isotherm models
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This study presents an adsorbent material (activated carbon) used in the treatment of wastewater with the role of removing ibuprofen, acetaminophen, diclofenac and ketoprofen pollutants. The wastewater treatment efficiencies of the activated carbon were systematically investigated using adsorption kinetics. The parameters studied were: pH (4 and 6 values of pH), initial concentration of wastewater (1, 5, and 10 mg/L), contact time (10 min), adsorbent quantity (0.1, 0.5, and 1 g), and isotherm models (Langmuir and Freundlich). The highest wastewater treatment efficiency was obtained at the 6 pH value. The determination of four anti-inflammatory drugs, frequently monitored in wastewater, was performed by a simple and fast method using the HPLC-technique-type DAD (diode array detector). The method was linear when the concentration ranged between 0.5 and 20 m/L for all compounds. The equilibrium concentration was obtained after 8 min. The octanol/water coefficient influenced the removal efficiency of the four drugs by the adsorbent material (activated carbon). The dose of activated carbon (0.1 to 1 g) significantly influenced the efficiency of wastewater treatment, which increased considerably when the dose of the adsorbent material increased. Using 1 g of the adsorbent material for the treatment of wastewater containing 1 mg/L initial concentration of pollutant compounds, the efficiencies were 98% for acetaminophen, 92% for diclofenac, 88% for ketoprofen and 96% for ibuprofen.

Abstract With polydioxyethylene ether as the bridge chain, a new fungal modified material with diamidoxime groups was prepared by a series of uncomplex synthesis reaction. The orthogonal experiment obtained its optimized adsorption conditions as follows: the initial pH value 6.5, the initial uranyl concentration 40 mg L-1, the contact time 130 min, and the solid-liquid ratio 25 mg L-1. The maximum adsorption capacity of target material was 446.20 mg g-1, and it was much greater than that of the similar monoamidoxime material (295.48 mg g−1). The linear Langmuir (R2 = 0.9856) isotherm models and the linear pseudo-second-order kinetic model (R2 = 0.9931) fit the experimental data of uranium (VI) adsorption better, indicating the adsorption mechanism should mainly be the monolayer adsorption and chemical process. In addition, the relevant experiments exhibited the prepared material was of the good reuse and the excellent anti-interference performance, which suggested the new acquisition should also have well-applied prospect in the future.

Currently, the growth of tannery industries causes a significant volume of waste disposal to the environment due to harmful Cr(VI). Long-time exposure to Cr(VI) imposes serious hazards on all living organisms. Hence, the treatment of tannery waste to remove Cr(VI) is not a choice but mandatory. Therefore, this study focused on the removal of Cr(VI) from the aqueous solutions via a teff (Eragrostis tef) straw based-activated carbon (TSAC) which was derived from locally available agricultural solid waste, teff straw (TS). The prepared TSAC was characterized using BET, FTIR, SEM, and XRD. A central composite approach-based RSM analysis was undertaken for statistical modeling and optimization for maximized Cr(VI) removal with respect to four important factors, namely, initial concentration of Cr(VI), the dosage of TSAC, pH, and adsorption time. Optimized values for maximizing adsorption of Cr(VI) (95% of removal) were acquired to be initial Cr(VI) concentration: 87.57 mg/L, TSAC dosage: 2.742 g/100 mL, pH: 2.2, and contact time:109 min. The results from the design of the experiment were also analyzed for the significance of the interaction between the selected process parameters. In addition, the pseudo-second-order kinetic and Langmuir isotherm models were found suitable for describing the adsorption data. The adsorption capacity of Cr(VI) on TSAC was 19.48 mg/g. The observed thermodynamic characteristics reveal that Cr(VI) adsorption on TASC is endothermic in nature. From the results, TSAC had shown a potential Cr(VI) efficiency on optimized process conditions that can be exploited effectively as adsorbent for removal of Cr(VI)-contaminated wastes.

Abstract The process of manufacturing Sasirangan - a traditional fabric of South Kalimantan - has an impact that affects environmental pollution, namely the dyeing process of the fabric. The synthetic dyes used contain heavy metals and one of those toxic metals is copper (Cu). This study aims to determine the adsorption capacity of rice husk activated carbon adsorbent by adjusting the adsorption pattern based on isotherm models as the treatment to sasirangan liquid waste. The method consists of three stages: preparation of adsorbent by carbonization process, chemical and physical activation, then continued by adsorption process of Cu metal with carbon from rice husks with variations of adsorbent dose (2, 4, and 6 grams). This treatment was conducted by batch process. In this reseach, the adsorption capacity of rice husk adsorbent towards heavy metal Cu in sasirangan liquid waste was determined from the equilibrium state with the Langmuir isotherm equation and Freundlich isotherm equation. Based on isothermal studies of adsorption data, the correlation coefficient values obtained from the isotherm model approaches are: for dose of 2 grams adsorbent, Langmuir R2 = 0.9991 and Freundlich R2 = 0.9981; for dose of 4 grams adsorbent, Langmuir R2 = 0.9992 and Freundlich R2 = 0.9989; for dose of 6 grams adsorbent, Langmuir R2 = 0.9990 and Freundlich R2 = 0.9986. The results of investigation indicate that adsorption data correlated well with Langmuir isotherm model.

