Search

Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Adsorption of Cu(II) from aqueous solution on the activated carbon (AC) prepared from Arenga pinnata Merr fruit shell (APMFS) waste with the assistance of ultrasound was evaluated by conducting batch mode experiments. As a result, KOH activation using 40 kHz of ultrasound restructured active binding sites and produced more pores on the APMFS-AC according to FT-IR and SEM analyses, respectively. Increasing the sonication time from 45 min to 135 min increased the adsorption capacity from 6.535 mg/g to 7.042 mg/g, respectively, at the initial Cu(II) concentration of 257.213 mg/L, 27°C and pH 5. With an increment of the adsorption temperature to 45°C, it increased the adsorption capacity up to 11.765 mg/g. The investigation on the independent variables showed the optimum conditions of adsorption which were 257.213 mg/L of the initial Cu(II) concentration, 60 min of contact time, pH 5 and 45°C using 135 min of sonicated APMFS-AC. The Cu(II) adsorption isotherm was fitted with the Langmuir model at the optimum condition. The Langmuir mono-layer adsorption capacity obtained was 11.765 mg/g with the BET saturation capacity, and the total pore volume values were 13.029 mg/g and 3.987 L/mg, respectively. The Cu(II) adsorption followed the pseudo second-order kinetics model with the adsorption rate 0.473 g/mg.min. Thermodynamic parameters of enthalpy change (ΔH0, 27.035 kJ/mol), Gibbs free energy (ΔG0, 7.292 kJ/mol), entropy change (ΔS0, 0.062 kJ/mol.K), and activation energy (E, 22.637 kJ/mol) were determined. These results confirmed that endothermic, spontaneous and chemical adsorption took place. [ABSTRACT FROM AUTHOR]

Excited-state species are a vital component of plasma chemistry modeling. Many previous works have studied the reactions of excited-state species. In almost all of these studies, the thermodynamic properties of the excited states are obtained via a modification of the formation enthalpy. It is often assumed that the error introduced by this procedure can be neglected. However, this is not true when vibrational states are included in the chemical mechanism. Specifically, we find that the error in adiabatic flame temperature can be as high as 100 K, and the error in NO concentration is as large as 50%. In this work, we will demonstrate how to consistently compute the thermodynamic data for these species. Key in computing thermodynamic data for excited-state species is the realization that an excited state is a subset of a full molecule description. The main challenge then becomes the consistently distributing the internal states over individual species. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new arrangement of a single flash geothermal power plant with a transcritical carbon dioxide recovery cycle is presented. • Energy analysis and exergy have been performed for both BASIC and recovery performance modes. • The results show that the proposed system in the recovery mode with a net power of 401.40 kW, energy efficiency of 53.6%, and exergy efficiency of 46.32% has been calculated. • Compared to the basic operating mode, the total output values of energy, energy efficiency and exergy efficiency show an increase of 149.9 kW, 2.39% and 12.12%, respectively. The use of new energy sources, such as geothermal energy, is rapidly expanding worldwide, and it is a viable alternative to fossil fuels. This paper proposes a geothermal power generation system (combined single flash geothermal cycle with transcritical carbon dioxide recovery cycle). To improve system performance, a recuperator is used to recover some of the heat loss. The proposed system simulation is performed in EES software and then validated by previous research. The proposed system is analyzed from the perspective of energy and exergy. The effects of the proposed system separator pressure, carbon dioxide turbine inlet pressure and carbon dioxide condenser outlet temperature on energy efficiency, exergy efficiency and system net power output have been investigated. Findings show that the proposed system in recovery mode has a net power output of 401.40 kW, energy efficiency of 53.6 percent, and exergy efficiency of 46.32 percent, which are significantly higher than the basic mode's values of 149.9 kW, 2.39 percent, and 12.12 percent, respectively. [ABSTRACT FROM AUTHOR]

Combining fresh material drying/cooling and environment regulation of residential buildings, a new integrated energy supply (IES) system based on heat pump is proposed to improve the energy efficiency, comfort of living condition and retention rate of agricultural products in rural areas. To balance supply and demand, the IES system, based on the characteristics of energy utilization in rural areas, is able to operate among four basic modes: Building Heating (BH), Building Cooling (BC), Material Drying (MD), Material Cooling (MC), and two integrated modes: BHMC and BCMD. Under typical working conditions, thermal performances including cooling capacity, heating capacity, compressor input power and coefficient of performance (COP) are compared among different operation modes when refrigerants are R32, R152a, R22 and R1234yf, respectively. It can be found that integrated energy supply system have lower cooling and heating capacity, and higher compressor power, but its COP is also the biggest. Comparison results also show that the time ratio of integrated operation mode (t r) and time ratio of one operation mode (t s) are important factors effecting the entire energy efficiency. • An IES system is used to supply energy for living and produce processing in rural areas. • Performance are simulated for six running modes with four different refrigerants. • Much Higher COP can be got in integrated modes than in one-purpose ones. [ABSTRACT FROM AUTHOR]

Hydrate-based H 2 purification is promising for removing impurities owing to the cage-like structures formed by water molecules. Understanding the competition mechanism of multicomponent gas molecule in hydrate is critical for improving gas purification efficiency. This study investigated the hydrate structure, thermodynamics, and kinetics of ternary gas mixture (H 2 –CO 2 –CO) from natural gas reforming products. The results identified H 2 –CO 2 –CO hydrate as type sI and determined the lattice parameters using X-ray diffraction. Raman spectroscopy results confirmed the presence of H 2 , CO 2 , and CO gas molecules in the hydrate phase. Increasing pressure, compared to cooling, enhanced CO 2 content in hydrate phase. The phase equilibrium conditions and average hydrate dissociation enthalpy (53.47 J/g) were determined using a high-pressure microcalorimeter. Gas chromatography identified that the content of CO 2 in the hydrate was the highest, followed by H 2 , and CO was the least abundant. The molecule dynamics simulation results show CO 2 molecule numbers reflected trends in 51262 cages, H 2 numbers correlated with changes in 512 cages, while CO numbers showed insignificant variation. Under the gas composition studied, the ability of gas molecules to be incorporated within hydrates decreases in the following order: CO 2 , H 2 , and CO. [Display omitted] • H 2 –CO 2 –CO hydrate type is sI and its lattice parameters are determined. • Phase equilibrium and dissociation enthalpy for H 2 –CO 2 –CO hydrate was quantified. • Increasing pressure, compared to cooling, enhanced CO 2 content in hydrate phase. • The content of CO 2 in the hydrate was the highest, followed by H 2 , and CO. [ABSTRACT FROM AUTHOR]

This paper proposes an alternative to the calculation of the liquid entropy of ammonia/NaSCN and ammonia LiNO3 solutions in the form of correlation equations with higher computation speed. These correlation equations were obtained by using both the least squares method for the modelling of the reference liquid entropy and a classical matrix computer solving for modeling the liquid entropy. Goodness-of-fit parameters such as sum of squares of estimation errors (SSE), Pearson's factor (R-squared), root mean square error (RMSE) and relative error (ε) were computed and the different results were compared with those of the digitized data. The suggested correlations showed good accuracy in estimating the liquid entropy of ammonia/NaSCN and ammonia/LiNO3 solutions, with an average SSE of 1.23. 10-4, R-squared of 0.99, RMSE of 2.90. 10-3 and ε of 0.59 % for ammonia/LiNO3, and SSE of 1.57. 10-4, R-squared of 0.99, RMSE of 3.2. 10-3 and ε of 0.83 % for ammonia/NaSCN. These correlations are for the temperature range from 0 to 100 °C, and are decision support tools for combined systems for waste heat recovering at very low temperature and in which the couples ammonia/NaSCN and ammonia/LiNO3 must be used. [ABSTRACT FROM AUTHOR]

