Determination and Removal of Selected Pharmaceuticals and Total Organic Carbon from Surface Water by Aluminum Chlorohydrate Coagulant

In the present research, the removal of Total Organic Carbon (TOC) and erythromycin (ERY), fluoxetine (FLX), amoxicillin (AMO), colistin (COL), ethynylestradiol (EE), and diclofenac (DIC) from surface water by coagulation is studied. The concentration of selected pharmaceuticals in 24 surface water samples originating from some rivers located in Lesser Poland Voivodeship and Silesia Voivodeship, Poland, was determined. The removal of TOC and pharmaceuticals was carried out using the application of Design of Experiments (DOE), Response Surface Methodology (RSM), and by addition of aluminum chlorohydrate (ACH) as a coagulant. The study found that the concentration ranges of ERY, FLX, AMO, COL, EE, and DIC in analyzed water samples were 7.58−412.32, 1.21−72.52, 1.22−68.55, 1.28−32.01, 5.36−45.56, 2.20−182.22 ng/L, respectively. In some cases, concentrations lower than 1 ng/L were determined. In optimal conditions of coagulation process of spiked surface water (pH = 6.5 ± 0.1, ACH dose = 0.35 mL/L, Time = 30 min; R2 = 0.8799, R2adj = 0.7998), the concentration of TOC, ERY, FLX, AMO, COL, EE, and DIC was decreased by 88.7, 36.4, 24.7, 29.0, 25.5, 35.4, 30.4%, respectively. Simultaneously, turbidity, color, Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Total Nitrogen (Total N), and Ammonium-Nitrogen (N-NH4) were decreased by 96.2%, >98.0%, 97.8%, 70.0%, 88.7%, 37.5%, respectively. These findings suggest that ACH may be an optional reagent to remove studied pharmaceuticals from contaminated water.

Adopting Sustainable Jatropha Oil Bio-Based Polymer Membranes as Alternatives for Environmental Remediation

This study aimed to optimize the removal of Cu(II) ions from an aqueous solution using a Jatropha oil bio-based membrane blended with 0.50 wt% graphene oxide (JPU/GO 0.50 wt%) using a central composite model (CCD) design using response surface methodology. The input factors were the feed concentration (60–140) ppm, pressure (1.5–2.5) bar, and solution pH value (3–5). An optimum Cu(II) ions removal of 87% was predicted at 116 ppm feed concentration, 1.5 bar pressure, and pH 3.7, while the validated experimental result recorded 80% Cu(II) ions removal, with 95% of prediction intervals. A statistically non-significant term was removed from the analysis by the backward elimination method to improve the model’s accuracy. Using the reduction method, the predicted R² value was increased from −0.16 (−16%) to 0.88 (88%), suggesting that the reduced model had a good predictive ability. The quadratic regression model was significant (R² = 0.98) for the optimization prediction. Therefore, the results from the reduction model implied acceptable membrane performance, offering a better process optimization for Cu(II) ions removal.

A polyurethane foam membrane filled with double cross-linked chitosan/carboxymethyl cellulose gel and decorated with ZSM-5 nano zeolite: Simultaneous dye removal

A novel bio-based polyurethane foam was fabricated using double cross-linked chitosan/carboxymethyl cellulose gel, filled with ZSM-5 nano zeolite, and hot-pressed into the membrane. The prepared foam membrane was characterized using FESEM, FTIR, BET, TGA, and pH_ZPC analyses and then used for continuous dye removal. The results modification of polyurethane foam with chitosan/carboxymethyl cellulose gel and ZSM-5 nano zeolite would increase the retention ability of positive cationic methylene blue. Also, the foam could simultaneously remove methyl orange, eriochrome black T, and methylene blue from the binary and trinary solutions but could effectively be used to selectively removal methylene blue. In addition, the dye removal ability at the breakthrough was enhanced with decreasing flow rate, and increasing bed height, pH, initial dye concentration, and nano zeolite content in the foam. To describe the breakthrough curves different models were utilized which best fits were obtained with Modified Dose-Response as compared to Thomas, Adams & Bohart, Yoon-Nelson, and Wolborska models.

