Phenol removal from aqueous solution by adsorption and ion exchange mechanisms onto polymeric resins

The removal of phenol from aqueous solution was evaluated by using a nonfunctionalized hyper-cross-linked polymer Macronet MN200 and two ion exchange resins, Dowex XZ (strong anion exchange resin) and AuRIX 100 (weak anion exchange). Equilibrium experimental data were fitted to the Langmuir and Freundlich isotherms at different pHs. The Langmuir model describes successfully the phenol removal onto the three resins. The extent of the phenol adsorption was affected by the pH of the solution; thus, the nonfunctionalized resin reported the maximum loading adsorption under acidic conditions, where the molecular phenol form predominates. In contrast both ion exchange resins reported the maximum removal under alkaline conditions where the phenolate may be removed by a combined effect of both adsorption and ion exchange mechanisms. A theoretical model proposed in the literature was used to fit the experimental data and a double contribution was observed from the parameters obtained by the model. Kinetic experiments under different initial phenol concentrations and under the best pH conditions observed in the equilibrium experiments were performed. Two different models were used to define the controlling mechanism of the overall adsorption process: the homogeneous particle diffusion model and the shell progressive model fit the kinetic experimental data and determined the resin phase mechanism as the rate-limiting diffusion for the phenol removal. Resins charged after the kinetic experiments were further eluted by different methods. Desorption of nonfunctionalized resin was achieved by using the solution (50% v/v) of methanol/water with a recovery close to 90%. In the case of the ion exchange resins the desorption process was performed at different pHs and considering the effect of the competitive ion Cl⁻. The desorption processes were controlled by the ion exchange mechanism for Dowex XZ and AuRIX 100 resins; thus, no significant effect for the addition of Cl⁻ under acidic conditions was observed, while under alkaline conditions the total recovery increased, specially for Dowex XZ resin.     

Adsorption affinity of certain biomolecules onto polymeric resins: Interpretation from molecular orbital theory

Molecular interactions have been studied for adsorption of certain biomolecules in aqueous solutions using two different types of polymeric resins as adsorbents. Molecular modeling study is based on molecular orbital theory. Adsorption affinity expresses as the slope of the linear region of the isotherm for a solute is found to be different for different adsorbents, and this difference can be interpreted from the differences in sorbent surface chemistry and morphological structure. The adsorptive interaction on the polymeric resins computed on the basis of frontier orbital theory seems to correlate well with the experimentally measured adsorption affinity. Electronic states of adsorbent and adsorbate were calculated using the semiempirical molecular orbital (MO) method from which energy of adsorption in aqueous solution was estimated. It was found that charge transfer interaction plays an important role in the adsorption of certain biomolecules on aqueous solution. The experimentally measured enthalpy of adsorption seems to correlate well with the adsorptive interaction energy computed from molecular orbital theory.     

The superior adsorption capacity of phenol from aqueous solution using Modified Date Palm Nanomaterials: A performance and kinetic study

This work investigates the prospective usage of dried Date palm fibers (DPF) and amino silica modified Date palm fibers nanomaterials (Si-DPF) for phenol removal from water. We studied the characteristics of both dried DPF and Si-DPF nanomaterials based on their composition and morphology. The characterization includes diverse types of instruments such as Fourier-transform infrared spectroscopy (FTIR), Brunauer Emmett Teller (BET), scanning electron microscopy (SEM), and transmission electron microscope (TEM). Batch mode experimentations were continued and studied utilizing various significant factors such as the dose of adsorbent, solution pH, contact time, and the initial quantity of phenol molecules as a pollutant. Under optimum conditions (pH: 7.00, adsorbent dose: 2.00 g/L, initial concentration of phenol: 100 ppm and contact time: 24 h), the maximum adsorption capacities were calculated to be 19.57 and 31.25 mg/g for DPF and Si-DPF respectively. Further, to study the mechanism of the adsorption process of the under-investigated toxic molecules on the active sites of the nanomaterials, we introduced kinetic models involving pseudo-first-order, pseudo-second-order, and models based on intra-particle diffusion. To study the equilibrium isotherms, the Langmuir and Freundlich isotherms were considered, and the Langmuir isothermal model (R² ≈ 0.997 and 0.984 for DPF and Si-DPF respectively) which largely deals with the results of the experiments achieved.     

