Central Composite Design Method Research Articles

Modification and Optimization of Groundnut (Arachis hypogaea) Roasting Machine

Roasting of groundnut is essential to ensure quality improvement, easy handling, safe storage, further processing, and value addition of the product. Therefore, the aim of the study was modified and optimized a groundnut roasting machine. Standard design parameters were used for the design modification. The design of the experiment had 27 runs. Machine speed (6.60, 12.80 and 19 rpm), roasting temperature (120, 160 and 200℃), and feed rate (120, 180 and 240 kg/h) were used as independent parameters, and the response variables include the moisture content of the groundnut, roasting efficiency, mechanical damage, throughput and quality efficiency of the machine. Response Surface Methodology (RSM) of the Design Expert Version 11 was adopted for the optimization process by applying the central composite design method for the Analysis of Variance (ANOVA) and optimized responses within the limit of the independent factors tested. Roasting temperature (200℃), machine speed (19 rpm) and feed rate (240 kg/h) were found as the optimum operational conditions which will optimally result in the optimal machine performance of 8.76% moisture content (r2 = 0.94), 76.99% roasting efficiency (r2 = 0.90), 2.46% mechanical damage (r2 = 0.86), 62.32 kg/h machine throughput (r2 = 0.98), 74.3% quality performance efficiency (r2 = 0.86) with the high desirability of 88%. An increase in machine speed increased the moisture content of the groundnut, roasting efficiency, mechanical damage, throughput, and quality efficiency of the machine. The study showed the optimal machine parameters for a groundnut roasting machine.

Empirical Modeling and Optimization of Laser Bending Process Parameters using the Central Composite Design Method for HDD Slider PSA/RSA Adjustment

This paper details the development and optimization of a laser adjustment process for the pitch static attitude and roll static attitude (PSA/RSA) to achieve the maximum bending angle without the burning of materials. The effects of process parameters (or factors) including the laser power, pulse repetition rate, and scanning time were investigated based on the central composite design method. Experiments were performed on a stainless steel (SST-300 series) suspension using a solid-state laser system and a charge-coupled device camera with image processing technology. Regression models of positive and negative PSA/RSA (or response) values were developed through a total of 20 experimental runs. The results showed that the PSA/RSA bending angle increases with increasing laser power and pulse repetition rate, while the bending angle decreases with increasing scanning time. The optimization determined that a higher laser power and lower scanning time had a more significant effect on the bending angle. However, the laser power cannot be increased above the melting point of the material, as this will lead to the formation of spongy debris on the stainless steel. The models were shown to accurately describe the relationship between the factors and responses. In addition, the laser bending mechanism for the PSA/RSA adjustment of a hard disk drive slider was investigated.

Surface functionalization of recycled polyacrylonitrile fibers with ethylenediamine for highly effective adsorption of Hg(II) from contaminated waters

In this research, recycled polyacrylonitrile fibers (PANFs) acquired from the textile recycling process were amino-functionalized in one simple step by means of ethylenediamine (EDA). The amino-functionalized polyacrylonitrile fibers (AF-PANFs) were utilized for adsorption of Hg(II) ions from aquatic media. Temperature and contact time during the synthesis were optimized by the Central Composite Design (CCD) method. FE-SEM, EDS, BET, and FT-IR analysis, and pHZPC measurement were conducted to characterize the features of the AF-PANFs. The average diameter of raw fiber was 20 μm, which increased 20 percent after functionalizing. The impact of independent parameters on the adsorption process was investigated using the Box-Behnken Design (BBD) method during the batch experiments. The column tests were conducted in a semi-continuous system with the removal efficiency of over 99% for various initial concentrations after specific cycles. Freundlich, Langmuir, UT, Redlich-Peterson, and Temkin isotherm models were employed to analyze the relation between the final concentration of Hg(II) (Co) and the equilibrium adsorption capacity (qe) of the AF-PANFs. According to the isotherm models and experimental results, the maximum qe of the AF-PANFs was 1116 mg g−1 at initial Hg(II) concentration of 850 mg L−1, contact time of 120 min, solution pH of 6, and at 40 °C. Kinetic and thermodynamic studies illustrated the approximate equilibrium time and endothermicity or exothermicity of the process. Regeneration of the AF-PANFs was accomplished for seven times without efficiency drop. The superb performance of the AF-PANFs in the presence of co-existing ions did not decline.

