Optimization of preparation conditions for activated carbon from palm oil fronds using response surface methodology on removal of pesticides from aqueous solution

Palm oil fronds were used to prepare activated carbon using the physiochemical activation method, which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO₂) gasification. The effects of variable parameters activation temperature, activation time and chemical impregnation ratios (KOH: char by weight) on the preparation of the activated carbon and for the removal of pesticides: bentazon, carbofuran and 2,4-Dichlorophenoxyacetic acid (2,4-D) were investigated. Based on the central composite design (CCD), two factor interaction (2FI) and quadratic models were respectively employed to correlate the effect of variable parameters on the preparation of activated carbon used for the removal of pesticides with carbon yield. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The optimum conditions for preparing the activated carbon from oil palm fronds were found as follows: activation temperature of 750 °C, activation time of 2 h and chemical impregnation ratio of 2.38. The percentage error between predicted and experimental results for the removal of bentazon, carbofuran and 2,4-D were 8.2, 1.3 and 9.2%, respectively and for the yield of the palm oil frond activated carbon was 5.6.     

Adsorption of cationic methylene blue dye using microwave-assisted activated carbon derived from acacia wood: Optimization and batch studies

This study assesses the performance of optimized acacia wood-based activated carbon (AWAC) as an adsorbent for methylene blue (MB) dye removal in aqueous solution. AWAC was prepared via a physicochemical activation process that consists of potassium hydroxide (KOH) treatment, followed by carbon dioxide (CO₂) gasification under microwave heating. By using response surface methodology (RSM), the optimum preparation conditions of radiation power, radiation time, and KOH-impregnation ratio (IR) were determined to be 360 W, 4.50 min, and 0.90 g/g respectively, which resulted in 81.20 mg/g of MB dye removal and 27.96% of AWAC’s yield. Radiation power and IR had a major effect on MB dye removal while radiation power and radiation time caused the greatest impact on AWAC’s yield. BET surface area, mesopore surface area, and pore volume of optimized AWAC were found to be 1045.56 m²/g, 689.77 m²/g, and 0.54 cm³/g, respectively. Adsorption of MB onto AWAC followed Langmuir and pseudo-second order for isotherm and kinetic studies respectively, with a Langmuir monolayer adsorption capacity of 338.29 mg/g. Mechanism studies revealed that the adsorption process was controlled by film diffusion mechanism and indicated to be thermodynamically exothermic in nature.     

Synthesis of activated carbon foams with high specific surface area using polyurethane elastomer templates for effective removal of methylene blue

Carbon foams have gained significant attention due to their tuneable properties that enable a wide range of applications including catalysis, energy storage and wastewater treatment. Novel synthesis pathways enable novel applications via yielding complex, hierarchical material structure. In this work, activated carbon foams (ACFs) were produced from waste polyurethane elastomer templates using different synthesis pathways, including a novel one-step method. Uniquely, the produced foams exhibited complex structure and contained carbon microspheres. The ACFs were synthesized by impregnating the elastomers in an acidified sucrose solution followed by direct activation using CO₂ at 1000 ℃. Different pyrolysis and activation conditions were investigated. The ACFs were characterized by a high specific surface area (S_BET) of 2172 m²/g and an enhanced pore volume of 1.08 cm³/g. Computer tomography and morphological studies revealed an inhomogeneous porous structure and the presence of numerous carbon spheres of varying sizes embedded in the porous network of the three-dimensional carbon foam. X-ray diffraction (XRD) and Raman spectroscopy indicated that the obtained carbon foam was amorphous and of turbostratic structure. Moreover, the activation process enhanced the surface of the carbon foam, making it more hydrophilic via altering pore size distribution and introducing oxygen functional groups. In equilibrium, the adsorption of methylene blue on ACF followed the Langmuir isotherm model with a maximum adsorption capacity of 592 mg/g. Based on these results, the produced ACFs have potential applications as adsorbents, catalyst support and electrode material in energy storage systems.     