超高交联树脂NXD-4对水中邻苯二甲酸单丁酯的去除性能

以新合成的超高交联吸附树脂NXD-4为吸附剂,以邻苯二甲酸单丁酯(MBP)为目标污染物,通过吸附等温线和动力学实验,考察了NXD-4对MBP的去除性能并与活性炭AC-1进行了对比。结果表明,NXD-4和AC-1对MBP的去除均以物理吸附为主,在288~313 K温度范围内,最大吸附量随温度的升高而降低;相同条件下,NXD-4对MBP的吸附量明显大于AC-1的;而且,它们对MBP均具有较快的去除速率,在1750min左右即可达到吸附平衡,但AC-1对MBP的吸附速率大于NXD-4的;脱附再生实验表明,相比于AC-1,NXD-4的脱附再生效果更好,脱附率可以达到96%以上。因此,NXD-4作为吸附剂,对水体中邻苯二甲酸单酯的去除方面具有良好的应用前景。     

Adsorption of phenol from aqueous solution onto zeolites Y modified by silylation

The present work consists in studying the adsorption of phenol onto zeolites Y modified by silylation, in order to increase their hydrophobic character. The operation was carried out by chemical liquid deposition with trimethylchlorosilane (TMCS). Study of the effect of certain parameters like initial concentration, pH and ionic strength were conducted. Experimental data were fitted by the models of Langmuir, Freundlich and Dubinin-Raduskevich calculated by non-linear regression. Results obtained show that the adsorption of phenol on samples is very fast and supported at acidic values of pH. We also found that phenol uptake increases with Si/Al ratio and modification by silylation improves the percentage of adsorption by approximately 30%.     

胺化木质素对水中硝基苯吸附性能的研究

含硝基苯的工业废水对环境造成了严重的污染.本文用环氧氯丙烷、乙二胺对碱木质素进行改性制备胺化木质素,详细研究了溶液pH、接触时间、温度、浓度等因素对胺化木质素吸附水溶液中硝基苯性能的影响.结果表明:溶液pH对吸附有较大的影响,吸附的最佳pH为8,胺化木质素对硝基苯吸附3h后达到平衡,与准一级吸附动力学模型有较好的拟合;...     

介孔碳CMK-3对苯酚的吸附动力学和热力学研究

研究了介孔碳CMK-3对苯酚的吸附性能, 与传统商用活性碳(CAC)进行了比较, 结果表明, CMK-3比CAC的吸附量大、吸附速率快、达到平衡时间短, 是一种较好的吸附剂. 同时探讨了介孔碳CMK-3对苯酚的吸附热力学和动力学特征. CMK-3对苯酚的吸附行为可用Langmuir和Freundlich等温式进行描述, 相关性都较好, 但更符合Freundlich经验公式. 分别采用模拟一阶反应和二阶反应模型考察了吸附动力学, 并计算了这些动力学模型的速率常数. 模拟二级反应模型和实验数据之间有较好的相关性. 分别计算了热力学参数ΔG0, ΔS0和ΔH0, 结果表明, CMK-3对苯酚的吸附过程是吸热和自发的.     