Catalytic activation of persulphate with Mn3O4 nanoparticles for degradation of acid blue 113: process optimisation and degradation pathway

ABSTRACT The performance of the persulphate/Mn3O4 nanoparticles (PS/Mn3O4) oxidation process was investigated for the degradation of acid blue 113 (AB113) azo dye. XRD, N2 adsorption-desorption analysis, FE-SEM and EDX confirmed the successful synthesis of Mn3O4 nanoparticles. The effect of three independent variables including PS concentration, Mn3O4 dosage and solution pH on the system response was optimised by genetic algorithm (GA) and central composite design (CCD) techniques. The results of ANOVA and fit statistics (P-value < 0.0001, = 0.9772) showed that the proposed quadratic model can predict the AB113 removal efficiency with high confidence. The optimum points for PS concentration, Mn3O4 dosage and solution pH were predicted to be 61.46 mg/L, 57.69 and 3.00, respectively, by CCD method. Under these conditions, after 60 min of reaction, the maximum experimental removal efficiency of AB113 in the PS/Mn3O4 oxidation system and separate application of PS and Mn3O4 were obtained 96.70%, 18.0% and 7.0%, respectively. The pseudo-first-order rate constants of AB113 degradation the PS/Mn3O4 oxidation system and separate application of PS and Mn3O4 were 0.0597, 0.0029 and 0.0015 min−1, respectively. In this way, the synergistic effect for degradation of AB113 in the PS/Mn3O4 was determined 92.6%. Oxalic acid, naphthalen-1-ol and acetic acid were the major identified intermediates due to AB113 degradation.

Prediction of 1-butanol and diesel fuel blend heat capacity by response surface methodology

In this study, using the response surface methodology (RSM) method, 1-butanol and diesel fuel blends heat capacity is predicted. The study of heat capacity was performed with three factors of molar fraction, viscosity, and temperature. In this study, the prediction of 1-butanol and diesel fuel blends heat capacity by central composite design (CCD) method is considered, which in addition to reducing the time and cost, can provide suitable models. A simple two-factor interaction (2FI) model, which is a function of viscosity (μ), temperature (T), and molar fraction (X1-b), is presented and the adequacy of the model is investigated using R2, R2adjusted, R2predicted values, Box–Cox, and Normal Plot.

Thermodynamic Analysis and Statistical Investigation of Effective Parameters for Gas Turbine Cycle using the Response Surface Methodology

In this paper, the statistical analyses are presented to study the thermal efficiency and power output of gas turbine (GT) power plants. For analyzing gas turbine operation and performance, a novel approach is developed utilizing the response surface methodology (RSM) which is based on the central composite design (CCD) method. An attempt is made to study the effect of some operational factors (inlet temperatures of turbine and compressor, inlet pressure of compressor, lower heating value of fuel (LHV) and air mass flow rate) and design parameters (pressure drop of combustion chamber and isentropic efficiency of equipment) on the system’s response. Based on the DoE analysis, regression models are presented to quantify the effects of these parameters on thermal efficiency and net work of the Brayton based gas turbine cycle. The proposed correlations obtained by the analysis have a remarkably satisfactory performance for all simulation data. The error analysis shows a maximum error of 5.5% in numerical computations of response functions for GT power plants. The optimal point of the thermal efficiency and net power output based on the optimized conditions were found to be 45.71% and 4.182 MW, respectively

Optimization of process parameters for the minimization of surface residual stress in turning pure iron material using central composite design

Surface residual stress, induced by process parameters, has a significant effect on the performance of workpiece. Focusing on the minimization of surface residual stress in turning DT4E pure iron, the influence of cutting speed (vc, 80–240 m/min), feed rate (f, 0.04–0.20 mm/rev) and depth of cut (ap, 0.05–0.25 mm) on surface tensile residual stress (στ in cutting direction, σr in feeding direction) is analyzed, and the optimal combination of process parameters is found. Central composite design (CCD) method is first used to design the turning experiments of pure iron material. By means of range analysis and the main effect plot, the relations between the process parameters and responses are discussed in detail. Subsequently, the non-linear mapping models of στ and σr with regard to turning parameters are established respectively using support vector regression (SVR) method. The experimental database is utilized to validate the effectiveness of SVR models. Taking the total stress σ as the optimization objective of process parameters, the optimal combination of turning parameters within given parameter ranges is finally obtained by combining SVR models with improved particle swarm optimization (PSO) algorithm. Further, the comparisons between genetic algorithm (GA), traditional and improved PSO algorithms are conducted, which indicate that the improved PSO algorithm has an advantage in convergence efficiency. Finally, verification experiments are performed to confirm the minimization of surface residual stress. The results show that the proposed optimization strategy of process parameters is effective and reliable, while at the same time providing a good prediction accuracy.