This paper presents the design, evaluation, and optimization of an electricity generation system based on the two-stage organic Rankine cycle (TS-ORC), which utilizes the waste heat of an existing fluidized bed sewage sludge incineration (FBSSI) facility. The facility incinerates an average of 300 tons per day of sewage sludge with a dry matter content of 22%. After the drying process, the sewage sludge is burned in a fluidized bed combustor, and exhaust gas at a temperature of about 850-900°C is released due to the combustion. The system provides the energy required to dry the sludge from this exhaust gas. In this study, a TS-ORC is designed to be coupled to the exhaust gas flowlines discharged to the atmosphere at two different points in the FBSSI plant. The exergy efficiency of the FBSSI facility is found to be 70.5%. Three different working fluids are selected to examine the variations of thermodynamic and thermoeconomic performance parameters of the designed TS-ORC system. The highest power generation in the TS-ORC system (183.40 kW) is achieved using R1234yf as working fluid. R1234yf is also the most expensive fluid for electricity generation among the other working fluids (10.57 $/h). The least electricity generation in the TS-ORC (142.70 kW) occurs at the thermoeconomically most affordable cost with R245fa (9.35 $/h). [ABSTRACT FROM AUTHOR]

The three organic residuals of pistachio, peanut, and almond were investigated for the removal capacity and removal mechanism of cadmium ion from aqueous. Adsorption efficiency on reducing cadmium was evaluated with batch experiment parameters, contact time, sorbent dose, pH, and Cd2+ amount. The sorption process of metal ions was defined well with the pseudo-second order kinetic, and Langmuir isotherm model having an adsorption capacity (qe max) of 51.28 mg g−1 of pistachio, 62.11 mg g−1 of peanut, 78.74 mg g−1 of almond. The adsorbent was characterized by SEM, FTIR, and elemental analysis. The characterization study revealed that recycled lignocelluloses are composed of rough and porous surfaces with many active sites, contribute to metal ions removal in many ways, such as electrostatic interaction, ion exchange, complex formation, and physical adsorption. These findings highlighted that the shells can be effectively applied removal of divalent metal from aquatic solution. [ABSTRACT FROM AUTHOR]

Adsorption techniques are widely used to remove certain classes of pollutants from waters, especially those that are not easily biodegradable. The aim of this study was to evaluate the adsorption of Methylene Blue (MB) dye onto activated carbon from aqueous solutions was realized in a batch system. However, some examined factors such as contact time, pH solution, initial concentration of MB, adsorbent dosage and temperature were found to have significant impacts on the adsorption capacity of AC. The AC was characterized by BET surface area measurement, Point of Zero Charge (pHpzc), FTIR spectroscopy and X-ray diffraction analysis. Batch studies were conducted in order to determine the optimal parameters required to reach the adsorption equilibrium. The maximum adsorption capacity of the AC for MB at 298 K was determined to be 170.357 mg/g. The adsorption kinetic data were analyzed employing several kinetic models: pseudo-first order, pseudo-Second order, Elovich equation, and intraparticles diffusion model. It was established that the adsorption process obeyed the pseudo-second-order kinetic model with a determination coefficient (R2) equal to 0.999. The evaluation of thermodynamics parameters such as the Gibbs free energy ΔG° (−7.856 to −6.142 kJ/mol), positive enthalpy ΔH° (13.384 kJ/mol) and the change of entropy (63.46 J/mol K) indicated a spontaneous and endothermic nature of the reaction with a chemisorption process. Comparative tests by the heterogeneous photocatalysis of MB in the presence of a semiconductor will be the subject of the rest of this study. [ABSTRACT FROM AUTHOR]

In the textile industry, various acidic, basic and reactive dyes are used for different applications; the aim of this study is to eliminate Methylene blue (MB) a dangerous dye by a zeolithe produced at low economic cost by adsorption in batch mode. The adsorbent was characterized by the FTIR spectroscopy, X-ray diffraction (XRD), and point of zero charge (pHpzc = 10.42). Some examined factors were found to have a significant impact on the adsorption capacity of the zeolithe like the initial dye concentration (5–25 mg/L), solution pH (2–14), adsorbent dose (0.1–2 g/L), agitation speed (150–500 rpm), particles size (100–500 µm) and temperature (298–333 K). The best capacity was found at pH 6 with an adsorbent dose 0.2 g/L, an agitation speed 200 rpm and a contact time of 40 min. Modeling the Kinetics and Isotherms data shows respectively that the pseudo-second-order kinetic model and Langmuir isotherm provide better fitness to the experimental data with the maximum adsorption capacity of 12.50 mg/g at 25°C. The adsorption isotherms at different temperatures have been used for the determination of the free energy (ΔG°); enthalpy (ΔH°) and entropy (ΔS°) to predict the nature of MB adsorption. The positive values of ΔG° and ΔH° indicate a non-spontaneous and endothermic MB adsorption with a physisorption process. The adsorbent elaborated from the zeolithe was found to efficient and suitable for the removal of reactive dyes from aqueous solutions, due to its, low cost preparation and good adsorption capacity. The photocatalysis of MB in the presence of hybrid semiconductor (TiO2/Zeolithe) constitutes the logical continuation of this study. [ABSTRACT FROM AUTHOR]

The adsorption of indigo carmine dye onto Activated Pomegranate Peels (APP) from aqueous solutions was followed in a batch system. The adsorbent was characterized by the BET method (specific surface area S BET: 51.0674 m2/g) and point of zero charge (pHpz = 5.2). However, some examined factors were found to have significant impacts on the adsorption capacity of pomegranate peels (APP) such as the initial dye concentration (10–60 mg/L), solution pH (2–12), adsorbent dose (1–10 g/L), agitation speed (100–600 rpm), and temperature (298–308 K). The best adsorption capacity was found at pH 2 with an adsorbent dose 1 g/L, an agitation speed 300 rpm and a contact time of 45 min. The adsorption mechanism of IC onto (APP) was studied by using the first-pseudo order, second-pseudo order, Elovich, and Webber-Morris diffusion models. The adsorptions kinetic were found to follow rather a pseudo-second order kinetic model with a determination coefficient (R 2) of 0.999. The equilibrium adsorption data for IC onto (APP) were analyzed by the Langmuir, Freundlich, Elovich, and Temkin models. The results indicate that the Langmuir model provides the best correlation with capacities (q max of 158.73 mg/g at 298 K). The adsorption isotherms at different temperatures have been used for the determination of thermodynamic parameters like the free energy; enthalpy and entropy to predict the nature of adsorption process. The negative values Δ G ° and Δ H ° indicate that the overall adsorption is spontaneous and exothermic with a physisorption process. The adsorbent elaborated from pomegranate peels material was found to very effective and suitable for the removal of reactive dyes from aqueous solutions, due to its availability, low cost preparation, and good adsorption capacity. [ABSTRACT FROM AUTHOR]

