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Mineralization of ampicillin, a semi-synthetic β-lactam penicillin, was investigated in subcritical water medium in the presence of hydrogen peroxide. Optimisation of the employed method was performed by the central composite design of the response surface methodology. Effects of each independent variable such as temperature, treatment time, and concentration of the oxidizing agent and their co-effects on TOC removal percentages were evaluated. 81.59% of TOC removal was obtained at 403 K of temperature, 80 mM of hydrogen peroxide and 147.3 min of treatment time. The reliability of the method was assessed by ANOVA and the theoretical equation was proposed for TOC removal of ampicillin. F value was obtained as 113.88 and p-value was obtained to be lower than 0.0001. The applicability of the theoretical model was proved by a series of validation experiments.

In this study, we formulated and synthesized an efficient visible light-active magnetic nano-photocatalyst, Fe3O4@SiO2@AgCl/Ag/Ag2S, to decompose methyl orange (MO) as a model organic pollutant. XRD, SEM, TEM, EDS, DRS, and VSM analyses were used to characterize the developed magnetic nano-photocatalyst. Moreover, central composite design (CCD) modeling, which is based on response surface methodology (RSM) modeling, is utilized to optimize the synthetic and operating conditions to maximize the photocataytic performance. The CCD-optimized values for molar ratio of AgCl to Fe3O4, molar ratio of Ag2S to Fe3O4, and the photocatalyst dosage are found to be 0.8, 0.27, and 1.27 g/L, respectively. The developed Fe3O4@SiO2@AgCl/Ag/Ag2S nano-photocatalyst shows a superior photocatalytic activity in decomposition of MO, degrading around 90% and 99% of MO in 30 min and one hour, respectively, under visible light illumination, at which the predicted values are in a good agreement with the experimental values (R2 = 0.971 and Adj-R2 = 0.945). Meanwhile, the morphological, physicochemical, and magnetic properties of the developed nano-photocatalyst are largely retained over ten successive cycles of photocatalytic reactions, and no significant decline in the photocatalytic activity is observed.

Ammonium and manganese may cause the aesthetic deterioration of drinking water quality if their penetration into the water intake is not controlled. The current physical chemical methods may be unable to treat polluted raw water alone, so a biological method is used to bolster the current physical capabilities. In this study, the biological removal of ammonium and manganese was performed using a slow sand biofilter (SSB) and optimized based on a central composite design (CCD) with response surface methodology (RSM). RSM was used to study the interaction among the process variables, namely, the feed concentration of ammonium (NH4-N) and manganese (Mn), the aeration rate (AR) and retention time (RT). The optimum conditions suggested by the response model were 2.01 mg NH4-N/L and 3 mg Mn/L feed concentrations, a 6 L/min AR and a 9.45 h RT. The condition resulted in an 89% and 98% reduction of ammonium and manganese, respectively. The microbial community attached on the SSB was identified using a polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method. Eight strains were obtained and identified as closest to Clostridium sp., Desnuesiella sp., Aeromonas sp., Pseudoalteromonas sp., Romboutsia sp., and Plasticicumulans sp. Of the bacteria identified in the community, Aeromonas sp. is known to have the ability to oxidize ammonium, and Pseudoalteromonas sp. is involved in oxidation of soluble Mn2+ to insoluble Mn4+.

The dependence of fresh-water for biomass growth is a major drawback in third generation microalgae biofuels, which need to be replaced with alternate sources. Optimizing nutrient concentrations already present in wastewater and its utilization towards microalgae growth could be a sustainable approach. In the present study, native microalga Chlorella thermophila (MF179624) was isolated and identified as model strain to optimize low-nutrient content campus sewage wastewater (CSW) using central composite design (CCD) followed by steepest ascent method (SAM). In consideration to the statistical optimization, addition of 325 mg L−1 and 1.8 g L−1 of KH2PO4 and NaNO3 resulted in 60% enhancement of biomass yield (2.59 g L−1) with two fold lipid productivity (81.38 mg L−1 d−1). In addition, substantial nutrient removal of ammonia (98.48 ± 1.52%), nitrate (86.37 ± 3.73%), phosphate (73.83 ± 4.28%), along with COD (82.53 ± 4.37%) were achieved. Further, TGA, FTIR, and 1H-NMR based characterization of lipid revealed its potential as a biofuel feedstock. To confirm that, two-step acid-base catalytic transesterification reaction was performed, which resulted in 474.42 mg L−1 FAME yield containing 85.14% C16 and C18.