Poly(lactic acid)-poly(ethylene glycol)/Magnesium Silicate Membrane for Methylene Blue Removal: Adsorption Behavior, Mechanism, Ionic Strength and Reusability Studies

In this work, the effect of magnesium silicate (MgSiO3) as a filler on poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) membrane was investigated towards the enhancement of adsorption capacity for removal of cationic dye. The preparation and fabrication of membranes were performed through copolymerization and phase inversion techniques. Analysis of functional groups, tensile strength, morphology and surface wettability were employed in the characterization of the membranes. After the addition of MgSiO3, it was found that the PLA-PEG/MgSiO3 membrane presented a higher hydrophilic property with improved mechanical strength. Next, the adsorption of methylene blue (MB) was optimized using response surface methodology (RSM) with the parameters mass of membrane and initial concentration of MB solution. The effects of pH and ionic strength were also examined to determine the mechanism involved during adsorption processes, which later were found to be electrostatic interaction and ion-exchange mechanism. From the isotherms and kinetics studies, the PLA-PEG/MgSiO3 membrane was well fitted by the Freundlich model and pseudo second order model, respectively. This membrane also demonstrated reusable character of up to six cycles.

Investigation of Taguchi optimization, equilibrium isotherms, and kinetic modeling for cadmium adsorption onto deposited silt

The feasibility of deposited silt as an adsorbent to eliminate Cadmium (Cd) from aqueous solution is assessed in this study. The optimum adsorption condition was determined with the help of the Taguchi experimental design. The treatment process of the deposited silt is controlled by various parameters like pH of the solution; a dose of deposited silt; initial Cd metal concentration, and contact time are optimized in batch mode. It also recognizes the contribution of each well-regulated factor. The outcomes of experiments show that the major contribution of the controllable factors for Cd removal is the pH of the solution > stirring time > dose of deposited silt > initial concentration of Cd metal ions. Analysis of Variance (ANOVA) was used to determine significant parameters which contribute to the adsorption process. Results indicate that cadmium removal is mostly influenced by pH 88.17 %, followed by contact time 5.86%, adsorbent dose, 2.41%, and initial metal ion concentration 0.60%. Cadmium adsorption data well fitted to the Langmuir isotherm model. The pseudo-second-order is the best model that explained cadmium adsorption kinetics.

Total Reflection X-Ray Fluorescence Spectroscopy (TXRF) Method Validation: Determination of Heavy Metals in Dietary Supplements

Dietary supplements may contain heavy metals with the property of bioaccumulation in humans. The aim of this research was to validate and apply two analytical methods to determine Pb, As, Cr, and Hg in dietary supplements by Total Reflection X-ray Fluorescence Spectroscopy (TXRF). Methods validation was conducted through a multivariate analysis using a central composite design (CCD) and a desirability function. Critical values for each study variable were established. The TXRF_DS_1 method was proposed for Pb, As, and Cr determinations, while the TXRF_DS_2 was established for Hg analysis. The digestion method with an acid mixture (HNO3 + HCl + H2O2) was used to break down the organic material of dietary supplements. A solution of 10 μg L−1 Ga was used as an internal standard. Excellent analytical performance was obtained as LODs of 0.59, 0.41, 0.57, and 0.75 μg L−1 and LOQs of 1.95, 1.35, 1.90, and 2.50 μgL −1 for Pb, As, Cr, and Hg, respectively. Calibration curves showed a good linearity for all elements (R2>0.999). Excellent accuracy and precision in measurements (% RSD) was achieved. The real and spiked samples analysis demonstrated the applicability of the TXRF technique (percentage recovery 91–108%). Besides, two samples were analyzed in a comparison study between the TXRF_DS_1 method and the ICP-OES method. The results obtained showed good agreement between both techniques. The TXRF technique allows the analysis of toxic heavy metals in dietary supplements, which are marketed in a wide variety of presentations.