Thermodynamic analyses of concentrating solar power plants and optimizing these cycles relying on the energetic and exergetic optimal efficiencies are quite common. However, it is found that just considering the efficiency of the system for performance optimization and neglecting the adverse effects of the plant's wrong operation timings, which is a function of the solar working fluid flow rate, can easily give misleading optimization results. This study's primary goal is to find the optimal operating point of the cycle in terms of the thermodynamic efficiencies considering the system's operating time. Thus, the Sliding Mode Control (SMC) approach is employed to provide a proper mass flow rate for the working fluid from the solar collector field to achieve a precise output temperature from the collectors in different operating conditions. Multi-objective optimization is performed using the Particle Swarm Optimization (PSO) algorithm. The results of power block sensitivity analysis indicate that a 70? increase in the solar collector outlet temperature remarkably enhances electricity generation and exergetic efficiency by 67 and 48%. The twoobjective optimization shows 22.01%, 2.10%, and 5.46% enhancement in response time, thermal efficiency, and exergetic efficiency, and the three-objective optimization reveals 3.68% and 3.74% improvement in efficiency (thermal and exergetic), respectively. [ABSTRACT FROM AUTHOR]

Cyclodextrin's ability to form an inclusion complex with a guest molecule is a function of two factors. The first is steric and depends on the relative size of cyclodextrin cavity to the guest molecule, while the second is the thermodynamic interaction between the different system components. This study therefore aims to determine the effect of β-cyclodextrin and hydroxypropyl-β-cyclodextrin as complex formers, on thermodynamic parameter values (ΔH, ΔG, and ΔS) in the formation of inclusion complex with p-methoxycinnamic acid (pMCA). The pMCA complex formation with β-cyclodextrin or hydroxypropyl-β-cyclodextrin was determined in 0.02 pH 4.0 M acetate buffer and 0.02 M pH 7.0 phosphate buffer, with a 0.2 µ value at 32, 37, and 42 ± 0.5 °C. This experiment was carried out in a waterbath shaker until a saturated solution was obtained. Subsequently, pMCA concentration was determined using UV spectrophotometer at the maximum pMCA wavelength, at each pH. The result showed pMCA formed inclusion complex with β-cyclodextrin or hydroxypropyl-β-cyclodextrin and exhibited increased solubility with increase in β-cyclodextrin or hydroxypropyl-β-cyclodextrin concentration. This temperature rise led to a decrease in the complex's constant stability (K). Furthermore, the interaction showed a negative enthalpy (∆H<0) and is a spontaneous processes (∆G<0). At pH 4.0, an increase in the system's entropy occurred (∆S>0), however, at pH 7.0, the system's entropy decreased (∆S<0). The rise in pMCA solubility with increase in cyclodextrin solution concentration indicates an inclusion complex has been formed, and is supported by thermodynamic data. [ABSTRACT FROM AUTHOR]

The study investigates the kinetic and thermodynamic characteristics of the lumber industry's mixed waste wood (as lignocellulosic biomass) catalytic pyrolysis in the presence of an eggshell-based, metal-ion-impregnated catalyst. Thermogravimetric analysis was performed to estimate the kinetic and thermodynamic characteristics of the pyrolysis process, and isoconversional methods (KAS, OFW, Starink, DAEM, and Friedman) were used to estimate the reaction parameters. The reaction mechanism was determined using a non-isothermal integral model of Coats-Redfern. The thermogravimetric analysis of catalytic pyrolysis shows a reduction in dehydration temperature and devolatilization temperature by an average value of 14.72 K. While an additional peak was observed in the lignin decomposition zone, which signifies the decomposition of lignin content in the presence of a catalyst. Among the tested catalysts, the Fe-based catalyst proved to be efficient. The reduction in average activation energy was observed from 189.9 – 141.8 kJ mol−1, and the subsequent reduction in enthalpy change is 184.9 – 136.8 kJ mol−1, which signifies the reduction in temperature and overall energy requirements. Coats-Redfern modeling analysis shows that catalytic pyrolysis reduces the diffusional resistance compared to the pyrolysis process without the addition of a catalyst. Overall, results suggest that using an eggshell-derived Fe-based catalyst can lower the process temperature, energy consumption, and cost for catalyst preparation and improve the reactor design. [Display omitted] • Eggshell-derived metal impregnated catalyst was tested to valorise industrial biomass waste. • Introducing eggshell-derived catalyst to LBW reduced the pyrolysis reaction temperatures. • The activation energy for LBW pyrolysis with catalyst is reduced from 189.9 to 141.8 kJ mol−1. • The reduction in enthalpy change for the pyrolysis of biomass waste in the presence of catalyst is from 184.9 kJ mol−1 to 136.8 kJ mol-1. • In the presence of the catalyst, nucleation replaces diffusion mechanism at earlier stages of conversion. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigates the potential use of activated carbon, prepared from pomegranate peels, as an adsorbent activated using H3PO4 and its ability to remove crystal violet from an aqueous solution. The adsorbent was characterized by the Brunauer–Emmett–Teller method (specific surface area: 51.0674 m2 g−1) and point of zero charge (pHPZC = 5.2). However, some examined factors were found to have significant impacts on the adsorption capacity of activated carbon derived from pomegranate peels such as the initial dye concentration (5–15 mg L−1), solution pH (2–14), adsorbent dose (1–8 g L−1), agitation speed (100–700 r/min), and temperature (298–338 K). The best adsorption capacity was found at pH 11 with an adsorbent dose of 1 g L−1, an agitation speed at 400 r/min, and a contact time of 45 min. The adsorption mechanism of crystal violet onto activated carbon derived from pomegranate peels was studied using the pseudo-first-order, pseudo-second-order, Elovich, and Webber–Morris diffusion models. The adsorption kinetics were found to rather follow a pseudo-second order kinetic model with a determination coefficient (R 2) of 0.999. The equilibrium adsorption data for crystal violet adsorbed onto activated carbon derived from pomegranate peels were analyzed by the Langmuir, Freundlich, Elovich, and Temkin models. The results indicate that the Langmuir model provides the best correlation with q max capacities of 23.26 and 76.92 mg g−1 at 27°C and 32°C, respectively. The adsorption isotherms at different temperatures have been used for the determination of thermodynamic parameters like the free energy, enthalpy, and entropy to predict the nature of adsorption process. The negative values Δ G 0 (−5.221 to −1.571 kJ mol−1) and Δ H 0 (−86.141 kJ mol−1) indicate that the overall adsorption is spontaneous and exothermic with a physisorption process. The adsorbent derived from pomegranate peels was found to be very effective and suitable for the removal of reactive dyes from aqueous solutions, due to its availability, low-cost preparation, and good adsorption capacity. [ABSTRACT FROM AUTHOR]