Optimization and mass transfer simulation of remazol brilliant blue R dye adsorption onto meranti wood based activated carbon

Remazol brilliant blue R dye (RBBR) brings toxicity to living organisms once it enters the environment. This study utilized response surface methodology (RSM) and Polymath software for optimization and mass transfer simulation purposes, respectively. RSM revealed that the optimum preparation conditions of meranti wood-based activated carbon (MWAC) were 441 W, 5.76 min, and 1.35 g/g for radiation power, radiation time, and KOH:char impregnation ratio (IR), respectively, which translated into 86.39 mg/g of RBBR uptakes and 31.94 % of MWAC’s yield. The simulation study predicted the mass transfer rate, r_m to be 112.20 to 1007.50 s^?1 and the adsorption rate, k₁ to be 3.96 to 4.34 h^?1. The developed model predicted the adsorption surface area, a_m to be 790.04 m²/g and this value is highly accurate as compared to the actual mesopores surface area of 825.58 m²/g. Mechanism analysis divulged that the interaction that occurred between RBBR molecules and MWAC’s surface were hydrogen bond (methylene and alkyne), dipole–dipole force (alkyl carbonate, terminal alkyne, and methoxy), and ion–dipole force (primary amine). The isotherm and kinetic studies found that the adsorption data obeyed the Freundlich model and pseudo-first-order (PFO) model the best, respectively. The Langmuir maximum adsorption capacity, Q_m was computed to be 327.33 mg/g. Thermodynamic parameters were calculated to be ?4.06 kJ mol^?1, 0.06 kJ mol^?1 K^?1, –22.69 kJ mol^?1, and 16.03 kJ mol^?1 for ΔH°, ΔS°, ΔG°, and E_a, respectively, which signified the adsorption process studied was exothermic, spontaneous and governed by physisorption.     

Kinetics of adsorption and desorption of Pb(II) in aqueous solution on activated carbon by two-site adsorption model

The adsorption and desorption equilibrium and kinetics of lead ions from aqueous solutions on a granular activated carbon (GAC) were examined. Rapid increase followed by slow increase in Pb(II) amount on the GAC was observed as a function of time for the adsorption, while rapid decrease and consecutive very slow decrease was observed in desorption. Based on the experimental results, a two-site adsorption model was proposed for the adsorption and the desorption of Pb(II) under the study conditions. The Pb(II) adsorption on the GAC was estimated to have simultaneously occurred on the strong and the weak adsorption sites. Conventional Langmuir-type kinetic equations were introduced to quantitatively predict the adsorption and desorption with the two-site model by optimizing the parameters to fit the equilibrium and the kinetic experimental results. The equilibrium and kinetic experimental results could be represented by the equations by using one set of the common Langmuir parameters. Resultant kinetic parameters revealed that the adsorption equilibrium constant was two orders of magnitude greater for strong adsorption site than for weak adsorption site, though the maximum number of weak adsorption site was 1.5 times as great as that of strong adsorption site. The strong adsorption equilibrium constant resulted from a small desorption rate constant for the site. The equations were demonstrated to be applicable for predicting other desorption performances as well.     

Numerical investigations of response surface methodology for organic dye adsorption onto Mg-Al LDH -GO Nano Hybrid: An optimization,kinetics and isothermal studies

We developed Mg-Al LDH intercalated with NO₃^- decorated Graphene Oxide nanohybrid with positive cationic textile dye adsorption, such as methylene blue. Contact time, initial dye concentration, and pH were among the independent variables used in the study. The Response Surface Model (RSM) was used to optimise and describe the interdependencies of the different variables. The method was evaluated using the Box-Behnken design (BBD). A second-order polynomial model was used to understand the experimental results, and the effectiveness of the chosen model was verified by its strong agreement in determination coefficient values. The adsorption results suited the best for the Langmuir isotherm than the D-R and Freundlich isotherms, resulting in efficient adsorption of 187.62 ?mg/g, proving LDH-GO is an effective dye adsorbent. Simultaneously, the kinetics were based on the pseudo-second-order model, and additional kinetic factors such as Elovich, pseudo-first-order, and intra-particular diffusion were examined. According to Thermodynamic studies, the adsorption process is spontaneous, which is exothermic and characterised by increased randomness. According to a regeneration test, even after four cycles, 37% of the removal efficiency for MB can be achieved. Based on this report, these materials can be used as an adsorbent to remove the dye.     

