Equilibrium and kinetic studies on the adsorption of acidic dye by the gel anion exchanger

Preparation of Eco-Friendly Chelating Resins and Their Applications for Water Treatment

In the present study, two chelating resins were prepared and used for simultaneous adsorption of toxic metal ions, i.e., Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ (M^X+). In the first step, chelating resins were prepared starting with styrene-divinylbenzene resin, a strong basic anion exchanger Amberlite IRA 402(Cl^-) with two chelating agents, i.e., tartrazine (TAR) and amido black 10B (AB 10B). Key parameters such as contact time, pH, initial concentration, and stability were evaluated for the obtained chelating resins (IRA 402/TAR and IRA 402/AB 10B). The obtained chelating resins show excellent stability in 2M HCl, 2M NaOH, and also in ethanol (EtOH) medium. The stability of the chelating resins decreased when the combined mixture (2M HCl:EtOH = 2:1) was added. The above-mentioned aspect was more evident for IRA 402/TAR compared to IRA 402/AB 10B. Taking into account the higher stability of the IRA 402/TAR and IRA 402/AB 10B resins, in a second step, adsorption studies were carried out on complex acid effluents polluted with M^X+. The adsorption of M^X+ from an acidic aqueous medium on the chelating resins was evaluated using the ICP-MS method. The following affinity series under competitive analysis for IRA 402/TAR was obtained: Fe³⁺(44 µg/g) > Ni²⁺(39.8 µg/g) > Cd²⁺(34 µg/g) > Cr³⁺(33.2 µg/g) > Pb²⁺(32.7 µg/g) > Cu²⁺ (32.5 µg/g) > Mn²⁺(31 µg/g) > Co²⁺(29 µg/g) > Zn²⁺ (27.5 µg/g). While for IRA 402/AB 10B, the following behavior was observed: Fe³⁺(58 µg/g) > Ni²⁺(43.5 µg/g) > Cd²⁺(43 µg/g) > Cu²⁺(38 µg/g) > Cr³⁺(35 µg/g) > Pb²⁺(34.5 µg/g) > Co²⁺(32.8 µg/g) > Mn²⁺(33 µg/g) > Zn²⁺(32 µg/g), consistent with the decreasing affinity of M^X+ for chelate resin. The chelating resins were characterized using TG, FTIR, and SEM analysis. The obtained results showed that the chelating resins prepared have promising potential for wastewater treatment in the context of the circular economy approach.

Innovative Polymer Microspheres with Chloride Groups Synthesis, Characterization and Application for Dye Removal

This article presents the synthesis and sorption characteristics of novel microspheres based on 4-vinylbenzene chloride (VBCl) with divinylbenzene (DVB) or ethylene glycol dimethylacrylate (EGDMA). To confirm the chemical structure of the homo- and co-polymers attenuated total reflectance, Fourier transform infrared spectroscopy (ATR-FTIR) was used. The presence of characteristic functional groups (−OH, −CH, −CH2, C−O, C=O and C–O–C) in obtained microspheres was confirmed. Differential scanning calorimetry (DSC) analysis confirms the good thermal resistance of the polymers. The decomposition of microspheres is closely related to the chemical structure of the monomers used. DVB-derived materials decompose in one step, whereas the decomposition of EGDMA derivatives is multi-stage. Obtained polymeric microspheres were applied for auramine O (AO) basic dye removal form aqueous solutions. Equilibrium studies confirmed that the Freundlich model described the system better than Langmuir or Temkin equations and the adsorption capacities kF ranged from 4.56 to 7.85 mg1−1/n L1/n/g. The sorption kinetic of AO from solutions of the 10 and 100 mg/L concentrations was very fast, and after 10 min, equilibrium was reached.