Adsorption of Cu2+ from aqueous solution onto iron oxide coated eggshell powder: Evaluation of equilibrium,isotherms, kinetics,and regeneration capacity

This study explored the adsorption behavior of Cu²⁺ onto iron oxide coated eggshell powder (IOESP) from aqueous solution. The effect of various operational parameters such as pH, contact time, initial adsorbate concentration, surfactant, and temperature on adsorption of Cu²⁺ ions was investigated using batch adsorption experiments. The optimum pH for Cu²⁺ adsorption was found to be 6.0. Kinetics of adsorption was found to follow the pseudo-second-order rate equation. The suitability of Langmuir and Freundlich adsorption models to the equilibrium data was investigated. The adsorption was well described by the Freundlich isotherm model indicating the presence of heterogeneous sites for Cu²⁺ adsorption. The adsorption of Cu²⁺ was increased in the presence of anionic surfactant (SDS) while cationic surfactant (CTAB) shows no significant change in adsorption capacity. Thermodynamic parameters showed that the adsorption of Cu²⁺ onto IOESP was feasible, spontaneous, and exothermic. Regeneration studies were performed using HCl, HCOOH, EDTA, and NaOH as eluting agent for Cu²⁺ desorption from saturated IOESP and the maximum regeneration was observed with HCl.     

Adsorption of chromium from aqueous solution using chitosan beads

A basic investigation on the removal of Cr(III) and Cr(VI) ions from aqueous solution by chitosan beads was conducted in a batch adsorption system. The chitosan beads were prepared by casting an acidic chitosan solution into an alkaline solution. The influence of different experimental parameters; pH, agitation period and different concentration of Cr(III) and Cr(VI) ions was evaluated. A pH 5.0 was found to be an optimum pH for Cr(III) adsorption, and meanwhile pH 3.0 was the optimum pH for the adsorption of Cr(VI) onto chitosan beads. The Langmuir and Freundlich adsorption isotherm models were applied to describe the isotherms and isotherm constants for the adsorption of Cr(III) and Cr(VI) onto chitosan beads. Results indicated that Cr(III) and Cr(VI) uptake could be described by the Langmuir adsorption model. The maximum adsorption capacities of Cr(III) and Cr(VI) ions onto chitosan beads were 30.03 and 76.92 mg g⁻¹, respectively. Results showed that chitosan beads are favourable adsorbents. The Cr(III) and Cr(VI) ions can be removed from the chitosan beads by treatment with an aqueous EDTA solution.     

Adsorptive treatment of phenol from aqueous solution using chitosan/calcined eggshell adsorbent: Optimization of preparation process using Taguchi statistical analysis

Phenol and its derivatives are known to be toxic causing adverse impact on human health and environment. Adsorption utilising waste materials is a cost effective method for abatement of such pollutants. The present study thus aims to remove the phenol from aqueous solutions using chitosan/calcined eggshell adsorbent. Taguchi L₂₇ Orthogonal array design methodology was used for the optimization of preparation variables. The statistical results obtained using ANOVA and S/N ratios showed that adsorption of phenol was significantly influenced by activation temperature (54.90%) and activation time (43.70%) whereas the mix ratio had fairly low impact on the output response (1.14%). The confirmation run in optimum preparation conditions of temperature (800 ?°C), time (60mins) and mix ratio (1:1) resulted in maximum adsorption capacity (10.82 ?mg/g) which confirmed that the optimization done by Taguchi model was valid and reliable. The characterization of adsorbent prepared under optimum conditions were done using scanning electron microscopy, X-ray diffraction (XRD), and the Fourier transform Infrared spectroscopy (FTIR). Adsorption and kinetic studies manifested that the adsorption phenomenon onto prepared adsorbent is illustrated well by linear Langmuir isotherm and pseudo second order kinetics.     

Adsorption behavior of Pd(II) ions from aqueous solution onto pyromellitic acid modified-UiO-66-NH2

A new adsorbent was successfully fabricated by chemically linking pyromellitic acid onto a zirconium-based metal-organic framework composite for selective adsorption of Pd(II) from an aqueous solution. The adsorbent was characterized by Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller equation and scanning electron microscope. The adsorption capacity, selectivity and repeatability of the adsorbent were tested by batch experiments. The optimum pH was 2.0, and the maximum adsorption capacity at room temperature was 226.1 mg/g. In the kinetic experiments, the adsorption process achieved equilibrium within 5 h and generally conformed to the quasi-second kinetics and Freundlich isotherm model. The N-H and OH groups on the adsorbent interacted with Pd(II) by electrostatic and coordination action. The adsorbent maintained excellent adsorption capacity after at least 5 cycles. At the same time, the selectivity of the adsorbent in aqueous solution is excellent from interfering ions. Therefore, the new adsorbent will have an obvious application prospect on the recovery of palladium.     