The aim of this work was to study the removal of anionic Biebrich Scarlet (BS) dyes from aqueous solution by using magnetic Fe3O4 zeolite 13X (Fe3O4/13X). The composite adsorbent, synthesized by co-precipitation method, was characterized by X-ray Powder Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Vibrating Sample Magnetometry (VSM), as well as Inductively Coupled Plasma (ICP) and Zeta Potential (ZP) measurements. The three-factor Central Composite Design (CCD) combined with Response Surface Modeling (RSM) was used for maximizing the BS dye removal from aqueous solution. The three independent variables, namely the solution pH (in the 3–9 range), initial dye concentration (30–100 mg/L) and adsorbent mass (90–350 mg/L) served as inputs to the quadratic model of adsorption capacity. The findings yielded by analysis of variance (ANOVA) confirmed the high significance of the regression model. The predicted values of the BS adsorption capacity were in good agreement with the corresponding experimental values. Optimized conditions for maximum BS dye removal by Fe3O4/13X were pH 3.10, 98.05 mg/L initial dye concentration, and 288.82 mg/L adsorbent mass. The validity of the quadratic model was examined by conducting experiments in which the optimum values of process variables were employed, and good agreement was found between the experimental and predicted values. The present study shows that magnetic zeolite can be used as an adsorbent for highly efficient BS dye removal.

There has been increasing interest on the use of natural organic coagulants to replace synthetic inorganic coagulants due to environment and health concerns and its failure to comply with discharge regulations. In this study, chickpea (Cicer arietinum) was utilized as a natural and novel coagulant and flocculant in the treatment of palm oil mill effluent (POME) produced from crude palm oil extraction. The standard jar test method was utilized to investigate the effects of pH, dosage and rapid mixing speed on the removal of total suspended solids (TSS), turbidity and chemical oxygen demand (COD). By applying response surface methodology with a central composite design, the optimum condition was established at pH of 6.69, chickpea dosage of 2.6 g/L, and rapid mixing speed of 140 rpm. At the optimum condition, the removal percentages of turbidity, COD and TSS were determined to be 86%, 56% and 87% respectively. Characterization of chickpea with Fourier transform infrared spectroscopy revealed the presence of OH, CH, NH, CC, CO, CN bonds which is most likely to be found in proteins and polysaccharides; while results from scanning electron microscopy showed the rough and porous structure of chickpea and confirms the interaction between the suspended solid pollutants of POME and chickpea. On top of that, analytical results from energy dispersive x-ray spectroscopy and bomb calorimeter discovered that the dewatered sludge recovered post-treatment at optimum condition have a high potential to be used as a clean solid biomass fuel.

Nanoscale Fe-Ni bimetallic particles with Polyvinyl pyrrolidone (PVP) as a stabilizer were synthesized for dye decolourization and characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and nano particle size analyser. Analysis of variance (ANOVA) for decolourization was done by the central composite design (CCD) with response surface methodology (RSM). Three operational factors concentration of nanoparticles, concentration of dye and pH were selected for design of experiments. The influence of reaction duration, alkali and salt addition on dye decolourization was also studied. Dye degraded product and breaking of chromophoric group was analysed by gas chromatography–mass spectrometry (GCMS) and FT-IR analysis. The dye decolourization of was 97.89% obtained with reduction in COD and BOD value was achieved with negligible generation of the sludge.

