Soluble natural sweetener from date palm (Phoenix dactylifera L.) extract using colloidal gas aphrons generated with a food-grade non-ionic surfactant.

Date palm (Phoenix dactylifera L.) is the most commonly cultivated fruit tree in the Middle East and North Africa. Date fruits are an excellent source of nutrition due to their high sugar content and high levels of phenols, minerals, and antioxidants. This work aimed to prepare a soluble natural sweetener from date fruit extract using colloidal gas aprons (CGAs) generated with a food-grade non-ionic surfactant (Tween 20). Various process parameters, such as the flow rate of the CGAs, the volume of the feed, the temperature of the CGAs, and the feed solution, were varied to obtain the optimal parameters. In the foam phase, the maximum soluble sugar enrichment of 92% was obtained at a flow rate of 50 mL/min of CGA and a solution temperature of 23 °C. The formation of intermolecular hydrogen bonding between the glucose molecules and the surfactant Tween 20 was confirmed by molecular modeling studies. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05907-9.

Colloidal gas aphrons for biotechnology applications: a mini review.

Colloidal gas aphrons (CGAs) are highly stable, spherical, micrometer-sized bubbles encapsulated by surfactant multilayers. They have several intriguing properties, including: high stability, large interfacial area, and the ability to maintain the same charge as their parent molecules. The physical properties of CGAs make them ideal for biotechnological applications such as the recovery of a variety of: biomolecules, particularly proteins, yeast, enzymes, and microalgae. In this review, the bio-application of CGAs for the recovery of natural components is presented, as well as: experimental results, technical challenges, and critical research directions for the future. Experimental results from the literature showed that the recovery of biomolecules was mainly determined by electrostatic or hydrophobic interactions between polyphenols and proteins (lysozyme, ß-casein, ß-lactoglobulin, etc.), yeast, biological molecules (gallic acid and norbixin), and microalgae with CGAs. Knowledge transfer is essential for commercializing CGA-based bio-product recovery, which will be recognized as a viable technology in the future.

Microalgae harvesting using colloidal gas aphrons generated from single and mixed surfactants.

Harmful algal blooms (HABs) caused by microalgae are becoming increasingly common and pose serious threats to human health, aquaculture, and marine environments and, therefore, their removal is becoming essential. Colloidal gas aphrons (CGAs), a recent technology adapted in flotation, showed promise in removing several contaminants from aqueous solutions. This study aimed to investigate the potency of CGAs in removing several microalgae strains (Spirulina platensis, Nannochloropsis oculata, and Chlorella vulgaris) from aqueous solutions. Surfactants, including cationic hexadecyl trimethyl ammonium bromide (HTAB), anionic sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), and their mixes, were used to prepare stable CGAs. The effect of different environmental parameters like algae concentration, pH, and salinity, on removing Spirulina platensis was thoroughly investigated. Operating conditions, including surfactant type, flotation time, flowrate, and solution temperature, were optimized. At pH 5 and 50 °C, Spirulina platensis, Chlorella vulgaris, and mixed microalgae were fully removed using CGAs produced from cationic HTAB surfactant. About 95% removal of Nannochloropsis oculata was achieved using mixed surfactant CGAs. The results obtained from this work demonstrated the promising potential of CGAs produced from both single and mixed surfactants in harvesting various microalgae from aqueous media.

Isolation and characterization of phenol utilizing bacteria from industrial effluent-contaminated soil and kinetic evaluation of their biodegradation potential.

Microbial degradation of phenol by pure bacterial species is a well-known approach towards alleviation of environmental pollution. In this study, five phenol-degrading bacterial species designated as CUPS-1 to CUPS-5 were isolated from the oil-effluent dumped sites of Haldia Industrial area of West Bengal, India. Detailed morphological, biochemical and molecular characterization identified CUPS-3 as a novel strain- Stenotrophomonas maltophilia (GU358076), while the others could be identified as Pseudomonas (CUPS-2, 5), Delftia (CUPS-1) and Micrococcus (CUPS-4) genera, respectively. Although all of these strains utilized phenol as their sole carbon source supporting growth, three among them, CUPS-2, CUPS-3 and CUPS-5 proved potential phenol degraders and hence used for further biodegradation studies. Degradation experiments were carried out for several initial phenol concentrations of 500 mg/L, 750 mg/L, 1000 mg/L, 1250 mg/L and 1500 mg/L. The novel strain, CUPS-3 could completely degrade 500 mg/L phenol within 48 h, with 0.0937/h substrate degradation rate and 16.34 mg/L/h substrate consumption rate. The strains degraded phenol via meta-cleavage pathway. Prediction of kinetic parameters of the biodegradation was accomplished Haldane model using the experimental data of degradation rate and phenol concentration as function of time.

Low-cost field test kits for arsenic detection in water.

Arsenic, a common contaminant of groundwater, affects human health adversely. According to the World Health Organization (WHO), the maximum recommended contamination level of arsenic in drinking water is 10 µg/L. The purpose of this research was to develop user-friendly kits for detection of arsenic to measure at least up to 10 µg/L in drinking water, so that a preventive measure could be taken. Two different kits for detection of total arsenic in water are reported here. First, the arsenic in drinking water was converted to arsine gas by a strong reducing agent. The arsine produced was then detected by paper strips via generation of color due to reaction with either mercuric bromide (KIT-1) or silver nitrate (KIT-2). These were previously immobilized on the detector strip. The first one gave a yellow color and the second one grey. Both of these kits could detect arsenic contamination within a range of 10 µg/L-250 µg/L. The detection time for both the kits was only 7 min. The kits exhibited excellent performance compared to other kits available in the market with respect to detection time, ease of operation, cost and could be easily handled by a layman. The field trials with these kits gave very satisfactory results. A study on interference revealed that these kits could be used in the presence of 24 common ions present in the arsenic contaminated water. Though the kits were meant for qualitative assay, the results with unknown concentrations of real samples, when compared with atomic absorption spectrophotometer (AAS) were in good agreement as revealed by the t-test.

Removal of arsenic from drinking water by ferric hydroxide microcapsule-loaded alginate beads in packed adsorption column.

In this paper we have presented a unique low cost arsenic removal technique using ferric hydroxide microcapsule-loaded alginate beads (FHMCA) as an adsorbent in a continuous packed column. The microencapsulated particles of ferric hydroxide were produced in a spray dryer and subsequently coated with calcium alginate to form spherical beads of about 2 mm diameter. Batch experiments were conducted with these beads to generate isotherm data. The loading capacity was found to be 3.8 mg arsenic/gm of adsorbent. The experimental data conformed to Freundlich adsorption isotherm. A generalized mathematical model was also developed and the visual basic codes run with the physical parameters of the adsorbent and isotherm data that were evaluated experimentally was achieved for a continuous 75 days' operation. The safe disposal of the spent adsorbent was confirmed by the toxicity characteristic leaching procedure (TCLP) results. With known set of physical parameters of the adsorbent, input water flow rate and its arsenic concentration, the model could predict the number of days the column would run with output below a specific arsenic concentration.