Biscarbene complexes of Bithiophene

Binuclear mixed biscarbene complexes of bithiophene were synthesized via the classical Fischer method of synthesis. The metal carbonyls, Mo(CO)6, Cr(CO)6, W(CO)6 and Mn(MeCp)(CO)3 were reacted with dilithiated bithiophene to afford complexes of the formula, [M(CO)5{C(OEt)C4H2S-C4H2SC(OEt})M'(CO)5] (in case of manganese, M(CO)5 is replaced with MMeCp(CO)2), where [M] and [M'] are the metal carbonyls in different combinations. Quenching was achieved with triethyl oxonium tetrafluoroborate. In all the reactions the products included monocarbene complexes, biscarbene complexes and the decomposition products. C-C coupling reactions produced unexpected biscarbene complexes of Cr, W, and Mo having extended bithiophene spacers. The complexes were of the formula, [M(CO)5{C(OEt)C4H2S-C4H2SC(R)-C(R)C4H2S-C4H2SC(OEt})M'(CO)5] (R = O, OH or OEt). These complexes were characterized with NMR, infrared spectroscopy and some with mass spectrometry. Furthermore, three biscarbene complexes of the metal combinations Mo(CO)6 and Cr(CO)6, W(CO)6 and Cr(CO)6, and Mn(MeCp)(CO)3 and Cr(CO)6 were all reacted with 3-hexyne. The result was the benzannulation or the Dötz products.ChemistryM. Sc. (Chemistry

Synergistic effect of ZnO/Ag2O@g-C3N4 based nanocomposites embedded in carrageenan matrix for dye degradation in water

This research achieved success by synthesizing innovative nanocomposite composed of zinc oxide (ZnO), graphitic carbon nitride (g-C3N4) and silver oxide (Ag2O) nanomaterials incorporated into a carrageenan matrix, thus creating an environmentally friendly and stable support structure. The synthesis process involved hydrothermal and chemical precipitation methods to create photocatalytic g-C3N4, ZnO, and Ag2O nanocomposites. The success is evident through the characterization results, which unveiled distinctive peaks corresponding to Zn–O (590-404 cm−1) and Ag–O (2072 cm−1) stretching in the Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses, conclusively confirming the successful synthesis of g-C3N4, ZnO, Ag2O, and their respective nanocomposites. Further validation through a scanning electron microscope coupled with an energy dispersive spectrometer (SEM-EDX) and elemental mapping affirmed the presence of Zn, O, Ag, C, and N. Additionally, transmission electron microscope (TEM) imaging unveiled the nanosheet morphology of g-C3N4, the nanorod structure of ZnO, and the spherical form of Ag2O nanomaterials. ZnO and Ag2O nanomaterials demonstrated a consistent 10–20 nm size range. To underscore their ability to harness visible light, the nanomaterials were excited at 380 nm, emitting visible light emission within the 400–450 nm range. The synthesized nanocomposites showcased outstanding adsorption and photocatalytic properties, achieving efficiency ranging from 80 % to 98 %, attributed to the synergistic interactions between the various components. These findings culminate in a confirmation of the research's success, validating the exceptional potential of these nanocomposites for various applications

Effective Desalination of Acid Mine Drainage Using an Advanced Oxidation Process: Sodium Ferrate (VI) Salt

The screening and treatment of acid mine drainage (AMD) using Na2FeO4 was explored. Elemental composition was performed, using an Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) for the raw and treated AMD. The AMD samples were collected from three different sampling sites:(Raw Tailing Water 1 (RTW1), Raw Tailing Water 2 (RTW2) and Raw Tailing Water 3 (RTW3)) in Pretoria, South Africa, with acidic pH ranging between 2.50 and 3.13. Total dissolved solids and the electrical conductivity of AMD samples ranged between 960 and 1000 mg L−1, 226 and 263 µS. cm−1, respectively. The final pH of treated water samples increased up to ≥9.5 after treatment with sodium ferrate (VI) (Na2FeO4). Liquid Na2FeO4 was quantitatively produced through a wet oxidation method and was fully characterized, using Fourier Transform Infra-Red (FTIR), X-ray Diffraction spectroscopy (XRD) and UV-Vis instruments. Na2FeO4 showed dual functions by removing metals and raising the pH of the treated water. Concentrations of most trace elements did not comply with WHO and DWAF guideline standards in raw AMD while after treatment with Na2FeO4, the concentrations were below guidelines for domestic and irrigation purposes

