Optimized preparation of Phragmites australis activated carbon using the Box-Behnken method and desirability function to remove hydroquinone

ZIF-67 and Biomass-Derived N, S-Codoped Activated Carbon Composite Derivative for High-Effective Removal of Hydroquinone from Water

Hydroquinone (HQ) in wastewater is of great concern, as it is harmful to human health and threatens the ecological environment. However, the existing adsorbents have low adsorption capacity for HQ. To improve the removal of HQ, N,S-codoped activated carbon-ZIF-67 (NSAC-ZIF-67@C) was synthesized in this study by in situ growth of ZIF-67 on N,S-codoped activated carbon (NSAC) and carbonization. The influence of pH, contact time, and initial concentration on the adsorption behaviors of NSAC-ZIF-67@C on HQ were investigated. Owing to the synergistic effect of abundant active sites and well-developed pore structure, the NSAC-ZIF-67@C achieved a prominent adsorption capacity of 962 mg·g-1 and can still retain high adsorption performance after 5 cycles for HQ, which is superior to that of reported other adsorbents. HQ adsorption follows the pseudo-second-order kinetics model (R2 = 0.99999) and the Freundlich isotherm model. X-ray photoelectron spectroscopy (XPS) analysis before and after adsorption as well as density functional theory (DFT) calculation results showed that pyridinic-N-termini were conducive to the π-π interactions and hydrogen-bonding interactions. Therefore, the adsorption mechanisms of NSAC-ZIF-67@C on HQ involve pore filling, electrostatic attraction, π-π interaction, and hydrogen bonding. This study is expected to provide a reference for designing highly effective adsorbents for wastewater treatment.

Multi-objective optimization and 4E (energy, exergy, economy, environmental impact) analysis of a triple cascade refrigeration system

The post-pandemic energy crisis and ever-increasing environmental degradation necessitate researchers to scrutinize refrigeration systems, major contributors to these issues, for minimal environmental impact and maximum performance. Thus, this study aims to comprehensively examine a triple cascade refrigeration system (TCRS) equipped with hydrocarbon refrigerants (1-butene/Heptane/m-Xylene). This system is specifically designed for ultra-low temperature applications, including vaccine storage, quick-freezing, frozen food preservation, cryogenic processes, and gas liquefaction. The investigation integrates conventional thermodynamic analysis with economic and environmental impact assessments, and finally multi-objective optimization (MOO) to ascertain optimal operating conditions for the system. The effect of (1) evaporator temperature, Tevap (2) condenser temperature, Tcond (3) Lower Temperature Circuit (LTC) condenser temperature, TLTC (4) Mid Temperature Circuit (MTC) condenser temperature, TMTC and (5) Cascade Condenser temperature difference, Δ T on three objective functions (COP, exergy efficiency, and overall plant cost) have been investigated employing a parametric analysis. Subsequently, quadratic equations for these objective functions are generated using the Box-Behnken method, and MOO utilizing the Genetic algorithm has been performed to maximize COP and exergy efficiency while minimizing the overall cost rate. The decision-making techniques TOPSIS and LINMAP are used to retrieve a unique solution from the Pareto Front, and the system performance has been assessed at the optimal point. The optimization result demonstrates that for the 10-kW capacity TCRS, COP, exergy efficiency, and total plant cost are 0.71, 0.51, and 38262.05 $/year respectively, at optimum condition (Tevap = -101.023 °C , Tcond = 36.545 °C , TLTC = - 69.047 °C and TMTC = - 34.651 °C ). Exergy analysis identifies HTC compressor (19.3 %) and throttle valve (15.5 %) as key contributors to total exergy destruction, while economic analysis underscores capital and maintenance costs (72 %) as the primary contributors to the overall cost, with evaporator (43 %) and condenser (20 %) accounting for 63 % of this cost.

Muscovite clay for methylene blue removal: advanced optimization and Al-guided breakthroughs-an independent application from prior antibiotic removal investigation

This study evaluates the efficacy of muscovite mineral clay as an adsorbent for removing Methylene Blue (MB) from water-based solutions. The research examined the impact of initial MB concentration, adsorbent mass, and time on the MB removal process. Two modeling techniques, namely Box-Behnken design with response surface methodology (BBD-RSM) and Artificial Neural Network (ANN), were employed to accurately predict the MB removal efficiency. The RSM and ANN models yielded satisfactory results in estimating MB removal efficiency. To further enhance the optimization process, conventional and techno-economic methods were implemented. The conventional method aimed to maximize dye removal efficiency (R), while the techno-economic approach incorporated multiple objectives. The comparative analysis demonstrated that the techno-economic optimization method outperformed the conventional method. This study emphasizes the significance of considering multiple objectives and integrating techno-economic factors in optimizing clay adsorption processes. The successful application of the techno-economic optimization approach highlights its potential as a robust optimization method, particularly in the field of wastewater treatment. The findings provide valuable insights for optimizing adsorption and advancing environmental remediation practices.