In this research study the potential of date palm leaves as an efficient biosorbent to adsorb crystal violet as one of the toxic cationic dyes from aqueous solution was investigated. Date palm leaves were characterized by SEM-EDX, BET, and FT-IR. The influence of prominent parameters such as pH, temperature, time, initial dye concentration, and amount of biosorbent on the removal (%) were studied using central composite design (CCD). RSM modeling was utilized to state the removal (%) as a function of the studied experimental parameters. Two statistical approaches were employed to develop RSM models: stepwise selection and ant colony optimization (ACO). Using another ACO algorithm, the best obtained operational conditions were 10.10, 55.92 °C, 21.10 min, 16.35 mg L−1, and 48.64 mg for pH, temperature, time, initial dye concentration, and biosorbent amount, respectively. The final results confirmed higher capability and accuracy of ACO-RSM in prediction compared with stepwise-RSM with shorter equation phrases. Maximum adsorption percent of 99.5 ± 0.4 predictably and 99.1 ± 0.1 experimentally were achieved under the optimal conditions. The experimental data were found to be suitably fitted to the Freundlich model with maximum adsorption capacity of 37.736 mg g−1.

This work studies low-cost coagulants and flocculants with satisfactory efficiency, using the flower from Musa sp. as raw material. Many coagulants already used in the market, have high application cost and they may also be polluters. The tannins, natural biocoagulants, coming from the secondary mechanism of plants, are somewhat chemically reactive and they have already been used in processes. The present work has the objective of obtaining tannins using hot percolation as the extraction method, with the following factors: extraction solvent type, batch extraction number and percolation time. To evaluate the best extraction condition, a response surface methodology characterized by a Central Composite Design (CCD) was used, which could analyze each of the respective factors in five levels. The optimization of the model generated from the response surface aiming at a higher concentration of tannins was done using the Generalized Reduced Gradient (GRG) algorithm. Under these conditions, the tannin concentration was 0.93 μg/mL in the experimental conditions defined by the following factors: acetic acid solution 12.5% v/v, 6 batch with 45 min each. Under these conditions, the efficiency of the extract in the coagulation and flocculation of sludge from the mining industry was 98.78% for turbidity removal and 99.24% for solid removal.

This investigation is a new attempt to utilize the low cost chicken fat and waste chicken eggshell as catalyst for the production of chicken oil biodiesel and optimizing the transesterification process parameters. The performance, combustion and emission characteristics of the diesel engine have been analyzed by using the produced biodiesel. Esterification is carried out to reduce the free fatty acid of the chicken oil below 1 mg KOH/g of oil. The transesterification process variables are optimized using response surface methodology and the experiments are conducted based on central composite design. The optimum transesterification conditions are 1:13 M ratio, catalyst concentration of 8.5 wt.% of oil, 5 h reaction time, 57.5 °C reaction temperature and fixed agitation speed of 500 rpm. The most significant factor affecting biodiesel yield is identified as molar ratio. Validation of the model shows that the maximum biodiesel yield 90.41% is close to the predicted value 92.29%. Reusability study of the recovered catalyst has been done. The engine emission study shows carbon monoxide, hydrocarbon and filter smoke number of the pure biodiesel and its blend are lower than diesel. The heat release rate for diesel is higher than all other test fuels. Finally, the experimental work reveals that chicken fat and eggshell as catalyst could be a suitable feedstock for biodiesel production.

Keratin proteins are a major constituent of feathers which largely contribute to environmental pollution. The present study reports a potent feather degrading fungi isolated from soil and molecularly characterized (18S rDNA gene sequencing) and identified as Trichoderma harzianum isolate HZN12 (KP235366). Assessment of keratinase production from the isolate revealed better production under solid state fermentation (SSF) conditions (1320 U/g) over submerged (185 U) using chicken feathers. The effect and contribution of independent process variables were studied by Plackett–Burman design. Additionally, statistical modeling by central composite design of response surface methodology was applied to optimize the culture conditions for keratinase production under SSF. Maximum keratinase production (10,150 U/g) was validated with a 7.7 fold increase under the optimized conditions (chicken feather meal 3 g/20 ml, yeast extract 0.2%, glucose 0.9%, pH 8.5 and temperature of 37 °C) with a correlation coefficient (R2) = 95.56%. Keratinase was employed for dehairing of goat hide and assessed based on different organoleptic properties. The keratinase dehaired skin exhibited superior properties in comparison to the chemical treatment. Furthermore, keratinase also showed good stability and compatibility with the tested commercial detergents making it suitable for industrial applications such as, leather and detergent industries. The results suggest an ecofriendly approach for biodegradation of chicken feather waste.