The present study describes the facile synthesis of silver nanoparticles (AgNPs) by green method using aqueous extract of Gazania rigens. The size, morphological, compositional and optical properties of silver nanoparticles were examined through X-ray diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscope (SEM), and UV-Vis spectroscopy respectively. Ultraviolet-Visible spectra showed the absorbance band between 425–460 nm which indicated the synthesis of stable AgNPs. Average size of AgNPs was calculated from XRD spectra as 31.35 nm. SEM and EDX spectra confirmed the synthesis of spherical shaped AgNPs. FTIR spectra showed that different functional groups were present in aqueous extract of plant which acted as reducing agents in the formation of stable silver nanoparticles. The value of DPPH radical inhibition by AgNPs was 75.45±1.12% at 1000 µg/mL concentration revealing its moderate antioxidant activity. Synthesized AgNPs showed good total phenolic contents (262.60±1.2 mg/g GAE) as well as good total antioxidant activity (1.11±0.07). Then the synthesized AgNPs were used as catalyst for the removal of toxic organic dyes i.e methylene blue (MB) and congo red (CR). Various factors like temperature, pH, adsorbent dosage, dye concentration and contact time were examined and optimized for maximum removal of dyes. Thermodynamic factors like enthalpy (ΔH°), Gibb’s free energy (ΔG°), and entropy (ΔS°) of the system were also determined. Kinetics of the system was studied with the help of Lagergren’s model. Adsorption parameters were also calculated using Langmuir and Freundlich, isotherm models [ABSTRACT FROM AUTHOR]

Since, cobalt, zinc, mercury and lead ions are high toxic heavy metals; this work aims to investigate the efficiency of eggshell as a low cost sorbent for their ions from aqueous solution. Adsorption of heavy metals on surfaces of eggshell obeyed second order kinetics. Adsorption isotherm belonged to Freundlich model and displayed multilayer adsorption. The maximum adsorption capacity was estimated as 204, 153, 121 and 98 mg/g for Co3+, Zn2+, Hg2+ and Pb2+ respectively. The values of free energy of adsorption evidenced the physical adsorption occurrence. It is demonstrated that eggshell, as an industrial waste, was efficiently used as an adsorbent for wastewater treatment. Eggshells powder removed efficiently heavy metal ions from a tannery wastewater and removal efficiency reached up to 99%. [ABSTRACT FROM AUTHOR]

In this study, Paliurus spina-christi Mill, fru-tis and seeds (PSCFS) was used as an adsorbent for Pb(II) ions removal from water solutions. The effect of various experimental parameters was investigated using a batch adsorption technique. In the adsorption experimental, temperature, contact time and concentrations effects upon Pb (II) ions on PSCFS were thoroughly examined at pH 5.2. Results show that a temperature value of 45 ℃ is favorable for the adsorption of Pb (II) ions. The isothermal data could be well described by the Freundlich equation. The kinetic data fit well with the pseudo-second-order kinetic model. The adsorption capacity of PSCFS was found to be 14.97°1 mg g1 at 45 ℃ according to pseudo-second-order model data. Thermodynamic parameters such as activation energy (Ea) and change in the free energy (AG°), the enthalpy (AH°), and the entropy (AS°) were also evaluated. The all adsorption process was endothermic and spontaneous. The results indicate that PSCFS could be employed as low-cost materials for removal from water of Pb (II) ions. [ABSTRACT FROM AUTHOR]

Copyright of Tecnologia em Metalurgia, Materiais e Mineração is the property of Associacao Brasileira de Metalurgia e Materiais and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Acid hydrolysis of cassava peel (CP) to reducing sugar (RS) was undertaken at 70, 90 and 110 °C, and 0.5, 1.0 and 1.5 M concentrations of H 2 SO 4. Kinetics and thermodynamics of the study were tested for their statistical consistency using analysis of variance (ANOVA). The RS was characterised for its bioactive chemical compositions and functional groups. Maximum RS of 47.70 g/l from a 50 g/l of the CP with the highest rate constant (k) of 0.00247 min−1 was attained at 1.5 M and 110 °C. The ANOVA results of F > F crit and p < 0.05 revealed that the AC at constant temperature has a significant effect on the hydrolysis. The thermodynamic analysis revealed that the highest value of 3.06 × 103 Jmol−1 for ΔH (1.5 M and 110 °C), and the lowest value of ΔS = −7.65 × 10 Jmol−1 (0.5 M and 70 °C) were obtained. The bioactive chemical indicated the presence of compounds effective against several diseases. The functional groups obtained among others include alkanols, aldehyde, and alkanoates. Therefore, CP hydrolysis is a significant way of reducing the cost of RS as it contains essential ingredients for pharmaceutical, food and medicinal purposes. [ABSTRACT FROM AUTHOR]

Phenol and its derivatives are considered as dangerous pollutants due to these harmful effects on health and the environment. Treatment of the waters charged by these compounds by adsorption remains very important. For these reasons, this study was designed to prepare nickel oxide by precipitation method in order to remove these pollutants from aquatic environments. Indeed, structural and textural properties of this solid have been determined by various physicochemical methods (X-ray diffraction, Fourier transform in the infrared, N2 adsorption/desorption (BET), ATD / ATG thermal analysis and scanning electron microscopy (SEM)). In addition, several adsorption tests were carried out in order to show the effectiveness of this solid for the elimination of phenol in aqueous solution and to determine the physicochemical parameters which affect adsorption. Our results have shown 5.29 mg·g−1 of adsorption capacity with 98% of yield. Furthermore, it was shown that adsorption process was endothermic. For the kinetic study, it was demonstrated that phenol adsorption on NiO follows the pseudo-second-order and the Langmuir model better adaptable for the isotherm of desorption. Moreover, thermodynamic study shows positive values of ΔS ° (266.6 JK−1·mol−1) suggesting a randomness increase of the solid/liquid interface. ΔH ° (60.41 kJ·mol−1) was also positive confirming the endothermic nature of the adsorption processes. However, ΔG ° (kJ·mol−1) was negative suggesting the spontaneity of the phenol adsorption. In summary, this work suggests that phenol adsorption on NiO was linked to the chemical adsorbate/adsorbent interactions. [ABSTRACT FROM AUTHOR]

This work introduces a newly developed kinetic mechanism and thermodynamic study that gives a clear theoretical insight between the iodine and chromium in acid solution. The paper mainly focuses on evaluating kinetic mechanism and thermodynamic properties of the oxidation of iodide by dichromate ion in acidic medium. This study was investigated using iodometric method. The rate has been studied by appropriate choice of concentrated conditions at constant temperature and ionic strength. The kinetic studies revealed half order reaction with respect to dichromate ion, first order for iodide ion and second order for hydrogen ion concentration. The dependence of reaction rate on the temperature was monitored in order to generate some thermodynamic parameters, which can be used in predicting the direction and spontaneity of the reaction. The thermodynamic studies of this reaction revealed negative values for ΔG, ΔS and positive values for ΔH which is an indication that the reaction was spontaneous and endothermic. The oxidant chromium (vi) exist in acidic media as H2CrO4. The effect of ionic strength on the rate of redox reaction was investigated. The ionic strength was adjusted by varying the concentration of the nitrate to maximum. The effect of temperature was also studied to evaluate the thermodynamic parameters. Transition metals should be use as catalyst for future purpose to monitor the rate of redox reaction. The techniques employed on this research are very useful in determining the rate of a redox reaction. [ABSTRACT FROM AUTHOR]

