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This study investigates the pyrolysis behaviour of peanut shell waste (PNS) and the resulting biochar in the presence of calcium oxide (CaO). The pyrolysis test of PNS was carried out in a fixed-bed vertical reactor at 600 °C, with a heating rate of 5 °C min⁻¹ and a holding time of 30 min. Catalytic pyrolysis experiments were conducted using CaO at 5 and 10 wt.%, respectively. The kinetic analysis was performed using the Vyazovkin method (VZ) at dynamic heating rates of 10, 20, and 30 °C min⁻¹, revealing that activation energy varied with the degree of conversion. The physicochemical characterisation of PNS confirmed its suitability as an efficient pyrolysis feedstock. TGA-FTIR analysis demonstrated that CaO addition significantly reduced emissions of CO, CO₂, ether, and carbonyl compounds. Further, the addition of CaO increased biochar yield by approximately 6.5 % due to enhanced carbonation reactions. The untreated biochar exhibited a surface area of 113.40 m² g⁻¹, while biochar was produced with 5 and 10 wt.% CaO had reduced surface areas of 78.18 m² g⁻¹ and 51.55 m² g⁻¹, respectively. SEM analysis revealed altered surface morphology and reduced pore sizes caused by swelling and melting. FTIR analysis indicated a decrease in oxygenated functional groups in biochar with CaO addition. Furthermore, elemental and EDS analyses revealed a reduction in carbon content and an increase in oxygen content. Additionally, CaO incorporation increased biochar bulk density but reduced its higher heating value (HHV) due to changes in elemental composition. Finally, Raman spectroscopy indicated a decline in graphitic content with the addition of CaO.

This study investigates the pyrolysis kinetics behaviour and temperature effects on biochar yield and properties during pyrolysis. The kinetic study of biomass was performed using a thermogravimetric analyser at dynamic heating rates (10, 30, and 50 °C min−1) in an inert atmosphere. The kinetic parameters were estimated using Kissinger-Akahira-Sunose (KAS), Distributed Activation Energy Model (DAEM), and Vyazovkin model (VZ). The pyrolysis experiment was performed in a stainless steel semi-batch reactor at 400, 600, and 900 °C, 10 oC min-1 heating rate, 45 min holding time and 100 mL min−1 nitrogen gas flow rate. The produced biochar was characterised using proximate analysis, ultimate analysis, heating value, bulk density, BET surface area analyser, TGA, FTIR, and FE-SEM analysis. The physicochemical results support the candidacy of biomass for biochar and fuel production. Further, the kinetic analysis of MWS using KAS, DAEM, and VZ was found to be 233.39, 238.11, and 224.74 kJ mol−1, respectively. The experimental results reveal that higher temperatures (600 and 900 °C) generally reduce biochar yield (19 %) due to increased devolatilization but enhance the biochar's surface area (17 %) and carbon content (4.84 %). The characterisation results of biochar confirmed higher carbon content (76.02 wt. %), HHV (36.97 MJ kg−1), and significant oxygen content (22.01 %) at 900 °C. Also, the thermal profile and surface morphology of the biochar suggest that biochar derived at 600 and 900 °C can be used for carbon-based applications, whereas biochar derived at 400 °C can be used for soil amendment or fertiliser applications.

Chitosan (CS) is a naturally occurring polycationic linear amino polysaccharide produced commonly through the deacetylation of chitin. This study describes the synthesis of Chitosan (CS) modified with sodium tripolyphosphate (STPP) using an efficient coated Cross-linked method. The study investigated the efficacy of chitosan-tripolyphosphate (CS-STPP) nanoparticles for the efficient adsorption of As (III) ions from a wastewater solution. The effect of initial Arsenic (III) ion concentration, solution pH, and temperature on adsorption efficiency was thoroughly investigated. The highest adsorption capacity of CS-STPP nano adsorbents for As (III) was found to be 39.8 mg/g and 39.6 mg/g, respectively, at pH 5.5, and a temperature of 30 °C. The FESEM, SEM, HRTEM, XRD, FTIR, DLS, and TGA results indicated that the adsorption process of As (III) was chemically dominating. As (III) Determine with the anodic linear sweep voltammetry 797 VA Computrace (Metrohm). The Langmuir parameters of 40.9 mg/g and 1000 L/mg were found for maximum adsorption capacity, which indicated monolayer adsorption on a homogeneous site, Freundlich isotherm is applicable for multilayer adsorption onto heterogeneous sites. The thermodynamic study showed that the adsorption of As (III) by CS-STPP was spontaneous, feasible, and exothermic at temperatures ranging from 30 °C to 50 °C. The kinetic model indicated that the adsorption processes persist well to the pseudo-second-order kinetics model. The reaction is suitable for a pseudo-second-order model, it indicates an inclination for chemisorption. Adsorption-desorption processes are determined efficiency of bio adsorbent by several physicochemical cycles. All results indicate that the prepared CS-STPP nanoparticles might be considered a cost-effective adsorbent for removing As (III) from wastewater.

