Environmental Applications of Biosurfactants: Recent Advances

Increasing public awareness of environmental pollution influences the search and development of technologies that help in clean up of organic and inorganic contaminants such as hydrocarbons and metals. An alternative and eco-friendly method of remediation technology of environments contaminated with these pollutants is the use of biosurfactants and biosurfactant-producing microorganisms. The diversity of biosurfactants makes them an attractive group of compounds for potential use in a wide variety of industrial and biotechnological applications. The purpose of this review is to provide a comprehensive overview of advances in the applications of biosurfactants and biosurfactant-producing microorganisms in hydrocarbon and metal remediation technologies

Development of processes for metals recovery from special waste with production of nanoparticles

Mechanical and hydrometallurgical routes have been developed aiming to recover metals from spent batteries such as lithium ion, primary lithium and nickel metal hydride batteries. Moreover nanoparticles of manganese carbonate were synthesized by microemulsione mediated route with the future goal of performing a production of nanoparticles downstream of a hydrometaluurgical process for batteries valorization

Determination of cadmium in used engine oil, gasoline and diesel by electrothermal atomic absorption spectrometry using magnetic ionic liquid-based dispersive liquid-liquid microextraction

In this study, a sensitive and matrix-effect free analytical method for Cd determination in engine oils and fuel samples by dispersive liquid-liquid microextraction with electrothermal atomic absorption spectrometry has been successfully developed. The extractant solvent used for the microextraction procedure was a magnetic ionic liquid (MIL) (i.e., bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate (II) [Emim]2[Co(SCN)4]), which presents a paramagnetic property, and allows an easy phase separation using a magnet. In order to eliminate the well-known drawbacks of direct introduction of MIL in the graphite furnace, a back-extraction procedure was performed to transfer the analyte into an aqueous phase. The main experimental factors affecting the extraction of Cd (i.e., amount of sample and MIL, extraction and back-extraction time and concentration and amount of nitric acid) were optimized using a multivariate analysis consisting in two steps: a Plackett-Burman design followed by a circumscribed central composite design. Under optimum conditions (i.e., amount of sample: 6.2 g; amount of MIL: 119 mg; extraction time: 1 min; amount of nitric acid: 200 mg; nitric acid concentration: 1 mol L-1 and back-extraction time: 1 min), the proposed analytical method was validated and successfully used to analyze three real-world samples (i.e., used engine oil, gasoline and diesel). The three samples were spiked at two levels (i.e., 10 and 20 μg kg-1 of Cd for used engine oil and 1 and 3 μg kg-1 of Cd for gasoline and diesel). RSD and recovery values were within the range of 6–11% and 95–110%, respectively.The authors would like to thank the Spanish Government (projects n. CTQ2016-79991-R and PGC 2018-098363-100), Fundación Séneca (Project n. 19888/GERM/15) and European Union (FEDER funds) for the financial support

Systematic review on applicability of magnetic iron-oxides integrated photocatalysts for degradation of organic pollutants in water

Owing to biocompatibility, abundance, and low cost, magnetic iron oxides are well suited for the design of efficient and magnetically separable photocatalysts for water treatment. This review presents a detailed survey of magnetic iron oxide–integrated photocatalysts (MIOIPs), in which we have discussed essential conditions needed for designing of efficient MIOIPs for water purification. The synthesis methods and detailed experimental setups for fabrication of MIOIPs were discussed, and the integration manners of iron oxides (Fe2O3, Fe3O4, FeO, and ferrites) with binary, ternary, and quaternary non-magnetic photocatalysts have been categorized. The mechanistic view of enhanced photocatalytic activity caused by different MIOIPs under various light sources was also elaborately argued. The role of various reactive species in photocatalytic oxidative degrading of organic pollutants was investigated. Altogether, this review article has compressively considered and discussed various signs of advancements made toward the synthesis of MIOIPs and their stability, recyclability, and catalytic efficacy for wastewater treatment

Applications of Surface Active Ionic Liquids

The overall objective of this thesis is to take advantage of the existence of polar/non-polar domains in ionic liquids, specifically surfactants, to develop new applications of these salts. Silver chloride nanoparticles were synthesised using solely the surfactant ionic liquid trihexyl(tetradecyl)-phosphonium chloride and AgCl bulk powder. The nanoparticles were characterised and tested as nanocatalysts in the photodegradation of Orange II. An almost complete degradation can be achieved, in optimal conditions, and the nanoparticles can be recycled. The same method of synthesis was used to prepare ionanofluids consisting of AgI nanoparticles in the ionic liquid trihexyl(tetradecyl)phosphonium chloride. High concentrate and stable nanofluids were obtained and characterised. The use of this method, with a careful consideration in the selection of the ionic liquid and nanoparticles, allows obtaining nanofluids of enhanced properties. The capability of 1-alkyl-3-methylimidazolium surfactant ionic liquids to improve surfactant enhanced oil recovery methods was analysed. Liquid–liquid equilibria of water + [Cnmim][NTf2] (n = 10 or 12) + n-dodecane ternary systems were measured at 298.15 and 348.15 K. These systems can be classified as Winsor III. Some drawbacks were detected to use these ionic liquids in oil recovery. However the PC-SAFT equation of state was able to predict the equilibria. Thus, this model can be a fast and cheap initial method for the screening of possible surfactants for this application. The bistrifluoromethylsulfonylimide anion of the previously tested ionic liquids was changed for acetate. The dynamic interfacial tensions between several formulations, containing the ionic liquid, and crude oil (Saharan blend) were evaluated by the spinning drop method. The results obtained significantly improve upon previous results obtained up to with other ionic liquids. Surfactant ionic liquids can be used for the synthesis of nanoparticles and ionanofluids, and are promising alternatives to evaluate for oil recovery

Development of New Environment Friendly Adsorption Media for the Removal of Hazardous Anions from Water.