The potential of Saccharomyces cerevisiae for bioremoval of low concentrations of Hg2+ ions at ppb level in aqueous solutions was investigated. The effects of biomass, initial pH-value and initial Hg concentration on the removal efficiency of yeast were studied, and these parameters were optimized by central composite design. Verification of Hg2+ removal data was accomplished based on analytical quality assurance before instrumental analysis. Obtained data revealed that the optimal conditions for Hg biosorption were: 5.45, 79.8 μg/L and 47.7 × 107 CFU for pH-value, initial Hg2+ concentration and biomass, respectively; the maximum Hg2+ removal efficiency under optimal conditions was found to be 88.9%. These findings suggest that, in addition to its known ability to remove high levels of heavy metals in wastewater, S. cerevisiae can even be used for mitigation of very low concentrations of precarious elements such as mercury, usually considered as pollutants in water treatment and food processing industry.

A new mesocellular silica foam (MCSiF) were successfully formed on the surface of activated carbon (AC) and subsequently for increases of surface and pours area of samples the AC was removed by calcination and products was functionalized by polymixin B as an antimicrobial cationic amphiphile agent. The synthesis samples structures were characterized with several techniques including X-ray diffraction (XRD), Fourier transform infrared (FT-IR), filed emission scanning electron microscopy (FESEM), nitrogen adsorption-desorption analysis. Functionalized MCSiF exhibits enhanced performance for removal of Cu(II) and Zn(II) ions from aqueous solution. The central composite design (CCD) was used to find out the main and interaction effect of operational factors (initial Cu(II) and Zn(II) concentration (7–35 mg L−1), pH values (3.5–9.5), adsorbent mass (5–45 mg) and sonication time (0.5–6.5 min)) on Cu(II) and Zn(II) ions removal efficiency and subsequently optimized the operating variables condition by desirability function method under CCD. The obtained experimental data were analyzed by Pareto chart, analysis of variance (ANOVA) and second-order polynomial models. The maximum removal efficiencies of 99.99% and 99.987% was obtained for Cu(II) Zn(II) at optimize condition set as at 20 mg L−1 of Cu(II), 15 mg L−1 of Zn(II) ions, 4 min sonication time, 40 mg adsorbent mass and pH value of 6.5.

The discharge of textile industries wastewaters into waterbodies remains a constant threat for environment. Through this study, we aim to optimize Textile Bio-refractory Wastewater (TBW) treatment by electrocoagulation (EC) process. EC runs were carried out in batch mode using an electrolytic cell equipped with iron electrodes, in parallel monopolar (MPP) configuration. TBW’s characterization has revealed a low biodegradability index value ( B O D 5 / C O D = 0.02). Most of optimizations studies have focused on traditional “one-factor-at-a time” methodology. However, this approach is visibly time consuming, does not take into account interactions effects and could give unreliable results. Therefore, we opted for Response surface methodology (RSM) which is a powerful statistical-based technique for modelling and optimization of complex processes. In this perspective, factorial experimental design (FD: 2k=3) was used to determine the influent parameters on textile pollutants removal. Electrolysis time ( X 1 ) and Current intensity ( X 2 ) were the main influential parameters with a cumulative contribution superior to 94 % for each of the three responses studied (turbidity, COD, Absorbance) whereas interactions and pH contributions are almost negligible ( 4% for pH). Afterwards, a central composite design (CCD) has been used to determine optimal conditions that maximize simultaneously all responses. Experimental results predicted by RSM model (99.95 % of Turbidity; 78.87 % of COD; 84.91 % Absorbance) under optimal conditions (75 min; 2.61 A and pH = 6.83) were close to the theoretical ones. EC process operated under optimal conditions involves a total cost of 4.95 US$/ m3 of treated TBW including chemicals, energy and electrode consumption.