Ammonium salt vanadium precipitation process has excellent performance in industrial production, but its shortcomings such as high cost and environmental impact are not conducive to sustainable development. In this paper, ethylenediamine was selected as the precipitant, and vanadate was precipitated from acidic simulated vanadium-rich solutions by the ammonium salt precipitation process. The high purity V2O5 product was obtained after calcination. Under optimal conditions, the precipitation rate of vanadium reached 94.8 %, and the purity of vanadium was as high as 99.1 %. The vanadium precipitation product was hexamethyl ammonium, and the vanadium product was V2O5. It can be derived by the differential method that the reaction order was n = 2.4, the reaction rate equation was CV-1.4=kt+a, and the apparent activation energy was 27.8097 kJ/mol, which can be classified as the diffusion-controlled reaction. This innovative process enables a savings of 5050 yuan per ton of V2O5. On this basis, a complete V2O5 production process with zero waste discharge was designed.

Purifying water for diverse uses is vital, but concerns lie with the sustainability and accessibility of purification materials. As such, this study converted readily available water treatment plant sludge (WTPS) into activated adsorbent for phosphate removal in wastewater. WTPS was activated via thermal activation at 300 °C temperature and chemical activation processes of 3 M acid concentration, 4 h activation time, and 75 °C activation temperature, and then characterized using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared, elemental analyzer, and differential scanning calorimetry. SEM and BET analyses revealed a highly porous adsorbent (279.2 m2/g) for efficient adsorption. On top of the activation process, preliminary experiments and numerical optimization using response surface methodology (RSM) were designed and conducted. Through optimizing conditions, it was found that 70 min of contact time, pH 3, 3 g/L adsorbent dose, and 30 mg/L initial phosphate concentration as optimal, yielding 83% removal efficiency. Furthermore, adsorption kinetics and isotherm models were examined and the second-order kinetics and Langmuir isotherm models indicated best fit. Notably, the activated sludge could be regenerated for three cycles before efficiency dropped below 70%. Thus, activated WTPS presents a promising, sustainable, and readily available adsorbent for phosphate removal in wastewater treatment. HIGHLIGHTS Water treatment plant sludge (WTPS) was activated through thermal activation and chemical activation.; The activated WTPS adsorbent has a surface area of 279.2 m2/g.; The activated WTPS showed an 83% removal efficiency.; The regeneration test indicated that the activated sludge can be used three times, repeatedly, before its efficacy falls below 70%.;

The presence of persistent organic compounds in wastewater poses significant challenges to both biotic community and natural environment, resulting in a severely adverse effect on the ecosystem. In view of the urgent scenarios, the removal of pollutants from wastewater effluent has a significant potential to restore ecological equilibrium and maintain the social value of sustainability. Among the various methods used for wastewater treatment, photocatalytic advanced oxidation processes have gained as a viable and promising alternative approach. The objective of this review paper is to provide a comprehensive exploration of the various photocatalytic materials used in wastewater treatment with potential scopes for future enhancements. Further, various factors affecting the removal of pollutants from wastewater are highlighted. In particular, the selection, design aspects and scaleup criteria of photocatalytic reactors could assist in the establishment of commercial scale process. This review stimulates research on the kinetic study in order to get a deeper understanding of the mechanisms involved in the formation of novel photo-catalyst materials. Thus, photo catalytic advanced oxidation process could become as a spectacular treatment method for wastewater.

Coffee is the most essential drink today, aside from water, the high consumption of coffee and the byproducts of its soluble industries such as spent coffee grounds can have a negative effect on the environment as a source of toxic organic compounds. Therefore, caffeine removal from the spent coffee ground can be applied as a method to limit the effect of its production on the environment. The aim of this study is to determine the kinetics and thermodynamics parameters and develop models for both processes based on the process parameters by using traditional solid-liquid extraction and Ultrasound-assisted extraction methods. The processes were performed at a temperature range of 25 to 55 °C for traditional and ultrasound baths, and experimental time ranged from 5- 60 min. The results demonstrated that under the above conditions, the extraction process applies to the pseudo-first-order reaction, where the rate constant K value increases with temperature. The transition state parameters were also discussed where these parameters indicated that the system of the process exhibited an activated complex formation state resulting in a thermodynamically unfavorable process, and the thermodynamic parameters at the equilibrium state were also evaluated in terms of the obtained yield percentage. The results also showed that the ultrasound-assisted bath process showed a spontaneous behavior at temperatures of 45 °C and 55 °C with D°G of -1192.9703 and - 2725.25 J/mole. On the other hand, for the traditional method, the extraction process was approaching a spontaneous behavior with the temperature increasing where at 25 °C the D°G value was 10379.944 J and at a temperature of 55 °C it reached 8004.26 J/mole.

In the ozonation process, the phenol degradation in wastewater undergoes a low mass transfer mechanism. In this study, ozonized packed bubble column reactor was designed and constructed to remove phenol. The reactor’s inner diameter and height were 150 and 8 cm, respectively. The packing height was kept constant at 1 m in accordance with the reactor hydrodynamics. The gas distributor was designed with 55 holes of 0.5 mm. The phenol removal efficiency was evaluated at ozone concentrations of 10, 15, and 20 mg/L, contact times of 15, 30, 45, 60, 75, 90, 105, and 120 min, and phenol concentrations of 3, 6, 9, 12, and 15 mg/L. The results indicated that the highest phenol removal efficiency of 100% was achieved at 30 min in presence of packing. Moreover, the use of packing improved the contact between the gas and liquid, which significantly enhanced the phenol degradation. Actually, a thin film over a packing surface enhances the mass transfer. Also, it was found that the phenol is degraded into CO2 and H2O through a series of reaction steps. Additionally, a kinetic study of a first-order reaction provided an efficient estimation of reaction parameters with a correlation factor of 0.997.

