Separation of Boron and Arsenic from Geothermal Water with Novel Gel-Type Chelating Ion Exchange Resins: Batch and Column Sorption-Elution Studies.

In this research, the removal of boron and arsenic from geothermal water was examined by using novel N-methyl-d-glucamine functionalized gel-like resins (abbreviated as 1JW and 2JW) synthesized by the membrane emulsification method. The outcomes were compared with those of commercially available boron selective chelating ion exchange resin (Diaion CRB 05). According to the results obtained with the novel resins, it was possible to reduce both boron and arsenic concentrations in geothermal water by using these novel gel-like chelating resins below their permissible levels for agricultural irrigation (<1 mg B/L) and drinking water (<0.01 mg As/L) by using the batch method. The optimum resin concentration required for almost complete boron removal (more than 95%) with the two chelating resins was determined to be 2 g/L. The novel gel-like chelating resins 1JW and 2JW achieved 94% of arsenic removal by using the resin concentration of 8 g/L, while the required resin concentration was 32 g/L for 94% of arsenic removal using commercially available Diaion CRB05 resin. In addition, the column performance characteristics of the novel chelating resins for the separation of boron were studied, and the results were compared to those obtained with Diaion CRB05. According to the column data obtained, the total resin capacities of the Diaion CRB05, 1JW, and 2JW resins were calculated as 6.29, 5.08, and 4.64 mg B/mL-resin, respectively.

Molecularly Imprinting Microfiltration Membranes Able to Absorb Diethyl Phthalate from Water.

In this study, polypropylene porous membranes with an average pore size of 1.25 µm were modified by barrier discharge plasma. Next, molecularly imprinted layers with an imprint of diethyl phthalate (DEP) ware grafted of their surface. In order to optimize the composition of the modifying mixture various solvents, the ratios of functional monomers and the cross-linking monomer as well as various amounts of phthalate were verified. It was shown that the most effective membranes were obtained during polymerization in n-octane with the participation of functional monomers in the ratio 3:7 and the amount of phthalate 7 wt.%. The membranes were tested in the filtration process as well as static and dynamic sorption. In all of these processes, the imprinted membranes showed better properties than those without the imprint. The diethyl phthalate retention coefficient was 36.12% for membranes with a grafting yield of 1.916 mg/cm2. On the other hand, DEP static sorption for the imprinted membranes was 3.87 µmol/g higher than for non-imprinted membranes. Also, in the process of dynamic sorption higher values were observed for membranes with the imprint (DSMIM, 4.12 µmol/g; DSNIM, 1.18 µmol/g). The membranes were also tested under real conditions. In the process of filtration of tap water contaminated with phthalate, the presence of imprints in the membrane structure resulted in more than three times higher sorption values (3.09 µmol/g) than in the case of non-imprinted membranes (1.12 µmol/g).

Electro-Driven Materials and Processes for Lithium Recovery-A Review.

The mass production of lithium-ion batteries and lithium-rich e-products that are required for electric vehicles, energy storage devices, and cloud-connected electronics is driving an unprecedented demand for lithium resources. Current lithium production technologies, in which extraction and purification are typically achieved by hydrometallurgical routes, possess strong environmental impact but are also energy-intensive and require extensive operational capabilities. The emergence of selective membrane materials and associated electro-processes offers an avenue to reduce these energy and cost penalties and create more sustainable lithium production approaches. In this review, lithium recovery technologies are discussed considering the origin of the lithium, which can be primary sources such as minerals and brines or e-waste sources generated from recycling of batteries and other e-products. The relevance of electro-membrane processes for selective lithium recovery is discussed as well as the potential and shortfalls of current electro-membrane methods.

Modified Poly(vinylidene fluoride) by Diethylenetriamine as a Supported Anion Exchange Membrane for Lithium Salt Concentration by Hybrid Capacitive Deionization.

This paper shows the investigation for the optimal anion exchange membranes (AEM) supporting the desorption step of the HCDI process. The chemical modification of PVDF by diethylene triamine created the AEM. To confirm the ion-exchange character of materials, the chemical analysis with FTIR, SEM, surface energetics, and transportation analysis were applied. Next, the investigated membranes were applied for the sorption and desorption of lithium chloride. The specific sorptive parameters were higher according to the incorporation of the nitrogen groups into polymeric chains. Considering the desorption efficiency, membranes modified by four days were selected for further evaluation. The application in the HCDI process allowed reaching the desorption efficiency at 90%. The system composed of PVDF-DETA4 membrane was suitable for sorption 30 mg/g of salt. By applying the PVDF-DETA4 membrane, it is possible to concentrate LiCl with four factors. The anion exchange character of the developed membrane was confirmed by adsorption kinetics and isotherms of chlorides, nitrates, sodium, and lithium. The prepared membrane could be considered a perspective material suitable for concentration salt with electro-driven technologies for the above reasons.

Deposition of Zinc Oxide on Different Polymer Textiles and Their Antibacterial Properties.