Over last three decades, the important thrust area among the researches are to provide uncontaminated drinking water and for other domestic uses. New technologies in field of water purification are developing steadily but it almost remains same in actual affected fields. In India, one of the main sources for domestic, industrial, agricultural and other purposes is the ground water. The ground water pollution with hazardous anions like fluoride, arsenate specifically, and other anions like nitrate, phosphate, sulphate, chromate etc. is a major issue that causes various adverse health effects. Many domestic purification processes are there in application, but not exactly applicable in rural area due to many factors like regular maintenance, cost and non-availability of electricity. So there is a huge research gap between technology available for water purification and its field application in actual affected area. In this project two specific ions fluoride and anions of arsenic are targeted for its removal from water environment. This dissertation focuses on the remediation of the above-mentioned anionic pollutants by designing suitable materials. Various techniques were applied for the removal of these anionic contaminants so far. Among them adsorption techniques with suitable adsorbent has been an efficient method. In this present research work, four different types of materials have been synthesized for adsorption of arsenic and fluoride from contaminated water separately. In the first project, we have prepared Fe-Al 6mixed oxide nanoparticle by precipitation method which was used as an adsorbing material to remove fluoride from synthetic aqueous solution. The results revealed that the Fe- Al mixed oxide nanoparticle results better affinity towards fluoride. The maximum adsorption capacity of the material for fluoride was found to be 103.9 mg g-1 with the optimum condition. (0.08 g of the adsorbent, pH 7 and temperature of 40°C). The experimental data are best fitted with Freundlich adsorption isotherm. The pseudo 2nd order kinetic model described the kinetics of adsorption process. In the same direction, in the second project, Chitosan encapsulated magnetic nanoparticle modified was synthesized via co-precipitation method and applied for de-fluoridation of water by adsorption. Experimental results showed that the prepared material works very well for practical purpose. The magnetic chitosan nano particle acts as a good adsorbent for fluoride ions due to interesting interactions of fluoride with amino functionalized Iron. The pseudo 2nd order kinetics is best fitted to the adsorption with a maximum removal capacity of 33.62 mg g-1 calculated from Langmuir isotherm model. In third project, Lanthanum incorporated Zirconium Phosphate mesoporous material was synthesized for remediation of fluoride by precipitation by followed by hydrothermal treatment. The mesostructured Zr-P compounds showed greater removal efficiency due to higher specific surface area. The maximum adsorption capacity of the material for fluoride was 83.90 mg g-1 with the optimum condition at adsorbent dose of 0.2 g, pH 6 and temperature of 60°C. The adsorption process was best suited to Langmuir adsorption isotherm model and the pseudo 2nd order kinetic model. In the fourth part of this work, Mg/Fe/carbonate layered double hydroxide was prepared for arsenic decontamination by simple precipitation method followed by heat treatment. Presence of the inter layer anions between two cationic layers, facilitates the ion-exchange mechanism for efficient As(V) removal. The maximum removal of arsenic was 271.00 mg g-1 at the optimum condition of 0.1 g of the adsorbent, pH of 7. The equilibrium data of As(V) were best described by Langmuir adsorption isotherm model and kinetics of adsorption followed the pseudo 2nd order kinetic model. To check the role of flow rate, initial concentration and bed volume on adsorption of fluoride ions using synthetic aqueous solution, fixed bed column study was conducted. The mechanism of adsorption process were studied by using analytical methods like SEM, EDX, TEM, XRD, FTIR, TGA-DSC and BET surface area before and after treatment. All the results suggested that the above said materials have a strong and specific affinity towards the anionic contaminants, and can be considered as excellent material for treatment of real contaminated water system

Surface Modification of Fe3O4 as Magnetic Adsorbents for Recovery of Precious Metals

Magnetic nanoparticles such as magnetite have been studied intensively for their unique properties that are susceptible to a magnetic field, ready to coat with silica and able to modify with a variety of functional groups. The magnetite-silica core-shell system offers flexibility for extensive modification. The magnetic core is also important in the separation by the use of a magnetic field. The shell, meanwhile, is needed for protection of the magnetic core and further modification. Functional groups at the surface shell are critical in the reaction with target precious metal ions during application. In this contribution, we will have a comprehensive look at the preparation, characterization, and use of the magnetite core-shell modified with functional groups as a magnetic adsorbent. After adsorption, the materials together with the ions can be recovered by the use of magnet before further separation and purification