The relevance of the study is caused by the need to develop new methods for the disposal of metal waste. This direction, with the participation of various intensifying influences, refers to resource-saving, technological, minimizing the volume of capital costs for raw materials, production and subsequent sales. Purpose: to study physical and chemical methods for alkaline and acid processing of aluminum waste in the field of ultrasound, consider the mechanisms of these processes, compare kinetic characteristics, identify the pros and cons of the methods, and, based on a comparative analysis, conclude which of the methods is the most effective. Objects: samples of aluminum waste in the form of plates and shavings. Methods: volumetry, sonochemical synthesis, evaluation and analysis of the kinetic curves of the process at different temperatures, X-ray phase analysis. Results. The analysis of kinetic curves, rate constants of processes at different temperatures, and orders of chemical reactions has been carried out. The values ​​of the activation energies of the target chemical reactions and the characteristics of the kinetic regions of the processes were compared with each other. Despite the long induction period, the kinetic potential of acid processing of aluminum waste turned out to be 2 times higher than that of alkaline processing at temperatures of 313–323 K. Ultrasonic radiation did not significantly affect this characteristic, although it reduced the induction effect by 2 times. The mechanisms of the ongoing sonochemical processes in these methods turned out to be very similar to each other, no fundamental differences were observed. The products obtained during chemical processing in the form of hydrogen, hydroxide, chloride and aluminum orthophosphate are currently in high demand in the energy, chemical and silicate industries, as well as in medicine.

The aim of this review is to understand the progress in waste material management through pyrolysis to produce eco-energy. The growing demand for energy, combined with the depletion of traditional fossil fuels and their contribution to environmental problems, has led to the search for waste-to-energy technologies in pursuit of carbon neutrality. While municipal residues are only part of the waste management problem, the impact of discarded plastics on the environment and landfills is significant. Plastics not only take centuries to decompose, but also seriously pollute the oceans. Pyrolysis is a thermochemical process that allows for the thermal decomposition of waste in the absence of oxygen. There are several types of pyrolytic reactors, including batch and continuous ones. Batch reactors are preferred to process polymeric waste, with studies highlighting the importance of optimizing parameters, i.e., type of feedstock, heating rate, and pyrolysis temperature. Moreover, the choice of reactor type can influence the yield and structure of the final compounds. Furthermore, various studies have highlighted the gas heating value obtained through waste pyrolysis and how the composition of the liquid fraction is influenced by the type of polyethylene used. Though scientific interest in pyrolysis is remarkable, as publications have increased in recent years, kinetics studies are scarce. Overall, pyrolysis is a promising technique for managing waste materials to produce energy. Ongoing research and development in this area offer significant potential for improving the sustainability of waste management systems.

The demand for lithium-ion batteries (LIBs) is driven by environmental concerns and market growth, particularly in the transportation sector. The EU’s push for net-zero emissions and the European Green Deal accentuates the role of battery technologies in sustainable energy supply. Organic acids, like gluconic acid, are explored for the eco-friendly leaching of valuable metals from spent batteries. This study investigates leaching kinetics using gluconic acid (hydrolyzed glucono-1.5-lacton), analyzing factors such as temperature, acid concentration, particle size, and reaction time. Results reveal the temperature’s influence on leaching efficiency for cobalt, nickel, and lithium. The mechanism for Co follows a surface chemical reaction model with an activation energy of 28.2 kJ·mol−1. Nickel, on the contrary, shows a diffusion-controlled regime and an activation energy of 70.1 kJ·mol−1. The reaction of leaching Ni and Co using gluconic acid was determined to be first-order. The process within this environmentally friendly alternative leaching agent shows great potential for sustainable metal recovery.

A new sol-gel method that employs cation exchange from an aqueous metal ion solution with H+ ions of granulated alginic acid was developed for synthesizing high-purity Y2O3 nanoparticles. In this study, the cation exchange kinetics of H+~Y3+ in aqueous solution were analyzed using on-line pH technology and off-line inductively coupled plasma-atomic emission spectrometry (ICP-AES) analysis. Pseudo 2nd-order models were utilized to evaluate the parameters of the kinetics, suggesting that the concentration of H+~Y3+ involved in the cation exchange reaction was 1:1.733. Further, a comprehensive understanding of the Y-ALG calcination process was developed using thermo-gravimetric analysis, along with results obtained from differential scanning calorimetry (TGA/DSC). A detailed analysis of the XRD Rietveld refinement plots revealed that the crystallite sizes of Y2O3 nanoparticles were about 4 nm (500 °C) and 15 nm (800 °C), respectively. Differential pulse voltammetry (DPV) was employed to investigate the electrochemical oxidation of catechol. The oxidation peak currents of catechol at Y2O3 (500 °C)/GCE and Y2O3 (800 °C)/GCE showed two stages linear function of concentration (2.0~20.0 × 10−6 mol/L, 20.0~60.0 × 10−6 mol/L). The results indicated that the detection limits were equal to 2.4 × 10−7 mol/L (Y2O3 (500 °C)/GCE) and 7.8 × 10−7 mol/L (Y2O3 (800 °C)/GCE). The study not only provided a method to synthesize metal oxide, but also proposed a promising on-line pH model to study cation exchange kinetics.

