Water Softening Using a Light-Responsive, Spiropyran-Modified Nanofiltration Membrane

Enhanced EDC removal from water through electron beam-mediated adsorber particle integration in microfiltration membranes

The existence of endocrine disrupting chemicals (EDCs) in water and wastewater gives rise to significant environmental concerns. Conventional treatment approaches demonstrate limited capacity for EDC removal. Thus, incorporation of advanced separation procedures becomes essential to enhance the efficiency of EDC removal. In this work, adsorber composite microfiltration polyethersulfone membranes embedded with divinyl benzene polymer particles were created. These membranes were designed for effectively removing a variety of EDCs from water. The adsorber particles were synthesized using precipitation polymerization. Subsequently, they were integrated into the membrane scaffold through a phase inversion process. The technique of electron beam irradiation was applied for the covalent immobilization of particles within the membrane scaffold. Standard characterization procedures were carried out (i.e., water permeance, contact angle, X-ray photoelectron spectroscopy and scanning electron microscopy) to gain a deep understanding of the synthesized membrane properties. Dynamic adsorption experiments demonstrated the excellent capability of the synthesized composite membranes to effectively remove EDCs from water. Particularly, among the various target molecules examined, testosterone stands out with the most remarkable enhancement, presenting an adsorption loading of 220 mg m-2. This is an impressive 26-fold increase in the adsorption when compared to the performance of the pristine membrane. Similarly, androst-4-ene-3,17-dione exhibited an 18-fold improvement in adsorption capacity in comparison to the pristine membrane. The composite membranes also exhibited significant adsorption capacities for other key compounds, including 17β-estradiol, equilin, and bisphenol-A. With the implementation of an effective regeneration procedure, the composite membranes were put to use for adsorption over three consecutive cycles without any decline in their adsorption capacity.

Evaluation of Strong Cation Ion-Exchange Resin Cost Efficiency in Manufacturing Applications-A Case Study

The effective ionic capacities of strong cation ion-exchange resins were investigated and compared using conditions similar to those found in white goods, in order to establish behavioral differences between commercial products and evaluate their capacity in a broader business context. Nine different products of equivalent TDS (Technical Data Sheet) capacity were observed to examine their differences in approximately real-life conditions. For a broader context of applicability analysis, besides the absolute ionic operating capacity, the following additional factors were included in the evaluation: the standard deviation in the resins’ performances and their relative prices. A complete method for material applicability evaluation was hereby proposed and shown to offer cost factor benefits of up to 21.1% within the range of products examined, in comparison to a cost-only evaluation for equivalent materials.

Nanocellulose for Sustainable Water Purification

Nanocelluloses (NC) are nature-based sustainable biomaterials, which not only possess cellulosic properties but also have the important hallmarks of nanomaterials, such as large surface area, versatile reactive sites or functionalities, and scaffolding stability to host inorganic nanoparticles. This class of nanomaterials offers new opportunities for a broad spectrum of applications for clean water production that were once thought impractical. This Review covers substantial discussions based on evaluative judgments of the recent literature and technical advancements in the fields of coagulation/flocculation, adsorption, photocatalysis, and membrane filtration for water decontamination through proper understanding of fundamental knowledge of NC, such as purity, crystallinity, surface chemistry and charge, suspension rheology, morphology, mechanical properties, and film stability. To supplement these, discussions on low-cost and scalable NC extraction, new characterizations including solution small-angle X-ray scattering evaluation, and structure-property relationships of NC are also reviewed. Identifying knowledge gaps and drawing perspectives could generate guidance to overcome uncertainties associated with the adaptation of NC-enabled water purification technologies. Furthermore, the topics of simultaneous removal of multipollutants disposal and proper handling of post/spent NC are discussed. We believe NC-enabled remediation nanomaterials can be integrated into a broad range of water treatments, greatly improving the cost-effectiveness and sustainability of water purification.

