Papers by Keyword: Adsorption Isotherm

Abstract: In the present study, removal of safranin dye from water bodies was investigated using natural biosorbent (Thyme leaves (TEL)). The influence of multiple factors such as as contact time (15 – 105 mins), adsorbent dose (25 to 350) mg/l , adsorbate dose (5 to 40)mg\L, and temperature (25 to 55)o C were taken for investigation. The adsorption isotherms were described by utilized Langmuir, Freundlich and Dubnin-Radushkevich models, Freundlich isotherm model found to be best suited with experimental data out of 3 isotherm The adsorption process followed pseudo second order model.

Abstract: Previous studies have evidenced that coconut copra is a potential biosorbent for removal of dissolved organic carbon from peat swamp runoff attaining an average removal of 96 %. The capability of coconut copra in removing heavy metals including cadmium (Cd), chromium (Cr) and nickel (Ni) is scarcely reported. In this paper, response surface methodology was applied to evaluate the optimum conditions for removal of Cd, Cr and Ni from aqueous solution using raw coconut copra. Batch adsorption experiments were conducted according to inscribed central composite design. Response surface models further identified the optimum dosage, pH and contact time for Cd removal is 1.5 g, pH 11 and 60 min, Cr removal is 0.1 g, pH 8.48 and 60 min while Ni removal is 0.1 g, pH 11 and 15 min. Bimodality is observed in response surface graphs, implying the possible existence of two equilibrium phase during the adsorption process. Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models were employed to describe the adsorption behaviour. Results revealed that raw coconut copra can remove 4.55 mg/g of Cd, 8.71 mg/g of Cr and 26.46 mg/g of Ni. The adsorption processes are physical adsorption.

Abstract: In this study, organo-montmorillonite was utilized as an additive for the fabrication of the nanostructured membrane via electrospinning process.The purpose of this study is to investigate the performance of 95% PSF and 5% O-MMT blend in terms of its adsorption capacity towards MB dye in wastewater and comparing it to pure PSF membranes. Pure PSF and 5% O-MMT blend were immersed in the simulated wastewater at different time intervals (1, 5, 12, 24 and 48 hours), and the change in MB dye concentration was observed by UV-Vis absorbance reading. To determine the mechanism of adsorption, the data obtained were subjected to pseudo-first order and pseudo-second order kinetic models, and were fitted to Langmuir, Freundlich and Temkin adsorption isotherms to determine the adsorption equilibrium data. The results show that the adsorption efficiency was improved by 5.32%.

Abstract: This work was focused on evaluating the potential of bamboo powder modified with manganese oxide (MnO-BP) as a low-cost byproduct adsorbent for the adsorption of cadmium(II) ion. A batch method was carried out at room temperature and the optimized conditions. The optimization of adsorption parameters including pH, equilibrium time, dosage and initial Cd(II) concentration was also systematically studied for the removal of cadmium(II) ion. The maximum monolayer adsorption capacity of MnO-BP was estimated as 8.57 mg/g that it more adsorption capacity than untreated-bamboo powder by about 5 times. The Langmuir and the Freundlich isotherms were used to describe the adsorptive mechanism and calculated the maximum monolayer adsorption capacity. It was found that the data from MnO-BP fitted well to the Freundlich isotherm with R²>0.99. It indicated that the adsorptive behavior of MnO-BP to cadmium(II) ion is preferable. In this work, MnO-BP was used for the removal of cadmium(II) ion in wastewater sample. The MnO-BP is a low-cost adsorbent that can be used to remove cadmium(II) effectively.

Abstract: Equilibrium adsorption of quaternary component mixture (phenol, butanol, butan-2-ol and 2-methyl butan-2-ol) onto activated carbon derived from oil-palm empty fruit bunch was studied. Henry isotherm 2-parameter model was used as an improvement to Langmuir and Freundlich 2-parameter isotherm model. The 3-parameter isotherm models applied to the quaternary adsorption system included Redlich Peterson, Sips and Toth. Trial and error method of excel solver was used to evaluate the parameters in the models. Data fitness was based on correlation coefficient (R2) and average percentage error (APE). For the two-parametric isotherm models, Langmuir predicted the adsorption equilibrium well with APE and R2 values of 0.20883 and 0.9868; 0.007669509 and 0.9338; and 3.64355718 and 0.9410 for butanol, butan-2-ol and 2-methyl butan-2-ol respectively. The maximum mono-layer capacity (qm) obtained from Langmuir model for butanol, butan-2-ol and 2-methyl butan-2-ol adsorption were 3558.962mg/g, 2.064233mg/g and 22.6423mg/g respectively. Sip and Toth fitted excellently well among the three- parametric isotherm models. The Sip isotherm model gives APE and R2 values of 0.010536 and 0.9346; and 5.14458 and 0.9250 for phenol and 2-methyl butan-2-ol respectively. The Toth isotherm model gives APE and R2 values of 4.83521 and 0.9866; and 0.02595 and 0.9411 for butanol and butan-2-ol respectively. The isotherm models prove applicable for the quaternary adsorption system.

