Optimization of arsenite removal by adsorption onto organically modified montmorillonite clay: Experimental & theoretical approaches

Optimization of divalent mercury removal from synthetic wastewater using desirability function in central composite design of response surface methodology

Heavy metals exist in the ecosystem both naturally and due to anthropogenic activities and as recalcitrant pollutants; they are non-biodegradable and cause acute and chronic diseases to human beings and many lifeforms. A statistical experimental approach was applied in this current study to optimize the detoxification of mercury [Hg(II)] from mono-component biosorption system by a novel hybrid granular activated carbon (biosorbent) prepared from maize plant residues. The analysis of variance by the application of central composite design shows that all the studied independent factors greatly influence Hg(II) removal efficiency and uptake capacity. The optimum experimental condition of 30 min contact time, 0.5 g/L biosorbent dosage, and 15 mg/L initial Hg(II) concentration were achieved after seeking 20 optimization solutions at 0.903 desirability. The optimum percentage removal and uptake capacity of Hg(II) at the optimal experimental setup was 96.7% and 10.8 mg/g, respectively. To confirm the quadratic models developed for the prediction of the responses as a function of the independent factors, confirmatory laboratory experiments were performed at the optimum condition. The results show that at the established best experimental condition, the optimum Hg(II) removal efficiency of 98.3% and uptake capacity of 11.2 mg/g were attained, which were within the prediction intervals indicating the suitability of the quadratic models in predicting future cases. The TEM and XRD analyses show that the Hg(II) ions were adsorbed by the biosorbent successfully and this suggests the potential and applicability of this novel biosorbent in treating water contaminants, especially heavy metals.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-023-00888-5.

Response surface optimization and modeling in heavy metal removal from wastewater-a critical review

The existence of hazardous heavy metals in aquatic settings causes health risks to humans, prompting researchers to devise effective methods for removing these pollutants from drinking water and wastewater. To obtain optimum removal efficiencies and sorption capacities of the contaminants on the sorbent materials, it is normally necessary to optimize the purification technology to attain the optimum value of the independent process variables. This review discusses the most current advancements in using various adsorbents for heavy metal remediation, as well as the modeling and optimization of the adsorption process independent factors by response surface methodology. The remarkable efficiency of the response surface methodology for the extraction of the various heavy metal ions from aqueous systems by various types of adsorbents is confirmed in this critical review. For the first time, this review also identifies several gaps in the optimization of adsorption process factors that need to be addressed. The comprehensive analysis and conclusions in this review should also be useful to industry players, engineers, environmentalists, scientists, and other motivated researchers interested in the use of the various adsorbents and optimization methods or tools in environmental pollution cleanup.

Adsorptive removal of trace thallium(I) from wastewater: A review and new perspectives

Thallium is an emerging pollutant reported in wastewater along with the increasing mining and smelting of thallium-containing ores in recent years. The complete removal of Tl(I) from wastewater is of significant emergency due to its high toxicity and mobility, however, Tl(I) removal is always confronted with numerous technical difficulties because of the extremely low Tl(I) concentration in wastewater and the disturbances of many accompanying impurity ions. Adsorption is currently the most widely used method for Tl(I) removal on industrial scale and varied kinds of adsorbents such as Prussian blue analogues, biosorbents, and metal oxides have been developed. However, the adsorption process of Tl(I) is always affected by the co-existing cations, resulting in low Tl(I) removal efficiency. Recently, the development of a variety of novel adsorbents or ion sensors based on macrocyclic compounds for enrichment and accurate determination of trace Tl(I) in aqueous solutions exhibits great potential for application in Tl(I) removal from wastewater with high selectivity and process efficiency. This paper provides an overview of the adsorption methods for Tl(I) removal from wastewater with emphasis on complexation properties between varied types of adsorbents and Tl(I). Future directions of research and development of adsorptive Tl(I) removal from industrial wastewater are proposed.

Removal of anionic arsenate by a PEI-coated bacterial biosorbent prepared from fermentation biowaste

As a problematic element in water systems, arsenic exists as As(III) and As(V). Adsorption techniques can be used to remove anionic As(V) as it is present as a polyatomic anion. In the case of As(III) which exists in zero-valent state under neutral pH, it can be also removed by adsorption after being converted into As(V). Many inorganic and organic materials have been examined as potential adsorbents for anionic As(V) removal. However, most exhibit relatively low adsorption capacities (<10 mg/g). The objective of this study is to examine As(V)-removal mechanism and practical potential of a PEI-coated bacterial biosorbent prepared from fermentation biowaste. The maximum As(V) uptake of the biosorbent was determined to be 62.99 mg/g by Langmuir model. The effects of various parameters including pH, biosorbent dosage, ionic strength and temperature were also examined. Kinetic and equilibrium models were used to interpret the experimental data mathematically. A 0.01 M NaOH solution was chosen as an effective As(V)-desorbing eluent for biosorbent regeneration. The adsorption capacity of the biosorbent remained above 85% over three successive cycles of adsorption and desorption. In conclusion, the biowaste-driven biosorbent is a promising anion adsorbent for treatment of As(V)-contaminated wasters.