Removal of nickel (II) ions from aqueous solutions using modified activated carbon: A kinetic and equilibrium study

Removal nickel from the aquatic environment is a serious environmental problem in view of public health. The present article studies the applicability of activated carbon, obtained from graphite, as a source of adsorbents to remove nickel from the aqueous polluted water. Activated carbon was obtained by steam activation of graphite and then was oxidized by nitric acid followed by modification with Tetraethylenepentamine (TEPA). The applicability of graphite activated carbon (GAC), and modified activated carbon by Tetraethylenepentamine (GACA) to remove nickel ions Ni(II) from aqueous media was studied. The effect of pH, initial concentration, contact time, and the temperature was evaluated during Ni(II) removal operating in a batch process. Experimental results show that the studied activated carbon have a good adsorption capacity for Ni(II) ions and could reduce the concentrations of it in the groundwater. A maximum removal efficient of Ni(II) was observed at 55°C. The experimental data showed an endothermic and spontaneous process, which was fitted to Langmuir isotherm. Based on our results, we can conclude that it is possible to use GAC and GACA for removing Ni(II) effectively from groundwater.     

Statistical analysis and optimization of photodegradation efficiency of methyl orange from aqueous solution using cellulose/zinc oxide hybrid aerogel by response surface methodology (RSM)

The photodegradation efficiency of cellulose-X/zinc oxide-Y (CA-X/ZnO-Y) aerogels was studied to degrade methyl orange (MO) as an organic dye pollutant from an aqueous solution under UV light irradiation. In this study, the initial pH of the solution (3, 7, and 11), the photocatalyst dosage (3, 6, and 9 g L^-1), the initial concentration of solution MO (10, 20, and 30 ppm), and the concentration of cellulose in CA-X/ZnO-Y hybrid aerogel (3, 6, and 9 wt%) were selected as four variable parameters, whereas the photoderadation performance was selected as the response. Moreover, the response surface methodology (RSM) analysis was carried out to investigate the influence of four various experimental factors at different times on the degradation of MO. The adequacy result of the proposed models displays that total of the proposed models can predict the photodegradation efficiency of MO by CA-x/ZnO-y aerogel. The optimization results of the process showed that pH = 3 and concentration of MO = 10 ppm, photocatalyst dosage (9 g L^-1), and MCC concentration (9 g) are the optimal level of the studied parameters. Also, the results showed that desirability of 0.96 confirms the acceptance and applicability of the model where the RSM model is a helpful technique for the optimum conditions design.     

Monitoring of Zn(II) and Cd(II) adsorption on activated carbon from aqueous multicomponent solutions by differential pulse polarography (DPP)

The adsorption process of Zn(II) and Cd(II) from aqueous solution has been investigated from both kinetic and equilibrium standpoints, using differential pulse polarography (DPP) on a mercury dropping electrode as the analytical technique. With such an aim, adsorption experiments were performed using not only a single metal ion–Zn(II) or Cd(II) solution but also a multi-component ion metal–Zn(II), Cd(II) and Hg(II) solution. The influence of the pH change in the multi-component ion metal solution on the adsorption of Zn(II) and Cd(II) was also studied. The adsorption processes is relatively fast for Zn(II) and Cd(II). The presence of two foreign ions in the solution slightly speeds up the adsorption process for Zn(II) and significantly slows it down for Cd(II). The adsorption isotherms are similarly shaped for Zn(II) and Cd(II). The addition of the foreign ions has a more unfavourable effect on the adsorption for Cd(II) than for Zn(II). At pH 2, neither Zn(II) nor Cd(II) is adsorbed practically on the carbon. The voltammetric approach has proved to be a fast and efficient method that, at the same time, enables one to monitor the adsorption of Zn(II) and Cd(II) with potential on-line application, which could be useful in waste-water treatment.     