A surface modification of polyamide 6 (PA), polyethylene terephthalate (PET) and polypropylene (PP) textiles was performed using zinc oxide to obtain antibacterial layer. ZnO microrods were synthesized on ZnO nanoparticles (NPs) as a nucleus centers by chemical bath deposition (CBD) process. Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) indicated that wurzite ZnO microrods were obtained on every sample. Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and Liquid Absorption Capacity (LAC) analysis indicate that the amount and structure of antibacterial layer is dependent on roughness and wettability of textile surface. The rougher and more hydrophilic is the material, the more ZnO were deposited. All studied textiles show significant bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). A possible mechanism and difference in sensitivity between Gram-negative and Gram-positive bacteria to ZnO is discussed. Considering that antibacterial activity of ZnO is caused by Reactive Oxygen Species (ROS) generation, an influence of surface to volume ratio and crystalline parameters is also discussed.

Preparation of Fouling-Resistant Nanofibrous Composite Membranes for Separation of Oily Wastewater.

A facile and low-cost method has been developed for separation of oily wastewater. Polyvinylidene fluoride/polyacrylonitrile (PVDF/PAN) nanofibers laminated on a supporting layer were tested. In order to create highly permeable and fouling-resistant membranes, surface modifications of both fibers were conducted. The results of oily wastewater separation showed that, after low vacuum microwave plasma treatment with Argon (Ar) and chemical modification with sodium hydroxide (NaOH), the membranes had excellent hydrophilicity, due to the formation of active carboxylic groups. However, the membrane performance failed during the cleaning procedures. Titanium dioxide (TiO2) was grafted onto the surface of membranes to give them highly permeable and fouling-resistance properties. The results of the self-cleaning experiment indicated that grafting of TiO2 on the surface of the membranes after their pre-treatment with Ar plasma and NaOH increased the permeability and the anti-fouling properties. A new surface modification method using a combination of plasma and chemical treatment was introduced.

How To Functionalize Ceramics by Perfluoroalkylsilanes for Membrane Separation Process? Properties and Application of Hydrophobized Ceramic Membranes.

The combination of microscopic (atomic force microscopy and scanning electron microscopy) and goniometric (static and dynamic measurements) techniques, and surface characterization (surface free energy determination, critical surface tension, liquid entry pressure, hydraulic permeability) was implemented to discuss the influence of perfluoroalkylsilanes structure and grafting time on the physicochemistry of the created hydrophobic surfaces on the titania ceramic membranes of 5 kD and 300 kD. The impact of molecular structure of perfluoroalkylsilanes modifiers (possessing from 6 to 12 carbon atoms in the fluorinated part of the alkyl chain) and the time of the functionalization process in the range of 5 to 35 h was studied. Based on the scanning electron microscopy with energy-dispersive X-ray spectroscopy, it was found that the localization of grafting molecules depends on the membrane pore size (5 kD or 300 kD). In the case of 5 kD titania membranes, modifiers are attached mainly on the surface and only partially inside the membrane pores, whereas, for 300 kD membranes, the perfluoroalkylsilanes molecules are present within the whole porous structure of the membranes. The application of 4 various types of PFAS molecules enabled for interesting observations and remarks. It was explained how to obtain ceramic membrane surfaces with controlled material (contact angle, roughness, contact angle hysteresis) and separation properties. Highly hydrophobic surfaces with low values of contact angle hysteresis and low roughness were obtained. These surfaces possessed also low values of critical surface tension, which means that surfaces are highly resistant to wetting. This finding is crucial in membrane applicability in separation processes. The obtained and characterized hydrophobic membranes were subsequently applied in air-gap membrane distillation processes. All membranes were very efficient in MD processes, showing good transport and selective properties (∼99% of NaCl salt rejection). Depending on the membrane pore size and used modifiers, the permeate flux was in the range of 0.5-4.5 kg·m(-2)·h(-1) and 0.3-4.2 kg·m(-2)·h(-1) for 5 kD and 300 kD membranes, respectively.

Plasma nanostructuring of porous polymer membranes.

Several methods for membrane modification have been presented. Chemical modification of a neat polymer followed by membrane formation and modification of just formed membranes have been compared to plasma action. The following plasma modes are discussed in detail: treatment with non-polymerizable gases, treatment with vapors and plasma initiated grafting. Some examples of modified membrane properties are given. Finally, it was concluded that plasma treatment offers the fastest, environment friendly and versatile method that allows tailoring brand new membranes.

Polymeric microspheres with N-methyl-D-glucamine ligands for boron removal from water solution by adsorption-membrane filtration process.

Polymeric microspheres with N-methyl-D-glucamine (NMDG) ligands have been tested in the adsorption-membrane filtration process for boron removal from aqueous solutions. The chelating resins were synthesized by reacting NMDG with the vinylbenzyl chloride-styrene-1,4-divinylbenzene (VBC/S/DVB) copolymer at the reflux temperature and in the microwave reactor. VBC/S/DVB spheres with a gel structure that contained 6 wt% DVB were obtained by membrane emulsification followed by suspension polymerization. By selecting the optimal emulsification and polymerization parameters, it was possible to obtain 25-microm-diameter particles with a narrow size distribution. Resins obtained by microwave modification showed the higher boron adsorption capacity.