This study investigates the potential use of activated carbon, prepared from pomegranate peels, as an adsorbent activated using H3PO4 and its ability to remove crystal violet from an aqueous solution. The adsorbent was characterized by the Brunauer-Emmett-Teller method (specific surface area: 51.0674 m² g-1) and point of zero charge (pHPZC = 5.2). However, some examined factors were found to have significant impacts on the adsorption capacity of activated carbon derived from pomegranate peels such as the initial dye concentration (5-15 mg L-1), solution pH (2-14), adsorbent dose (1-8 g L-1), agitation speed (100-700 r/min), and temperature (298-338 K). The best adsorption capacity was found at pH 11 with an adsorbent dose of 1 g L-1, an agitation speed at 400 r/min, and a contact time of 45 min. The adsorption mechanism of crystal violet onto activated carbon derived from pomegranate peels was studied using the pseudofirst-order, pseudo-second-order, Elovich, and Webber-Morris diffusion models. The adsorption kinetics were found to rather follow a pseudo-second order kinetic model with a determination coefficient (R2) of 0.999. The equilibrium adsorption data for crystal violet adsorbed onto activated carbon derived from pomegranate peels were analyzed by the Langmuir, Freundlich, Elovich, and Temkin models. The results indicate that the Langmuir model provides the best correlation with qmax capacities of 23.26 and 76.92 mg g-1 at 27°C and 32°C, respectively. The adsorption isotherms at different temperatures have been used for the determination of thermodynamic parameters like the free energy, enthalpy, and entropy to predict the nature of adsorption process. The negative values ΔG0 (-5.221 to -1.571 kJ mol-1) and ΔH0 (-86.141 kJ mol-1) indicate that the overall adsorption is spontaneous and exothermic with a physisorption process. The adsorbent derived from pomegranate peels was found to be very effective and suitable for the removal of reactive dyes from aqueous solutions, due to its availability, low-cost preparation, and good adsorption capacity. [ABSTRACT FROM AUTHOR]

This study examined the corrosion inhibition of mild steel in 1.5M HCl solution using cocoa leaf extract as an inhibitor. The effect of inhibitor concentrations, kinetics, and time of immersion were undertaken at 30oC while the thermodynamic parameters were determined with temperature range of 35oC - 55oC. FTIR result indicated that the actual adsorption of the inhibitor is as a result of donation of single pair of electrons on oxygen to the vacant d - orbitals of the metal (mild steel) that leads to the formation of complexes on the mild steel surface. The corrosion rate decreased from 1.64 g/cm2hr to 0.09gm/cm2hr in the presence of inhibitor used. However, increased in temperature showed a decreased in inhibition efficiency this resulted to an increase in rate of corrosion. Half - life of the corrosion kinetics ranges from 49.71 - 53. 15hr which is directly proportional to the inhibitor concentrations. Activation energy Ea, enthalpy (ΔHo), and entropy (ΔSo) calculated showed good interactions. The enthalpy of activation ranges from 63.28kJ/mol to 97.55kJ/mol. Rise in activation energy with inhibitor concentration confirmed the physical (physisorption) adsorption mechanism for the corrosion of mild steel surface. Endothermic nature of the corrosion process is ascertained with the positive value of ΔHo obtained. [ABSTRACT FROM AUTHOR]

Selected bacterial strain Corynebacterium glutamicum MTCC 2745 was immobilized on the surface of neem leaves/MnFe 2 O 4 composite (NL/MnFe 2 O 4 composite). The uptake of the biosorbent in combination with the bacterial strain to act as arsenic scavengers from synthetically prepared wastewater was evaluated. The influence of contact time and temperature on the removal of both As(III) and As(V) was investigated. The effect of temperature and initial concentration on the adsorption kinetics was also examined. The equilibrium was achieved after about 240 min at a temperature of 30 °C. Nonlinear regression analysis was done for determining the best-fit kinetic model on the basis of three correlation coefficients and three error functions and also for predicting the parameters involved in kinetic models. The results showed that Fractal-like mixed 1, 2 order model for As(III) and Brouser–Weron–Sototlongo as well as Fractal-like pseudo second order models for As(V) were capable to deliver realistic explanation of biosorption/bioaccumulation kinetic. The adsorption kinetics data also followed pseudo second order kinetic model proposing chemisorption nature of the process. Intraparticle diffusion model confirmed that intraparticle was not a fully operative mechanism. Applicability of various mechanistic models in the present study showed that the rate controlling step in the biosorption/bioaccumulation of both As(III) and As(V) was film diffusion rather than intraparticle diffusion. The estimated thermodynamic parameters Δ G 0, Δ H 0 and Δ S 0 exposed that biosorption/bioaccumulation of both As(III) and As(V) was feasible, spontaneous and exothermic under studied conditions. The activation energy (E a) calculated from Arrhenius equation indicated the nature of biosorption/bioaccumulation being ion exchange type. Increasing concentration of As(III) and As(V) furthermore improved the initial sorption rate h , from 3.91 to 343.54 mg/g min and 4.3 to 550.67 mg/g min, respectively. Spectroscopic studies (Fe-SEM and FT-IR) confirmed that ion exchange process was responsible for the uptake of arsenic (As(III) or As(V)) onto immobilized cells. [ABSTRACT FROM AUTHOR]

• Formalization of Gestalt and cell assembly theory in algebraic information topology. • Axiomatization of consciousness and probability by topos' constructive logic. • Formal theory of learning directly applied to data analysis. • Unified topological expression of consciousness within thermodynamic. • Unification of main models of consciousness (IIT, GNW, FEP, LD). Elementary quantitative and qualitative aspects of consciousness are investigated conjointly from the biology, neuroscience, physic and mathematic point of view, by the mean of a theory written with Bennequin that derives and extends information theory within algebraic topology. Information structures, that accounts for statistical dependencies within n-body interacting systems are interpreted a la Leibniz as a monadic-panpsychic framework where consciousness is information and physical, and arise from collective interactions. The electrodynamic intrinsic nature of consciousness, sustained by an analogical code, is illustrated by standard neuroscience and psychophysic results. It accounts for the diversity of the learning mechanisms, including adaptive and homeostatic processes on multiple scales, and details their expression within information theory. The axiomatization and logic of cognition are rooted in measure theory expressed within a topos intrinsic probabilistic constructive logic. Information topology provides a synthesis of the main models of consciousness (Neural Assemblies, Integrated Information, Global Neuronal Workspace, Free Energy Principle) within a formal Gestalt theory, an expression of information structures and patterns in correspondence with Galois cohomology and discrete symmetries. The methods provide new formalization of deep neural network with homologicaly imposed architecture applied to challenges in AI-machine learning. [ABSTRACT FROM AUTHOR]

Emergency alternative evaluation (EAE) is crucial to improve emergency management performance, which is considered an important factor in achieving sustainable development. This paper proposes an integrated fuzzy method to deal with the EAE problem. The existence of information uncertainties and decision-makers (DMs) psychological behavior are considered due to the complexity of emergency environments. By utilizing trapezoidal intuitionistic fuzzy numbers to depict the fuzziness and uncertainty of information, prospect theory is developed to portray DMs' heterogeneous psychological behavior and convert the initial decision matrixes into decision prospect matrixes. A thermodynamic approach that comprises operations on entropy, energy, and exergy is introduced to maximize the use of decision-making information, determine each criterion weight value, and assess information quantity and quality. Trapezoidal intuitionistic fuzzy Choquet integral operator and weighted averaging operator are presented to integrate the overall prospect value of each alternative. A score function with risk attitudinal parameter of DMs is introduced to obtain the final ranking order of the alternatives. A multi-step framework and solution procedure is then presented, and an illustrative case study is followed to investigate the EAE problem by selecting a provincial highway department in China, which confirms the practicability of our proposed solution approach. [ABSTRACT FROM AUTHOR]