Evaluation of Surface Water Quality Using Various Indices for Heavy Metals in Sasolburg, South Africa

The purpose of the study was to determine the concentrations of heavy metals in surface waters used for domestic and farming activities. This study investigated various water quality parameters, including pH, electrical conductivity (EC), total dissolved solids (TDS), and major and trace elements such as Al, As, Cd, Co, Cr, Fe, Mn, Mo, Ni, Pb, Sb, Se, Sr, Tl, and V, which were investigated during the dry and wet seasons from samples collected at Meulsteenpan Lake, Coalplex Stream, and Natref Stream in Sasolburg, Free State, South Africa (2019–2020). The results revealed that the pH of water collected from Meulsteenpan Lake (7.86–7.89) and Coalplex stream (7.13–7.37) were within the Department of Water Affairs and Forestry (DWAF), World Health Organization (WHO), and Environmental Protection Agency (EPA) permissible guideline values for domestic and agricultural use. On the other hand, the pH from Natref stream (6.16–7.68) was within the permissible guideline values set by the DWAF for domestic use but below the permissible guideline values set by the WHO and EPA for domestic use, and the DWAF for agricultural use. The mean TDS and EC values in Meulsteenpan Lake (796–980 mg/L) and (1.20–2.00 mS/m) exceeded permissible guideline values set by the DWAF and WHO domestic use for TDS, Coalplex stream (309–326 mg/L) and (0.65 mS/m), and Natref Stream (269–413 mg/L) and (0.89–0.96 mS/m) were within the permissible guideline values for the DWAF and WHO domestic use for TDS. The results obtained for metal concentration revealed higher mean concentrations for Al, Fe, and Mo, Mn in the study area, which could pose adverse health risks to aquatic life and humans. Various pollution and health assessments (Cf, m-Cd, m-HPI, HEI, NEI, and WQI) were used to evaluate the quality status of the surface water on all sampling sites. WQI revealed that in the wet and dry seasons, surface waters from Coalplex Stream and Natref Stream had “excellent” water quality, while Meulsteenpan Lake had “excellent” water quality in the dry season, but in the wet season, the water quality was “unsuitable for drinking”

Evaluation of Surface Water Quality Using Various Indices for Heavy Metals in Sasolburg, South Africa

The purpose of the study was to determine the concentrations of heavy metals in surface waters used for domestic and farming activities. This study investigated various water quality parameters, including pH, electrical conductivity (EC), total dissolved solids (TDS), and major and trace elements such as Al, As, Cd, Co, Cr, Fe, Mn, Mo, Ni, Pb, Sb, Se, Sr, Tl, and V, which were investigated during the dry and wet seasons from samples collected at Meulsteenpan Lake, Coalplex Stream, and Natref Stream in Sasolburg, Free State, South Africa (2019–2020). The results revealed that the pH of water collected from Meulsteenpan Lake (7.86–7.89) and Coalplex stream (7.13–7.37) were within the Department of Water Affairs and Forestry (DWAF), World Health Organization (WHO), and Environmental Protection Agency (EPA) permissible guideline values for domestic and agricultural use. On the other hand, the pH from Natref stream (6.16–7.68) was within the permissible guideline values set by the DWAF for domestic use but below the permissible guideline values set by the WHO and EPA for domestic use, and the DWAF for agricultural use. The mean TDS and EC values in Meulsteenpan Lake (796–980 mg/L) and (1.20–2.00 mS/m) exceeded permissible guideline values set by the DWAF and WHO domestic use for TDS, Coalplex stream (309–326 mg/L) and (0.65 mS/m), and Natref Stream (269–413 mg/L) and (0.89–0.96 mS/m) were within the permissible guideline values for the DWAF and WHO domestic use for TDS. The results obtained for metal concentration revealed higher mean concentrations for Al, Fe, and Mo, Mn in the study area, which could pose adverse health risks to aquatic life and humans. Various pollution and health assessments (Cf, m-Cd, m-HPI, HEI, NEI, and WQI) were used to evaluate the quality status of the surface water on all sampling sites. WQI revealed that in the wet and dry seasons, surface waters from Coalplex Stream and Natref Stream had “excellent” water quality, while Meulsteenpan Lake had “excellent” water quality in the dry season, but in the wet season, the water quality was “unsuitable for drinking”

