Modified natural zeolite using ammonium quaternary based material for Acid red 18 removal from aqueous solution

The Use of Various Types of Waste Paper for the Removal of Anionic and Cationic Dyes from Aqueous Solutions

This study examined the possibility of using various types of waste paper-used newsprint (NP), used lightweight coated paper (LWC), used office paper (OP), and used corrugated cardboard (CC)-for the removal of anionic dyes, Acid Red 18 (AR18) and Acid Yellow 23 (AY23), and cationic dyes, Basic Violet 10 (BV10) and Basic Red 46 (BR46), from aqueous solutions. The scope of this research included the characterization of sorbents (FTIR, SEM, BET surface area, porosity, pHPZC, effectiveness of water coloration), determination of pH effect on the effectiveness of dye sorption, sorption kinetics (pseudo-first-order model, second-order model, intraparticular diffusion model), and the maximum sorption capacity (Langmuir models and Freundlich model) of the tested sorbents. The use of waste paper materials as sorbents was found to not pose any severe risk of aquatic environment contamination. AR18, AY23, and BV10 sorption intensities were the highest at pH 2, and that of RB46 at pH 6. The waste paper sorbents proved particularly effective in removing cationic dyes, like in the case of, e.g., NP, which had a sorption capacity that reached 38.87 mg/g and 90.82 mg/g towards BV10 and BR46, respectively, and were comparable with that of selected activated carbons (literature data).

Synergistic effects of binary surfactant mixtures in the adsorption of diclofenac sodium drug from aqueous solution by modified zeolite

In this paper, the surfactant-modified clinoptilolite zeolite (with two methods) were used to remove diclofenac sodium (DFS) as a widely used drug in an aqueous solution. Clinoptilolite was modified by using pure cationic surfactant (cetyltrimethylammonium chloride, CTAC) and the mixed surfactants of CTAC + Triton-X100 (TX100). In the new approach, the synergistic effects between CTAC and TX100 were determined by surface tension measurements in different mole fractions and the optimum ratio (y₁ ≈ 0.8) was identified with the maximum synergism. According to the mole fraction of this composition, the surface of clinoptilolite was modified by mixed surfactants (MSMZ) for the adsorption of DFS and then results compared with modified zeolite with pure cationic surfactant (SMZ). The raw and modified (SMZ and MSMZ) zeolites were characterized by Fourier transform infrared spectroscopy (FT-IR), BET analysis, the scanning electron microscopy (SEM) images, Zeta potential and X-ray. The experimental data of adsorption in equilibrium conditions were also analyzed using different adsorption isotherm models (Langmuir, Freundlich, Hill, Khan, Sips, Redlich-Peterson and Toth) in non-linear forms, and finally, the best model consistent with experimental data is determined (SMZ:Sips and MSMZ:Toth). According to the best isotherm model, the amount of absorption capacity in MSMZ was obtained almost 57% higher than SMZ. In addition, the kinetic adsorption data were correlated with eight various models in order to selection the best model for these systems. The kinetic adsorption data were well described by fractal-like pseudo-first-order (FL-PFO) and IKL models for SMZ and MSMZ adsorbents, respectively. Eight error functions were used to estimate the best fitted isotherm and kinetic models.

Chitosan/lemon residues activated carbon efficiently removal of acid red 18 from aqueous solutions: batch study, isotherm and kinetics

In this research, chitosan-decorated activated carbon (AC-CS) was proposed. The AC was cross-linked with glutaraldehyde to prepare an adsorbent (AC-CS). The AC-CS has a rough surface. Adding the AC-CS directly to the dye solution can achieve simple and convenient removal of anionic azo dyes acid red 18 (AR-18). In the dye solution, the AC-CS was used as an adsorbent. The effects of pH, contact time, temperature, initial concentration of AR-18 and the AC-CS dosage on the adsorption efficiency were investigated. Full kinetic and isotherm analyses were also undertaken. In addition, the reusability of the AC-CS was evaluated, and the results showed that the removal rate of AR18 after regeneration remained relatively stable, above 90%. This experiment has shown that AC-CS is a promising anionic azo dye adsorbent.