Decorating graphene oxide with zeolitic imidazolate framework (ZIF-8) and pseudo-boehmite offers ultra-high adsorption capacity of diclofenac in hospital effluents

This study reports on an easy and scalable synthesis method of a novel magnetic nanocomposite (GO/ZIF-8/γ-AlOOH) based on graphene oxide (GO) nanosheets decorated with zeolitic imidazolate framework-8 (ZIF-8), pseudo-boehmite (γ-AlOOH), and iron oxide (Fe₃O₄) nanoparticles by combining solvothermal and solid-state dispersion (SSD) methods. The nanocomposite was successfully applied to remove of diclofenac sodium (DCF) - a widely used pharmaceutical - from water. Response Surface Methodology (RSM) was used to optimize the adsorption process and assess the interactions among the influencing factors on DCF removal efficiency; including contact time, adsorbent dosage, initial pH, solution temperature, and DCF concentration. Adsorption isotherm results showed a good fitting with the Langmuir isotherm model with an exceptional adsorption capacity value of 2594 mg g^-1 at 30 °C, which was highly superior to the previously reported adsorbents. In addition, kinetic and thermodynamic investigations further illustrated that the adsorption process was fast (equilibrium time = 50 min) and endothermic. The regeneration of GO/ZIF-8/γ-AlOOH nanocomposite using acetic acid solution (10% v/v) after a simple magnetic separation was confirmed in five consecutive cycles, which eliminate the usage of organic solvents. The nanocomposite has also shown a superior performance in treating a simulated hospital effluent that contained various pharmaceuticals as well as other organic, and inorganic constituents.

Characterizing the Deacidification Adsorption Model of Organic Acids and Phenolic Compounds of Noni Extract Using Weak Base Ion Exchanger

Although noni (Morinda citrifolia L.) has been used to treat a broad range of diseases, many people avoid consuming the fruits because of its unpleasant odor caused by organic acids. Even though ion exchange resins were able to reduce the odor, it also reduced beneficial antioxidant compounds. Thus, to preserve antioxidants (phenolic compounds) during deacidification, it is important to characterize the interaction of ion exchange resin with both organic acids and phenolic compounds. Adsorption capacities of organic acids and phenolic compounds commonly found in the noni fruit were conducted onto Amberlite IRA 67 resin. The phase contact time to reach equilibrium for octanoic acid and hexanoic acid compounds was 326.86 and 160.72 min, respectively. The values of initial adsorption rate, 1/K1, and adsorption extent, 1/K2, decreased with the increase of initial concentration for all compounds studied. Results for all the compounds studied fitted well to the Langmuir model. The effect of pH in adsorption capacity of the actual system (noni juice) has been applied based on the model system studied.

Improved adsorption performance of nanostructured composite by ultrasonic wave: Optimization through response surface methodology, isotherm and kinetic studies

In this work, ultrasound-assisted adsorption of an anionic dye, sunset yellow (SY) and cationic dyes, malachite green (MG), methylene blue (MB) and their ternary dye solutions onto Cu@ Mn-ZnS-NPs-AC from water aqueous was optimized by response surface methodology (RSM) using the central composite design (CCD). The adsorbent was characterized using Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX) and EDX mapping images. The effects of various parameters such as pH, sonication time, adsorbent mass and initial concentrations of SY, MG and MB were examined. A total 33 experiments were conducted to establish a quadratic model. Cu@ Mn-ZnS-NPs-AC has the maximum adsorption efficiency (>99.5%) when the pH, sonication time, adsorbent mass and initial concentrations of SY, MG and MB were optimally set as 6.0, 5min, 0.02g, 9, 12 and 12mgL^-1, respectively. Sonication time has a statistically significant effect on the selected responses. Langmuir isotherm model was found to be best fitted to adsorption and adsorption capacities were 67.5mgg^-1 for SY, 74.6mgg^-1 for MG and 72.9mgg^-1 for MB. Four kinetic models (pseudo-first order, pseudo-second order, Weber-Morris intraparticle diffusion rate and Elovich) were tested to correlate the experimental data and the sorption was fitted well with the pseudo-second order kinetic model.