The bulk manufacturing of carbamazepine (CBZ) by pharmaceutical manufacturing industries leads to generation of huge amount of wastewater containing this recalcitrant compound. This necessitates the application of advanced oxidation processes (AOPs) as a pretreatment strategy for the treatment of such complex industrial wastewaters. Therefore, in the present study, effect of Fenton treatment was investigated for removal of CBZ from real wastewater containing higher CBZ concentrations. The preliminary studies were conducted to assess the significant factors in Fenton treatment and pH, Fenton dose and time were found to be statistically significant parameters affecting the Fenton process. Based on these results, further experimental trials were designed statistically using Central Composite Design in MINITAB 16 software. The process conditions were optimized using Response Surface Optimizer Tool in MINITAB 16 and pH = 3.5 and H2O2 concentration of 8.5 g/L was obtained as optimum condition leading to 49.39 ± 0.93% CBZ removal from pharmaceutical wastewater containing higher CBZ concentrations. The detoxification of Fenton-treated wastewater through granulated activated carbon (GAC) column resulted in an overall CBZ removal of 99.51 ± 0.02%. The detoxification was further corroborated through seed germination test which demonstrated a potential reduction in toxicity post-detoxification using GACs.

Zero valent iron nanoparticles (nZVI) were synthesized using anaerobic granular sludge under anaerobic conditions. UV–vis spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy and SEM-EDX were used for characterization of Bio-nZVI. The nZVI loaded anaerobic granular sludge (Bio-nZVI) was subsequently evaluated for removing methyl orange from aqueous solutions. Central composite design with three level factors has been employed for the determination of efficient process parameters such as methyl orange initial concentration (10–50 mg/L), weight of anaerobic granules (10–30 mg dry weight) and interaction time (90–240 min) for methyl orange removal from aqueous solution. Under the optimized conditions (weight of Bio-nZVI: 30 mg; interaction time: 240 min and initial methyl orange concentration: 10 mg/L), the removal percentage and removal capacity was found to be 99% and 168 mg/g respectively. The reduction of methyl orange by Bio-nZVI followed pseudo-second order kinetics. The granules were characterized for possible changes in the morphology and surface chemistry after methyl orange removal. The process applicability was further evaluated for removing methyl orange from ground water and lake water samples spiked with known concentrations of methyl orange.

The present study aims to develop a filtration system consisting of ceramic wastes as a treatment process of bathroom greywater to reduce chemical oxygen demand (COD), Total suspended solids (TSS), Total nitrogen (TN), and turbidity. Optimization of the reduction efficiency was investigated using response surface methodology (RSM) as a function of the ceramic practical sizes (0.25–1.18 mm) and hydraulic retention time HRT (1–3 h). The functional groups on the surface of the ceramic filter media were determined using Fourier transform irradiation (FTIR), while the scanning electron microscope (SEM) was used to determine the microstructure and the surface morphology of the ceramic particles. Results revealed that the optimal reduction of COD, TSS, TN, and turbidity was influenced by active sites of the filter media (C C, C O, C O H, and OH−) and was achieved under the operating conditions of 0.25 mm of ceramic particles after 3 h of HRT, the observed and predicted reduction for COD, TSS, TN, and Turbidity were 38.8 vs. 39.8%; 58.47 vs. 59.59%; 66.66 vs. 67.32%; 88.31 vs. 89.02%, respectively. It can be concluded that the effectiveness of the ceramic filter media is a potential source for the filtration of bathroom greywater.

The aim of this research was to investigate the optimum conditions in biodiesel production from waste frying oil using hydrodynamic cavitation process. The Central composite design of experiment was carried out using the MINITAB 17, and the results were analyzed using response surface methodology. The optimum conditions for biodiesel production were obtained when using oil to methanol molar ratio of 1:6, 1.1 wt.% of potassium hydroxide, inlet pressure at 3.27 bar with a reaction time of 8 min in hydrodynamic cavitation process. The highest yield (%) in the experiment and the model was 95.6 ± 0.8% and 97.56% respectively. The biodiesel production was confirmed, by studying the GC–MS and FTIR spectra. Fuel characteristics were tested according to ASTM D6751 standard.