A Review on the Use of Membrane Technology Systems in Developing Countries

Fulfilling the demand of clean potable water to the general public has long been a challenging task in most developing countries due to various reasons. Large-scale membrane water treatment systems have proven to be successful in many advanced countries in the past two decades. This paves the way for developing countries to study the feasibility and adopt the utilization of membrane technology in water treatment. There are still many challenges to overcome, particularly on the much higher capital and operational cost of membrane technology compared to the conventional water treatment system. This review aims to delve into the progress of membrane technology for water treatment systems, particularly in developing countries. It first concentrates on membrane classification and its application in water treatment, including membrane technology progress for large-scale water treatment systems. Then, the fouling issue and ways to mitigate the fouling will be discussed. The feasibility of membrane technologies in developing countries was then evaluated, followed by a discussion on the challenges and opportunities of the membrane technology implementation. Finally, the current trend of membrane research was highlighted to address future perspectives of the membrane technologies for clean water production.

Smart Self-Cleaning Membrane via the Blending of an Upper Critical Solution Temperature Diblock Copolymer with PVDF

Poly(2,2,2-trifluoroethyl methacrylate)-b-poly(imidazoled glycidyl methacrylate-co-diethylene glycol methyl ether methacrylate) (PTFEMA-b-P(iGMA-co-MEO₂MA)) containing an upper critical solution temperature (UCST) polymer chain was prepared and blended with poly(vinylidene fluoride) (PVDF) to produce a thermoresponsive membrane with smart self-cleaning performance. The successful preparation of the membrane was demonstrated by attenuated total reflection-Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy characterization. The membrane shows UCST performance, and its flux changes with the filtrate temperature as the UCST polymer chain stretches out and contracts in response to various temperatures. In addition, the UCST polymer chain can disrupt the foulant and push it away from the membrane when the temperature is above the UCST and thus enables membranes to exhibit a smart self-cleaning behavior. To the best of our knowledge, this work is the first report of a smart self-cleaning membrane based on the blending of a diblock copolymer containing a UCST polymer chain with PVDF.

Photochromic Polyamide 6 Based on Spiropyran Synthesized via Hydrolyzed Ring-Opening Polymerization

We report photochromic polyamide 6 (PA6) which was synthesized by hydrolyzed ring-opening polymerization of ε-caprolactam with spiropyran (SP) embedded in the polymer chains. It indicated that crystallinity degree of the resulting copolymers was decreased since only PA6 segments can crystallize with increasing content of SP modifier. Meanwhile, toughness of photochromic PA6 was decreased. The photochromic property analysis indicated that the sample with more flexibility and more content of SP was more sensitive to UV light at the beginning of irradiation than other samples and its color after being irradiated for 1 min tended to reddish. Investigation revealed that the UV-vis absorbance of SP-PA6-3 had negligible decay after 10 cycles, which indicated SP-modified PA6 possessed excellent photoresponse reversibility and fatigue resistance.

Removal of Ca2+, Mg2+, Ba2+ and Sr2+ from shale gas flowback water from the Sichuan Basin in China by chemical softening under the guidance of OLI Stream Analyzer: precipitation behaviors and optimization study

The disposal of flowback water is recognized as a key issue for the sustainable shale gas development and discharge after reasonable treatment is considered as a feasible pathway. One of the challenges during treatment is the severe mineral scaling potential in reverse osmosis desalination, especially with high amounts of Ca²⁺, Mg²⁺, Ba²⁺ and Sr²⁺ in flowback water. In this study, precipitation behaviors of Ca²⁺, Mg²⁺, Ba²⁺ and Sr²⁺ during traditional chemical softening was evaluated so as to achieve optimal chemical dosage. Both jar tests and OLI Stream Analyzer simulation revealed that the main precipitates were CaCO₃, SrCO₃ and BaSO₄ during Na₂CO₃ addition, and Ba²⁺ could not be removed efficiently by Na₂CO₃ unless a high dosage was applied since Ba²⁺ would react after the precipitation of Ca²⁺ and Sr²⁺. Reverse Osmosis System Analysis simulation indicated that Ba²⁺ was a concern because Ba²⁺ would form tenacious BaSO₄ scale on the reverse osmosis membranes. Finally, the Na₂SO₄-NaOH-Na₂CO₃ process was proposed for chemical softening as it has a high removal efficiency and low chemical cost. Overall, this study presents an effective chemical softening method and OLI Stream Analyzer could serve as a reliable tool for the calculation, which would finally improve the design and operation of shale gas flowback water treatment.