Optimization of simultaneous ultrasound assisted toxic dyes adsorption conditions from single and multi-components using central composite design: Application of derivative spectrophotometry and evaluation of the kinetics and isotherms

Present study is devoted on the efficient application of Sn (O, S)-NPs -AC for simultaneous sonicated accelerated adsorption of some dyes from single and multi-components systems. Sn (O, S) nanoparticles characterization by FESEM, EDX, EDX mapping and XRD revel its nano size structure with high purity of good crystallinity. Present adsorbent due to its nano spherical shape particles with approximate diameter of 40-60nm seems to be highly effective in this regard. The effects of five variables viz. pH (3.5-9.5), 0.010-0.028g of adsorbent and 0.5-6.5min mixing by sonication is good and practical conditions for well and expected adsorption of MB and CV over concentration range of 3-15mgL^-1. Combination of response surface methodology (RSM) based on central composite design (CCD) and subsequent of analysis of variance (ANOVA) and t-test statistics were used to test the significance of the independent variables and their interactions. Regression analysis reveal that experimental data with high repeatability and efficiency well represented by second-order polynomial model with coefficient of determination value of 0.9988 and 0.9976 for MB and CV, respectively following conditions like pH 8.0, 0.016g adsorbent, 15mgL^-1 of both dyes 4min sonication time is proportional with achievement of experimental removal percentage of 99.80% of MB and 99.87% of CV in batch experiment. Evaluation and estimation of adsorption data with Langmuir and Freundlich isotherm well justify the results based on their correlation coefficient and error analysis confirm that Langmuir model is good model with adsorption capacity of 109.17 and 115.34mgg^-1 in single system and 95.69 and 102.99mgg^-1 in binary system for MB and CV, respectively. MB and CV kinetic and rate of adsorption well fitted by pseudo-second order equation both in single and binary systems and experimental results denote more and favorable adsorption of CV than respective value in single system. The pseudo-second-order rate constant k₂ in binary system larger than single system.

Parametric and adsorption kinetic studies of methylene blue removal from simulated textile water using durian (Durio zibethinus murray) skin

In this study, durian (Durio zibethinus Murray) skin was examined for its ability to remove methylene blue (MB) dye from simulated textile wastewater. Adsorption equilibrium and kinetics of MB removal from aqueous solutions at different parametric conditions such as different initial concentrations (2-10 mg/L), biosorbent dosages (0.3-0.7 g) and pH solution (4-9) onto durian skin were studied using batch adsorption. The amount of MB adsorbed increased from 3.45 to 17.31 mg/g with the increase in initial concentration of MB dye; whereas biosorbent dosage increased from 1.08 to 2.47 mg/g. Maximum dye adsorption capacity of the durian skin was found to increase from 3.78 to 6.40 mg/g, with increasing solution pH. Equilibrium isotherm data were analyzed according to Langmuir and Freundlich isotherm models. The sorption equilibrium was best described by the Freundlich isotherm model with maximum adsorption capacity of 7.23 mg/g and this was due to the heterogeneous nature of the durian skin surface. Kinetic studies indicated that the sorption of MB dye tended to follow the pseudo second-order kinetic model with promising correlation of 0.9836 < R(2) < 0.9918.

Removal of lead and yellow 44 acid dye in single and binary component systems by raw Posidonia oceanica and the cellulose extracted from the raw biomass

This study examined the sorption behaviour of Pb(II) and C.I. Acid Yellow 44 on Posidonia oceanica, an abundant Mediterranean biomass. A comparison with sorption onto cellulose extracted from the raw material was carried out to identify those site characteristics that play a predominant role in the adsorption of both dye and metal ions. Kinetic and equilibrium studies were performed for single and binary component systems, and the experimental data were analyzed by a non-linear method. The pseudo second-order kinetic model was successfully applied for both dye and metal retention onto sorbents in single and binary systems. Both sorbents were found to be more effective for lead than for Yellow 44 removal. However, lead sorption was more effective on raw P. oceanica suggesting that the metal ions are sorbed into the whole available biomass sites (cellulose and lignin). An opposite behaviour was reported for Yellow 44 sorption, which was found to be more effective on the extracted cellulose than raw P. oceanica. This finding proves that the only available sites for dye sorption are the cellulosic ones. The binary component experimental studies indicated competition between dye and lead for the available sites of raw P. oceanica. However, this competition was found to be less prevalent for sorption by cellulose extracted from raw P. oceanica suggesting that, in binary component systems, the cellulosic sites are equally available for both pollutants, the only limiting parameter being the size of the molecular sorbate. Langmuir and Freundlich isotherms were used to fit the experimental data using the non-linear method for parameter determination.