Response surface methodology for the modelling of copper removal from aqueous solutions using micellar-enhanced ultrafiltration

Response surface methodology (RSM) was used to study the cumulative effect of the various parameters, namely surfactant (sodium dodecyl sulphate (SDS), anionic) concentration, pH, and surfactant/metal molar ratio and to optimise the process conditions for the maximum removal of copper from aqueous solutions via micellar-enhanced ultrafiltration (MEUF). For obtaining the mutual interaction between the variables and optimising these variables, a central composite design (CCD) by use of response surface methodology was employed. The analysis of variance (ANOVA) of the quadratic model demonstrated that the model was highly significant. The model was statistically tested and verified by experimentation. Values of pH at the range of ca. 7.5 were very successful for the separation. The maximum rejection coefficient of 98.4% was obtained for the following optimal conditions: SDS/Cu²⁺ molar ratio *r = 7.85, *pH 7.36, *C_surf = 6.82 g/l SDS. A modification of micellar-enhanced ultrafiltration for the removal of copper from aqueous solutions was studied by the implementation of sodium dodecyl sulphate–polyethylene glycol (PEG) aggregates. A full factorial design (FFD) was employed for studying the effect of molar ratio of surfactant/metal, pH and mass ratio of surfactant/polymer at a constant concentration of surfactant equal to 5 g/l. The comparison of the two systems in the region of their common factors showed that the addition of polyethylene glycol caused a slight increase in rejection coefficient of copper but also could function as ‘scavenger’ for surfactant species.     

Selective adsorption and removal ability of pine needle-based activated carbon towards Al(III) from La(III)

Rare earth elements are an important strategic resource. As one of the most valuable member, lanthanum plays a key role in lanthanide. However, trace Al(III) impurity in lanthanum materials can seriously damage the performance of lanthanum materials. In this paper, a nitrogen-containing activated carbon, AC-PN-700, was synthesized using pine needle as raw material and KOH as activator. The AC-PN-700 was characterized by surface area analyzer, elemental analysis and FT-IR. The adsorption and selective ability of AC-PN-700 towards Al(III) were investigated. The BET specific surface area of AC-PN-700 was 596.4 m².g^?1, and the average pore diameter was 2.7?nm. Depend on its large specific surface, well-developed internal pore structure and abundant nitrogen-containing functional groups, the AC-PN-700 possesses strong adsorption affinity and excellent recognition selectivity towards Al(III). The adsorption capacity of AC-PN-700 towards Al(III) could reach to 3.89?mg.g^?1, removal rate towards Al(III) was almost 100%, and relative selectivity coefficients with respect to La(III) is 9.5. The empirical Freundlich isotherm was found to describe well the equilibrium adsorption data. In addition, AC-PN-700 possesses better regeneration ability and reusability.     

Optimization of cadmium adsorption from aqueous solutions by functionalized graphene and the reversible magnetic recovery of the adsorbent using response surface methodology