This study examined the adsorption behavior of anionic dye (orange G) from aqueous solution onto the raw and activated a mixture of illite, kaolinite and chlorite clays from area of Zorbatiya (east of Iraq).The chemical treatment involved alkali and acid activation. The alkali activation obtained by treated the raw clay (RC) with 5M NaOH (ACSO) and the acid activation founded by treated it with 0.25M HCl (ACH) and 0.25M H_2 〖SO〗_4 (ACS). The thermal treatment carried out by calcination the produce activated clay at 750oC for acid activation and 105oC for alkali activation. Batch adsorption method was used to study the adsorption of orange G dye onto raw and activated clays. The impact of different factors related to the adsorption process was studied such as: agitation time, clay dosage, solution pH, starting OG dye concentration, temperature and ionic strength. The adsorption process was described by using Langmuir, Freundlich, Temkin and Dubinin-Raduchkevish isotherm models. Thermodynamic functions like change in enthalpy〖∆H〗^°, change in entropy 〖∆S〗^° and change in Gibbs free energy 〖∆G〗^°were estimated based on Vanʼt Hoff equation.

In this study, chitosan was extracted from shrimp shells by demineralization and deproteination processes. The extracted chitosan was used to modify the layered double hydroxide and used as an adsorbent for the removal of congo red from aqueous solutions. Composites were successfully synthesized using M2+/Al (M2+ = Zn, Mg, Ni) and chitosan (CH) and the samples obtained were characterized using XRD and FTIR. The X-ray diffraction (XRD) pattern appeared at the layered double hydroxide peak of 2? = 11.63°; 23.00°; 35.16°; and 61.59° and chitosan at 2? = 7.93° and 19.35. The composite appearing in the layered double hydroxide and chitosan indicated that the composite material has been successfully synthesized. The XRD diffraction patterns of Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH showed low crystallinity. The Fourier Transform Infrared (FTIR) spectra verifying absorption spectrum showed the presence of two bands at 3448 cm-1, 1382cm-1 characteristic to both chitosan and LDH. Adsorption of Congo Red (CR) followed the pseudo-second-order and Langmuir isotherm models. The adsorption capacities of Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH were 181.818 mg/g, 227.273 mg/g, and 344.828 mg/g, respectively. The layered double hydroxide-chitosan composite adsorption was endothermically characterized by positive enthalpy and entropy values. On the other hand, the adsorption spontaneously was characterized by a negative Gibbs free energy value. The composites in this study were formed from LDH modified from chitosan extracted from shrimp shells to form Zn/Al-CH, Ni/Al-CH, and Mg/Al-CH. The results of the characterization showed a number of characteristics that resembled the constituent materials in the form of LDH and chitosan. After being applied as an adsorbent to absorb Congo red dye, it then showed the most effective results using Mg/Al-CH adsorbent with an adsorption capacity of 344.828 mg/g.

One of the most widely used antitumor chemotherapeutic drugs is “Cisplatin” (active substance - cis-diaminodichloroplatinum), the side effects of which are the cumulative ototoxic, nephrotoxic and neurotoxic effects. The use of drug carrier systems for targeted delivery and adsorbents for extraction, in particular magnetite-carbon nanocomposites, will minimize unwanted toxic effects without reducing the therapeutic effect of cisplatin. For this purpose, a nanocomposite (NCs) of Fe3O4/Al2O3/С with a carbon surface was synthesized, where a layer of alumina protects magnetite during the pyrolysis of carbohydrates. The synthesized samples were characterized by TEM, XRD, mass spectrometry methods, magnetic properties and specific surface area were studied. It has been found that the used heat treatment mode (T = 500 °С, argon medium) is sufficient for complete carbonization of sucrose and preserves the phase of magnetite which does not lead to deterioration of magnetic characteristics. The results of TEM studies and magnetic measurements indicate the formation of the Fe3O4/Al2O3/С nanocomposite of the core-shell type. The adsorption of Cisplatin on the surface of NCs Fe3O4/Al2O3/С was performed and the adsorption process dependent on the contact time, pH of the solution and cisplatin concentration was studied. The experimental results of kinetic studies were analyzed for compliance with the theoretical models of Boyd and Morris-Weber, models of pseudo-first and pseudo-second orders. Langmuir and Freundlich isotherm models were used to model adsorption processes. The limiting factor of adsorption is the external diffusion mass transfer processes, which correlates with the calculated parameters of the pseudo-first-order model (r2 = 0.985). The correlation of theoretical and practically obtained values of adsorption capacity indicates the possibility of using the Freundlich model to describe the adsorption of Cisplatin on the surface of Fe3O4/Al2O3/C.

This present work describes the competitive coordination of iron (III) and copper (II) ions with amidoximated polyacrylonitrile nanofiber and the catalytic performance of the resulting complex (Fe-Cu-AO- n-PAN). The coordination results showed that the increase of the initial concentration of metal ions was beneficial to the increase of the coordination amount. There were both competition and synergistic effects between the two metal ions. But AO- n-PAN was more inclined to coordinate with Fe3+ ions. The promotion effect of Cu2+ ions on iron coordination due to weak positive electric property and small ion radius increased with its initial concentration in the solution. The Langmuir-Freundlich isotherm model among of four selected isotherm models for binary system showed the best fit to the co-coordination reaction between AO- n-PAN and Fe3+-Cu2+ binary solution. Fe-Cu-AO- n-PAN as heterogeneous Fenton catalyst displayed improved catalytic performance than mono-metal complexes due to its better dye adsorption and the synergistic effect between Cu2+ and Fe3+ ions during degradation process, and both the alkali-resistant and the reusability of it were improved at the same time.