Predictive thermodynamic modeling and experimental measurements on solubility of active pharmaceutical ingredient: Lornoxicam case study

Low solubility of some drugs in water is a challenging issue in pharmaceutical area which should be properly addressed to achieve drugs with high efficacy. The solubility of an active pharmaceutical ingredient (API) namely lornoxicam in carbon dioxide at supercritical conditions is measured in this work. The experimental measurements were carried out utilizing gravimetric technique, at the pressure and temperature intervals of 120–400 bar and 308–338 K, respectively. The determined mole fraction of solubility revealed that the solubility of this drug is between 3.08 × 10 to 3.54 × 10 . It was perceived that pressure has strong and direct effect on the solubility in which the solubility increases with rising system's pressure. Unlike pressure, the effect of temperature depends on the cross-over point which is between 160 and 200 bar for lornoxicam. Above the cross-over point, the solubility indicated direct relationship with temperature due to improvement of sublimation pressure which is the dominant mechanism. In addition to the experimental measurements, the solubility data are correlated using five semi-empirical correlations namely Mendez-Santiago-Teja (MST), Bartle et al., Chrastil, Kumar and Johnston (KJ) and Garlapati & Madras with minimum average absolute relative deviation (AARD %) 6.2% for Bartle et al. model. −5 −

A water-stable functionalized NiCo-LDH/MOF nanocomposite: green synthesis, characterization, and its environmental application for heavy metals adsorption

Removal of toxic heavy metals from aquatic environments has become a major concern due to environmental problems and the potential hazards and risks posed by them. Nowadays, the adsorption method as one of the most effective methods of removing pollutants has attracted increasing attention among chemists and environmental researchers. However, one of the challenges is to design and develop more effective adsorbents as well as to prepare them via greener and safer approaches. In line with these goals, a functionalized Ni50Co50-layered double hydroxide/UiO-66- (Zr)-(COOH)2 nanocomposite (LDH/MOF NC) was prepared via a facile and ‘‘green‘‘ synthesis protocol and used as an effective adsorbent for removal of mercury and nickel cations from aqueous media. UiO-66-(Zr)-(COOH)2 nanoparticles were in situ grown homogeneously over the surface of the functionalized two-dimensional ultrathin Ni50Co50-LDH sheets. A green organic-solvent-free route was used to prepare the LDH/MOF NC in which the water is used as a green solvent. The adsorption performance of LDH/MOF NC for removal of Hg(II) and Ni(II) cations was studied and the influence of some experimental factors, such as solution pH, initial metal concentration, and contact time, on the adsorption process were investigated. The theoretical maximum adsorption capacities based on the Langmuir isotherm were found to be 509.8 mg g 1 and 441.0 mg g 1 for Hg(II) and Ni(II), respectively, under constant conditions. We believe that the facile and ‘‘green” synthesis method used in this work can be a starting point for the fabrication and development of similar composite materials for future works, especially for use in adsorption, extraction, catalysis, and drug delivery applications

Using static method to measure tolmetin solubility at different pressures and temperatures in supercritical carbon dioxide

Tolmetin is a non-steroidal anti-infammatory drug being used to decrease the level of hormones which are the reasons for pain, swelling, tiredness, and stifness for osteoarthritis and rheumatoid arthritis cases. We evaluated its solubility in supercritical carbon dioxide (SC-CO2) with the aim of drug nanonization, considering temperature and pressure variations between 120 and 400 bar and 308– 338 K, in the experiments. In this way, a PVT solubility cell based on static solubility approach coupled with a simple gravimetric procedure was utilized to evaluate the solubility of tolmetin. The solubility values between 5.00 × 10−5 and 2.59 × 10−3 mol fraction were obtained for tolmetin depending on the pressure and temperature of the cell. The measured data demonstrated a direct correlation between pressure and solubility of tolmetin, while the effect of temperature was a dual effect depending on the crossover pressure (160 bar). The calculated solubility data were modeled using several semi-empirical correlations, and the ftting parameters were calculated using the experimental data via appropriate optimization method. The correlated solubility data revealed that the KJ model was the most accurate one with an average absolute relative deviation percent (AARD%) of 6.9. Moreover, the carried out self-consistency analysis utilizing these correlations illustrated great potential of these models to extrapolate the solubility of tolmetin beyond the measured conditions

A new insight into catalytic ozonation of sulfasalazine antibiotic by plasma-treated limonite nanostructures: Experimental, modeling and mechanism