Novel functionalized graphene adsorbent was prepared and characterized using different techniques. The prepared adsorbent was applied for the removal of cadmium ions from aqueous solution. A response surface methodology was used to evaluate the simple and combined effects of the various parameters, including adsorbent dosage, pH, and initial concentration. Under the optimal conditions, the cadmium removal performance of 70% was achieved. A good agreement between experimental and predicted data in this study was observed. The experimental results revealed of cadmium adsorption with high linearity follow Langmuir isotherm model with maximum adsorption capacity of 502 mg g^?1, and the adsorption data fitted well into pseudo‐second order model. Thermodynamic studies showed that adsorption process has exothermic and spontaneous nature. The recommended optimum conditions are: cadmium concentration of 970 mg L^?1, adsorbent dosage of 1 g L^?1, pH of 6.18, and T = 25 °C. The magnetic recovery of the adsorbent was performed using a magnetic surfactant to form a noncovalent magnetic functionalized graphene. After magnetic recovery of the adsorbent both components (adsorbent and magnetic surfactant) were recycled by tuning the surface charges through changing the pH of the solution. Desorption behavior studied using HNO₃ solution indicated that the adsorbent had the potential for reusability.     

Green synthesis of activated carbon doped tungsten trioxide photocatalysts using leaf of basil (Ocimum basilicum) for photocatalytic degradation of methylene blue under sunlight

Tungsten oxide (WO₃) nanoparticles were prepared hydrothermally by basil leaves extract, and Activated Carbon (AC) was prepared by the carbonization of date pits. Moreover, 1, 2 and 3% of AC doped WO₃ nanoparticles have been fabricated under hydrothermal conditions. The obtained samples have been characterized by using different techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), simultaneous thermogravimetric analysis (TG-DTGA), fourier transform infrared (FT-IR), BET surface area, and Ultra-Violet spectroscopy (UV–Vis). It was observed that band-gap energy of the fabricated materials decreases by increasing AC amount. Similarly, BET surface area and porosity results showed increasing the content of AC, surface area, pore size and pore volume were decreased. The functional groups, determined by FT-IR, played a significant role in the photocatalytic performance. The photocatalytic performance of fabricated samples was used for the degradation of methylene blue (MB) at neutral pH under visible light radiations, and it is observed that WO₃/3%AC photocatalyst showed the highest degradation of MB. Both, capped phytochemicals of basil extract and the nanocomposites, were improved the photocatalytic performance, about 94% photodegradation was observed within 25 min under the reaction conditions. The photocatalyst was stable and about 85% and 81% photodegradation of MB were found under the two times of reusability tests.     

Adsorption of antimony using amino-functionalized magnetic MIL-101(Cr): Optimization by response surface methodology

Amino-functionalized magnetic MIL-101(Cr) was prepared via a one-step solvothermal method, characterized, and applied in adsorptive Sb(III) removal. The effects of solution pH, adsorbent dosage, and coexisting substances on the adsorption of Sb(III) by MIL-101(Cr)–NH₂/MnFe₂O₄ were studied. The adsorption kinetics were analyzed using pseudo-first order, pseudo-second order, intraparticle diffusion, and Elovich models, while Freundlich and Langmuir isotherm models were used to fit the experimental data. The pseudo-second-order kinetic model provided the best fit for the kinetic data. The maximum adsorption capacity of MIL-101(Cr)–NH₂/MnFe₂O₄ for Sb(III) was 91.07 ​mg/g, as calculated using the Langmuir adsorption isotherm model. Thermodynamic analysis revealed that the adsorption of antimony onto MIL-101(Cr)–NH₂/MnFe₂O₄ is spontaneous and endothermic, while response surface optimization revealed that the optimal conditions for Sb(III) adsorption by MIL-101(Cr)–NH₂/MnFe₂O₄ are an adsorbent loading of 222.55 ​mg/L, a pH of 4.5, and a temperature of 294.59 ​K. The predicted adsorption capacity of MIL-101(Cr)–NH₂/MnFe₂O₄ for Sb(III) is only a 1.8% deviation from the actual value. Furthermore, MIL-101(Cr)–NH₂/MnFe₂O₄ exhibits strong magnetism, allowing it to be separated from wastewater using a magnet. Finally, a preliminary economic analysis showed that the cost of treating a ton wastewater containing 25 ​mg/L antimony using this composite would be 26.24 USD. Thus, MIL-101(Cr)–NH₂/MnFe₂O₄ is promising for treatment of Sb(III)-containing wastewater.     