Plackett-Burman design (PBD), steepest ascent method (SAM) and central composite design (CCD) using response surface methodology (RSM) were applied to explore the effects of sixteen media components on carbazole degradation by Pseudomonas aeruginosa RS1. Carbazole acclimatized P. aeruginosa RS1 was grown on 100 mg/L carbazole provided as sole substrate in 50 mL mineral media and residual carbazole was quantified after 8 days. PBD revealed media components, MnCl2·4H2O (L), NiCl2·6H2O (J) and CaCl2·2H2O (P) as the most significant. SAM indicated that increasing concentration of MnCl2·4H2O (L) and decreasing concentrations of NiCl2·6H2O (J) and CaCl2·2H2O (P) from their center point levels increased carbazole degradation. CCD using RSM indicated the optimum concentrations of L, J and P as 57.04, 0.046 and 15 mg/L, respectively. Carbazole degradation in the optimized media (67 ± 2.7%) closely matched the theoretically predicted value (67%) and was much higher than that in the unoptimized media (38 ± 1.2%). Culture growth was significantly enhanced in the optimized media and disc diffusion studies confirmed growth inhibitory effect of J and P at concentration beyond the optimum values identified. Some accumulation of metabolites was also observed over the log growth phase. Increase in L caused enhanced accumulation of metabolites at the end of log phase, thus, it possibly enhanced carbazole degradation by increasing the activity of upper pathway enzymes having Mn as a cofactor.

The synthesis of new environmentally friendly and biocompatible material is an exciting research field to remove various pollutants from water/wastewater samples. The main objective of this paper is the successful synthesis of an Eco-friendly and novel modified silica aerogel (NMSA) by adding a small amount of Quince seed mucilage (QSM, 0.05 wt%) to water glass precursor and an ambient pressure drying method. The prepared NMSA was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and N2 adsorption/desorption isotherms. Results showed that adding a small amount of QSM to the precursor causes the formation of relatively uniform nanoparticles with an approximate size of 20 nm. The synthesized NMSA was then used for Pb(II) removal from an aqueous solution. Pb(II) adsorption in NMSA was about 30% more than raw Silica aerogel (SA). After performing some preliminary experiments and confirming the excellent efficiency of the NMSA in Pb(II) removal, RSM (response surface methodology) study via a central composite design (CCD) optimization approach was made to study the effects of the interaction of the influencing variables on the adsorption efficiency. The maximum Pb(II)-removal efficiency of 75% was achieved for the optimized run with conditions of pH: 4, contact time: 62 min, NMSA dosage: 1.4 g/L, and initial Pb(II) concentration: 50 mg/L. The Pb(II) removal by the modified NMSA adsorbent well obeyed the Langmuir isotherm and a pseudo-second-order rate kinetics model.

Textile and food industries wastewaters are characterized by a strong coloration due to use of dyes, among which azo dyes are the most frequently used. These compounds are harmful and their discharge without an adequate treatment causes a negative impact on the environment. Given that conventional biological treatment processes are usually not sufficient to degrade azo dyes, other treatment alternatives must be studied. Enzymes have demonstrated their effectiveness to degrade several types of recalcitrant compounds. In this study, enzymatic degradation of Crystal Ponceau 6R (CP6R) azo dye by turnip (Brassica rapa) peroxidase was assessed in the presence of 100 μM redox mediator (1-hydroxybenzotriazole). The treatment performance was evaluated at different pH values (3, 4, 5, 6 and 7) and the most appropriate pH and contact time were determined. Moreover, a kinetic model of the enzyme-catalyzed reaction was developed by mathematical description of the degradation mechanism, being further validated with experimental data. For the estimation of the kinetic parameters and model validation, a central composite design of type “start points” was made. The results showed that the enzymatic treatment was very effective. CP6R dye degradation higher than 97% was achieved in less than 1 min of reaction at the optimum pH (i.e., 4), at which the maximum reaction rate (43 μM min−1) was obtained. At the other tested pH values, degradation performance was substantially lower (

Developing photocatalytic systems by major design to achieve deep degradation of contaminants such as antibiotics to improve environmental conditions is highly desirable. Herein, we reported a facile method to fabrication of composite consisting of g-C3N4 layers and TiO2/Ag3PO4 nanoparticles (TiO2/Ag3PO4/g–C3N4) through calcination and precipitation methods. The as-prepared photocatalyst was used for the photodegradation of metronidazole (MNZ) in a designed continuous flow-loop photoreactor which is equipped with blue light-emitting diodes (LEDs) irradiation based on central composite design (CCD). According to the desirability function, the degradation efficiency of MNZ was also reported to be 97.18% under optimal conditions. The experiments indicated the photocatalytic degradation of MNZ by the as-prepared samples were in the order of TiO2/Ag3PO4/g-C3N4 > TiO2/g-C3N4 > TiO2/Ag3PO4 > TiO2. The strengthened visible-light-driven photocatalytic performance can be assigned to the formation of a Z-scheme system, surface plasmon resonance (SPR) effect, and high charge separation compared to pure and binary samples for degradation of MNZ. Based on trapping results, hydroxyl radicals were the major active radicals in the degradation of MNZ. Besides, the photodegradation pathway of MNZ was clarified via the analysis of intermediate products, and a mechanism of charge-carrier separation for MNZ photodegradation via TiO2/Ag3PO4/g–C3N4 was proposed.