Quantification and characterization of the sludge generated from synthetic acid mine drainage treatment using sodium ferrate (VI) as an advance oxidation process

A major problem in the active treatment of acid mine drainage (AMD) is the generation of large volumes of sludge through pH neutralization, oxidation of iron (II) and subsequent metal precipitation. The sludge settling rate, sludge volume index (SVI) and sedimentation process are ones of parameters identifying a good treatment of AMD. Sodium ferrate (VI) (Na2FeO4) is one reagent currently used to treat water due to its quick reaction rate, easy implementation and relatively low chemical and operational costs. However, very limited information is available in the literature related to the detailed characterization and dewaterability of Na2FeO4-treated AMD sludge. This study aimed at characterizing and monitoring settling rate and densification process of synthetic AMD sludge after treatment with Na2FeO4. The results confirmed a complete removal of iron from the synthetic AMD due to high oxidation strength of ferrate (VI) in acidic medium (Eᵒ = 2.2V) and showed the presence of different minerals formed in the sludge after treatment. The concentrations of the sludge collected at different intervals were justified by the densification process and high density of the sludge was obtained after 25 minutes while high weight percent of iron was found at 10 min and Fe and O dominated other elements in the sludge. The study demonstrated very good settling properties of the sludge and the low SVI value ranging between 30 and 60 mL/g TSS

Influence of the Zeolite ZSM-22 Precursor on a UF-PES Selective Substrate Layer for Salts Rejection

Fabrication of the ZSM-22/Polyethersulfone (ZSM-22/PES) membranes as selective salt filters represent a growing membrane technological area in separation with the potential of high economic reward based on its low energy requirements. The incorporation of ZSM-22 zeolite material as additives into the PES polymer matrix has the prospective advantage of combining both the zeolite and polymer features while overcoming the limitations associated with both materials. This work investigated the influence of the nature of the silica precursor on ZSM-22 zeolite hydrothermally synthesised using colloidal (C60) and fumed (C60) silica to Si/Al of 60. The successful synthesis of the highly crystalline zeolitic materials was confirmed through XRD, FTIR, and SEM with EDX. The ZSM-22 additives were directly dispersed into a PES polymeric matrix to form a casting solution for the preparation of the ZSM-22/PES selective substrate layers via a phase inversion method for salts rejection. The polymeric PES was selected as an organic network in which the content of the ZSM-22 zeolite (ranging between 0 and 1.0 wt.%), was obtained and characterised by XRD, FTIR, and SEM analysis, as well as water contact angle (WCA) measurement and dead-end filtration cell. The phase inversion preparation method has induced the resulting ZSM-22/PES NF substrates anisotropy, as attributed to a high water flux to the above 700 L·m−2·h−1; high selectivity and rejection of salts to above 80% is revealed by the obtained results. The materials also exhibited improved antifouling behavior to above 70% flux recovery ratios. As such, the nature of the silica precursor influences ZSM-22 zeolite synthesis as a potential additive in the PES polymer matrix and led to the enhanced performance of the pure PES ultrafiltration membrane

Advances in the extraction, classification, modification, emerging and advanced applications of crystalline cellulose: A review

The distinctive characteristics and versatile applications of crystalline cellulose have garnered considerable interest in the 21st century, making it an emerging and promising material. This review highlights the current state of the art in crystalline cellulose research, with a particular focus on its emerging and advanced applications. The sources, extraction techniques, classification, and modification of crystalline cellulose were also discussed. It was observed that plant biomass is the most utilized precursor for crystalline cellulose synthesis. Findings also revealed that crystalline cellulose-based materials have significant potential for a wide range of applications, including 3D printing, photonics, catalysis, energy storage and generation, electronics, biomedicine, and pharmaceuticals, amongst others. However, there are also several challenges associated with the adoption of crystalline cellulose-based materials. These include issues related to cost, scalability, recycling, and waste management. This review highlights the need for continued investment in research and development to optimize the properties and manufacturing processes of these materials, as well as for education and outreach to increase awareness and promote their adoption. In summary, this review emphasizes how crystalline cellulose has the potential to tackle critical global issues, including resource depletion and climate change. It also presents prospects for future research and opportunities to adopt these materials