Development of foamy-like 3-dimensional graphene networks decorated with iron oxide nanoparticles for strontium adsorption

ABSTRACT Three-dimensional magnetic graphene foam (3D-MGF) was improved for removal of strontium ions. Chemical Vapor Deposition (CVD) method and hydrothermal method were used to obtained 3D-MGFs, respectively. Central Composite Design (CCD) method was conducted to establish the optimum conditions for adsorption of strontium ions on 3D-MGFs. At the optimum conditions, the maximum adsorption capacity was calculated 39.68 mg/g. Freundlich isotherm model showed that a multilayer formation occurred in the 3D-MGF’s surface. Moreover, the adsorption process was endothermic, and recycle experiments showed there was about 25% loss in the adsorption capacity of 3D-MGFs for strontium ions after 5 times reuse.

CO2 Reactive Absorption into an Aqueous Blended MDEA and TMS Solution: Experimental and Modeling

In this research, the significant environmental process of CO2 capture is investigated into an aqueous blended MDEA + TMS solution using a stirrer reactor experimentally and numerically. The experiments were designed based on the response surface methodology (RSM) under operating conditions of a pressure range of 2–8 bar, a temperature range of 20–70 °C, MDEA, and TMS concentration range of 10–20 wt%. The results indicated that by enhancing the initial pressure from 3.5 to 8 bar, the equilibrium CO2 loading increases by 17.8%. Based on RSM and central composite design method, the maximum values of CO2 loading and absorption percentages were 0.308% and 72.73%, respectively, at appropriate conditions of the temperature of 32.5 °C, the pressure of 3.5 bar, and MDEA and TMS concentrations of 12.5 wt%. A new relation for CO2 loading was correlated with a correlation coefficient of 0.994, as a function of studied independent variables.

Design and fabrication of carbon paste electrode for determination of Cr(III) ion in real water samples using a new synthesis Schiff base as selective ionophore

Chromium has been widely applied in industrial of pigment, stainless steel and electroplating and tanning procedure that enters the water sources. In this work, a simple and reproducible potentiometric sensor was developed for the determination of Cr(III) ions in real solid samples. For this purpose, a new Schiff base (4-((E)-(2-amino-4 chlorophenylimino) methyl) -5-(hydroxymethyl)-2-methylpyridin-3-ol) were synthesized based on a chemical methods and utilized as a novel and sensitive ionophore for the preparation of Cr(III)-carbon paste electrode. Percentage of carbon paste electrode composition including, graphite powder, ionophore, paraffin oil as a binder, and graphene oxide(GO), was optimized with a chemometric approach using a central composite design method. The optimum percentage of ionophore and nanomaterial in the electrode was obtained 15%w/w. The predicted slope by the computational method and the obtained slope by the experimental method for the proposed sensor was not significantly different. The sensor was linear in the range of 1×10-10- 1×10-2 M for the determination of Cr(III).The effects of other parameters such as pH, response time, lifetime, and interfering ions were studied with one factor at the time method in the optimal composition of the sensor. Proper range of pH, lifetime and response time were acquired 3.5-9.0, 8 weeks and 10 s, respectively. The essential advantages of the proposed sensor were the suitable linear range, a wide range of pH, proper sensor stability, and fast response for the Cr(III) determination. Finally, the analytical application of prepared sensor evaluated to determine Cr(III) in waste and tap water samples.

Optimization of Microencapsulation Process of Green Coffee Extract With Spray Drying Method as a Dietary Supplement.

Green coffee has high content of chlorogenic acid which is potential to be developed into slimming diet supplement. Microencapsulation was used tomake herbal supplement. Spray drying process with the addition of maltodextrin as a coating material will protect the extract from high temperatures. The purpose of this study was to determine the percentage of maltodextrin and optimal skim milk to produce dietary supplement preparations and find out the quality of dietary supplement preparations obtained. Robusta coffee beans from Argopuro, Jember, East Java, was dry processed. This research optimized the microencapsulation process of green coffee extract using central composite design method. The method was response surface with two factors namely percentage of maltodextrin and percentage of skim milk. The response used was total phenolic content and antioxidant activity. The results showed the optimal percentage of maltodextrin and combined skim milk were 8.61% and 3.22% respectively with total phenol obtained at 58.75 mg GAE/g with an accuracy of 93.10% and IC50 65.10 ppm with an accuracy of 95.76%. Dietary supplement products on the market contain total phenol of 57.52 mg GAE/g and IC50 87.65 ppm. Comparison with other green coffee supplement products showed this microencapsulation have higher total phenol content and antioxidant activity.