Process optimization and modeling of Pb(II) ions adsorption on chitosan-conjugated magnetite nano-biocomposite using response surface methodology

This study aimed to investigate the performance of a magnetic nano-biocomposite, chitosan conjugated magnetite nanoparticle (CH-MNP), for the removal of lead ions. The magnetite nanoparticles were synthesized through a controlled co-precipitation technique and were stabilized with citric acid. Subsequently, they were covalently bonded to chitosan via carbodiimide chemistry using EDAC/NHS activation. One of the notable advantages of this nano-biocomposite is its chemical conjugation, which does not have the weakness of the ultimate chitosan detachment of a physical bond and makes it an encouraging candidate for magnetic separation with no secondary waste production. The CH-MNPs had a diameter of ∼10 nm, with a saturation magnetization of 76.01 emu/g ensuring a superparamagnetic property. The response surface methodology (RSM) with a central composite design (CCD) framework was used for optimizing the adsorption process. The optimum conditions to achieve 92.15% of Pb(II) removal were found to be at a pH of 6.1 with the nano-adsorbent concentration of 1.04 g/L and a contact time of 59.92 min. Our adsorption isotherm data were fitted well with the Langmuir adsorption isotherm model, and the equilibrium data followed the pseudo-second-order kinetics and intraparticle diffusion kinetic model. The maximum Langmuir Pb(II) adsorption capacity was calculated to be 192.308 mg/g. These results suggest that the proposed synthetic nano-biocomposite is quite an ideal nano-adsorbent for Pb(II) removal in wastewater treatment technology.

Fabrication of Zn-based magnetic zeolitic imidazolate framework bionanocomposite using basil seed mucilage for removal of azo cationic and anionic dyes from aqueous solution

The Basil seeds mucilaginous polysaccharide exhibits remarkable physical and chemical properties like high water-absorbing capacity, emulsifying, and stabilizing properties. The metal-organic frameworks are one of the most promising precursors made of metal clusters and organic connectors for the fabrication of advanced adsorbents due to their unique properties. In this study, the bionanocomposite of magnetic zeolitic imidazolate framework-8 was successfully synthesized and applied to adsorb azo cationic and anionic dyes. The synthesized magnetite nanoparticles were pretreated with mucilage extracted from basil seeds to acquire negatively charged magnetite surface, followed by nucleation through attracting zinc cation, and then the growth of metal-organic frameworks which yields high-quality ZIF-8 crystals. The samples were characterized by Field Scanning Electron Microscopy, X-ray Diffraction, Fourier Transform Infrared Spectrometry, vibrating sample magnetometer, and Brunauer-Emmett-Teller surface area analysis. In the process of adsorption, influencing factors and recycling regeneration were discussed, and the adsorption mechanisms such as kinetics, isotherm, and thermodynamics were explored. The results of the adsorption process showed that maximum adsorption capacities were 9.09 and 13.21 mg/g for Methylene blue and Eriochrome Black T, respectively. The excellent reusability combined with its magnetic separation property makes the nanocomposite a promising adsorbent for the removal of cationic and anionic dyes.

A Review of Different Types of DOE Methods as a Useful Platform for Improving the Performance of Nano Adsorbents in Removal Systems of Pollutants

Background:

In recent years, the Design of Experiments (DOE) is used for removing pollutant from wastewater by nano-adsorbent. Some methods are Taguchi, Response Surface Methodology (RSM) and factorial design. The aim of this paper is to review different used methods of DOE in removing pollutant to suggest some notations to scholars.

Methods:

The reviewed papers were searched in Google Scholar, Scopus, and Web of Science randomly and categorized based on DOE methods.

Results:

Number of factors and responses in DOE for removing pollutants from wastewater are between 2-6 and 1-4, respectively. There are several computer software programs that provide simple use of these methods, such as Qualitek, Design Expert, Minitab, R and Matlab Programming. All models have a coefficient of determination R-sq more than 0.9.