The relevance of the study is caused by the need to develop new methods for the disposal of metal waste. This direction, with the participation of various intensifying effects, refers to resource-saving, technological, minimizing the volume of capital costs for raw materials, production and subsequent sales. Purpose: to study the physical and chemical laws of aluminum waste acid processing in the field of ultrasound, propose a mechanism for this process, and, based on the established laws and the proposed mechanism, develop a method for aluminum waste acid processing to obtain reaction products that are in demand in the industry. Objects: samples of aluminum waste in the form of plates and shavings. Methods: volumetry, differential thermal analysis, evaluation and analysis of the kinetic curves of the process at different temperatures. Results. The kinetic curves were analyzed, the rate constants of the process at different temperatures were calculated, and the order of the chemical reaction was found. Based on the calculated activation energy of the process, a characteristic was given about the kinetic region of the process. The mass content of aluminum in the samples was found. According to the data obtained, exposure of the system to ultrasound contributed to an increase in the rate of the chemical process by 90 % at 303 K; by 5 % at 313 K. The process itself began within 10...30 seconds and completed within a few minutes, which confirms the possibility of recycling aluminum waste using acid solutions at low temperatures. The resulting hydrogen can be used in hydrogen energy, since it is the only gaseous product of the reaction, which eliminates the need for its purification before transportation. The aluminum chloride solution synthesized during the reaction can be used in wastewater treatment, wood processing, production of antiperspirants, as well as precipitated aluminum phosphate and used in the ceramic industry.

This study is aimed to model and optimize the decolorization of reactive black 5 (RB5) dye using Bacillus albus DD1. The response surface methodology (RSM) along with rotatable central composite design (rCCD) is used to optimize the response, % decolorization with four input variables: (i) pH (5–9), initial dye concentration (50–500 ppm), the composition of yeast extract as nitrogen source (0.2–1%) and amount of bacterial inoculum (5–25% v/v). The % decolorization is predicted to be ≈ 98% at the optimized condition (pH = 7.6, dye concentration = 200 ppm, bacterial inoculum = 20 v/v% and yeast extract = 0.4%). Furthermore, the kinetics and thermodynamics of RB5 degradation are also determined. The kinetic order of biodegradation of RB5 is found to follow first-order kinetics with a kinetic rate constant = 0.0384. The activation energy, Ea and frequency factor, A values are calculated as 34.46 kJ/mol and 24,343 (1/Day). A thermodynamic study is also carried out at different temperatures (298 K, 308 K, 310 K, 313 K, and 318 K) using optimized conditions. The values of the and ΔS are found to be +30.79 kJ/mol, and −0.1 kJ/mol/K, respectively using the Eyring–Polanyi equation. The values of ΔG are also calculated at all temperatures. HIGHLIGHTS RSM with rCCD is employed to optimize the decolorization of reactive black 5 using a novel bacterial strain.; Optimization of process parameters such as pH, yeast extract as a co-substrate, amount of bacterial inoculum and initial dye concentration.; Under optimized conditions, 98% removal was achieved within 72 hr.; The values of kinetic and thermodynamic parameters k, Ea, A, ΔH and ΔS are estimated.;

Environmental pollution by organic pollutants because of population growth and industrial expansion is a global concern. Following this, the fabrication of single and efficient nanomaterials for pollution control is highly demanded. Under this study, highly efficient and stable copper oxide nanoparticles (CuO NPs) were synthesized through the green method using Moringa stenopetala seed extract. XRD, UV–vis, FT-IR, and SEM were applied to characterize the synthesized material. From XRD data, the average particle size was found to be 6.556 nm, and the nanoparticles are crystalline in nature. The formation of CuO NPs was demonstrated by FT-IR spectra of Cu–O in different bending vibration bands at 535 cm-1 and 1122 cm-1, as well as stretching vibration of Cu–O at 1640 cm-1. From UV–visible spectroscopic measurements, the energy band gap of greenly synthesized CuO NPs was found to be 1.73 eV. The SEM result shows that the nanoparticles' surfaces are rough, with some of the particles having spherically random orientation. The photodegradation efficiency of green synthesized CuO NPs photocatalyst was found to be 98.35% for Congo red at optimum experimental parameters (initial concentration, 25 mg/L; exposure time, 120 min; catalyst dose, 0.2 g; and pH, 5) and 95.4% for Alizarin Red S at optimum experimental parameters (catalyst dose, 0.25 g; initial concentration, 40 mg/L; exposure time, 120 min; and pH, 4.6). The COD values determined for the degraded product strongly support the complete mineralization of the dyes toward nontoxic materials. Reusability of the catalyst was investigated for five cycles, and the results clearly indicate the green synthesized CuO NPs are highly stable, can be used for several times, and are cost-effective as well. The degradation of Congo red and Alizarin red S on the surface of the CuO NPs follows the MBG kinetic model.