Three-Dimensional Mass Transfer Modeling of Hydroquinone Adsorption on Phragmites australis Biochar

In this work, the overall adsorption kinetic process of hydroquinone on Phragmites australis biochar (PAC) was analyzed in depth. A 3D mass transfer model of pore volume and surface diffusion was established, and the diffusion mechanism was analyzed. The characterization results show PAC has a higher porosity value, which is conducive to the adsorption of hydroquinone. The adsorption process modeling results show that the combined effect of pore volume diffusion and surface diffusion promotes the total diffusion process of hydroquinone in the PAC particles, and the two mechanisms of pore volume and surface diffusion exist simultaneously. Under the different operating concentrations, the range of surface diffusion coefficient D_s is 2.5 × 10^-10-1.74 × 10^-9 cm²/s, and the contribution rate of surface diffusion SDCP% is close to 100%, which is much larger than pore volume diffusion, revealing that regardless of the contact time and position, surface diffusion occupies the main position in intraparticle diffusion.

Effective Removal of Metal ion and Organic Compounds by Non-Functionalized rGO

Effective removal of heavy metals from water is critical for environmental safety and public health. This work presents a reduced graphene oxide (rGO) obtained simply by using gallic acid and sodium ascorbate, without any high thermal process or complex functionalization, for effective removal of heavy metals. FTIR and Raman analysis show the effective conversion of graphene oxide (GO) into rGO and a large presence of defects in rGO. Nitrogen adsorption isotherms show a specific surface area of 83.5 m2/g. We also measure the zeta-potential of the material showing a value of -52 mV, which is lower compared to the -32 mV of GO. We use our rGO to test adsorption of several ion metals (Ag (I), Cu (II), Fe (II), Mn (II), and Pb(II)), and two organic contaminants, methylene blue and hydroquinone. In general, our rGO shows strong adsorption capacity of metals and methylene blue, with adsorption capacity of qmax = 243.9 mg/g for Pb(II), which is higher than several previous reports on non-functionalized rGO. Our adsorption capacity is still lower compared to functionalized graphene oxide compounds, such as chitosan, but at the expense of more complex synthesis. To prove the effectiveness of our rGO, we show cleaning of waste water from a paper photography processing operation that contains large residual amounts of hydroquinone, sulfites, and AgBr. We achieve 100% contaminants removal for 20% contaminant concentration and 63% removal for 60% contaminant concentration. Our work shows that our simple synthesis of rGO can be a simple and low-cost route to clean residual waters, especially in disadvantaged communities with low economical resources and limited manufacturing infrastructure.

High-Surface-Area-Activated Carbon Derived from Mango Peels and Seeds Wastes via Microwave-Induced ZnCl2 Activation for Adsorption of Methylene Blue Dye Molecules: Statistical Optimization and Mechanism

In this study, Mango (Mangifera indica) seeds (MS) and peels (MP) seeds mixed fruit wastes were employed as a renewable precursor to synthesize high-surface-area-activated carbon (MSMPAC) by using microwave-induced ZnCl₂ activation. Thus, the applicability of MSMPAC was evaluated towards the removal of cationic dye (methylene blue, MB) from an aqueous environment. The key adsorption factors, namely A: MSMPAC dose (0.02–0.1 g), B: pH (4–10), and C: time (5–15 min), were inspected using the desirability function of the Box-Behnken design (BBD). Thus, the adsorption isotherm data were found to correspond well with the Langmuir model with a maximum adsorption capacity of (232.8 mg/g). Moreover, the adsorption kinetics were consistent with both pseudo-first-order and pseudo-second-order models. The spontaneous and endothermic nature of MB adsorption on the MSMPAC surface could be inferred from the negative ∆G° values and positive value of ∆H°, respectively. Various mechanisms namely electrostatic forces, pore filling, π-π stacking, and H-bonding govern MB adsorption by the MSMPAC. This study demonstrates the utility of MS and MP as renewable precursors to produce high-surface area MSMPAC with a potential application towards the removal of cationic organic dyes such as MB.

Remarkable adsorption of hydroquinone as an anion contaminant by using the magnetic supported bimetallic (NiCu-MOF@MAC) nanocomposites in aqueous solutions

The purposes of this work were to synthesize the core-shell magnetic and nonmagnetic supported bimetallic metal-organic frameworks (MOFs) on the walnut-based activated carbon by the facile preparation method to investigate the feasibility of the performance adsorption of hydroquinone in the aqueous solutions. Activated carbon as a substrate and nickel, copper, and trimesic acid were employed in the structure of the prepared MOFs. The adsorbents were characterized by XRD, FTIR, FESEM, EDX, TEM, BET, and VSM analysis. The goethite and magnetite phases were detected in the morphology of the magnetic adsorbent as confirmed by the XRD pattern. Increases in the pH value from 6 and the adsorption temperature led to a lower adsorption capacity of the samples. The maximum adsorption capacity for the well-dispersed nanoparticles of magnetic (NiCu-MOF@MAC and nonmagnetic (NiCu-MOF@AC) was calculated to be 303.03 and 454.54 mg/g by using linear Langmuir isotherm as an appropriate model, respectively. The achievements from the reusability evaluation illustrated that the magnetic bimetallic MOF nanocomposite could successfully be applied to remove hydroquinone from the wastewater on an industrial scale. The kinetic experimental data was in good agreement with the pseudo-second-order model.