Optimization of adsorption parameters for Fe (III) ions removal from aqueous solutions by transition metal oxide nanocomposite

Manganese oxide nanocomposite (Mn₂O₃/Mn₃O₄) was prepared by sol-gel technique and used as an adsorbent. Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and Field Emission Scanning Electron Microscopy (FE-SEM) were used to characterize the adsorbent. The response surface methodology (RSM) was employed to evaluate the effects of solution pH, initial Fe (III) ions concentration, adsorbent weight, and contact time on the removal ratio of the Fe (III) ions. A total of 27 adsorption experimental runs were carried out employing the detailed conditions designed based on the Box-Behnken design (BBD). Results showed that the pH of the solution and initial Fe (III) ions concentration were the most significant parameters for Fe (III) ions removal. In process optimization, the maximal value of the removal ratio of Fe (III) was achieved as 95.80%. Moreover, the corresponding optimal parameters of adsorption process were as: contact time?=?62.5?min, initial Fe (III) concentration?=?50?mg/L, adsorbent weight?=?0.5?g, and pH?=?5. The experimental confirmation tests showed a strong correlation between the predicted and experimental responses (R²?=?0.9803). The fitness of equilibrium data to common isotherm equations such as Langmuir, Freundlich, and Temkin were also tested. The sorption isotherm of adsorbent was best described by the Langmuir model. The kinetic data were analyzed using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models. The adsorption kinetics of Fe (III) ions were well fitted with the pseudo-second-order kinetic model.     

Statistical optimizing of electrocoagulation process for the removal of Cr(VI) using response surface methodology and kinetic study

Optimization of electrocoagulation (EC) using copper electrode in terms of Cr(VI) removal from simulated waste water was executed by applying surface methodology and kinetic study. In this research, electrocoagulation process was applied to evaluate the outcome of operational parameters such as initial Cr(VI) concentration, pH, electrode distance, current density and supporting electrolyte (NaCl) concentration for the removal of Cr(VI). The experimental results showed that current density of 41.32 A/m², electrode distance of 1.4 cm, initial pH of 5.65, time of electrocoagulation of 40 min and initial conductivity 0.21 ms are the optimal operating parameters to attain 93.33% removal efficiency of Cr(VI) ions from simulated waste water. The high value of R² = 98.15 and R²_adj = 96.49 show that fitted model confirms a good agreement with the real and predicted Cr(VI) removal percentage. It was concluded that Cr(VI) ion removal follows the first-order kinetic model by kinetic study of EC process.     

The efficacy of sono-electro-Fenton process for removal of Cefixime antibiotic from aqueous solutions by response surface methodology (RSM) and evaluation of toxicity of effluent by microorganisms

The increasing use of antibiotics by humans and their persistence in the environment leads to the development of drug resistance, which is nowadays considered as an environmental problem. The aim of this study was to determine the efficacy of sono-electro-Fenton process for removal of Cefixime antibiotic from aqueous solutions by Response Surface Methodology (RSM) and to evaluate the toxicity of effluent by microorganisms. In the present study, the degradation of synthetic wastewater containing Cefixime was investigated in a reactor (with a useful volume of 1 L) located in the chamber of the ultrasonic device. The effects of pH, hydrogen peroxide concentration, voltage, initial antibiotic concentration, and electrolysis time were investigated using the Box-Behnken model, and the optimal conditions for elimination were obtained by analyzing the variance. The performance of the electro-Fenton and ultrasonic process was evaluated separately and in combination under optimal conditions. Toxicity of inlet and outlet was tested by Escherichia coli and Staphylococcus aureus, and growth inhibition percentage was calculated. The intermediates were determined by LC-MS with the lowest molecular mass. The results showed that the sono-electro-Fenton process under optimum conditions, including pH of 3.07, hydrogen peroxide concentration of 0.85 mL/L, voltage 15 V, initial antibiotic concentration 10.4 mg/L and electrolysis time of 81.5 min has a percentage of removal of 97.5%. Under optimum conditions, the percentage of removal by electro-Fenton and ultrasonic separately were 81.7% and 9%, respectively, and in the hybrid process of sono-electro-Fenton, the percentage of removal increased to 97.5%. The results also showed that the biological toxicity of the outlet effluent from the sono-electro-Fenton process, compared to the inlet solution, was significantly reduced. So, we conclude that the Sono-electro-Fenton process has a significant effect on the removal of Cefixime from aqueous solutions and can also significantly reduce the biological toxicity of the effluent.     