PERFORMANCE TEST OF THE 2BDE-2 TYPE MILLET FINE AND SMALL-AMOUNT ELECTRIC SEEDER

This work designed a 2BDE-2 type millet fine and small-amount electric seeder to solve certain problems, such as difficult cultivation and large workload of millet in hilly and mountainous areas. This seeder can finish the sowing operations, such as ditching, fine and small-amount of seed discharging, covering soil and suppressing at one time. The central composite design method was used to test the seeding performance of the seeder along with the factors of the seed metering plate amplitude and operating speed. This task was undertaken to determine the optimal working parameters of the seeder. The mathematical model of the average number of seeds in each 100 mm section and the variation coefficient of seeding uniformity were established. The influence of single factor effects and interaction on the seeding performance was also analysed. The optimum combination after parameter optimisation was determined as follows: seed metering plate amplitude of 109 μm and seeder operating speed of 0.76 m/s. The field sowing experiment was conducted according to the parameter combination. Results showed that the average number of seeds in each 100 mm section was 7.8, and the variation coefficient of seeding uniformity was 19.64%. The relative errors with the predicted values were 1.28% and 4.98%. The research can be used for sowing a small amount of millet in the hilly mountain area.

Catalytic activity of magnetic iron oxide nanoparticles for hydrogen peroxide decomposition: optimization and characterization

AbstractBACKGROUNDThe present study is focused on the decomposition of hydrogen peroxide (H2O2) using magnetic iron oxide nanoparticles (Fe3O4 NPs). Intrinsic peroxidase mimicking activity of Fe3O4 NPs helps in decomposition of H2O2 for the generation of •OH radicals during the Fenton process. A response surface methodology based central composite design (CCD) method was adopted to optimize five different process parameters: reaction time, temperature, pH, Fe3O4 NP concentration and H2O2 concentration.RESULTSCCD‐predicted H2O2 decomposition (%) showed close agreement with the experimental results, confirming the good fit of the experimental data to the model. A maximum H2O2 decomposition of 92.31% was achieved with an initial H2O2 concentration of 31.07 mg L−1, Fe3O4 NPs of 1.34 wt%, pH of 5.29, temperature of 23.1 °C and reaction time of 5.6 min as optimal values. The morphology and structure of Fe3O4 NPs before and after the reaction process were characterized using scanning electron microscopy, energy‐dispersive X–ray spectroscopy, Fourier transform infrared spectroscopy, X‐ray diffraction spectroscopy and thermogravimetric analysis.CONCLUSIONThe characterization data showed no significant changes in the structure of Fe3O4 NPs after the reaction compared to the pristine Fe3O4 NPs. The catalytic efficiency of these NPs was found to be in close agreement with other similar materials reported in previous literature. These optimization variables for H2O2 decomposition using Fe3O4 NPs may be useful in designing protocols for practical application at a large scale. © 2020 Society of Chemical Industry

Performance optimization of hybrid fiber concretes against acid and sulfate attack

Concrete elements used in underground structures and industrial areas are frequently exposed to acid and sulfate attacks as a result of industrial growth and climate changes. In this study, effects of different fibers, aggregates and binder types to the performance of hybrid fiber concretes against acid and sulfate attack are investigated with the help of central composite design method. Steel, glass, synthetic and propylene fibers, crushed stone and electrical arc furnace slag aggregates, fly ash and cement are hybridized each other to produce hybrid fiber concretes. Strength and mass loss of 30 different hybrid fiber concrete samples which were kept in H2SO4 and Na2SO4 solutions for 400 days, determined. Variance analysis of experimental results was performed and regression models were obtained. Steel and propylene fibers were strong against acid attack. Sulfate resistance of hybrid fiber concretes increase with contribution of steel, glass and propylene fibers. But synthetic fibers were weak both against acid and sulfate attack. Multi-objective optimization was performed to minimize the compressive strength and mass loss of the hybrid fiber concretes. Parameters for optimum concrete production are proposed as 0.04 steel fiber, 0.18% glass fiber, 0.23% synthetic fiber, 0.03% propylene fiber addition; 10.02% fly ash, 70.29% EAFS replacement and 305.41 kg/m3 binder dosage.