Background & aim: Today, the production of effluents containing medicinal compounds, including tetracyclines, is one of the major threats to the environment and endanger human health. Accordingly, the need for an efficient system to remove these compounds from aquatic environments is felt. Therefore, the aim of this study was to optimize and model the removal of tetracycline antibiotics using TiO2 / N / S nanocatalyst in the presence of visible light in aqueous solutions. Methods: In this experimental study conducted in 2019, nanocatalyst was synthesized by sol-gel method and then its characteristics were analyzed using SEM, XRD, EDS and BET analyzes. Secondly, by changing the reaction conditions such as changing the synthesized photocatalyst dose (0.1-2) g/l, antibiotic concentration (1-50) mg/l, reaction time (2-90) minutes and solution pH (2-10) and by visible light irradiation to remove tetracycline from synthetic effluent and the effect of these variables on process performance by response surface method and CCD method and determination of optimal conditions, investigation of reaction kinetics, tetracycline mineralization and photocatalyst performance in real wastewater treatment Was evaluated. Tetracycline was determined by reverse phase high performance liquid chromatography (HPLC). The collected data were analyzed using analysis of variance. Results: The software has proposed a complete quadratic model as the best model, based on ANOVA analysis of variance. The maximum removal efficiency of tetracycline with this process in optimal conditions with a pH of 6 and a time of 56 minutes and a concentration of tetracycline of 13 mg/l was the catalyst value of 1.2 g/l was 77%. The mineralization efficiency of tetracycline antibiotics under optimal conditions was 47% and the kinetic study presented that the data followed the quasi-first-order model well and eliminate the tetracycline process in the wastewater of Imam Sajjad Hospital of Yasuj by 72%. Conclusion: The results indicated that the efficiency of TiO2/N/S photocatalytic process exposed to visible light radiation in the removal of tetracycline due to lack of by-products as well as mineral end products (carbon dioxide and water) as a desirable process.

Adsorption of anthraquinone dye Acid Blue 111 by alumina-iron oxide doped particles prepared by sol-gel method from aqueous solutions was studied. The adsorbent morphology was revealed by FESEM and the crystallographic phase is analyzed by the XRD technique. The effect of adsorbate and adsorbent concentrations, pH value, type of adsorbent and thermodynamic parameters on dye removal by adsorption was studied. The change of dye concentration during the adsorbtion was followed using the UV-Visible spectrophotometer. The change of the adsorbent surface before and after dye removal was observed using the Fourier Transformation-infrared spectroscopy (FT-IR). The adsorption kinetics is in accordance with the pseudo-second-order kinetics model. The Langmuir and Freundlich adsorption isotherm models were used to describe the adsorption process. The thermodynamic study of dye adsorption proves the process is spontaneous with exothermic nature.

Eggshell-derived calcium oxide (CaO) materials were used as a heterogeneous base catalyst for biodiesel production from palm oil with methanol at room temperature (30±2 C). The physicochemical properties of the catalyst were characterized by TG-DTA, XRD, FT-IR, SEM-EDX, Hammett indicator method, BET surface area, and CO2-TPD. The comparison of catalytic performance transesterification reaction at the temperature of 65 C against room temperature was investigated. Kinetics of the reaction were studied following pseudo-first order with under the optimal condition with catalyst loading amount of 15 wt.%, methanol to oil molar ratio of 15:1 and 10% v/v of the co-solvent in methanol. Under the optimal reaction conditions, the result showed that the yield of fatty acid methyl ester (FAME) was achieved 96.6% in 9 h and the obtained k value was 3.28×10-1h-1which higher than that of without co-solvent system (3.07×10-1h-1). After purification with a cation-exchange resin to remove calcium ion (Ca2+), high-quality biodiesel product with the fuel properties of the biodiesel especially the major physicochemical properties meet both the ASTM and EN standard specifications. Utilization of waste eggshell-derived CaO as catalysts and performing the reaction at room temperature were not only environmentally-friendly technique but also decreasing biodiesel production cost.

< p>Hydrogen in spite of having a chain transfer agent role is one of the most important factors which directly affecting on kinetic of propylene polymerization. Hydrogen causes to dramatically increase the percentage of activated sites in proportion to being total potential sites on the catalyst surface. On the other hand, the chain transfer agent role of hydrogen gives rise to changing some vital indices of final product properties. This study has attempted to present a validated mathematical model that able to predicting profile polymerization rate and also calculating some of the vital indices of the final product, properties to be derived from kinetic equations. Furthermore, in this paper, we present a developed model that calculates fraction activated sites catalyst via hydrogen concentration based on dormant site theory and determining the best process condition. The modeling approach is based on the polymer moment balance method, i.e. population balance technique, and validated by experimental works. The main aim of this study is assigned to investigate the behavior change of polymerization rate to hydrogen. The experimental data and model outputs were compared and concluded that the global errors were in the acceptable range.

The kinetics study of NCA leaching in the HCl system was proposed. Various kinetic models such as shrinking core, logarithmic rate law, and Avrami equation were used to find out the most appropriate kinetic models for this process. The effect of HCl concentrations, leaching temperatures, solid to liquid (S/L) ratio, and leaching duration were observed. The optimum conditions of NCA leaching were at HCl concentration of 4 M, temperature of 80 °C, S/L ratio of 100 g/L, and leaching time of 1 h. The result shows that shrinking core model with diffusion control process of residue layer describes well the leaching mechanism in this research, which is indicated by the good fitting of coefficient values of correlation (R2) and confirmed by the activation energy values of Ni, Co, Al that were less than 40 kJ/mol.

Alumina is found to be a good adsorbent for the removal of fluoride. In the present study, rice husk ash-derived NaA zeolite has been modified with colloidal hydrated alumina in a cost-effective process for efficient removal of fluoride ions. The prepared NaA zeolite powder was added into colloidal hydrated alumina under stirring at 70°C/2 h followed by drying at 100°C/6 h to obtain modified zeolite. The product reveals enhanced adsorption efficiency (95–99%) for the removal of fluoride ions at wide ranges of adsorbate concentration (~5–200 mg/L), adsorbent concentration (0.5–10 g/L), pH (3–10), and temperature (30–70°C). Regeneration study shows that adsorption remained >90% up to third cycle followed by gradual decrease of adsorption for consecutive cycles. Kinetics study of fluoride adsorptions shows best fit for pseudo-second-order model demonstrating chemisorption process through a monolayer formation. The adsorption isotherm reveals that Langmuir isotherm is the best fit model indicating maximum adsorption capacities of 104.16, 68.12 and 36.13 mg/g for the adsorbent doses of 0.5, 1 and 2 g/L, respectively. Colloidal hydrated alumina modified NaA zeolite derived from rice husk ash could be utilized as low cost adsorbent for effective removal of fluoride ions from water.