Nalidixic acid is the first antimicrobial quinolone and today extensively applied in human and veterinary medicine. Recently, it is detected in the surface waters and is on the rise. In this study, the renewable adsorbent based on Graphene oxide (i.e., NiZrAl-layered double hydroxide-graphene oxide-chitosan (NiZrAl-LDH-GO-CS NC)), was synthesized and employed effectively for the adsorptive removal of Nalidixic acid (NA). The successful synthesis of the nanocomposite was evaluated using Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Analysis (EDX), X-ray powder diffraction (XRD), RAMAN spectroscopy, pHZPC and Barrett-Joyner-Halenda (BJH)/ Brunauer–Emmett–Teller (BET) analyses. The NiZrAl-LDH-GO-CS NC presented fast adsorption rates towards NA and maximum adsorption capacity on the basis of the pseudo-second-order (PSO) kinetic model reached 277.79 mg g−1, much higher than those reported by different nano-based adsorbents. The adsorption process was examined using the central composite design (CCD), adaptive network-based fuzzy inference system (ANFIS), and general regression neural network (GRNN) under various operational conditions of adsorbent dose, initial NA concentration, pH, temperature, and time. The comparison of the models revealed that ANFIS model outperformed compared to the others, with R2 = 0.9997, MSE = 0.0004, RMSE = 0.0082, and MAE = 0.0068, demonstrating that ANFIS is a powerful methodology for modeling NA adsorption by NiZrAl-LDH-GO-CS nanocomposite. Moreover, to express the most applicable conditions, RSM-GA and RSM-DFA based optimization is implemented and verified in practice (more than %92 NA removal is achieved). Further thermodynamic and kinetic assessments both signify the chemisorption mechanisms in this adsorption system. To sum up, LDH-GO-CS as a renewable adsorbent, will possibly have noteworthy effects on pharmaceutical wastewater remediation and can be considered for advanced researches as an efficient reagent for practicable remediation techniques.

Palm oil mill sludge (POMS) is a significant industrial waste generated in Malaysian palm oil mills. The re-utilisation of POMS as a value-added adsorbent for copper sequestration is highly desirable as a means for solid waste reduction. Therefore, this research aimed to evaluate the adsorption performance of POMS towards copper pollutant comprehensively. Adsorption attributes of the POMS-copper system were investigated using batch experiments, followed by statistical modelling to establish the simultaneous interactive effects of parameters and to optimise the system. POMS was determined to exhibit 9.72 point of zero charge, with a rough surface containing pore sizes within 1–7 µm and functional groups such as hydroxyl interacted with the copper. The statistically optimised adsorption capacity (15.84 mg g−1) was attained at 0.3 g POMS dosage, pH 4.56, 200 mg L−1 concentration and 60 min. The regeneration ability of POMS was satisfactory up to 5 adsorption-desorption cycles. Equilibrium and kinetic adsorption data were modelled based on the sum of normalised error (SNE) approach. The adsorption equilibrium was well represented by the Langmuir model (SNE: 3.69), with 16.56 mg g−1 Langmuir maximum adsorption capacity at 30 °C. Adsorption kinetics studies revealed that the pseudo-second-order kinetic (SNE: 2.98) was the most appropriate model, with copper ions chemisorbed onto POMS surface via multiple mechanisms such as boundary layer and intraparticle diffusion. The new POMS-copper system was thermodynamically exothermic (ΔH°: −12.72 to −4.25 kJ mol−1) and spontaneous (ΔG°: −19.07 to −11.44 kJ mol−1). Conclusively, POMS was an effective, low cost and eco-friendly adsorbent for the removal of toxic copper from aqueous environment.

