breakthrough in removing these metals. For Zn, Cd and Ni, this breakthrough occurred even without HA being added. Adding kaolinite (representative of SS) had no effect on Pb and Cu, but it did on the other metals

Removal and recovery of phosphate from water using sorption

Sorption is an effective, reliable, and environmentally friendly treatment process for the removal of phosphorus from wastewater sources which otherwise can cause eutrophication of receiving waters. Phosphorus in wastewater, if economically recovered, can partly overcome the future scarcity of phosphorus resulting from exhaustion of natural phosphate rock reserves. The authors present a comprehensive and critical review of the literature on the effectiveness of a number of sorbents, especially some novel ones that have recently emerged, in removing and recovering phosphate. Mechanisms and thermodynamics of sorption, as well as regeneration of sorbents for reuse using acids, bases, and salts, are critically examined. © 2014 Copyright Taylor & Francis Group, LLC

Column studies on the removal of dissolved organic carbon, turbidity and heavy metals from stormwater using granular activated carbon

© 2014 Balaban Desalination Publications. All rights reserved. Stormwater pollutants have the capacity to damage aquatic environments if they are discharged untreated. Suspended solids (turbidity), dissolved organic carbon (DOC) and heavy metals removal from stormwater were investigated in batch and fixed-bed column experiments. Field studies revealed that turbidity and DOC in stormwater were effectively removed at filtration velocities of 5, 10 and 11.5 m/h using a 100 cm high granular activated carbon (GAC) filter column. At the higher filtration velocities of 10 and 11.5 m/h, adding a pre-treatment 100 cm high anthracite filter column further improved DOC and turbidity removal. Batch and column laboratory adsorption experiments at pH 6.5–7.2 using GAC showed that the order of removal efficiency for solutions containing single and mixed metals was Pb, Cu > Zn > Ni, Cd. This order was related to the solubility product and first hydrolysis constants of these metals’ hydroxides. This study confirmed that GAC filter is effective in removing turbidity, DOC and heavy metals from stormwater

Removal of strontium from aqueous solutions and synthetic seawater using resorcinol formaldehyde polycondensate resin

© 2017 Elsevier B.V. Strontium (Sr) is a valuable metal found in abundance in seawater. However, its recovery from seawater has received little attention despite its many industrial applications. Batch and column adsorption experiments were conducted on the removal of Sr by resorcinol formaldehyde (RF) resin in the presence of co-existing cations at pH 7.5–8.5, where maximum adsorption was found. Batch adsorption capacities of cations followed the decreasing order of Sr > Ca > Mg > K, the order being the same as that of reduction of negative zeta potential. The adsorption data for Sr, Ca and Mg satisfactorily fitted to the Langmuir adsorption model with maximum adsorption capacities of 2.28, 1.25 and 1.15 meq/g, respectively. Selectivity coefficients for Sr with respect to other metals showed that Sr was selectively adsorbed on RF. Column adsorption data for Sr only solution fitted well to the Thomas model. Sr adsorption capacity in the presence of seawater concentrations of Ca, Mg, K and Na was reduced in both batch and column experiments with highest effect from Ca and Mg. However, if Ca and Mg are removed prior to RF adsorption process by precipitation, the negative effect of these ions on Sr removal can be significantly reduced

Nitrate removal using Purolite A520E ion exchange resin: batch and fixed-bed column adsorption modelling

© 2014, Islamic Azad University (IAU). Removing excessive nitrate from water is essential because it causes eutrophication which in turn has a harmful effect on aquatic life, resulting in a reduction in biodiversity and posing a danger to people’s health when the water is used for drinking. In this study, nitrate removal from aqueous solutions was studied using an ion exchange resin (Purolite A520E) in batch and fixed-bed column experiments. Batch adsorption kinetics was very well described by pseudo-first-order, pseudo-second-order and homogeneous surface diffusion models for resin doses 1.5 and 3.0 g/L at a nitrate concentration 20 mg N/L. Column kinetic data satisfactorily fitted to the empirical Thomas model and a numerical model based on advection–dispersion equation for filtration velocities 2.5 and 5.0 m/h at a column height of 12 cm and inlet concentration 20 mg N/L. The experimental and Thomas model predicted breakthrough adsorption capacity ranges for the two filtration rates were 12.0–13.5 and 8.2–9.7 mg N/g, respectively, whereas the maximum adsorption capacity determined using Langmuir adsorption isotherm model in the batch study was 32.2 mg N/g

Optimization of production of subtilisin in solid substrate fermentation using response surface methodology

Subtilisin (EC 3.4.21.62) is a type of serine protease that is of high commercial importance. It is mainly produced by Bacillus species as an extra cellular enzyme. Subtilisin being stable over a wide range ofpH and temperature is exploited as a detergent enzyme and also favoured by its non-specificity. The yield of this enzyme needs to be optimized for cost effective production of subtilisin for commercialization. Here, various solid substrates were screened for the production of subtilisin using Bacillus subtilis MTCC 441 and the maximum yield was found with green gram husk. Response surface methodology (RSM) was used to optimize pH, temperature, and moisture content. The optimal conditions were obtained after solving the polynomial equation using inverse matrix. The optimum pH, temperature and moisture content obtained under the conditions of study were 7.00, 30.04°C, and 73.38% respectively. The predicted response under these conditions was to be 571.73 U/mg proteinwhereas the actual response was found to be 571.32 U/mg protein