Mechanistic investigation of ciprofloxacin recovery by magnetite-imprinted chitosan nanocomposite: Isotherm, kinetic, thermodynamic and reusability studies

Recovery of antibiotics from water and wastewaters has recently gained a great deal of attention due to their serious health and environmental problems. In this work, a magnetite imprinted chitosan polymer nanocomposites (Fe-CS NCs) were synthesized and applied for the adsorptive removal of ciprofloxacin (CIFO) as a model fluoroquinolone antibiotics. The composition and surface morphology of Fe-CS NCs were studied by SEM, BET, XRD, TEM, FTIR and zeta potential meter. Modelling and optimization of adsorption process were studied using response surface methodology (RSM). The reliability of the RSM models was tested by fitting the data. A comparative analysis of the results derived from the models demonstrated that the second-order model was the best. From the contour plotting results, at pH < pH_iep low adsorption rate was observed due to protonation of the chitosan NH₂ groups, whereas the adsorption rate was significantly enhanced and achieved to a maximum level at pH 6 due to the electrostatic interactions and hydrophobic interactions. Under optimum conditions, maximum removal efficiency and maximum adsorption capacity were obtained 68% and 142 mg/g, respectively. Well regenerability of Fe-CS together with its high capacity of fluoroquinolone antibiotics removal provide a promisable strategy to remediation of wastewaters.

Adsorption Analyses of Phenol from Aqueous Solutions Using Magadiite Modified with Organo-Functional Groups: Kinetic and Equilibrium Studies

Organically-modified magadiite (MAG–CTAB–KH550) was synthesized via ion-exchange method and condensation reaction in the presence of pure magadiite (MAG), cetyltrimethylammonium bromide (CTAB) and γ-aminopropyltriethoxysilane (KH550) in aqueous solution in this research. This new adsorbent material was studied using scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and N₂ adsorption/desorption isotherms process. It was found that the MAG–CTAB–KH550 has high Brunaur-Emmet-Teller (BET) specific surface area and mesoporous pore size distribution which enhanced its ability to remove phenol in aqueous solution; and, the value of pH has a relatively large impact on the adsorption behavior of the sorbent. Finally, the adsorptive behavior of the mesoporous material on phenol was followed pseudo-second-order kinetic adsorption model. In contrast, the adsorption equilibrium isotherm was better performed Langmuir isotherm model than the Freundlich isotherm model; in addition, the results also showed that the MAG–CTAB–KH550 had a better adsorption capacity and removal efficiency than MAG.

Kinetic and modeling data on phenol removal by Iron-modified Scoria Powder (FSP) from aqueous solutions

Phenol present in industrial effluents is a toxicant matter which causes pollution of environments aqueous. In this work, scoria was modified by iron in order to increasing of adsorbent efficiency and effective removing of phenol. Effects of independent variables including pH, adsorbents dosage, contact time and adsorbate concentration on removing of phenol were studied by response surface methodology (RSM) based on the central composite designs (CCD). The characterization of raw scoria powder (RSP) and Iron-modified Scoria Powder (FSP) was determined via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The obtained data showed modification by iron caused the growth of new crystalline of iron oxide on the surface of FSP. Evaluated data by RSM indicated the all variables especially pH are effective in removing of phenol (P-value < 0.001) and optimum condition was obtained at pH = 5, phenol concentration = 50 mg/l, adsorbent dosage = 1 g/l and contact time = 100 min to the value of 94.99% with desirability of 0.939. Results revealed that data were fitted by Langmuir isotherm (R² = 0.9938) and pseudo second order kinetic (R² = 0.9976). It was found that iron causes increasing the site active of scoria and let to significant removal of phenol.

Dataset on photodegradation of tetracycline antibiotic with zinc stannate nanoflower in aqueous solution - Application of response surface methodology

Removal of pharmaceutical ingredients such as tetracycline from aqueous solution has a great importance. The aim of the current study was to investigate the degradation of tetracycline antibiotic in the presence of a triode semiconductor oxide as well as modeling of the photocatalytic degradation process in order to determine optimal condition Zinc stannate nanoflower (Zn₂SnO₄) was synthesized by hydrothermal process and characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM) techniques. Response surface methodology (RSM) was used to model and optimize four key independent variables, including photocatalyst dosage, initial concentration of tetracycline antibiotic (TC) as model pollutant, pH and reaction time of photocatalytic degradation. The proposed quadratic model was in accordance with the experimental results with a correlation coefficient of 98%. The obtained optimal experimental conditions for the photodegradation process were the following: zinc stannate (ZTO) dosage=300 mg L^-1, initial concentration of TC= 10 mg L^-1, reaction time= 100 min and pH=4.5. Under the optimal conditions, the predicted degradation efficiency was 95.45% determined by the proposed model. In order to evaluate the accuracy of the optimization procedure, the confirmatory experiment was carried out under the optimal conditions and the degradation efficiency of 93.54% was observed, which closely agreed with the predicted value.

Data on performance of air stripping tower- PAC integrated system for removing of odor, taste, dye and organic materials from drinking water-A case study in Saqqez, Iran

Unpleasant taste or smell are more importantly constituents of drinking-water, lead to complaints from consumers. Dye and organic matter as well change in disinfection practice may generate taste and an odorous compound in treated water. According to low efficiency of conventional methods to remove taste and odor compounds, present study was aimed to evaluate the performance of air stripping tower- Poly Aluminum Chloride (PAC) integrated system to remove odor and taste, dye and organic materials from drinking water. Different air to water ratio and PAC doses were used to remove considered parameters in certain condition. The results of this study indicated that the maximum removal efficiency of 86.2, 76.47, 58.46 and 41.27% of taste and odor, dye, COD and TOC were achieved by the air stripping tower- PAC integrated system, respectively. However, the physico-chemical characteristics of water and adsorbent effect on the of substances removal efficiency considerably. It can be stated that the air striping tower - PAC integrated system is able to reduce the odor and taste-causing substances and organic matter to a level which is recommended by the Institute of Standards and Industrial Research of Iran.