Conclusion:

All the mentioned methods are appropriate because of the high R-sq value. Since the largest number of runs are used in RSM, it is not suitable for the experiments which are conducted by expensive materials and process. Furthermore, Design Expert and Minitab are the most popular software used by scholars in DOE methods for the removal of pollutant.

Improved lead removal from aqueous solution using novel porous bentonite - and calcite-biochar composite

Biochar-mineral (bentonite/calcite) composite (BC-CM) prepared at different temperatures were tested under varied conditions for effective removal of lead (Pb) from aqueous solution. With increasing pyrolysis temperature, increased surface area, pore volume, bentonite decomposition and less or no decomposition of calcite occurred. Bentonite-biochar (BCS) and calcite-biochar (CCS) prepared at 700 °C were found most suitable for efficient removal of Pb (99.9%). Bentonite and calcite acted as catalyst and contributed to changes in yield, pH, texture, functional groups, minerals and carbonization that facilitated efficient Pb removal by BCS 700 and CCS 700. Pb concentration, pH, dose of BCS and CCS, and contact time were further optimized using response surface methodology (RSM) for maximizing removal percentage (R%) of Pb and adsorption capacity (qt). Both BCS 700 and CCS 700 showed similar effects (positive/negative) of factors on R% and qt. Under optimized conditions, 0.21 g of BCS 700 effectively removed 99.2% of 431 mg/L in 3.6 h at solution pH of 4.2, while 0.07 g CCS 700 removed 97.06% of 232 mg/L in 3.5 h at 5.5 pH. Removal of Pb onto both BCS and CCS was by monolayer adsorption with maximum adsorption capacity of 500 mg/g. Rapid Pb removal was observed within 2 h of contact time (CCS 700 > BCS 700) and equilibrium was achieved within 10 h. BCS 700 followed first order and CCS 700 followed second order kinetic model. Electrostatic attraction between Pb ions and mineral groups present in BCS 700 and CCS 700 also played important role in Pb removal. This study clearly demonstrated that composite of biochar with bentonite or calcite under optimized conditions significantly improved Pb removal and adsorption capacity that can be further utilized for larger scale applications.

Use of Response Surface Methodology To Develop and Optimize the Composition of a Chitosan-Polyethyleneimine-Graphene Oxide Nanocomposite Membrane Coating To More Effectively Remove Cr(VI) and Cu(II) from Water

Response surface methodology was successfully used to optimize the amounts of chitosan (CS), polyethyleneimine (PEI), graphene oxide (GO), and glutaraldehyde (GLA) to produce a multifunctional nanocomposite membrane coating able to remove positively and negatively charged heavy metals, such as Cr(VI) and Cu(II). Batch experiments with different concentrations of the four coating components (GO, CS, PEI, and GLA) on cellulose membranes were carried out with solutions containing 10 ppm Cr(VI) and Cu(II) ions. Reduced quadratic equations for the Cr(VI) and Cu(II) removal were obtained based on the observed results of the batch experiments. The numerical analysis resulted in an optimized solution of soaking for 30 min in CS, 1.95% PEI, 1000 ppm GO, and 1.68% GLA with predicted removal of 90 ± 10 and 30 ± 3% for Cr(VI) and Cu(II), respectively, with a desirability of 0.99. This mathematically optimized solution for the coating was experimentally validated. To determine the best membrane material for the coating, stability of the nanocomposite coating was determined using attenuated total reflectance-infrared spectroscopy in eight membrane materials before and after exposure to four solutions with different water chemistries. The glass microfiber (GMF) membranes were determined to be one of the best materials to receive the coating. Then, the coated GMF filter was further investigated for the removal of Cr(VI) and Cu(II) in single and binary component solutions. The results showed that the coatings were able to remove successfully both heavy metal ions, suggesting its ability to remove positively and negatively charged ions from water.