This study investigates the application of novel natural and plasma-treated iron (III) oxide-hydroxide (limonite) catalysts on the degradation/mineralization of sulfasalazine (SSZ) antibiotic by ozone-based advanced oxidation processes (AOPs). The limonite nanostructures were prepared by non-precursor, environmentally friendly, and fast glow discharge plasma technology under oxygen (PTL/O2) and oxygen/argon (PTL/O2/Ar) gaseous atmosphere. The characteristic analysis demonstrated enhanced surface area, morphology, active surface sites, and physical stability after the plasma treatment. It was found that SSZ degradation/mineralization was effectively improved (36%) in the heterogeneous catalytic ozonation process (HCOP) using PTL/O2/Ar compared to sole ozonation. Modeling and optimization of SSZ degradation through the central composite design (CCD) and artificial neural network (ANN, topology of 4:7:1) showed that complete SSZ degradation can be achieved at the optimized condition (initial pH = 7, ozone concentration = 15 mg L-1, catalyst loading = 1.5 g L-1 and treatment time = 50 min). The effect of organic and inorganic salts confirmed that the reactive oxygen species, mainly hydroxyl radicals, were responsible for SSZ degradation by HCOP. The main intermediates during SSZ oxidation were identified. The toxicity of SSZ solution and electrical energy consumption were decreased using PTL/O2/Ar nanocatalysts in HCOP. Economic studies demonstrated 46% reduction in energy consumption of HCOP using PTL/O2/Ar compared to NL samples. For the first time, molecular dynamics simulation was applied to provide a deeper insight into the adsorption mechanisms of SSZ and ozone onto limonite surface (1 1 1) during HCOP

Synthesis of multi‑organo‑functionalized fibrous silica KCC‑1 for highly efficient adsorption of acid fuchsine and acid orange II from aqueous solution

Multi-functionalized fibrous silica KCC-1 (MF-KCC-1) bearing amine, tetrasulfide, and thiol groups was synthesized via a post-functionalization method and fully characterized by several methods such as FTIR, FESEM, EDX-Mapping, TEM, and N2 adsorption–desorption techniques. Due to abundant surface functional groups, accessible active adsorption sites, high surface area (572 m2 g−1), large pore volume (0.98 cm3 g−1), and unique fibrous structure, mesoporous MF-KCC-1 was used as a potential adsorbent for the uptake of acid fuchsine (AF) and acid orange II (AO) from water. Different adsorption factors such as pH of the dye solution, the amount of adsorbent, initial dye concentration, and contact time, affecting the uptake process were optimized and isotherm and kinetic studies were conducted to find the possible mechanism involved in the process. For both AF and AO dyes, the Langmuir isotherm model and the PFO kinetic model show the most agreement with the experimental data. According to the Langmuir isotherm, the calculated maximum adsorption capacity for AF and AO were found to be 574.5 mg g−1 and 605.9 mg g−1, respectively, surpassing most adsorption capacities reported until now which is indicative of the high potential of mesoporous MF-KCC-1 as an adsorbent for removal applications

Novel bimodal micro-mesoporous Ni50Co50-LDH/ UiO-66-NH2 nanocomposite for Tl(I) adsorption

Ni50Co50-layered double hydroxide/UiO-66-NH2 metal–organic framework nanocomposite (Ni50Co50-LDH/UiO-66-NH2 NC) was synthesized through a facile ultrasonic-assisted hydrothermal method. UiO-66-NH2 MOF nanocrystals were in situ grown on the surface of ultrathin 2-dimensional functionalized Ni50Co50-LDH nanosheets. Using this method, a uniform nanocomposite architecture was obtained by uniformly distributing MOF nanocrystals on Ni50Co50-LDH. The synthesized LDH/MOF NC possesses essential properties of potential nano adsorbent such as high surface area (907 m2 g 1 ), large pore volume (0.91 cm3 g1), bimodal micro mesoporous structure, and chemical functionality. Accordingly, Ni50Co50-LDH/UiO-66-NH2 NC was used as an adsorbent for the uptake of toxic thallium (I) from water. Isotherm, thermodynamic, and kinetic studies were conducted to gain a better insight into the adsorption mechanism (s) involved in the removal process. Langmuir and pseudo-first-order models present a better fit to the isotherm and kinetic data, respectively, and the maximum Langmuir adsorption capacity was found to be 601.3 mg g 1 after non-linear fitting analysis (pH=7.0, solution volume=30 mL, initial thallium (I) concentration=50 mg L–1, contact time=15 min, solution temperature=293 K

A novel and facile green synthesis method to prepare LDH/MOF nanocomposite for removal of Cd(II) and Pb(II)

To date, many nanoadsorbents have been developed and used to eliminate heavy metal contamination, however, one of the challenges ahead is the preparation of adsorbents from processes in which toxic organic solvents are used in the least possible amount. Herein, we have developed a new carboxylic acid-functionalized layered double hydroxide/metal–organic framework nanocomposite (LDH/MOF NC) using a simple, efective, and green in situ method. UiO-66-(Zr)- (COOH)2 MOF nanocrystals were grown uniformly over the whole surface of COOH-functionalized Ni50Co50-LDH ultrathin nanosheets in a green water system under a normal solvothermal condition at 100 °C. The synthesized LDH/MOF NC was used as a potential adsorbent for removal of toxic Cd(II) and Pb(II) from water and the infuence of important factors on the adsorption process was monitored. Various non-linear isotherm and kinetic models were used to fnd plausible mechanisms involved in the adsorption, and it was found that the Langmuir and pseudo-frst-order models show the best agreement with isotherm and kinetic data, respectively. The calculated maximum adsorption capacities of Cd(II) and Pb(II) by the LDH/MOF NC were found to be 415.3 and 301.4 mg g−1, respectively, based on the Langmuir model (pH= 5.0, adsorbent dose = 0.02 g, solution volume = 20 mL, contact time = 120 min, temperature= 25 ℃, shaking speed 200 rpm)