Modelling and Optimizing Pyrene Removal from the Soil by Phytoremediation using Response Surface Methodology, Artificial Neural Networks, and Genetic Algorithm

This study aimed to model and optimize pyrene removal from the soil contaminated by sorghum bicolor plant using Response Surface Methodology (RSM) and Artificial Neural Network (ANN) with Genetic Algorithm (GA) approach. Here, the effects of indole acetic acid (IAA) and pseudomonas aeruginosa bacteria on increasing pyrene removal efficiency by phytoremediation process was studied. The experimental design was done using the Box-Behnken Design (BBD) technique. In the RSM model, the non-linear second-order model was in good agreement with the laboratory results. A two-layer Feed-Forward Back-Propagation Neural Network (FFBPNN) model was designed. Various training algorithms were evaluated and the Levenberg Marquardt (LM) algorithm was selected as the best one. Existence of eight neurons in the hidden layer leads to the highest R and lowest MSE and MAE. The results of the GA determined the optimum performance conditions. The results showed that using indole acetic acid and pseudomonas bacteria increased the efficiency of the sorghum plant in removing pyrene from the soil. The comparison obviously indicated that the prediction capability of the ANN model was much better than that of the RSM model.

Optimization of biochar preparation from the stem of Eichhornia crassipes using response surface methodology on adsorption of Cd2

In this study, preparation of Eichhornia crassipes stem biochar (ECSBC) was optimized and applied for the removal of Cd²⁺ from aqueous solution. To obtain the best adsorption capacity of ECSBC, the response surface methodology (RSM) was used to optimize the preparation conditions of ECSBC (OECSBC). The interactions among heating time (X₁), heating temperature (X₂) and heating rate (X₃) were designed by Box-Behnken Design (BBD) experiments. The software gave seventeen runs experiment within the optimal conditions towards two response variables (removal rate and adsorption capacity for Cd²⁺). The results showed that the mathematical model could fit the experimental data very well and the significance of the influence factors followed the order as heating temperature (X₂) > heating rate (X₃) > heating time (X₁), and the influence of interaction term is: X₁ and X₂ (heating time and heating temperature) > X₂ and X₃ (heating temperature and heating rate) > X₁ and X₃ (heating time and heating rate). Based on the analysis of variance and the method of numerical expected function, the optimal conditions were heating time of 2.42 h, heating temperature of 393 °C, and heating rate of 15.56 °C/min. Under the optimum conditions, the predicted the maximum removal rate and adsorption capacity were 85.2724% and 21.168 mg/g, respectively, and the experimental value of removal rate and adsorption capacity for Cd²⁺ were 80.70% and 20.175 mg/g, respectively, the deviation from the predicted value were 5.36% and 4.69%. The results confirmed that the RSM can optimize the preparation conditions of ECSBC, and the adsorption capacity of OECSB was improved.

Preparation of novel molecularly imprinted magnetic graphene oxide and their application for quercetin determination

In this work, quercetin (Que) molecular imprinted polymer (MIP) material decorated on magnetic graphene oxide (MGO) with high performance was prepared for the first time using a surface-imprinting technique. Magnetic graphene oxide was synthesized using the solvothermal route. Methacrylic acid (MAA) was used as functional monomer, ethylene glycol dimethyl acrylate (EGDMA) as cross-linker; Que. was used as template, for the decoration with MIP. The prepared nanocomposite was examined by different characterization methods including fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM). The adsorption performance was investigated. MGO-MIP was found to have high loading (369 mg g^-1) and selective capacity making the nanomaterial more performant than previous similar reported nanomaterials. The determination of Que. was carried out by mean of magnetic solid phase extraction method coupled with high-performance liquid chromatography (HPLC) and the extraction conditions studies were also performed out. Under the optimized conditions, MGO-MIP showed great performance for the extraction, separation and determination of Que. in green tea and serum samples, compared to the flavonoid analogs luteolin (Lut) and rutin (Rut) in the same matrix samples.

Effect of Mix Proportion Parameters on Behaviors of Basalt Fiber RPC Based on Box-Behnken Model

Basalt fibers are widely used in the modification of concrete materials due to its excellent mechanical properties and corrosion resistance. In this study, the basalt fibers were used to modify reactive powder concrete (RPC). The effect of four mix proportion parameters on the working and mechanical properties of basalt fiber reactive powder concrete (BFRPC) was evaluated by the response surface methodology (RSM). The fluidity, flexural and compressive strength were tested and evaluated. A statistically experimental model indicated that D (the silica fume to cement ratio) was the key of interactions between factors, affecting other factors and controlling properties of BFRPC. The increase in basalt fiber content had a remarkable effect on increasing the flexural and compressive strength when D = 0.2. The addition of basalt fiber obviously improved the mechanical properties of RPC. While when D = 0.4, the decrease of fiber content and the increase of quartz sand content could increase the compressive strength.