Removal of orange 16 reactive dye from aqueous solutions by waste sunflower seed shells

In this work, the use of an agro-industrial waste, i.e., sunflower seed shells, was investigated as a sorbent for the removal of Orange 16 reactive dye from aqueous environments. Batch experiments were performed as a function of pH, sorbent dose, dye concentration, temperature and contact time. The percent dye removal increased with increasing sorbent dose and temperature of the aqueous solution, and decreased with increasing dye concentration; the required contact time was five hours. The Freundlich, Langmuir, Dubinin-Radushkevich and Tempkin adsorption isotherms were used to describe the equilibrium sorption data and to determine the corresponding isotherm constants. The thermodynamic parameters ?G, ?H and ?S were also determined. These parameters indicated that the sorption of reactive dye onto sunflower seed shells was a spontaneous, endothermic and entropy-driven process. The kinetic data were evaluated by pseudo-first order, pseudo-second order and intra-particle diffusion kinetic models. The results of the kinetic study indicated that the sorption of Orange 16 reactive dye onto sunflower seed shells is a complex process and both chemical surface sorption and intraparticle diffusion contribute to the rate-limiting step. Therefore, the sunflower seed shell showed itself to be a promising cheap sorbent for the decolourization of aqueous coloured solutions or effluents.

Preparation and utilization of wheat straw bearing amine groups for the sorption of acid and reactive dyes from aqueous solutions

Removal of Acid Red 73 (AR 73) and Reactive Red 24 (RR 24) onto modified wheat straw (MWS) from aqueous solutions was investigated. Sorption experiments were carried out as function of MWS dosage, contact time, initial concentration, pH and temperature. Characterizations of MWS were measured and a mass of amine groups were observed in the framework of MWS. The equilibrium sorption data were well represented by the Langmuir isotherm equation, and the calculated thermodynamic parameters indicated a spontaneous and endothermic nature for sorption process. It was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. More over, the high maximum sorption capacity (q(e max), 714.3 mg g(-1) for AR 73 and 285.7 mg g(-1) for RR 24) and low cost (1.24 US$ kg(-1)) of MWS provided strong evidence of the potential of MWS for the technological applications of anionic dyes removal from aqueous solutions.

Comparison of the efficiency of activated carbon and neutral polymeric adsorbent in removal of chromium complex dye from aqueous solutions

The removal efficiency of chromium complex dye Lanasyn Navy M-DNL from aqueous solution using the activated carbon (AC) and the neutral polymeric adsorbent Macronet MN 200 (MN 200) has been investigated under various experimental conditions: initial dye concentration, pH and temperature. The effectiveness of MN 200 for the dye removal was found relatively higher than that of AC in both acidic and neutral solutions. Two theoretical models (pseudo-second-order-reaction and intraparticle diffusion) were used to describe the sorption kinetics, and to determine the constants of sorption rate (k(2)), intraparticle (k(i)) and film diffusion (k(s)). The both sorption systems dye-AC and dye-MN 200 follow the pseudo-second-order model with a higher k(2) value for dye-MN 200 in acidic media at 20 degrees C when compared with that of the dye-AC. With increase in the solution temperature from 20 to 40 degrees C the k(2) value for dye-AC indicate an increase in acidic media and decrease in alkaline media; whereas k(2) values for dye-MN 200 decrease in both acidic and neutral media. The rate of dye adsorption on both adsorbents is dependent on intraparticle and film diffusion proceeding simultaneously. The boundary layer effect is more pronounced in acidic solutions and with increase in temperature.