• Activated alumina was modified with sodium hydroxide and potassium hydroxide solutions to enhance carbon dioxide adsorption. • The process optimization was carried out using response surface methodology (RSM) based on central composite design (CCD). • The effect of operating parameters including NaOH and KOH (%), T, P on CO adsorption process were investigated. • The optimum adsorption capacities for adsorbents with 30% NaOH and KOH were found to be 146.70 and 130.84mg/g, respectively. • Thermodynamic parameters revealed that the adsorption process is exothermic and spontaneous. Activated alumina (AA) was modified with sodium hydroxide and potassium hydroxide solutions to enhance carbon dioxide adsorption capacity. The process optimization was carried out using response surface methodology (RSM) based on central composite design (CCD) with two variables, the temperature and pressure in the range of (20–80 °C) and (2–10 bar), respectively. In addition, the effect of operating parameters including adsorbent amount, percentage of hydroxide solution, temperature and pressure on the CO 2 adsorption process were investigated. The optimum CO 2 adsorption capacities for modified activated alumina adsorbents with 30% NaOH and KOH at temperature of 20 °C and pressure of 6 bar were found to be 146.70 and 130.84 mg/g adsorbent , respectively. The Freundlich isotherm model was showed the best accordance with the experimental data and the kinetic modeling results indicated that the Elovich model is well-fitted for adsorption process by modified activated alumina. As well as thermodynamic parameters revealed that the adsorption process for the studied three adsorbents is exothermic and spontaneous. [ABSTRACT FROM AUTHOR]

This study, atermit factory solid wastes were used as an adsorbent to remove Reactive Red 45 (RR45) from aqueous solution by batch method. Effects of pH, initial dye concentration and time were studied. It was found that the removal of RR45 increased with increasing initial dye concentration Adsorption isotherms were analyzed by Langmuir and Freundlich models. Moreover, kinetic of adsorption were studied. Pseudo second order is the best model for the removal of RR45 from aqueous solution. Thermodynamic parameters were also studied. Gibbs free energy value was found to be -5.320 kJ/mol and indicating the spontaneity of the system. Atermit factory solid wastes were characterized by SEM. As a result, atermit factory wastes could be employed as no-cost and effective adsorbent for the removal of RR45 from aqueous solution. [ABSTRACT FROM AUTHOR]

The removal of Ni(II) using Uludag fir (Abies nordmanniana subsp. bornmuelleriana Mattf.) was investigated as a function of severeal parameters such as initial Ni(II) concentrations, solution pH, adsorbent dosage, temperature and contact time by batch experiments. Experimental data were analysed using the Langmuir and Freundlich isotherms. It was found that the isotherm data was best fitted with Langmuir isotherm (R²= 0.97). Kinetic studies indicated that the pseudo second order kinetic model fit better than the pseudo first order kinetic. Also the thermodynamic parameters (ΔG°, ΔH°, ΔS°) were performed and the results indicated that the adsorption process was feasible, spontaneous and endothermic in nature. The results obtained that use the waste to treat the waste. The results suggested that Uludag fir (Abies nordmanniana subsp. bornmuelleriana Mattf.) is a potent candidate for efficient biosorbent for removing Ni(II) from aqueous streams. [ABSTRACT FROM AUTHOR]

Abstract Adsorption of Cu (II) ions using carnauba straw powder (CSP) as biosorbent was studied in batch experiments. The adsorption process was evaluated considering copper solution concentration and pH, biosorbent size and dosage, adsorption time, and temperature. The best results were obtained at pH 6 and 10 g/L of biosorbent. A decrease in cupric ion uptake was observed with the increase of Cu (II) concentration. The Cu (II) removal capacity was improved with the reduction of the biosorbent granule size. Adsorption data were well fitted by the Langmuir isotherm and pseudo-second order kinetic model. The process was both spontaneous and exothermic. Best adsorption results were obtained at 50 °C, reaching 9.5 mg Cu (II)/g biosorbent. [ABSTRACT FROM AUTHOR]

Abstract Cobalt contamination in wastewater from industries has been increased in many countries including Egypt. Adsorption is the most progressively for heavy metals, removing from wastewater by using agricultural waste and by-products such as rice straw. Unmodified and modified rice straw has been evaluated as their ability to bind with metal ions. In this study, four characterizations of raw rice straw have been conducted. The morphological characteristics by SEM, EDXA, and the functional group present in the rice straw by FTIR spectroscopy and the XRD technique. Rice straw contains about OH functional group that can bind with metal ions. To be able to enhance the sorption capacity of rice straw in metals, removing from waste water, alkali treatment should be done. This shows that rice straw can be used as adsorbent for removing cobalt ions from wastewater. The effect of pH, amount of adsorbent, different concentrations of cobalt, sorption kinetics and isotherms were studied in batch experiments. The good correlation coefficient was obtained from pseudo second-order kinetic model, which agreed with conception as the rate-limiting mechanism. Sorption isotherm test showed that equilibrium sorption data were better represented by Langmuir model than the Freundlich model. The thermodynamic parameters such as Δ H , Δ S , Δ G and E a are also calculated. [ABSTRACT FROM AUTHOR]

Industrial recovery of valuable elements in copper slag is the key to treat copper slag and protect the environment. However, the results of the industrial reduction of copper slag are not ideal at present, mainly because the oxidation problem caused by excess oxygen is not considered. In this study, the properties of three carbonaceous materials and the coupling reaction behavior of copper slag + C under CO 2 atmosphere were investigated by thermogravimetric and thermokinetic analyses. The results showed the activity of the three carbonaceous materials to be in the order of coke > anthracite > coal. Coke was more conducive to the reduction of copper slag under Ar atmosphere, whereas anthracite was more conducive under CO 2 atmosphere. The reduction amount and rate of copper slag under CO 2 atmosphere were higher than those under Ar atmosphere within a certain temperature range. Moreover, the carbon burning loss increased significantly so that CO 2 could re-oxidize the reduced metal elements after heating to 1300 ℃. The limiting steps of the reduction reaction of copper slag under Ar atmosphere mainly followed the three-dimensional diffusion (ZLT) model. On the other hand, under CO 2 atmosphere, the limiting steps of some of the reactions changed due to the influence of the coupling reaction. Overall, we observed that the activation energies of the reduction and oxidation reactions under coupling conditions were higher. ● Mathematical resolution of coupled reactions with oxidation and reduction reactions. ● Characteristics of Redox Reaction of Copper Slag in Ar/CO2 Atmospheres. ● Dynamics Characteristics of Copper Slag and Carbonaceous Materials. [ABSTRACT FROM AUTHOR]

A natural clinoptilolite zeolite was modified by ultrasonic-assisted chemicals (NaOH, FeCl 3 and HCl) to improve their performance in ammonium removal from (waste) water. The obtained modified zeolites were characterized by Field Scanning Electron Microscope (FESEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD) and gas sorption techniques to understand the relation between physiochemical factors of the modified zeolites and ammonium adsorption. The highest elimination efficiency of ammonium by the natural zeolite modified by ultrasonic-assisted HCl treatment, HZU2, was ≥ 99%. However, ammonium removal by the raw natural zeolite was only 51.66%. The efficiencies of ammonium removal in the presence of various disturbing anions and cations by the HZU2 and raw zeolite were in the range of 79–93% and 15–30%, respectively. The HZU2 was reused five times presenting stable adsorption removal of ammonium. The theoretical calculations were performed to identify the key kinetics and thermodynamics parameters controlling the adsorption rate. The maximum adsorption capacity (q max) of HZU2 obtained by the Langmuir model was about 142.85 (mg-ammonium/g-adsorbent) suggesting that the adsorption capacity of a monolayer and the relative content of alkali metal cations are suitable for the improvement of ammonium ion adsorption. The obtained thermodynamics parameters showed that the ammonium adsorption is a spontaneous and exothermic physisorption process. Consequently, we showed that ultrasonic-assisted chemical modification is a promising approach to control both textural properties and chemical composition of natural zeolites to enhance the ammonium removal from wastewater. [Display omitted] • An efficient approach of clinoptilolite zeolite modification was introduced. • Maximum ammonium adsorption capacity of modified zeolite increased by an order of magnitude. • Zeolite modification resulted higher resistance to disturbing ions in ammonium removal. • Modified zeolite was reusable at least five times. • Key parameters of kinetic and thermodynamic controlling ammonium adsorption were calculated. [ABSTRACT FROM AUTHOR]