Combined steam and CO2 reforming of methane (CSCRM) over Ni–Pd/Al2O3 catalyst for syngas formation

In order to syngas formation, combined steam and carbon dioxide reforming of methane (CSCRM) used in the presence of Ni–Pd/Al2O3 catalysts, which were synthesized by the sol-gel method. Al2O3 supported Ni–Pd catalyst exhibited the appropriate surface area of 176.2 m2/g and high dispersion of NiO phase with an average crystallite size of 11 nm, which was detected on catalyst surface utilizing transmission electron microscopy (TEM). The influence of three independent operating parameters including reaction temperature in the range of 500–1000 °C; (CO2 + H2O)/CH4 ratio, in the range of 1–3 and CO2/H2O ratio; in the range of 1–3, were investigated on the responses (i.e., CH4 conversion, H2 yield, CO yield, amount of coke formation on the catalyst surface and H2/CO ratio) in CSCRM by using response surface methodology–central composite design (RSM-CCD) method. The obtained results from ANOVA and the proposed quadratic models could fine forecast the responses. It was seen that the total methane conversion and CO yield was almost accessible at temperatures higher than 850 °C. Moreover, the CO2/H2O ratio exhibited no significant effect on the CH4 conversion, H2 yield and CO yield of Ni–Pd/Al2O3 catalysts in CSCRM reaction. However, the high CO2/H2O ratio in inlet feed led to the syngas formation with a low H2/CO ratio. The results revealed that lower CO2/H2O ratio and higher temperature as well as higher (CO2 + H2O)/CH4 ratio help to decrease the coke formation.

Novel preparation of MoO3/γ-Al2O3 nanocatalyst: application in extra-heavy oil visbreaking at atmospheric pressure

In this study, the effect of gamma alumina-based molybdenum oxide nanoparticles, on the viscosity reduction of extra-heavy crude oil in a catalytic cracking process in atmospheric pressure and at 250–350 °C investigated for the first time. Molybdenum oxide nanoparticles synthesized using the polyol method and heating by microwave radiation. According to the dynamic light scattering (DLS) analysis, obtained nanoparticles have an average size of 6 nm. These nanoparticles coated on gamma-alumina powder using the novel method of per-vaporation, and through this method, 0.011 g of molybdenum oxide nanoparticles coated over per 1 g of catalyst, during 14 days. The performance of the synthesized catalysts in the cracking process of extra-heavy crude oil investigated. Statistical design of the experiment (DOE) used to study the effect of catalyst concentration and process temperature on product viscosity and to obtain optimal value of these factors. Based on the central composite design (CCD) method, the cubic model developed to correlate the catalyst wt% and temperature for upgraded oil viscosity. By applying the synthesized nanocatalyst in the range of 0.59–4 wt%, the viscosity reduction from 32 to 86% was observed. The highest viscosity reduction happened at 350 °C and 2% weight percent of nanocatalysts, in which the viscosity reduced from 20,000 cp to 2800 cp.

Preparation, Optimization, and Evaluation of Epichlorohydrin Cross-Linked Enset (Ensete ventricosum (Welw.) Cheeseman) Starch as Drug Release Sustaining Excipient in Microsphere Formulation.

Ensete ventricosum (Welw.) cheeseman which belongs to the family of Musaceae is one of the main sources of starch in Ethiopia. This study aimed at evaluating epichlorohydrin cross-linked enset starch as a drug release sustaining excipient in microsphere formulations of theophylline. Extracted enset starch was cross-linked using epichlorohydrin as a cross-linking agent. The effect of cross-linker concentration, cross-linking duration, and cross-linking temperature on the degree of cross-linking and release rate of microspheres prepared by emulsion solvent evaporation method was investigated using the two-level full factorial design. Accordingly, the concentration of epichlorohydrin and duration of cross-linking were the most significant factors affecting both the degree of cross-linking and drug release rate. Thus, the effects of these two factors were further studied and optimized using the central composite design. As per the numerical method of central composite design, the optimal points were obtained at epichlorohydrin concentration of 13.70% and cross-linking time of 3.82 h. Under these optimal conditions, the model predicts the degree of cross-linking of 74.70% and drug release rate of 28.00 h1/2. The validity of these optimal points was confirmed experimentally. The microspheres of the optimum formulation also exhibited minimum burst release with sustained release for 12 h. Besides, the optimized formulation followed the Higuchi square root kinetic model with non-Fickian diffusion release mechanism. The finding of this study suggested that cross-linked enset starch can be used as an alternative drug-release-sustaining pharmaceutical excipient in microsphere formulation.