Saponin is an important plant-derived compound that is commonly found in sapindaceae plants, such as Sapindus rarak DC. Saponin is extensively used in plenty of industries as a detergent or emulsifying agent in cleansers, shampoos, and cosmetics. The extraction of saponin was previously studied and shows that the extraction assisted by ultrasonic waves was found to be an effective method. However, the previous studies have rarely examined the extraction kinetic study of the ultrasound-assisted extraction (UAE). In the present study, the extraction of saponin from Sapindus rarak DC and its extraction kinetics is conducted. The results show that the highest saponin yield of 354.92 (mg of saponin per gram of dry feed) was obtained from the extraction using a solid-to-liquid (S/L) ratio of 1:50 (w/v) at 50 °C. The amount of extracted saponin increased with the increase of extraction temperature as well as the solute ratio in the solution. However, increasing the temperature to 60 °C decreased the saponin yield. The results of a simple kinetics study of saponin extraction also show that the second-order kinetics model can better describe the UAE process, with an R2 value of 0.929 and a rate coefficient of 0.00495 L.g-1.min-1. The experimental results agree well with the practical calculations obtained using the second-order kinetics model based on an average error of 6.79%.

In this work, we studied the effect of various amounts (0.2-1.2 % mole ratio) of Cu doping to TiO2 nanoparticles (Cu/TiO2) on the photocatalytic removal efficiency of the food colorant E 131 VF. Two series of doped TiO2 (P25) photocatalysts were prepared in two different media (50%ethanol-50%acetone and 5% surfactant (Tween 20)-95%H2O) by using the impregnation method. The prepared samples were characterized by XRD, FTIR, Raman, diffuse reflectance spectroscopy and SEM/EDX analyses. The XRD results showed that the crystal dimension of TiO2 increased from 23 to 35 nm and rutile/anatase ratio decreased from 16% to 9% after Cu doping in two different media. The photoactivity of TiO2 was reduced in the presence of Cu even at low molar ratio. The photocatalytic degradation rate constant of TiO2 (P25) was 0.24 (au) but it decreased to 0.015 (au) in the presence of the sample containing 0.6% Cu. Several reasons were suggested to explain the dramatic decrease in the activity of the prepared Cu/TiO2samples.

ABSTRACT: Lipase enzyme originated from wheat germ was immobilized on nylon -6- grafted with polyglycidyl methachrylate (PGMA). The immobilization of enzyme experiments were designed and studied using face centred central composite design (FCCCD) under response surface methodology (RSM). Prior to immobilization, the polymer was activated with diethyl amine/ethanol to introduce an amine functional group to facilitate covalent bonding with the enzyme. The immobilized and free enzymes were characterized for effect of temperature and pH on enzyme activity, stability, storage and reusability as well as kinetics studies. ANOVA revealed that optimum lipase activity of 0.287 U/ml was achieved at immobilization time of 5 h, pH of 6 and 1.0 mg/ml for enzyme concentration. The optimum temperatures and pH for immobilized and free enzymes were 45 °C and 35 °C, and 8 and 7, respectively. The immobilized enzyme showed higher stability compared to free enzyme. The immobilized enzyme retained 18% of its activity after being recycled 8 times. In a storage stability test, immobilized lipase was able to retain 70% of its activity after being stored for 30 days, while free enzyme activity dropped to 15 % after 20 days of storage. ABSTRAK:Enzim Lipase telah dihasilkan daripada mikroorganisma pegun gandum di atas nilon -6- dan digraf bersama poliglisidel methakrilet (PGMA). Enzim pegun ini direka dan dikaji secara eksperimen menggunakan reka bentuk campuran pusat pada permukaan (FCCCD) di bawah kaedah tindak balas permukaan (RSM). Sebelum menjadi pegun, polimer ini telah diaktifkan dengan dietil amine/ethanol bagi menghasilkan kumpulan fungsi amine bagi membantu ikatan kovalen atom pada enzim. Enzim pegun dan bebas ini telah dikategorikan mengikut kesan enzim ke atas suhu, aktiviti enzim ke atas kesan pH, kestabilan, keboleh-simpanan dan keboleh-gunaan balik, serta ujian tindak balas kinetik. ANOVA membuktikan bahawa aktiviti optimum enzim lipase ini adalah sebanyak 0.287 U/ml telah terhasil selama 5 jam pegun, pada pH 6 dan kepekatan enzim sebanyak 1.0 mg/ml. Suhu dan pH optimum, pada enzim pegun dan enzim bebas ini adalah pada 45 °C dan 35 °C, dan pH 8 dan 7, masing-masing. Enzim pegun ini menunjukkan lebih stabil daripada enzim bebas. Enzim pegun dilihat kekal 18% daripada aktivitinya selepas 8 kali ulangan. Melalui ujian kestabilan simpanan, enzim lipase pegun dapat mengekalkan 70% daripada aktivinya selepas disimpan selama 30 hari, manakala aktiviti enzim bebas telah menurun kepada 15% selepas 20 hari dalam simpanan.