Magnetic NH2-MIL-101(Al)/Chitosan nanocomposite as a novel adsorbent for the removal of azithromycin: modeling and process optimization

In the present study, the magnetic NH₂-MIL-101(Al)/chitosan nanocomposite (MIL/Cs@Fe₃O₄ NCs) was synthesized and used in the removal of azithromycin (AZT) from an aqueous solution for the first time. The as-synthesized MIL/Cs@Fe₃O₄ NCs was characterized by SEM, TEM, XRD, FTIR, BET, and VSM techniques. The effect of various key factors in the AZT adsorption process was modeled and optimized using response surface methodology based on central composite design (RSM-CCD). The low value of p-value (1.3101e-06) and RSD (1.873) parameters, along with the coefficient of determination > 0.997 implied that the developed model was well fitted with experimental data. Under the optimized conditions, including pH: 7.992, adsorbent dose: 0.279 g/L, time: 64.256 min and AZT concentration: 10.107 mg/L, removal efficiency and AZT adsorption capacity were obtained as 98.362 ± 3.24% and 238.553 mg/g, respectively. The fitting of data with the Langmuir isotherm (R²: 0.998, X²: 0.011) and Pseudo-second-order kinetics (R²: 0.999, X²: 0.013) showed that the adsorption process is monolayer and chemical in nature. ΔH° > 0, ΔS° > 0, and ∆G° < 0 indicated that AZT removal was spontaneous and endothermic in nature. The effect of Magnesium on AZT adsorption was more complicated than other background ions. Reuse of the adsorbent in 10 consecutive experiments showed that removal efficiency was reduced by about 30.24%. The performance of MIL/Cs@Fe₃O₄ NCs under real conditions was also tested and promising results were achieved, except in the treatment of AZT from raw wastewater.

Acid red 18 removal from aqueous solution by nanocrystalline granular ferric hydroxide (GFH); optimization by response surface methodology & genetic-algorithm

The need for fresh water is more than before by population growth, and industrial development have affected the quality of water supplies, one of the important reason for water contamination is synthetic dyes and their extensive use in industries. Adsorption has been considered as a common methods for dye removal from waters. In this study, Acid Red18 removal in batch mode by using Granular Ferric Hydroxide (GFH) was investigated. The GFH characterized by XRD, FESEM and FTIR analysis. Experiments were designed using RSM-CCD method. The maximum removal efficiency was obtained 78.59% at pH = 5, GFH dosage = 2 g/l, AR18 concentration = 77.5 mg/l and 85 min of contact time. Optimization with RSM and Genetic Algorithm carried out and is similar together. The non-linear adsorption Isotherm and kinetic fitted with Freundlich (R2 = 0.978) and pseudo-second-order (R2 = 0.989) models, respectively. Thermodynamic studies showed that the AR18 adsorption is endothermic process and GFH nature was found spontaneous.

Effect of acid treated HY zeolites in adsorption of mesosulfuron-methyl

PURPOSE

Pollution of surface water and groundwater by bulky molecules such as pesticides has been recognized as a major problem in many countries due to their persistence in aquatic environment and potential adverse health effects. The main purpose of this study is the development of a capable adsorbent to remove these bulky molecules from wastewater such as the pesticide Mesosulfuron-Methyl (MM) by reducing the diffusion path, to overcome the problems of diffusional limitations on microporous adsorbents.

METHODS

The adsorption of mesosulfuron-methyl (MM) from aqueous solution is curried out using treated acid HY zeolite. Batch sorption equilibrium and kinetic experiments are conducted to evaluate the efficiency of these materials. Parent zeolites and their derivatives have been characterized by nitrogen adsorption-desorption, pyridine chemisorption followed by infrared spectroscopy and X-ray fluorescence.

RESULTS

The acid treatment leads to an increase in the specific surface from 691 to 853 m2 g- 1 for HY(30) and from 631 to 806 m2 g- 1 for the HY(16.6) zeolites. It also leads to a reduction in Lewis acidity from 74 to 25 µmol g- 1 and from 135 to 31 µmol g- 1 for HY(30) and HY(16.6) zeolites respectively, and increases the adsorbent-adsorbate interaction. The adsorption capacity increased from 83 to 99 % after acid treatment. The equilibrium adsorption time is decreased from 15 h to 10 min for the HY(30)_A and from 20 h to 20 min for the HY(16.6)_A for an initial concentration of 20 mg L- 1. The adsorption capacity depends on the pH solution, and the neutral form of the MM is more easily adsorbed into zeolite than the dissociated form via the framework bridged oxygen atoms. For all the samples, the pseudo-second-order kinetic model fits very well with the experimental data. In the case of the modified zeolites, the approaching equilibrium factor R w decreases from 0.08183 to 0.00008 when the Lewis acid sites decrease; indicating that the equilibrium is reached more quickly. S-shape adsorption isotherms indicates that cooperative adsorption phenomena. Nevertheless, the shape of acid treated zeolites evolves to an L type indicating a significant enhancement of the adsorbent - adsorbate interactions inducing better adsorption efficiency.