Transesterification is one of the main biodiesel production method that produces huge amount of wastewater due to the high organic substance content (COD =300000-400000 mg/L, oil and grease= 17000-25000 mg/L). Although there are several treatment methods, flotation is the current conventional treatment method for oil and grease (O&G) before the biological treatment. In this study solvent extraction method was developed for pre-refining of biodiesel wastewaters. For the solvent extraction method, hexane and methyl-tertiary-butyl ether (MTBE) were determined as the most efficient solvents for the extraction of O&G. In this work, extraction kinetics and extraction thermodynamics were investigated for COD and O&G. The effect of solution pH and solvent ratio were investigated onto the solvent extraction process to optimize the developed method. The experimental results show that extraction method effectively removes the COD and O&G by 99.0% at pH 2 for both solvents. Experimental results also showed that depending on free energy change COD removal efficiency of hexane is higher than MTBE. COD extraction kinetics perfectly fits to the pseudo-second order kinetics. The necessary solvent/water ratio was found as 1/1 volume ratio for both solvents. The experimental results show that hexane extraction could effectively remove the COD, O&G and TOC by 96.0%, 99.8% and 91.0%, respectively, at the optimized conditions of pH 2.0, 1/1 solvent-water ratio and 30 min extraction time. [ABSTRACT FROM AUTHOR]

Abstract A non-stoichiometry thermodynamic approach based on Gibbs free energy minimization is developed to predict the performance of hydrogen production from gasification of sewage sludge in supercritical water (SCWG). The study focuses on predicting of the influence of operating conditions on SCWG performance. It was done by varying the reaction temperature (400°C, 500°C, 600°C, 700°C, 800°C), feedstock concentration (5%–50%), and reaction pressure (25 MPa, 30 MPa, and 35 MPa). The potential addition of lignite coal into the process also has been investigated. The prediction results showed that the reaction temperature and feedstock concentration had a stronger influence than the reaction pressure. The higher temperature and lower feedstock concentration favored the hydrogen yield and cold gas efficiency. The addition of lignite coal during gasification of sewage sludge in supercritical water slightly influence to the H 2 yield and cold gas efficiency. It was expected that the present work is very helpful for evaluating and optimizing the performance of gasification process in supercritical water. [ABSTRACT FROM AUTHOR]

In this work, the P4VP was synthesized by radical polymerization. The quaternization of this polymer by octyl bromide leads to the two copolymers [poly(N-octyl-4-vinylpyridinium bromide] named P4VPC8Br 48.8% and P4VPC8Br 72%. The thermodynamic behavior associated with the potentiometric titration of the copolymers, was reported in the temperature range (293.16–333.16 K) and as a function of the concentrations (0.25×10−4 mmol/dm3 12.3×10−4 mmol/dm3). The free energy of dissociation ΔGdiss variation versus the neutralization degree shows the negative value due to the steric and electrostatic effect of the alkyl chains. The positive values of ΔH and ΔS confirmed the spontaneity and disorder of the reaction. The critical concentration C* of the two copolymers was determined from the enthalpy ΔH0 and entropy ΔS0 changes. The transition in conformation of the copolymer chains was influenced by the presence of hydrophobic-hydrophilic and hydrophobic-hydrophobic interactions. [ABSTRACT FROM AUTHOR]

Highlights • CRL supported on OPL-SiO 2 possess substantial thermal and storage stability. • CRL immobilized onto OPL-SiO 2 afforded 93.9% yield of butyl butyrate in 3 h. • CRL/OPL-SiO 2 -catalyzed esterification reaction by bi-bi Ping Pong mechanism. • Process factors for synthesizing butyl butyrate were successfully optimized by RSM. • Biocompatibility of OPL-SiO 2 competes favorably with TEOS and TMOS. Abstract The present study reports on Candida rugosa lipase (CRL) supported on magnetized nanosilica from oil palm leaves (CRL/Gl-A-SiO 2 -MNPs) and its utilization in the catalytic synthesis of butyl butyrate. Statistical optimization of process parameters, viz: enzyme loading, incubation time, temperature and substrate molar ratio (1-butanol:n-butyric acid), was executed using the Box–Behnken Design. Under optimized conditions, using 3.5 mg/mL of CRL/Gl-A-SiO 2 -MNPs, molar ratio of 2:1, incubated at 45 °C a 93.9% yield of ester was achieved in 3 h. CRL/Gl-A-SiO 2 -MNPs-catalyzed the esterification reaction according to Bi-Bi Ping Pong mechanism. The obtained kinetic values corresponded to V max of 0.298 mM/min, as well as Michaelis-Menten constants for substrates, n-butyric acid (K M a) and 1-butanol (K M b) of 17.274 and 13.780 mM, respectively. The values for K cat , K eff and inhibition constant for 1-butanol (K i b) for the CRL/Gl-A-SiO 2 -MNPs-catalyzed esterification are 5.109/min, 0.371/min mM−1 and 288.184 mM, respectively. CRL/Gl-A-SiO 2 -MNPs exhibited higher thermal-stability than the aggregated CRL, as seen in the attained higher values of half-life (45.894 min), D -value (152.45 min), E d (125 KJ/mol), Δ H d ∘ (122.64 KJ/mol) and Δ G d ∘ (11.957 KJ/mol) at 70 °C. Storage stability of CRL/Gl-A-SiO 2 MNPs was improved by ∼ 9 fold over the aggregated CRL when incubated at room temperature. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Simultaneous removal of MB and SO mixture via reactive adsorption is presented. • Kinetic and thermodynamic parameters were estimated using reactive adsorption. • Simultaneous degradation pathways of Methylene Blue and Safranin O are proposed. • k L , D, and k R were estimated using film solid pore diffusion model for MB and SO dyes. Abstract Simultaneous reactive adsorption of Methylene Blue (MB) and Safranin O (SO) was carried out from a binary aqueous mixture using Fe-GAC/H 2 O 2. Maximum simultaneous removal was found to be 96.2% and 90.2% for MB and SO respectively after 7 h of reactive adsorption using 0.5 g/L Fe-GAC and 20 mM H 2 O 2 optimized doses. Degradation activities of the dyes were accelerated by increasing temperature from 15 to 35 °C. Apparent kinetic reaction rate constant was also increased with increasing temperature and consequently, activation energies of the degradation of individual dyes present in mixture were estimated and found to be 28.59 kJ mol−1 and 32.53 kJ mol−1 for MB and SO respectively. Thermodynamic parameters for MB and SO activation were assessed for the degradation process. Thermodynamic study and ESI-MS analyses revealed that molecule of SO is more difficult to remove than MB. Degradation pathways for MB and SO have been proposed which indicated that the dyes were degraded via demethylation and hydroxylation processes. For pure adsorption of MB and SO, intraparticle diffusion model and extended Freundlich model were found suitable for kinetic and thermodynamic studies, respectively. A film solid pore diffusion model was developed and used to predict the surface mass transfer coefficients (k L), diffusion coefficients (D) for adsorption and reactive adsorption, along with surface reaction rate constants (k R) for reactive adsorption for a binary dye system containing MB and SO. Results from model and experiments were analogous and removal of MB was found to be faster than SO. [ABSTRACT FROM AUTHOR]