Abstract: This research aimed to study the preparation of activated carbon from sugarcane bagasse waste. The sugarcane bagasse adsorbent was prepared by calcination at 600°C for 2 hours with the use of sulfuric acid (H₂SO₄) as a chemical activation. The adsorption surface possessed high specific surface area (838 m²/g) with mesoporous diameter. Factors explaining adsorption including adsorption isotherm, adsorption kinetic and adsorption mechanism were constructed from methylene blue adsorption experiments. It was found that the equilibrium data was best represented by Freundlich isotherm, showing multilayer coverage of dye molecules at the outer surface of adsorbent with a cooperative adsorption (physisorption and chemisorption). The kinetic of methylene blue adsorption was found to follow pseudo-second-order rate kinetic model, with a good correlation coefficient. This indicated that the overall rate of the dye adsorption process was controlled by the chemisorption process.

Abstract: An autoclaved aerated concrete (ACC) was chemically modified with manganese oxide (MnO-ACC) for investigate as a high effective adsorbent for removal of lead ions from aqueous solution. The precipitation reaction of manganese oxide was easily done under a high basic solution, resulting manganese oxide in a micron scale occupy on the surface of ACC. The maximum removal efficiency of lead ions using MnO-ACC was obtained under a function of pH 7, adsorbent dosage of 5 g/L, equilibrium time of 15 min. The experimental data were analyzed by commonly adsorption models. The Langmuir adsorption isotherm model is more suitable with a good correlation coefficient of R²=0.99 than the Freundlich model. The maximum monolayer adsorption capacity (q_max) of MnO-ACC was found to be 43.22 mg g⁻¹ in which higher adsorptive capable than unmodified ACC by about 10 times. Based on kinetics study, the adsorption of lead ions onto MnO-ACC followed a pseudo second-order model with a good correlation coefficient of R²=0.99.

Abstract: The heat transfer rate of an adsorbent embedded heat exchanger can be significantly improved by as much as three folds using powder adsorbent coated by binder on the fin surfaces of exchangers. The overall performance of such exchangers in an adsorption chiller, however, is determined both by the heat transfer and adsorption mass transport phenomena, which are also highly interlaced in the chiller operations. If a severe suppression on the latter is observed as a result of the binder, the heat exchanger may eventually underperform. This work evaluates the overall effect of the binder on the mass transport. It focuses on a common adsorbent-adsorbate pair utilized in the chiller, i.e. silica gel type 3A-water. A hydroxyethyl cellulose (HEC) is used as the binder. Experiment is conducted to measure the water equilibrium uptake of the pure and binder added silica gel at various temperatures. Based on the results, the net influence of the binder on the water uptake rate in the adsorption heat transfer process is determined.

Abstract: Research on the application of chitosan derived from oyster (Anadara inflata) shell as adsorbent for heavy metal Cu (II) has been conducted. Optimum conditions for adsorption, including pH, reaction time, and mass of adsorbent were investigated. Adsorption capability of Cu (II) by chitosan under those optimum conditions was subsequently evaluated by determining their adsorption isotherms and interaction mechanism. The results showed that the optimum condition for adsorption were pH 8, contact time 60 min, and mass of adsorbent 300 mg. Under those optimum conditions, chitosan has a high percentage removal of Cu (II) from aqueous solution, up to 70%. The adsorption process was well described as Langmuir isotherm and it is assumed that the interaction between Cu (II) and chitosan was based on chemical mechanism.

Abstract: In this study, a three-dimensional (3D) copper-based metal-organic framework (MOF-199) is a microporous materials with structural formula Cu₃(BTC)₂ (1,3,5-benzene tricarboxylate) were successfully synthesized using nonsurfactant templating method. The preparations of MOF-199 utilized different length of straight carbon chain (oleochemical) fatty alcohols derived from palm oil were similar to those reported earlier by our group with some modifications [1]. This new method led to unique structure and properties of as-synthesized MOF-199. The addition of fatty alcohols such as octyl (C8) and decyl (C10) alcohol act as renewable template onto MOF-199 generating the required carbon template for microporous crystalline structure [2]. The MOF-199 had been synthesized using conventional hydrothermal method with the present of fatty alcohols to analyse the resulting MOF-199 in terms of structure, morphology, surface area and adsorption isotherm. MOF-199 synthesized in this study exhibited single crystal orthorhombic morphology at ca. 30 micron. The crystallinity of MOF-199 materials was improved by the addition of fatty alcohols as observed in the X-Ray Diffraction patterns.