CONCLUSIONS

Mesosulfuron-methyl adsorption has been successfully enhanced after acid treatments of zeolites HY.

Prediction of methyl orange removal by iron decorated activated carbon using an artificial neural network

Date Stones were used as a bio-degradable waste source for preparing iron impregnated activated carbon. The prepared activated carbon-containing oxides of iron were characterized using SEM, XRD, FTIR, and BET. The specific surface area of the iron decorated activated carbon was 738.65 m²/g. The XRD confirmed the presence of magnetite and hematite while the SEM images assured the presence of pores. The prepared activated carbon was used to remove methyl orange from wastewater. Genetic Algorithm was used to develop a model which could predict the removal efficiency of the dye. The ANN model was validated and the effect of different parameters like adsorbent dosage (0.1-1 g/L), initial dye concentration (2-20 mg/L), pH (2-11), time (10-55 min) and temperature (30-75°C) was estimated both experimentally and predicted using the model. The adsorption process follows the Freundlich isotherm and pseudo-second-order kinetic model. The values of 1/n and K_F obtained from the Freundlich isotherm designate good adsorption capacity. Both experimental and model-predicted data agrees with the kinetic model. The adsorption rate is proportionate to the square of the number of vacant adsorption sites. From the thermodynamic study, the positive worth of ΔH° indicates the energy-absorbing nature of the surface assimilation method and the process is endothermic in nature. The low values of each ΔG° (-200 to 0 kJ/mol) and ΔH° correspond to physical surface assimilation. A positive worth of ΔS° reflects the inflated randomness at the solid-aqueous interface with some structural changes in adsorbate and adsorbent.

Simultaneous removal of ammonium nitrogen, dissolved chemical oxygen demand and color from sanitary landfill leachate using natural zeolite

In this study, natural zeolite with maximum adsorption capacity of 3.59 mg g^-1 was used for the simultaneous removal of ammonium nitrogen (NH₄⁺-N), dissolved chemical oxygen demand (d-COD) and color from raw sanitary landfill leachate (SLL). Saturation, desorption and regeneration tests of zeolite were performed. Optimum adsorption conditions were found for particle size 0.930 µm, stirring rate of 1.18 m s^-1, zeolite dosage of 133 g L^-1 and pH 8. NH₄⁺-N removal efficiency reached 51.63 ± 0.80% within 2.5 min of contact. NH₄⁺-N adsorption follows mostly the linear pseudo-second order model, with intra-particle diffusion. NH₄⁺-N desorption follows the linear pseudo-second order model. Adsorption data fitted to the Temkin Isotherm in linear and nonlinear forms. Saturation tests showed that zeolite can be efficiently used in three successive adsorption cycles. NH₄⁺-N release from the saturated zeolite was not completely reversible, suggesting that the zeolite may be used as slow ΝΗ₄⁺-Ν releasing fertilizer and an attractive low cost material for the treatment of SLL. NH₄⁺-N removal with the regenerated zeolite exceeded 40% of the initial concentration in the fluid within 2.5 min. SEM analysis showed significant changes through saturation and regeneration. XPS revealed that adsorption of ΝΗ₄⁺-Ν to the zeolite was accompanied by ion exchange.

Modeling and optimizing parameters affecting hexavalent chromium adsorption from aqueous solutions using Ti-XAD7 nanocomposite: RSM-CCD approach, kinetic, and isotherm studies

BACKGROUND

Due to the high toxicity of chromium, particularly as Hexavalent chromium Cr (VI), it is removed from industrial effluents before their discharge into the environment by a variety of methods, including loading catalysts onto the polymeric supports. This study focused on the removal of Cr(VI) from aqueous solutions using Amberlite XAD7 resin loaded titanium dioxide (Ti-XAD7).

METHODS

Ti-XAD7 was synthesized using Amberlite XAD-7 impregnated with titanium tetraethoxide. The prepared Ti-XAD7 was characterized by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Isotherms and kinetic studies were carried out to describe the adsorption behavior of adsorbent for the removal of Cr(VI) ions. Quadratic models considering independent variables, i.e. the initial Cr(VI) concentration, adsorbent dosage, time, and pH, were evaluated and optimized to describe the behavior of Cr(VI) adsorption onto the Ti-XAD7 using RSM based on a Five-level-four-factor CCD approach.

