ABSTRACT This study aims to unambiguously resolve the controversy over the reaction mechanism (second‐order vs. autocatalytic) of the esterification between propionic anhydride (PAh) and 2‐butanol (2‐B) without concentrated sulfuric acid catalysis. A core strategy coupling reaction calorimetry (RC1e) with gas chromatography (GC) was employed. Isothermal experiments with different initial additions of product propionic acid (PAc) qualitatively confirmed the absence of autocatalytic behavior for this reaction, supporting the second‐order kinetic model. Kinetic parameters were acquired by fitting six sets of isothermal SBR experimental data using both second‐order and autocatalytic models. Comparative analysis of fitting performance (SSE, RMSE, R 2 , AIC and BIC), together with statistical validation (parameter correlation and residual diagnostics), further quantitatively demonstrated that the second‐order model was statistically superior to the autocatalytic model, thereby resolving the long‐standing controversy in the literature. The fitted kinetic parameters were validated via independent isoperibolic SBR, isothermal and isoperibolic BR experiments, as well as literature data, and the results showed that these parameters enabled accurate prediction of PAh conversion, temperature, and heat flow profiles across different operational modes. Key quantitative results are as follows: The fitted molar reaction enthalpy ΔHr, rate constant k ( T R ) ( T R = 80°C), and activation energy E are –63.6 kJ·mol − 1 , (8.18 ± 0.03) × 10 − 5 L·mol − 1 ·s − 1 , and 68.01 ± 0.44 kJ·mol − 1 , respectively. The derived kinetic parameters are slightly lower than literature results, owing to the superior heat transfer of the Hastelloy reactor, which provides more intrinsic kinetic data compared with conventional glass reactors.
ABSTRACT Micellar catalysis has evolved from a classical colloidal phenomenon into a sophisticated supramolecular strategy for manipulating chemical reactivity through nanoscale interfacial engineering. While early models attributed catalytic acceleration primarily to reactant concentration within confined pseudophases, contemporary investigations reveal that reactivity is governed by a complex interplay of counterion binding, interfacial hydration, and dynamic morphological transitions. This review provides a critical appraisal of the mechanistic foundations of ion selectivity in micellar catalysis, with particular emphasis on cationic surfactant systems and the seminal semi‐empirical kinetic frameworks. By synthesizing advanced experimental evidence from cryo‐TEM, rheo‐SAXS, and kinetic modeling, we elucidate how hydrophobic and aromatic counterions dictate micellar restructuring and catalytic pathway modulation via hydrophobic insertion and π‐cation interactions. Furthermore, we address current bottlenecks in scalability, reproducibility, and toxicity, while highlighting emerging frontiers such as machine learning‐guided surfactant design, stimuli‐responsive assemblies, and green nanoreactors. Ultimately, this review establishes ion selectivity as a foundational principle for modern colloid chemistry, offering a comprehensive blueprint for the design of precision‐controlled, sustainable supramolecular catalysts.
This study explores the potential of biosorption process towards the bioremediation of third-generation broad spectrum antibiotic Cefpodoxime proxetil (CP) using agricultural waste. This research focuses on using the fruit peel of Dimocarpus longan as an efficient and eco-friendly biosorbent. Furthermore, Acidified longan peel (ALP) powder has altered physicochemical properties of the Longan Peel (LP) with enhanced bio adsorption capacity for CP from 43% (8.60 mg/g) to 88% which implies that 17.62 mg/g of the antibiotic adsorbed on the ALP. The conditions at which the acidification was conducted for raw longan peel powder was with 0.5N HCl for overnight on agitation at 120 rpm on shaker. This chemical modification of the Longan peel improved adsorption process with a spike in the percentage of removal of antibiotic from 43% to 88%. This highest adsorption was obtained under the optimized conditions of agitation at 120 rpm, pH 3, concentration of antibiotic (100 mg/L), adsorbent dosage of 4% and with contact time of 5 h. The kinetic studies revealed that the adsorption mechanism follows a pseudo second order kinetics with an R 2 value of 0.89627 implying the process to be chemisorption associated with chemical bonds like pi-pi stacking, hydrogen bonding, hydrophobic-hydrophobic interactions, and electrostatic interactions. Equilibrium studies data shows that the process to closely fit into the Redlich-Peterson isotherm model with R 2 value of 0.90667 which indicates deviation from standard Langmuir and Freundlich models. The process follows both monolayer adsorption and multilayer adsorption. The Acidified Adsorbed Longan Peel (AALP) and the Acidified Unadsorbed Longan Peel (AULP) were characterized using FTIR, SEM-EDX, Zeta Potential, BET and XRD to analyze the structural and surface morphological changes before and after adsorption. Studies unrevealing the potential of agricultural biowaste as a promising and sustainable alternative towards circular economy.