Azolla Filiculoides (AF) were used for the sorption of tetracycline (TC) from aqueous solution. A systematic study of the adsorption process was performed by varying adsorbent amount, initial TC concentration, sorption time and temperature. The equilibrium adsorption data were analyzed using four widely applied isotherms: Langmuir, Freundlich, Dubinin-Radushkevich and Temkin. The results revealed that Langmuir isotherm fit the experimental results well. Kinetic analyses were conducted using pseudo-first and second-order models and the intra particle diffusion model. The regression results showed that the adsorption kinetics were more accurately represented by pseudo-second-order model. The Standard free energy changes (ΔG0), standard enthalpy change (ΔH0), and standard entropy change (ΔS0) were calculated using adsorption equilibrium constants obtained from the Langmuir isotherm at different temperatures. All ΔG0 values were negative; the ΔH0 values and ΔS0 values of Azolla Filiculoides biomass were 3.36 kJ/mol and 14.4 J/mol K, respectively. Results suggested that the TC adsorption on biomass was a spontaneous and endothermic process. [ABSTRACT FROM AUTHOR]

Hexavalent chromium Cr(VI), a constituent of wastewater from many industries, is regulated by the Environmental Protection Agency (EPA) as one of the priority pollutants. Adsorption is an important technique that can be used for Cr(VI) removal from wastewater. The challenge in adsorption techniques is to find a cheap, widely available adsorbent that has a high adsorption capacity to Cr(VI). Dates stones (DS) and palm fiber (PF) are two agricultural wastes that are produced from palm trees. These adsorbent materials were tested in batch systems to investigate the different factors that may affect the adsorption process, e.g. adsorbent dose, initial adsorbate concentration, pH of aqueous solution and agitation time. Equilibrium models tested include Langmuir, Freundlich, Temkin and Dubinin-Radushkevich. Freundlich adsorption isotherm was found to best fit the experimental data. The maximum adsorption capacities obtained for DS and PF were 16 and 6 mg/g, respectively. Kinetic studies indicated that the adsorption of Cr(VI) on both DS and PF was fast in the first stage of the adsorption process. The equilibrium was reached in less than 2 h for both adsorption systems. The adsorption process was found to be second order with both adsorbent and adsorbate concentration to affect the adsorption process. Film diffusion and intraparticle diffusion models were found to simultaneously influence the adsorption. The adsorption process was found to be favorable and of physical nature. [ABSTRACT FROM AUTHOR]

The massive burning of fossil fuels to fulfill the augmenting energy demands of world have triggered the ever-increasing emission of carbon dioxide (CO 2 ); the main cause of global warming. Photocatalytic reduction of CO 2 into solar fuels and chemicals using everlasting solar energy seems promising technology to contemporaneously curb the globa1 warming and partially fulfill the energy requirements. This study focused on understanding the main challenges in photocatalytic CO 2 reduction systems and strategies to improve the efficiency of solar fuels production. The overview of fundamentals and latest developments in titania (TiO 2 ) based photocatalytic CO 2 reduction systems have been discussed. More specifically, thermodynamics, mass transfer, selectivity and reaction mechanism of photocatalytic CO 2 reduction are critically deliberated. In the main stream, developments have been categorized as strategies to enhance the different aspects such as visible light response, charge separation, CO 2 adsorption and morphology of photo-catalysts for TiO 2 based photocatalytic CO 2 reduction systems. Different modification techniques to overcome the low efficiency by fabricating advance TiO 2 nanocomposites through surface modifications, doping of metals, non-metals and semiconductor are discussed. The challenges lingering on against achieving the higher photocatalytic conversion of CO 2 into solar fuels are also investigated. In conclusion, brief perspectives and recommendations on the development of efficient photocatalysts are outlined which would be of vital importance for the improvements of conversion efficiency of CO 2 reduction system. [ABSTRACT FROM AUTHOR]

In this study, the as-synthesized magnetic graphene oxide (mGO) nanocomposite was grafted with amine groups, namely the first and second generation of polyamidoamine dendrimer (mGO1st- and mGO2nd-PAMAM) with different oxidation levels and shown to be effective in removing Cd (II), Pb (II) and Cu (II) ions from aqueous solution in batch system. Raman spectroscopy, atomic force microscopy (AFM), Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to identify the structural characteristics of amine functionalized nanocomposites. The pH ZPC value of the sorbent was estimated to be 7.2 by titration methods. The different amine functionalization of the mGO stage of the two adsorbents and the differences in the behavior of the three metal ions under magnetic strength were found to be important in order to consider the performance of the adsorption systems. The adsorption capacities of metal ions were 435.85, 326.729 and 353.59 mg g −1 for Cd (II), Pb (II) and Cu (II), respectively. The obtained data were successfully fitted with the pseudo-second-order kinetic model. The adsorption capacity was dependent on the temperature and increased with the increase of temperature. Also, the equilibrium data were evaluated using the Freundlich, Langmuir, and Redlich–Peterson (R–P) isotherm models, suggesting the obtained data were fitted to the Freundlich isotherm model and the adsorption mechanism is heterogeneous. According to thermodynamic analysis, the adsorption process was found to be endothermic and spontaneous in nature. Moreover, the adsorbent was regenerated after a five time adsorption–desorption cycle without significant loss in adsorption capacity. The results from this study support that the as-synthesized adsorbent proves excellent removal ability of the metal ion from water and wastewater. [ABSTRACT FROM AUTHOR]

This study demonstrates the performance and characterisation of Borassus Flabellifer shell derived Nano Composite (BNC) in the adsorption process for the removal of reactive diazo dyes. Borassus flabellifer shell, an agricultural waste material, is evaluated and subjected to activation under CO 2 atmosphere to obtain Borassus Flabellifer shell derived activated carbon (BAC). The resulted BAC is modified as BNC using magnetite nanoparticles by precipitation method. The texture and composition of BAC and BNC are observed by various analytical determinations like pH pZc , FTIR, powder-XRD, BET surface area, FE-SEM, EDX and VSM analysis. The batch study is conducted by varying pH, dosage, initial concentration and equilibration time. The experimental studies are carried out using the optimised data and the maximum removal capacity of BNC for the adsorption of reactive yellow 84 (RY84) is found to be 40 mg/g. The Langmuir equation suits the best-fit equilibrium adsorption isotherm model, which predicts the monolayer adsorption of RY84. The reaction kinetics of the adsorption process is best expressed by pseudo-second order model equation. The thermodynamic parameters attribute the spontaneous and endothermic processes involved in the adsorption mechanism. The recovery of BAC and BNC are attempted and examined, while the regeneration of BNC is successful up to four cycles. [ABSTRACT FROM AUTHOR]