Adsorption of phenol and benzyl alcohol onto surfactant modified silica

The adsorption of the surfactant, dodecyltrimethylammonium bromide, DTAB, and the co-adsorption of the additives phenol and benzyl alcohol, onto silica from aqueous solutions are investigated. The adsorption of DTAB is found to increase with increasing alcohol concentration in solutions where the DTAB concentration is below the cmc. Moreover, the corresponding adsorption of DTAB decreases when the DTAB concentration is above the cmc. The co-adsorption of the alcohol is found to increase with increasing alcohol concentration, and benzyl alcohol co-adsorbs more strongly than phenol. The surfactant modified silica shows a very high ability to incorporate phenol and benzyl alcohol. The results are discussed in relation to solubilization site and surfactant aggregate shape.     

Removal of phenol from aqueous phase by using neutralized red mud

The objective of this study is to remove the phenol from aqueous solution by using the neutralized red mud in batch adsorption technique. The study was carried out as functions of contact time, pH, initial phenol concentration, red mud dosage and effect of salt addition. The experiments demonstrated that maximum phenol removal was obtained in a wide pH range of 1-9 and it takes 10 h to attain equilibrium. The adsorption data was analyzed using the Langmuir and the Freundlich isotherm models and it was found that the Freundlich isotherm model represented the measured sorption data well. The influence of addition of salt on phenol removal depends on the relative affinity of the anions for the red mud surface and the relative concentrations of the anions.     

Adsorption of metal ions from solution onto a piezoelectric quartz crystal

Many metal ions are spontaneously adsorbed onto a piezoelectric quartz crystal and change the oscillation frequency. The pH ranges in which the metal ions adsorbed were just below that of precipitate formation as the ‘hydroxides’; frequency changes caused by adsorption were not observed in these pH ranges where the ‘hydroxides’ formed. Cationic organic reagents, such as crystal violet and methylene blue, were also adsorbed on the piezoelectric quartz crystal but non-ionic and anionic organic compounds were not. These results showed that the crystal was negatively charged on the surface.     

Adsorption of basic dyes from aqueous solution onto pumice powder

The adsorption of methylene blue and crystal violet on pumice powder samples of varying compositions was investigated using a batch adsorption technique. The effects of various experimental parameters, such as adsorbent dosage, initial dye concentration, and contact time, were also investigated. The extent of dye removal increased with decreased initial concentration of the dye and also increased with increased contact time and amount of adsorbent used. Adsorption data were modeled using the Freundlich adsorption isotherm. The adsorption kinetic of methylene blue and crystal violet could be described by the pseudo-second-order reaction model.     

Adsorption equilibrium and kinetics of copper ions and phenol onto modified adsorbents

The adsorption equilibrium and kinetics of single and binary component copper ions and phenol onto powdered activated carbon (PAC), alginate beads and alginate-activated carbon beads (AAC) were studied. Adsorption equilibrium data for single component copper ions and phenol onto the adsorbents could be represented by the Langmuir equation. Multicomponent equilibrium data were correlated by the extended Langmuir and ideal adsorbed solution theory (IAST). The IAST gave the best fit to our data. The amount of copper ions adsorbed onto the AAC beads in the binary component was greater than that of phenol. The internal diffusion coefficients were determined by comparing the experimental concentration curves with those predicted from surface diffusion and pore diffusion model.     

