Recent advances of copolymer for water treatment.

Increasing water pollution due to anthropogenic activities prompts the quest for an effective water treatment method. Polymeric materials have gained attention as adsorbents for water purification. Membranes are majorly made from homopolymeric materials. However, recent studies have focused on using copolymeric materials for improved performance. In this review, the basics of copolymerization including various types of copolymers, synthetic approaches, and their applications in various water pollutants removal are discussed in detail. Advances in water treatment technology using copolymeric materials as adsorbent/membranes in the last 4 years are covered with insights into the future outlook and areas of improvement in terms of copolymer composites for water treatment. Studies from the literature did not only reveal effectiveness of copolymer as a flocculant/antifouling materials and in removal of selective toxic metals, oil, and microbes but also demonstrated recyclability of the copolymer sorbents/membrane. Full exploration of unique copolymer textural and structural properties could lead to great advancement in water treatment process. PRACTITIONER POINTS: The copolymer types and synthetic methods are discussed. Application of copolymer as adsorbent/membranes for water treatment is presented. Recent advances show good pollutants removal for toxic metals, oil, and organics. Copolymer composites have great potential as adsorbent/membranes for future use in water treatment processes.

Metal-organic frameworks (MOFs) composite of polyaniline-CNT@aluminum succinate for non-enzymatic nitrite sensor.

Nitrite has been linked to a variety of health issues, as well as cancer and oxygen deficiency when its allowable limit is exceeded. Nitrite monitoring and detection are required due to the negative effects on public health. Metal-organic frameworks (MOFs)-based nanomaterials/composites have recently been shown to have the potential for various biological and medical applications like sensing, imaging, and drug delivery. As a result, this research creates an efficient electrochemical sensor by incorporating MOFs into polyaniline (PANI)/carbon nanotube (CNT) cast on the GCE. In situ oxidative polymerization was used to construct an aluminum succinate MOF (Al-Succin)-incorporated CNT/PANI nanocomposite (PANI/CNT@Al-Succin) and well characterized by various characterization techniques, namely, field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric-differential thermal analysis (TGA-DTA), cyclic voltammetry (CV), and four probes to measure DC electrical conductivity. Cyclic voltammetry and linear sweep voltammetry techniques were employed to detect nitrite on the surface of PANI/CNT@Al-Succin-modified glassy carbon electrode (GCE). PANI/CNT@Al-Succin-modified GCE demonstrated good current response and electrocatalytic property towards nitrite compared to bare GCE. The newly synthesized electrode exhibited a high electrocatalytic activity towards nitrite oxidation and showed a linear response ranging from 5.7 to 74.1 µM for CV and 8.55-92.62 µM for LSV. The obtained LOD values for CV (1.16 µM) and LSV (0.08 µM) were significantly below the WHO-defined acceptable nitrite limit in drinking water. Results of recovery studies for real samples of apple juice, orange juice, and bottled water were 98.92%, 99.38%, and 99.90%, respectively. These values show practical usability of PANI/CNT@Al-Succin in real samples.

Solid-state synthesis of CdFe2O4 binary catalyst for potential application in renewable hydrogen fuel generation.

Clean energy is highly needed at this time when the energy requirements are rapidly increasing. The observed increasing energy requirement are largely due to continued industrialization and global population explosion. The current means of energy source is not sustainable because of several reasons, most importantly, environmental pollution and human health deterioration due to burning of fossil fuels. Therefore, this study develops a new catalyst for hydrogen and oxygen evolution by water splitting as a potential energy vector. The binary metal oxide catalyst CdFe2O4 was synthesized by the solventless solid-mechanical alloying method. The as-prepared catalyst was well characterized by several methods including field emission scanning electron microscopy (FESEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), Fourier Transform infrared red spectroscopy (FTIR), energy dispersive X-ray spectroscopy (XEDS). The as-prepared catalyst, CdFe2O4 was successfully applied for water electrolysis at a moderate overpotential (470 mV). Specifically, the onset potential for the oxygen and hydrogen evolution reactions (OER and HER) were 1.6 V/RHE and 0.2 V/RHE respectively (vs. the reversible hydrogen electrode). The electrode potential required to reach 10 mA/cm-2 for OER (in alkaline medium) and HER (in acidic medium) was 1.70 V/RHE (corresponding to overpotential η = 0.47 and - 0.30 V/RHE (η = - 0.30 V) respectively. Similarly, the developed OER and HER catalyst displayed high current and potential stability for a period of 12 h. This approach is seen as the right track of making water electrolysis for hydrogen energy feasible through provision of low-energy requirement for the electrolytic process. Therefore, CdFe2O4 is a potential water splitting catalyst for hydrogen evolution which is a clean fuel and an antidote for world dependence on fossil fuel for energy generation.

