Humic acid (HA) is a complex organic compound made up of small molecules. A variety of raw materials are used to manufacture HA, due to which the structure and composition of HA vary widely. In this study, nitric acid oxidation of two coal samples from Lakhra (Pakistan) was followed by HA extraction using 2.5, 3.0 and 3.5% KOH solutions. The impact of different operating parameters such as; the effect of KOH concentrations, KOH-coal proportion, extraction time and pH range influencing the HA extraction efficiency was optimally investigated. Commercial HA applications possess numerous challenges, including valuable applications and sub-optimal extraction techniques. A significant limitation of conventional experimental methods is that they can only investigate one component at a time. It is necessary to improve the current processing conditions, this can only be achieved by modelling and optimization of the process conditions to meet market demands. A comprehensive evaluation and prediction of HA extraction using Response Surface Methodology (RSM) are also being reported for the first time in this study. The maximum HA extraction efficiency of 89.32% and 87.04% for coal samples 1 and 2 respectively was achieved with the lowest possible pH of 1.09 (coal sample 1) and 1(coal sample 2), which is remarkably lower as compared to those reported in the literature for conventional alkaline extraction process. The model was evaluated for two coal samples through the coefficient of determination (R2), Root Means Square Error (RMSE), and Mean Average Error (MEE). The results of RSM for coal sample 1 (R2 = 0.9795, RMSE = 4.784) and coal sample 2 (R2 = 0.9758, RMSE = 4.907) showed that the model is well suited for HA extraction efficiency predictions. The derived humic acid from lignite coal was analyzed using elemental analysis, UV-Visible spectrophotometry and Fourier-transformed infrared (FTIR) spectroscopy techniques. Scanning Electron Microscopy (SEM) was applied to analyze the morphological modifications of the extracted HA after treatment with 3.5% KOH solution. For agricultural objectives, such as soil enrichment, enhancing plant growth conditions, and creating green energy solutions, this acquired HA can be made bioactive. This study not only establishes a basis for research into the optimized extraction of HA from lignite coal, but it also creates a new avenue for the efficient and clean use of lignite.
Water bodies are being polluted rapidly by disposal of toxic chemicals with their huge entrance into drinking water supply chain. Among these pollutants, heavy metal ions (HMIs) are the most challenging one due to their non-biodegradability, toxicity, and ability to biologically hoard in ecological systems, thus posing a foremost danger to human health. This can be addressed by robust, sensitive, selective, and reliable sensing of metal ions which can be achieved by Metal organic frameworks (MOF) based electrochemical sensors. In the present era, MOFs have caught greater interest in a variety of applications including sensing of hazardous pollutants such as heavy metal ions. So, in this review article, types, synthesis and working mechanism of MOF based sensors is explained to give general overview with updated literature. First time, detailed study is done for sensing of metal ions such as chromium, mercury, zinc, copper, manganese, palladium, lead, iron, cadmium and lanthanide by MOFs based electrochemical sensors. The use of MOFs as electrochemical sensors has attractive success story along with some challenges of the area. Considering these challenges, we attempted to highlight the milestone achieved and shortcomings along with future prospective of the MOFs for employing it in electrochemical sensing devices for HMIs. Finally, challenges and future prospects have been discussed to promote the development of MOFs-based sensors in future.
The production of synthetic drugs is considered a huge milestone in the healthcare sector, transforming the overall health, aging, and lifestyle of the general population. Due to the surge in production and consumption, pharmaceutical drugs have emerged as potential environmental pollutants that are toxic with low biodegradability. Traditional chromatographic techniques in practice are time-consuming and expensive, despite good precision. Alternatively, electroanalytical techniques are recently identified to be selective, rapid, sensitive, and easier for drug detection. Metal-organic frameworks (MOFs) are known for their intrinsic porous nature, high surface area, and diversity in structural design that provides credible drug-sensing capacities. Long-term reusability and maintaining chemo-structural integrity are major challenges that are countered by ligand-metal combinations, optimization of synthetic conditions, functionalization, and direct MOFs growth over the electrode surface. Moreover, chemical instability and lower conductivities limited the mass commercialization of MOF-based materials in the fields of biosensing, imaging, drug release, therapeutics, and clinical diagnostics. This review is dedicated to analyzing the various combinations of MOFs used for electrochemical detection of pharmaceutical drugs, comprising antibiotics, analgesics, anticancer, antituberculosis, and veterinary drugs. Furthermore, the relationship between the composition, morphology and structural properties of MOFs with their detection capabilities for each drug species is elucidated.
Synthesis of 2,5-bisarylthiophenes was accomplished by sequential Suzuki cross coupling reaction of 2-bromo-5-chloro thiophenes. Density functional theory (DFT) studies were carried out at the B3LYP/6-31G(d, p) level of theory to compare the geometric parameters of 2,5-bisarylthiophenes with those from X-ray diffraction results. The synthesized compounds are screened for in vitro bacteria scavenging abilities. At the concentration of 50 and 100 μg/mL, compounds 2b, 2c, 2d, 3c, and 3f with IC50-values of 51.4, 52.10, 58.0, 56.2, and 56.5 μg/mL respectively, were found most potent against E. coli. Among all the synthesized compounds 2a, 2d, 3c, and 3e with the least values of IC50 77, 76.26, 79.13 μg/mL respectively showed significant antioxidant activities. Almost all of the compounds showed good antibacterial activity against Escherichia coli, whereas 2-chloro-5-(4-methoxyphenyl) thiophene (2b) was found most active among all synthesized compound with an IC50 value of 51.4 μg/mL. All of the synthesized compounds were screened for nitric oxide scavenging activity as well. Frontier molecular orbitals (FMOs) and molecular electrostatic potentials of the target compounds were also studied theoretically to account for their relative reactivity.
A variety of imine derivatives have been synthesized via Suzuki cross coupling of N-(4-bromophenyl)-1-(3-bromothiophen-2-yl)methanimine with various arylboronic acids in moderate to good yields (58-72%). A wide range of electron donating and withdrawing functional groups were well tolerated in reaction conditions. To explore the structural properties, Density functional theory (DFT) investigations on all synthesized molecules (3a-3i) were performed. Conceptual DFT reactivity descriptors and molecular electrostatic potential analyses were performed by using B3LYP/6-31G(d,p) method to explore the reactivity and reacting sites of all derivatives (3a-3i).