Removal of copper from aqueous solution by aminated and protonated mesoporous aluminas: kinetics and equilibrium

A novel adsorbent, aminated and protonated mesoporous alumina, was prepared and employed for the removal of copper from aqueous solution at concentrations between 5 and 30 mg/l, in batch equilibrium experiments, in order to determine its adsorption properties. The removal of copper by the adsorbents increases with increasing adsorbent dosages. The adsorption mechanism is assumed to be an ion exchange between copper and the hydrogen ions present on the surface of the mesoporous alumina. The adsorbent was characterized by XRD, TEM, SEM, and BET methods. The sorption data have been analyzed and fitted to linearized adsorption isotherm of the Freundlich, Langmuir, and Redlich-Peterson models. The batch sorption kinetics have been tested for first-order, pseudo-first-order, and pseudo-second-order kinetic reaction models. The rate constants of adsorption for all these kinetic models have been calculated. Results also showed that the intraparticle diffusion of Cu(II) on the mesoporous catalyst was the main rate-limiting step.     

光催化降解过程中苯酚的分光光度法测定

提出了用双波长紫外分光光度法测定含对苯醌和苯酚混合液中苯酚的方法,解决了用分光光度法直接测定苯酚时对苯醌分析的干扰。选择测定波长为270和292nm。用于纳米二氧化钛光催化降解苯酚过程中苯酚的测定。标准样品的加标回收率为：99.79％～101．17％,相对标准偏差小于0．50％;样品测定的加标回收率为：99．14％～104．75％,相对标准偏差小于2．20％,苯酚的检出限为0．10mg／L。     

Adsorption properties and mechanism of sepiolite to graphene oxide in aqueous solution

Graphene oxide (GO) is widely used in various fields such as improving the performance of cement-based materials and making composite materials due to its large specific surface area and abundant oxygen-containing functional groups. However, it has also caused water pollution. To remove GO in aqueous solution, sepiolite (SEP) was used to adsorb it. The effects of pH, adsorbent quality, GO concentration, temperature and adsorption time on the ability of SEP to adsorb GO were investigated. The materials were characterized by SAP and laser particle size analyzer, and the adsorption performance and mechanism of SEP for GO were further analyzed by XRD, FTIR, SEM, TEM, XPS, AFM, and Zeta potential microscopic tests. The results showed that: 1) Under the conditions of temperature 303 K, pH = 3, adsorbent mass 30 mg, and initial concentration of GO 100 mg/L, the adsorption effect was the best, and the adsorption rate reached 94.8 %. 2) The adsorption reached equilibrium at 2160 min, and the adsorption process was more in line with the pseudo-second-order adsorption kinetic equation, and the adsorption behavior was controlled by chemical effects. 3) The adsorption of SEP to GO is more consistent with the Langmuir and Temkin adsorption isotherm model, and the reaction is a spontaneous, endothermic, and entropy-increasing process. Experiments showed that SEP had a strong adsorption capacity for GO, which provides a reference for the treatment of toxic GO in aqueous solution and the realization of water ecological protection.     

Adsorption of Congo red from aqueous solution onto calcium-rich fly ash

The adsorption of Congo red from solution was carried out using calcium-rich fly ash with different contact times, concentrations, temperatures, and pHs. While the amount of dye adsorbed per unit weight of fly ash increases with increasing concentration and temperature, it decreases slightly with increasing pH. The adsorption was between 93 and 98% under the conditions studied. Kinetic studies showed that the adsorption process obeyed the pseudo-second-order kinetic model. It was also determined that the adsorption isotherm followed Freundlich and Dubinin-Radushkevich models. From thermodynamic studies, it was seen that the adsorption was spontaneous and endothermic. Desorption studies suggested that desorption was 29.18% in the presence of 0.1 N HCl and was 47.21% in the presence of CH(3)COOH (50% v/v). This indicated that most of the dye was held by fly ash via chemisorption as well as ion exchange. Furthermore, FTIR study also shows that a chemisorption process occurs between CR and fly ash, probably indicating dye/fly ash complexing.