Revisiting the Impact of Morphology and Oxidation State of Cu on CO2 Reduction Using Electrochemical Flow Cell.

Electroreduction of carbon dioxide (CO2) in a flow electrolyzer represents a promising carbon-neutral technology with efficient production of valuable chemicals. In this work, the catalytic performance of polycrystalline copper (Cu), Cu2O-derived copper (O(I)D-Cu), and CuO-derived copper (O(II)D-Cu) toward CO2 reduction is unraveled in a custom-designed flow cell. A peak Faradaic efficiency of >70% and a production rate of ca. -250 mA cm-2 toward C2+ products have been achieved on all the catalysts. In contrast to previous studies that reported a propensity for C2+ products on OD-Cu in conventional H-cells, the selectivity and activity of ethylene-dominated C2+ products are quite similar on the three types of catalysts at the same current density in our flow reactor. Our analysis also reveals current density to be a critical factor determining the C-C coupling in a flow cell, regardless of Cu catalyst's initial oxidation state and morphology.

Solar Water Splitting Using Earth-Abundant Electrocatalysts Driven by High-Efficiency Perovskite Solar Cells.

Hydrogen is considered as the "holy grail" for the energy community. One of the most promising strategies to produce hydrogen is to split water using renewable energy such as solar radiation. The abundance of water and solar energy enables the potential of scaling-up of this new technology, if suitable electrocatalysts and solar cells are developed. In this work, a series of materials made of earth-abundant elements was investigated for hydrogen evolution or oxygen evolution reaction. Among the developed catalysts, MoS2 and NiFe showed the best activities for proton reduction and water oxidation, respectively. These catalysts were further integrated into an alkaline electrolyzer, which delivered a current density of 10 mA cm-2 at a cell voltage of 1.9 V for water splitting. Using two in-series-connected perovskite solar cells (PSCs) as a power source, a remarkable solar-to-hydrogen conversion efficiency of 12.67 % was achieved in an alkaline electrolyzer with a partial current density of 10.3 mA cm-2 for hydrogen production. The usage of earth-abundant catalysts in this study, together with the employment of low-cost perovskite light absorber, shows the potential of scaling up this type of photovoltaic electrolyzer for sustainable hydrogen production.

Development of Cd (II) Ion Probe Based on Novel Polyaniline-Multiwalled Carbon Nanotube-3-aminopropyltriethoxylsilane Composite.

Cadmium belongs to the group of potentially toxic metals that have high health and environmental significance. Due to its adverse effects on the environment, this study develops an effective electrochemical sensor for detecting a polyaniline-multiwalled carbon nanotube-3-aminopropyltriethoxysilane (PANI-MWCNT-APTES) substrate cast on the GCE. The as-prepared PANI-MWCNT-APTES was prepared by a wet chemical method, and its formation was investigated using several techniques. As a result, the prepared material exhibited a limit of detection of 0.015 µM for cadmium ions (Cd2+) in the linear dynamic range of 0.05 µM to 50 µM. Furthermore, the PANI-MWCNT-APTES-modified GCE current response was stable, repeatable, reproducible, and short. In addition, PANI-MWCNT-APTES/GCE was harnessed for the first time for cadmium detection in real water samples, and the result was satisfactory. Therefore, the recorded results suggest that the newly designed PANI-MWCNT-APTES is a promising material for detecting Cd in the near future for human health and environmental protection.