A novel natural source Vicia faba L. membranes as colourant: development and optimisation of the extraction process using response surface methodology (RSM)

In this research paper, an eco-friendly extraction process of dyes from Vicia faba L. membranes was developed. In this regard, the influence of independent process factors like the weight of material, the extraction time, the temperature and the sodium hydroxide concentration on the natural dye extraction from Vicia faba membranes was investigated. The optimisation of the extraction conditions and the effect evaluation of the different operating parameters were carried out using a Box–Behnken design under response surface methodology. The optimum conditions were found to be 66 °C, 90 min, 5 g and 0.1628 mol·L^?1 for extraction temperature, time, mass of the material and sodium hydroxide concentration, respectively. The efficiency of this extraction process under these optimum conditions was evaluated by measuring the total phenolic content (TPC), the total flavonoid content and the relative colour yield (K/S). In these operating conditions, good fastness ratios were observed for the dyed fabrics.     

Sequential injection analysis (SIA) and response surface methodology: A versatile small volume approach for optimization of photo-Fenton processes

Optimization of photo-Fenton degradation of copper phthalocyanine blue was achieved by response surface methodology (RSM) constructed with the aid of a sequential injection analysis (SIA) system coupled to a homemade photo-reactor. Highest degradation percentage was obtained at the following conditions [H₂O₂]/[phthalocyanine] = 7, [H₂O₂]/[FeSO₄] = 10, pH = 2.5, and stopped flow time in the photo reactor = 30 s. The SIA system was designed to prepare a monosegment containing the reagents and sample, to pump it toward the photo-reactor for the specified time and send the products to a flow-through spectrophotometer for monitoring the color reduction of the dye. Changes in parameters such as reagent molar ratios, residence time and pH were made by modifications in the software commanding the SI system, without the need for physical reconfiguration of reagents around the selection valve. The proposed procedure and system fed the statistical program with degradation data for fast construction of response surface plots. After optimization, 97% of the dye was degraded.     

Optimization of ultrasonic‐assisted extraction of phenolic antioxidants from Malus baccata (Linn.) Borkh. using response surface methodology

In this study, the optimum extraction conditions for maximum recovery of the content of total phenolics (TPC) and total antioxidant abilities were analyzed for Malus baccata (Linn.) Borkh. using response surface methodology. The effects of ethanol percentage (X₁,%), ultrasonic power (X₂, W) and extraction temperature (X₃, °C) on the total phenolic content (Y₁) and antioxidant ability (Y₂) were evaluated. A second‐order polynomial model produced a satisfactory fitting of the experimental data with regard to total phenolic content (R² = 0.9942, P < 0.0001) and antioxidant ability (R² = 0.9966, P < 0.0001). The optimized conditions were ethanol concentration of 61.0%, ultrasonic power of 308.6 W, extraction temperature of 51.1°C for TPC and 60.5%, 311.4 W, 51.6°C for antioxidant ability, the predicted values agreed well with the experimental values. Results implied that the major phenolic compounds in obtained extracts as chlorogenic acid, quercetin‐3‐gal/glu, quercetin‐3‐xyl/ara, phloretin‐2‐xyloside, quercetin‐3‐ rhamnoside, and phloridzin.