Abstract Heavy metal has become a public health concern because of its tendency to accumulate in living organisms. The biosorptive removal of hexavalent chromium (Cr(VI)) from aqueous solution was investigated by using waste mosambi peel dust, and response surface methodology was applied as optimizing technique. The adsorbent was characterized by pHZPC, scanning electron microscope and Fourier transform infrared spectroscopy. The optimize condition for removal of Cr(VI) was recorded as follows: pH 2; dose: 0.5 g/50 mL; initial concentration: 5 mg/L; contact time: 30 min; agitation speed: 150 mg/L. The significance of independent variables and their interactions were tested by the analysis of variance and t test statistics. The adsorption data are nicely fitted with D–R isotherm and followed pseudo-second-order kinetic model. The monolayer adsorption capacity was recorded as 3.623 mg/g. Finally, thermodynamic results demonstrated that Cr(VI) adsorption is endothermic in nature and spontaneous. Therefore, the present results highlighted that mosambi peel dust is an efficient adsorbent and its versatility represents an eco-friendly alternative that can be implemented as agricultural waste management.

Amine-Modified Silica (AMS) and Quaternary Amine-Modified Silica (QAMS) has been synthesized through the sol-gel process for adsorption Au(III) in aqueous solution. The aim of this work was to compare the effect of addition three methyl group of AMS to form QAMS on its character, thermodynamics and kinetics parameter of sorption of Au(III) in aqueous solution. Characterizations performed by FT-IR, XRD, SEM and BET analyzer. Sorption study was carried out in a batch system under the various experimental conditions including the effect of medium acidity, a variation of Au(III) concentration (thermodynamics study), and variation of contact time (kinetics study). Optimum pH of sorption Au(III) on AMS was 3 and shift into 5 on QAMS. Thermodynamics sorption study by Langmuir isotherm models indicates that there was an increase of sorption capacity from 37.94 mg/g (AMS) to 74.47 mg/g (QAMS). Kinetics sorption studies by Lagergren, Ho, and RBS models indicate that the sorption Au(III) in this research fitted well with the RBS models. The addition of 3 methyl group also increased the sorption rate of Au(III) on QAMS (ka = 77.29 min-1 (mole/L)-1) over AMS (ka = 69.22 min-1 (mole/L)-1) and reinforce the electrostatic interaction between active site of QAMS.

Investigation into the solid-state transition among drug polymorphs has been more intense lately. Many factors induce the transformation of polymorphs during manufacturing processes. Efavirenz (EFV), an AIDS therapy drug, has more than 23 polymorphs, but very little information has been reported on them. This study aimed to perform a characterisation of EFV polymorph properties and to predict the kinetics and mechanism of the polymorphic transformation of EFV during manufacturing processes. The bimorphism study was conducted by Differential Scanning Calorimetry (DSC) thermal analysis. The phase transition kinetics of the polymorphs was monitored by X-ray powder diffraction and the quantification of concomitant polymorphs was examined using Rietveld refinement with MAUD ver. 2.7 as a software aid. To predict the solid-state transition, correlation coefficients of solid-state kinetic models were fitted to the experimental data. The results show that Form I and Form II of EFV were thermodynamically shown to be monotropy related. By fitting the experimental data, it was found that isothermal treatment had the best model fit with the phase boundary reaction in the two-dimensional model (G2). Accordingly, by employing mechanical treatment (grinding), it was predicted that the transition mechanism is a second-ordered reaction (R2). The activation energy of the transition during isothermal treatment calculated by the Arrhenius plot was found to be 23.051 kJ mol−1; the half-lif of Form II at ambient temperature was 428.05 min (~7.1 h).

Simultaneous reverse and normal initiation technique for atom transfer radical copolymerization (SR&NI ATRP) of styrene and methyl methacrylate in the presence of hexamethyldisilazane (HMDS)-modified silica aerogel nanoparticles (H-SAN) and investigating the effect of addition of H-SAN on the copolymerization and thermal properties of the products are discussed. Some unique features of the H-SAN are evaluated using nitrogen adsorption/desorption isotherm, SEM and TEM. Conversion and molecular weight determinations were carried out using GC and SEC respectively. Adding of H-SAN by 3 wt% results in decrement of conversion from 94 to 73%. In addition, molecular weight of copolymer chains decreases from 19500 to 16000 g.mol-1. However, polydispersity index values increases from 1.29 to 1.65. Linear increase of ln(M0/M) with time for all the samples shows that copolymerization proceeds in a living manner. Increasing thermal stability of the nanocomposites is demonstrated by TGA. DSC results show a decrease in glass transition temperature from 70.3 to 63.5 °C by addition of 3 wt% H-SAN.