Efficient Synthesis and Characterization of Polyaniline@Aluminium-Succinate Metal-Organic Frameworks Nanocomposite and Its Application for Zn(II) Ion Sensing.

A new class of conductive metal-organic framework (MOF), polyaniline- aluminum succinate (PANI@Al-SA) nanocomposite was prepared by oxidative polymerization of aniline monomer using potassium persulfate as an oxidant. Several analytical techniques such as FTIR, FE-SEM, EDX, XRD, XPS and TGA-DTA were utilized to characterize the obtained MOFs nanocomposite. DC electrical conductivity of polymer-MOFs was determined by four probe method. A bare glassy carbon electrode (GCE) was modified by nafion/PANI@Al-SA, and examined for Zn (II) ion detection. Modified electrode showed improved efficiency by 91.9%. The modified electrode (PANI@Al-SA/nafion/GCE) exhibited good catalytic property and highly selectivity towards Zn(II) ion. A linear dynamic range of 2.8-228.6 µM was obtained with detection limit of LOD 0.59 µM and excellent sensitivity of 7.14 µA µM-1 cm-2. The designed procedure for Zn (II) ion detection in real sample exhibited good stability in terms of repeatability, reproducibility and not affected by likely interferents. Therefore, the developed procedure is promising for quantification of Zn(II) ion in real samples.

Novel Aminosilane (APTES)-Grafted Polyaniline@Graphene Oxide (PANI-GO) Nanocomposite for Electrochemical Sensor.

Lead is a potentially toxic element (PTE) that has several adverse medical effects in humans. Its presence in the environment became prominent due to anthropogenic activities. The current study explores the use of newly developed composite materials (organic-inorganic hybrid) based on PANI-GO-APTES for electrochemical detection of Pb2+ in aqueous solution. The composite material (PANI-GO-APTES) was synthesized by chemical method and was characterized with SEM, XPS, XEDS, XRD, TGA, FTIR, EIS and CV. The result of characterization indicates the successful synthesis of the intended material. The PANI-GO-APTES was successfully applied for electrochemical detection of Pb2+ using cyclic voltammetry and linear sweep voltammetry method. The limit of detection of Pb2+ was 0.0053 µM in the linear range of 0.01 µM to 0.4 µM. The current response produced during the electrochemical reduction of Pb2+ catalyzed by PANI-GO-APTES was also very repeatable, reproducible and rapid. The application of PANI-GO-APTES-modified GCE in real sample analysis was also established. Therefore, PANI-GO-APTES is presented as a potential Pb2+ sensor for environmental and human health safety.

Real time detection and monitoring of 2, 4-dinitrophenylhydrazine in industrial effluents and water bodies by electrochemical approach based on novel conductive polymeric composite.

Much attention has been given to detection and monitoring of hydrazine-based compounds in recent time because of its significant negative impacts on human health and ecosystem (aquatic lives). This prompted the current study focusing on detection of 2, 4-dinitrophenylhydrazine (2, 4-dnphz) using electrochemically synthesized poly-para amino benzoic acid-manganese oxide (P-pABA-MnO2) composite film. The synthesized P-pABA-MnO2 composite film was characterized in terms of its structural and morphological properties by X-ray diffraction spectroscopy and field emission scanning electron microscopy respectively. In addition, functionalities and binding energy of p-PABA-MnO2 were confirmed using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy respectively. Finally, electrochemical properties were investigated using electrochemical impedance spectroscopy and cyclic voltammetry. The synthesized P-pABA-MnO2 displayed good electrocatalytic reduction property towards 2, 4-dnphz with ultra-low limit of detection (0.08 µM; S/N = 3) and very high sensitivity (52 µAµ-1Mcm-2). The proposed sensor based on P-pABA-MnO2 also demonstrated good stability in terms of repeatability, reproducibility and interferents effects. Lastly, the proposed sensor was satisfactorily used in detection of 2, 4-dnphz in environmental real samples.