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This article addresses the effect of pore former (saw dust) characteristics on the properties (pore size and porosity) of low‐cost ceramic membranes. Two approaches were considered to reduce the average membrane pore size. Firstly, the variation was observed by varying saw dust concentration in the overall membrane mixture and lowest achievable pore size was noted. Secondly, further reduction in the pore size was achieved by reducing the saw dust average particle size. Dead‐end filtration mode was utilized for the determination of pore size, and porosity was determined using Archimedes' principle. Permeabilities of the membranes were also calculated. The pore size and porosities of the membranes significantly reduced with variation in the saw dust characteristics. Mathematically, the relationship between variations in average pore size and porosity with saw dust average particle size and concentration variation fits well with the predicted empirical model.

This article addresses the technical and cost competitiveness of microfiltration and centrifugation to produce organic clarified bottle gourd juice. The microfiltration (MF) process was conducted for fresh and centrifuged juices and for transmembrane pressures ranging from 103.4 to 172.4 kPa. Pertinent flux decline was extensively analyzed to account for the extent of irreversible membrane fouling using resistances in series model, flux decline, and recovery ratios. Feed, centrifuged, and permeate juice samples were evaluated for nutritional content and physico-chemical parameters to affirm that MF of fresh juice is the best among all investigated cases. Compared with the centrifugation process, the MF process performed comparatively better in terms of cost competitiveness, juice clarity, microbial, and protein rejection. For a variation in juice production capacity of 110–10,000 L, the MF-based juice processing cost varied from 1.19 to 0.37 $/L, which accounts to 31.27–26.32% of fresh juice cost to infer upon promising performance of the low-cost ceramic membranes.

This article presents the ultrasound-assisted extraction (UAE) of antioxidants, total phenolics and soluble proteins from bitter gourd (Momordica charantia). For comparative purposes, two sonication modes, namely normal and pulsed mode have been considered and the response variables have been addressed as a function of temperature, extraction time and vegetable to water ratio using response surface methodology (RSM) based design of experiments. Except for a few cases, the carried out investigations affirmed non-linear dependence of response variables (bioactive compound content) on control variables. Among all cases, pulsed mode sonication performed effectively than normal sonication mode with marginally lower vegetable to solvent ratio but higher bio-active content. These research findings indicate promising opportunities for pulsed mode ultra-sonication process with respect to conventional extraction methods for the production of bitter gourd aqueous extract for medicinal and functional food applications.

In this work, the influence of inorganic low-cost precursor compositions (viz. kaolin, feldspar, saw dust, sodium metasilicate and boric acid) has been investigated on the morphological characteristics (such as average pore size and porosity) of the ceramic membranes that were fabricated using dry compaction method and saw dust as the pore forming agent. In order to do so, kaolin to feldspar ratio has been varied from 0.48 – 2.05 and binder composition has been varied from 10 – 15 wt.%. For an inorganic precursor formulation of kaolin 38.77 wt.%, feldspar 23.03 wt.%, saw dust 8.19 wt.%, sodium metasilicate 15 wt.% and boric acid 15 wt.%, the sub-micron range low-cost ceramic membranes (95.8 nm average pore size and 13.95% porosity) have been achieved as a key novelty. With minor variations in the precursor composition, the microfiltration membranes could be converted to ultrafiltration membranes without undergoing any complex surface reactions or polymeric coatings. An empirical model has been as well developed to quantify the variation of dependent variables on the membrane characteristics.

This article aims to address the relevance of D-optimal mixture model based RSM design methodology for the optimal fabrication of carbonate free low cost ceramic membranes. The RSM design methodology was validated by targeting alterations in the composition of kaolin, feldspar and saw dust precursors during low cost ceramic membrane fabrication. Experimental findings of key dependent membrane product variables namely average pore size and porosity were regarded as biases to identify optimal kaolin, feldspar and saw dust precursor compositions. Further, a comparative study was conducted to evaluate upon the sensitivity of optimal compositions while considering flexural strength as an additional response variable. The optimal precursor compositions were 48.19 mass % kaolin, 28.62 mass % feldspar and 8.19 mass % saw dust for which optimal responses of average pore size and porosity were 1.00 ± 0.05 μm and 28.47 ± 0.29%. However, while considering flexural strength as additional response variable, the optimal compositions varied marginally (48 mass % kaolin, 27.81 mass % feldspar and 8.26 mass % saw dust) for which the optimal responses of pore size, porosity and flexural strength were evaluated as 0.93 ± 0.02 μm, 29.98 ± 1.10% and 8.75 ± 0.57 MPa. Hence, the most relevant RSM model refers to the model designed without considering flexural strength as an additional variable and with reduced model complexity.

The combinatorial optimality of membrane morphology and process parameters during dead end microfiltration of bottle gourd juice have been addressed in this article. Saw dust and kaolin based low cost ceramic membranes with varied morphology have been chosen to evaluate upon their microfiltration performance. For the chosen membranes, fresh, paper filtered and centrifuged juice samples were considered along with transmembrane pressure differential as process parameters. Combinatorial optimality was based on flux decline trends, fitness of fouling models, irreversible and reversible fouling data, irreversible permeation resistance and nutritional analysis of the permeate samples. An interesting feature of the article had been with respect to feed constitution playing a critical role in influencing the optimal choice of membrane morphology and transmembrane pressure differentials. Among all cases, paper filtered bottle gourd juice, 0.75 μm membrane and 137.9 kPa transmembrane pressure were found to be the best choice in terms of minimal irreversible fouling, lowest protein content, good clarity, good polyphenol and antioxidant activity in the permeate and appropriate flux.

This paper presents an experimental investigation of simultaneous extraction and recovery of harmful heavy metals from the industrial wastewater through Bulk Liquid Membrane (BLM) based technology. The selective extraction and stripping are achieved through the transportation of two such heavy metals viz., lead and cadmium. The environmentally benign coconut oil is selected as solvent of the Liquid Membrane (LM) through two phase equilibrium studies. Same studies are performed to optimize various physico-chemical parameters, such as pH of feed phase, concentrations of feed and strip phases, temperature, speed of stirring of feed phase, run time (duration of extraction), concentration of carrier etc., on the extraction of cadmium. The performance of LM is enhanced with respect to run time by the use of a suitable extracting agent i.e. carrier. Three phase transportation studies are thereby conducted through BLM at the same optimized operating parameters obtained in two phase studies. The extraction and recovery are found to be 72% and 64%, respectively. Further experimentations through BLM were conducted for transportation of lead with the same set of operating parameters. Both the extraction (82%) and recovery (77%) are found comparatively higher for lead as opposed to that of cadmium.

This paper introduces a proof of concept that liquid membrane technology that has always been used as a separation technique, can also be extended for the generation of value added products in its downstream side. It is possible to generate cadmium sulphide nanoparticles in the stripping phase of liquid membrane separation unit which have wide industrial application such as solar and photovoltaic cells. The process parameters such as concentration of cadmium salt and pH in feed phase, concentration of strippant, concentration of extractant/carrier agent, etc. were optimised leading to maximum production of CdS nanoparicles in the stripping phase. The characterisation of CdS nanoparticles were carried out using TEM, FESEM-EDX, FT-IR, XRD and SAED. The nanosize and nanocrystalline nature of the CdS particles were established.