In this study, Fe 3 O 4 nanoparticles (NPs) loaded onto SBA-15-HESI (SBA-15-HESI-Fe 3 O 4 -NPs) as a novel sorbent was prepared and subsequently was applied for dispersive solid phase magnetic extraction (MSPME) and preconcentration of La (III) ions in water samples by ICP-OES. The synthesized sorbent was characterized by FT-IR, SEM, TEM, BET, VSM, BJH and XRD techniques. The important variables such as concentration of solvent, volume of extraction solvent, desorption time, pH of the sample soloution, initial concentration of La(III) ions, sorbents dosage and adsorption time were investigated and optimized by central composite design (CCD) combined with desirability function (DF). The optimum condition, concluded from one at a time method was 2 mL of 0.1 mol L −1 HCl as extraction solvent and 5.0 min from desorption time. Linear calibration range 20–200 and 10–220 μg L −1 , detection limit 0.21 and 0.16 μg L −1 , the relative standard deviations (RSD%) of 3 and 2% were obtained for SBA-15-HESI and SBA-15-HESI-Fe 3 O 4 -NPs, respectively. The enrichment factor 7.6 and 9.8, the preconcentration factor 7.37 and 9.43, the adsorption capacity 1.27 and 2.81 mg g −1 were obtained for SBA-15-HESI and SBA-15-Fe 3 O 4 -NPs, respectively.

Present study revealed tremendous improvement in carbofuran degradation in a Microwave – Granular Activated carbon (MW-GAC) system compared to natural hydrolysis process and the degradation half-life was 12 and 0.189 min at a pH of 6 and 10 respectively at a reaction temperature of 80 °C. In addition, the effect of several operating parameters such as carbofuran concentration, MW output power and reaction time was modelled using Central composite design (CCD) and response surface methodology (RSM) with 17 experimental runs. Carbofuran degradation/mineralization process was described in terms of carbofuran concentration, MW output power and reaction time. The experimental outcomes from CCD indicated improved degradation and mineralization of carbofuran with the increase in reaction time. On the other hand, lower MW output power resulted in poor degradation and mineralization of carbofuran. RSM showed highest correlation coefficient for carbofuran removal per MW output power, R w (0.92) and COD removal efficiency, η COD (0.82). Therefore, quadratic models were developed using regression analysis to predict R w and η COD . Good correlation between the observed values and predicted values by the developed models indicated that the developed models can be used to design required R w and η COD within the experimental conditions.

In this work, the carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) were chemically modified with 3-aminopyrazole to synthesize MWCNTs-f. Then the three nanoadsorbents, i.e., MWCNTs, MWCNTs-COOH, and MWCNTs-f, have been separately used to the adsorption of Cd(II) ions from aqueous solutions. The adsorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron Microscope (FE-SEM), thermal gravimetric analysis (TGA), and Bruner-Emmet-Teller (BET) surface area measurement. The effects of pH, adsorbent dose, initial ion concentration, and temperature on adsorption efficiency were investigated by central composite design a subset of response surface methodology for experimental design to reducing the number of experiments runs having the interaction effects between the parameters. The optimum adsorption conditions for all adsorbents were 20 mg of the adsorbents, pH = 8–9, and 50 mg L −1 of Cd(II) ions at 45 °C. At the optimum conditions, Cd(II) ions removal efficiencies were 83.7, 65.9 and 35.7% for MWCNTs-f, MWCNTs-COOH, and MWCNTs, respectively. The quadratic model was applied for analysis of variance and indicated that pH and temperature were the most effective parameters in the adsorption process. The pseudo-second-order model was achieved from the adsorption kinetic studies. Also, various adsorption isotherm models at different temperatures were examined. The results show that the Langmuir isotherm is fitted suitably for the three adsorbents in this work and the best-selected isotherm models for the adsorption of Cd(II) ions by MWCNTs, MWCNTs-COOH, and MWCNTs-f were Langmuir, Dubinin–Radushkevich and Temkin models, respectively. Moreover, desorption study revealed the favorable regeneration ability of adsorbents powders, even after 3 adsorption-desorption cycles.