RESULTS

The accuracy and the fitting of the model were evaluated by ANOVA with R² > 0.725 and P value = 5.221 × 10^-5. The optimum conditions for the adsorption process were an initial Cr(VI) concentration 2750 ppb, contact time of 51.53 min, pH of 8.7, and Ti-XAD7 dosage of 5.05 g/L. The results revealed that the Langmuir and Sips isotherm models with R² = 0.998 and 0.999 were the best models fitting the experimental data. The adsorption capacity of Ti-XAD7 and R_L constant were 2.73 mg/g and 0.063-0.076 based on the Langmuir isotherm, respectively. Kinetic studies also indicated that the adsorption behavior of Cr(VI) was acceptably explained by the Elovich kinetic model with a good fitting (R² = 0.97).

CONCLUSIONS

Comparison of the Ti-XAD7 and XAD7 yield in chromium adsorption showed that modified XAD7 had higher removal efficiency (about 98%) compared to XAD7 alone.

Degradation of dimethyl phthalate using persulfate activated by UV and ferrous ions: optimizing operational parameters mechanism and pathway

The present study aimed to model and optimize the dimethyl phthalate (DMP) degradation from aqueous solution using UV_C/ Na₂S₂O₈/Fe²⁺ system based on the response surface methodology (RSM). A high removal efficiency (97%) and TOC reduction (64.2%) were obtained under optimum conditions i.e. contact time = 90 min, SPS concentration = 0.601 mM/L, Fe²⁺ = 0.075 mM/L, pH = 11 and DMP concentration = 5 mg/L. Quenching experiments confirmed that sulfate radicals were predominant radical species for DMP degradation. The effect of CO₃ ^- on DMP degradation was more complicated than other aquatic background anions. The possible pathway for DMP decomposition was proposed according to HPLC and GC-MS analysis. The average oxidation state (AOS) and carbon oxidation state (COS) values as biodegradability indicators demonstrated that the UV_C/SPS/Fe²⁺ system can improve the bioavailability of DMP over the time. Finally, the performance of UV_C/SPS/Fe²⁺ system for DMP treatment in different aquatic solutions: tap water, surface runoff, treated and raw wastewater were found to be 95.7, 88.5, 80.5, and 56.4%, respectively. Graphical abstract.

Untapped potential of zeolites in optimization of food waste composting

This study aims to examine the effect of zeolites in optimizing the process of food waste composting. A novel method of sequential hydrothermal was introduced to modify the natural zeolite and apply to in-vessel compost bioreactors. Raw and modified natural zeolites were applied at 10 and 15% (w/w) of the total waste and compared with un-amended control trial. Both raw and modified zeolites affected the composting process, but the notable results were observed for modified natural zeolite. The results for compost stability parameters were prominent at 15% modified natural zeolite concentration. The rapid and long-term thermophillic temperature and moisture content reduction to the optimum range was observed for modified natural zeolite. Furthermore, the total ammonium (NH₄⁺) and nitrate (NO₃^-) concentration in modified natural zeolite were increased by 11.1 and 21.5% respectively as compared to raw zeolite. Compost stability against moisture contents (MC), electrical conductivity (EC), organic matters (OM), total carbon (TC), mineral nitrogen, nitrification index (NI) and germination index (GI) was achieved after 60 days of composting that was in accordance with the international compost quality standards. The findings of this study suggested the suitability of modified natural zeolite addition at 15% to the total waste as the optimum ratio for the composting of food waste in order to achieve a stable nutrient-rich compost.

Data for efficiency comparison of raw pumice and manganese-modified pumice for removal phenol from aqueous environments-Application of response surface methodology

Present deadest collection was aimed to evaluate the efficiency of raw pumice (RWP) and Mn-modified pumice (MMP). Response surface methodology (RSM) based on the central composite designs (CCD) was applied to evaluate the effects of independent variables including pH, adsorbents dosage, contact time and adsorbate concentration on the response function and the best response values were predicted. The Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the adsorbents. Based on acquired data, the maximum efficiency removal of phenol was obtained 89.14% and 100% for raw and Mn-modified pumice respectively. The obtained data showed pH was effective parameter on phenol removal among the different variables. Evaluation of data using isotherms and kinetics models showed the fitted with Langmuir isotherm and pseudo second order kinetic for both adsorbents. According to obtained data was observed that modification of pumice can improve the efficiency removal of phenol to meet the effluent standards.