Cadmium contamination poses a critical threat to environmental and human health, while the invasive spread of Phragmites australis disrupts native ecosystems worldwide. This study converts P. australis biomass into sustainable lemon-activated carbon (SPLAC) using natural lemon extract as a renewable green activating agent instead of conventional corrosive chemicals. SPLAC prepared at 700 degrees C exhibited abundant oxygen-containing functional groups (-COOH, -OH, and C & boxH;O), a mesoporous structure, and a BET surface area of 76.69 m(2)& centerdot;g(-)(1). Comparison with non-activated carbon (SP700) confirmed that lemon activation significantly enhanced Cd(II) removal (91.3% vs. 76.0%) and Langmuir adsorption capacity (61.24 vs. 43.47 mg & centerdot;g(-)(1)). Under the optimum conditions (initial pH 6, 55 degrees C, and 90 min), SPLAC achieved 91.3% Cd(II) removal. Adsorption followed the Langmuir isotherm (Qmax & boxH; 61.24 mg & centerdot;g(-)(1), R-2 & boxH; 0.9942) and pseudo-second-order kinetics (R-2 > 0.99), while the Weber-Morris model revealed a three-stage diffusion process involving film diffusion, intraparticle diffusion, and equilibrium adsorption. Combined FTIR, point-of-zero-charge (pHpzc & boxH; 7.92), ionic-strength, diffusion, and thermodynamic analyses demonstrated that Cd(II) uptake is governed predominantly by inner-sphere surface complexation, supported by ion exchange, whereas electrostatic interactions play only a secondary role. Thermodynamic analysis confirmed that the adsorption process was spontaneous (Delta G degrees < 0), endothermic (Delta H degrees & boxH; +12.29 kJ & centerdot;mol(-)(1)), and entropy-driven (Delta S degrees > 0). SPLAC maintained a Cd(II) removal efficiency of 74.0 +/- 1.3% after three regeneration cycles, with only 2.3% mass loss. These findings demonstrate that lemon-activated carbon derived from invasive biomass provides a regenerable, low-cost, and environmentally sustainable adsorbent for Cd(II) removal, supporting both circular-economy principles and green chemistry
Methylene blue (mb) is a synthetic dye used in many industries due to its unique color and characteristics. Due to its usage on a large scale substantial amounts of this dye are constantly released into different environmental compartments, which have posed severe threats to the environment. As effective adsorbent has been developed for the remediation of this dye in the current study using Date Seed Biomass Precursors (DBP); a green biosorbent having low cost and is eco-friendly that will pose no hazardous effects on the environment. The DBP was characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. SEM studies reveal that the surface of DBP is rough and porous whereas the FTIR revealed the presence of various functional groups responsible for the electrostatic interactions and ion exchange, and so forth as required for the removal of mb from aqueous media. The pHPZC of the DBP was determined using the Drift Method. The pHPZC was found to be 6. The optimum conditions for the remediation of mb were; pH = 8, and DBP dosage = 0.5 g/50 mL of mb solution at 298 K. According to the validation of kinetic data, pseudo 2nd order kinetics has fully explained the kinetics data with R 2 value of 0.997 and Qcalculated value of 3.87 mgg-1, while, the adsorption isotherm data of the mb was well expressed by the Langmuir model with the value of R 2 = 0.9923 and qm = 12.106 mgg-1. The Qcalculated from kinetics adsorption data and isotherm adsorption data was approximately equal to the QExperimental data of kinetics and adsorption data. Various thermodynamic parameters were calculated using Vant Hoff equation. The values of Gibbs free energy (Delta G circle) at tested temperatures from low to high were: -5.035 kJ/mol, -6.430 kJ/mol, -6.715 kJ/mol and -7.330 kJ/mol, the indicative requirements of spontaneous and feasible process. The positive value of entropy (Delta S circle) 123 kJ/mol confirmed the high affinity and structural compatibility of DBP and mb. The loaded adsorbent was regenerated and used for five cycles still had appreciable adsorption capacity. The fabricated biosorbent could be a greener sorbent with appreciable adsorption capacity and could be a best alternative to commercial activated carbon, however, further validation against other pollutants would help in strengthening the present study claim.