Based on a combination of valence-bond and molecular mechanics functions which were fitted to high-level ab initio calculations, we constructed an analytical full-dimensional potential energy surface, named PES-2020, for the hydrogen abstraction title reaction for the first time. This surface is symmetrical with respect to the permutation of the three hydrogens in ammonia, it presents numerical gradients and it improves the description presented by previous theoretical studies. In order to analyze its quality and accuracy, stringent tests were performed, exhaustive kinetics and dynamics studies were carried out using quasi-classical trajectory calculations, and the results were compared with the available experimental evidence. Firstly, the properties (geometry, vibrational frequency and energy) of all stationary points were found to reasonably reproduce the ab initio information used as input; due to the complicated topology with deep wells in the entrance and exit channels and a “submerged” transition state, the description of the intermediate complexes was poorer, although it was adequate to reasonably simulate the kinetics and dynamics of the title reaction. Secondly, in the kinetics study, the rate constants simulated the experimental data in the wide temperature range of 25–700 K, improving the description presented by previous theoretical studies. In addition, while previous studies failed in the description of the kinetic isotope effects, our results reproduced the experimental information. Finally, in the dynamics study, we analyzed the role of the vibrational and rotational excitation of the CN(v,j) reactant and product angular scattering distribution. We found that vibrational excitation by one quantum slightly increased reactivity, thus reproducing the only experimental measurement, while rotational excitation strongly decreased reactivity. The scattering distribution presented a forward-backward shape, associated with the presence of deep wells along the reaction path. These last two findings await experimental confirmation.

Fourteen triterpene acids, viz., three tirucallane-type (1–3), eight ursane-type (4–11), two oleanane-type (12, 13) and one lupane type (21), along with boswellic aldehyde (14), α-amyrine (15), epi-amyrine (16), straight chain acid (17), sesquiterpene (19) and two cembrane-type diterpenes (18, 20) were isolated, first time, from the methanol extract of Boswellia elongata resin. Compound (1) was isolated for first time as a natural product, while the remaining compounds (2‒21) were reported for first time from B. elongata. The structures of all compounds were confirmed by advanced spectroscopic techniques including mass spectrometry and also by comparison with the reported literature. Eight compounds (1–5, 11, 19 and 20) were further screened for in vitro α-glucosidase inhibitory activity. Compounds 3–5 and 11 showed significant activity against α-glucosidase with IC50 values ranging from 9.9–56.8 μM. Compound 4 (IC50 = 9.9 ± 0.48 μM) demonstrated higher inhibition followed by 11 (IC50 = 14.9 ± 1.31 μM), 5 (IC50 = 20.9 ± 0.05 μM) and 3 (IC50 = 56.8 ± 1.30 μM), indicating that carboxylic acid play a key role in α-glucosidase inhibition. Kinetics studies on the active compounds 3–5 and 11 were carried out to investigate their mechanism (mode of inhibition and dissociation constants Ki). All compounds were found to be non-competitive inhibitors with Ki values in the range of 7.05 ± 0.17–51.15 ± 0.25 µM. Moreover, in silico docking was performed to search the allosteric hotspot for ligand binding which is targeted by our active compounds investigates the binding mode of active compounds and it was identified that compounds preferentially bind in the allosteric binding sites of α-glucosidase. The results obtained from docking study suggested that the carboxylic group is responsible for their biologic activities. Furthermore, the α-glucosidase inhibitory potential of the active compounds is reported here for the first time.

The development of ruthenium-based complexes for cancer treatment requires a variety of pharmacological studies, one of them being a drug’s binding kinetics to serum proteins. In this work, speciation analysis was used to study kinetics of ruthenium-based drug candidates with human serum proteins. Two ruthenium (Ru) complexes, namely [(η6-p-cymene)Ru(1-hydroxypyridine-2(1H)-thionato)Cl] (1) and [(η6-p-cymene)Ru(1-hydroxypyridine-2(1H)-thionato)pta]PF6 (2) (where pta = 1,3,5-triaza-7-phosphaadamantane), were selected. Before a kinetics study, their stability in relevant media was confirmed by nuclear magnetic resonance (NMR). Conjoint liquid chromatography (CLC) monolithic column, assembling convective interaction media (CIM) protein G and diethylamino (DEAE) disks, was used for separation of unbound Ru species from those bound to human serum transferrin (Tf), albumin (HSA) and immunoglobulins G (IgG). Eluted proteins were monitored by UV spectrometry (278 nm), while Ru species were quantified by post-column isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS). Binding kinetics of chlorido (1) and pta complex (2) to serum proteins was followed from 5 min up to 48 h after incubation with human serum. Both Ru complexes interacted mainly with HSA. Complex (1) exhibited faster and more extensive interaction with HSA than complex (2). The equilibrium concentration for complex (1) was obtained 6 h after incubation, when about 70% of compound was bound to HSA, 5% was associated with IgG, whereas 25% remained unbound. In contrast, the rate of interaction of complex (2) with HSA was much slower and less extensive and the equilibrium concentration was obtained 24 h after incubation, when about 50% of complex (2) was bound to HSA and 50% remained unbound.

Curing kinetics of natural rubber/ethylene propylene diene monomer (NR/EPDM) blends at different ratios of 2,2’-dithiobis(benzothiazole) (MBTS) and zinc diethyl dithiocarbamate (ZDEC) were studied. NR/EPDM blends were prepared using curative migration control technique. Kinetics studies employ Deng-Isayev and Kamal-Sorour models and kinetics parameters were evaluated using measured data from Moving Die Rheometer. Rate constant (k) and orders of reaction (n and m) were estimated through multivariable optimization using Matlab and activation energy (E) was determined using Arrhenius relationship. From the results, it is evident that the experimental data were in a good agreement with Kamal-Sorour model. It is also found that autocatalytic mechanism was more controlling than the others as indicated by k2>k1. Results also shows that rate constants were greatly influenced by temperature and the types of accelerator, while orders of reaction were dependent on temperature and independent on the types and amounts of accelerator. Combination of MBTS and ZDEC reduces energy activation of autocatalytic reaction. For desirable rate of curing, its ratio of 1.4 to 0.2 gave the lowest activation energy.