Optimization of rare earth carbonate reactive-crystallization process based on response surface method

Rare earth carbonate precipitation is mainly amorphous, of large volume and difficult to filter. To prepare crystalline rare earth carbonate, mother liquor of heavy rare earth was taken as research object, and the experimental scheme was designed based on the response surface central composite design (CCD) method. The concentration of mother liquor, aging time and seed crystal dosage were taken as independent variables, and the particle size of rare earth carbonate was taken as the response value to establish a quadratic polynomial numerical model to optimize the reactive-crystallization process of rare earth carbonate. The results show that these three factors have significant effect on the particle size of rare earth carbonate, and the influence order is mother liquid concentration > aging time > seed crystal dosage. Moreover, the interaction between mother liquor concentration and seed crystal dosage has a significant effect on the size of rare earth carbonate particles. The optimal parameters predicted by the model are as follows: the concentration of mother liquid is 1.75 g/L, seed crystal dosage is 13.56 wt%, and aging time is 8 h. Under these conditions, the predicted particle size is 28.74 μm, and the experiment particle size is 28.23 μm, between both, the relative error is 0.73%, which indicates that the established response surface model has a good prediction effect and a certain practical significance to guide the reactive-crystallization process of rare earth carbonate. The obtained rare earth carbonate has a crystallinity of 97.82%, uniform particles size, and low-hydrated crystals with a tengerite structure.

Optimisation on the production of biodegradable plastic from starch and cassava peel flour using response surface methodology

Biodegradable plastic is starch-based plastic that can be naturally decomposed by microorganisms. Cassava is one of the primary starch-producing plants. The increasing amount of cassava production increases cassava peel waste. Cassava peel has 50% of the starch content in the tuber. The factors that are affecting the production of biodegradable plastics are temperature and drying duration. This study aimed to obtain the optimum temperature and drying time to produce biodegradable plastics from starch and flour of cassava peel waste. Response Surface Methodology (RSM) with a Central Composite Design (CCD) method was employed. The experimental design included two factors and three responses. The first factor was the drying temperature (40 °C, 50 °C, and 60 °C) and the second factor was the drying duration (5 hours, 6 hours, and 7 hours). The responses measured were tensile strength, elongation, swelling and biodegradability. The study found that the optimum condition of the process was at the drying temperature of 57.79 °C and drying duration of 5 hours. At this optimum condition, the biodegradable plastic produced has the tensile strength of 2554.65 N/m2; elongation of 16.67%; and swelling of 124.17%. Biodegradation testing for 12 days resulted in a mass reduction of 58.30%.

Selective removal of lead ion from polluted seaport water using a highly porous functionalized monolithic silica sorbent prepared by agarose template

A simple and inexpensive method for the synthesis of silica-based highly porous monolithic sorbents using agarose gel templates was developed for selective and efficient removal of Pb2+ from polluted seaport water samples. By controlling the agarose gel concentration, sorbents with different porosities could be obtained. The agarose gel was shaped as discs, silanized with (3-aminopropyl) triethoxysilane, calcined in 700 °C and functionalized by (E)-2-hydroxy-5-(phenyldiazenyl) benzaldehyde. The synthesized monolithic sorbent was then characterized by Fourier transform infrared spectrometry, X-ray diffraction, scanning electron microscopy and nitrogen sorption measurements. The results confirmed the mesoporous structure of the sorbent. Using two agarose gel concentrations of 2.5 and 7%, silica sorbents with porosities of 32.2 and 33.8 m2 g−1 were obtained. Evidences of variations in the structures and particle sizes were observed for the two sorbents. The influence of four parameters on the removal of Pb2+ from aqueous samples were optimized using a multivariate central composite design method. Under the optimized conditions, i.e. using 100 mg of the adsorbent for a 9.1 mL water sample in pH 7.9 and stirring for 56 min, 96.8% removal efficiency was obtained with a relative standard deviation of 7.4% for 5 replicates. The sorbent could be easily regenerated by a 0.2 mol L−1 HCl solution to be also used for enrichment and sensitive determination of the target ion.