Showing papers on "Langmuir published in 2022"

The Past and the Future of Langmuir and Langmuir-Blodgett Films.

Abstract: The Langmuir-Blodgett (LB) technique, through which monolayers are transferred from the air/water interface onto a solid substrate, was the first method to allow for the controlled assembly of organic molecules. With its almost 100 year history, it has been the inspiration for most methods to functionalize surfaces and produce nanocoatings, in addition to serving to explore concepts in molecular electronics and nanoarchitectonics. This paper provides an overview of the history of Langmuir monolayers and LB films, including the potential use in devices and a discussion on why LB films are seldom considered for practical applications today. Emphasis is then given to two areas where these films offer unique opportunities, namely, in mimicking cell membrane models and exploiting nanoarchitectonics concepts to produce sensors, investigate molecular recognitions, and assemble molecular machines. The most promising topics for the short- and long-term prospects of the LB technique are also highlighted.

Adsorption of copper and nickel by using sawdust chitosan nanocomposite beads – A kinetic and thermodynamic study

Abstract: The adsorption behavior of biomaterial activated Sawdust-Chitosan nanocomposite beads (SDNCB) powder was investigated along with synthesis and experimental techniques approaches to study the removal efficiency of some heavy metal ions including Ni (II) and Cu (II) ions from aqueous solutions by assessing the surface-modified activated carbon by the cost-effective non-conventional method. Structural analysis of the entitled compound was evaluated by the PXRD techniques and its surface morphology was inferred by the following techniques: TEM, EDAX. The behavior of the functional group presents in the compound was discussed using the FTIR technique. Such parameters like dosage, pH, time, temperature, and initial concentration of copper and nickel were associated with this to examine the effect of adsorption of heavy elements that exist in the portable solution. Further, the cellulose and chitosan beads complex material have an appropriate surface area, it demonstrated metal ions removal efficiency was more appreciable due to the action of activated carbon, where this showed fast rate sorption kinetics due to strong involvement of Cu+ & Ni+ towards cellulose and chitosan's functional groups in the bio composite. The isotherm model so-called Langmuir, Freundlich, and Temkin model was utilized to plot the experimental adsorption dataset to infer the maximum adsorption capacity. Based on this model, the adsorption properties of the beads treated compound was determined by plotting the graphs in which sorption intensity (n) which implies expected sorption, and the correlation value are 1.989, 0.998, and 0,981 respectively.

Removal of drug and dye from aqueous solutions by graphene oxide: Adsorption studies and chemometrics methods

Abstract: Abstract Pharmaceutical products and dyes are the main environmental pollutants in the effluent of textile, cosmetic, and pharmaceutical industries. Therefore, in this study, the central composite design (CCD) based on the response surface methodology (RSM) was used to investigate the operating parameters and determine the optimal conditions for the removal of enrofloxacin (ENF) and Rhodamine B (RhB) by graphene oxide (GO). The structure and morphology of GO were studied using scanning electron microscopes (SEM) and X-ray diffraction (XRD) techniques. Quadratic model was confirmed to describe each of the removal efficiency responses (%R) a with high correlation coefficient ( R 2 = 0.9987 for ENF and R 2 = 0.9999 for RhB) (R 2 -Adj = 0.9963 for ENF and R 2 -Adj = 0.9991 for RhB). In optimal conditions, RhB concentration of 10 mg L −1 , adsorbent amount of 0.24 g, sonication time of 23 min, ENF concentration of 10 mg L −1 , and pH 7, removal rates of more than 92.5% were obtained for both analytes. Adsorption equilibrium was studied with Langmuir, Freundlich, Langmuir-Freundlich, Redlich-Peterson, Toth and Khan isotherm models. Equilibrium data were best fitted with the Langmuir-Freundlich isotherm model. Maximum adsorption capacity of ENF and RhB on GO were 45.035 mg g −1 and 107.230 mg g −1 , respectively. The recyclability of GO was evaluated during the ENF and RhB adsorption process. The results showed that up to 4 cycles of adsorbent, the adsorption efficiency is reduced by a tiny amount. The present study showed that GO is highly effective in removing ENF and RhB from environmental water samples.

Recent advances in nano-adsorbents for the sequestration of copper from water

Abstract: Adsorption using different adsorbents is seen as the most effective method of treating wastewater contaminated by heavy metal ions such as copper ions. In particular, nano-adsorbents have emerged as the state-of-the-art materials for heavy metal removal because of their unique physicochemical properties. The aim of this study was to review the progress made in the last decade (2011−2021) on the removal of copper ions from aqueous environment. Relevant works were sourced and carefully analysed. The findings revealed that various classes of nano-adsorbents have been employed in the copper ion removal, among which magnetic nanoparticles (MNPs) (43.4%) was the most frequently used class, while aerogels (1.2%) are the least frequently used class of nano-adsorbents. Best results were obtained by the modification/functionalization of the nano-adsorbents with other materials, which resulted in an increase in their specific surface area. The majority of the nano-adsorbents showed high removal efficiencies (>90%), while the highest adsorption capacity (1937.5 mg/g) was obtained experimentally with the aerogel class. The adsorption isotherm fitted well with the Langmuir and Freundlich models, while the kinetic data provided the best correlation with the pseudo-second order kinetic model for most of the nano-adsorbents. The MNPs, in particular, showed high reusability, with most of them maintaining high efficiencies even after 3–5 rounds of regeneration. Effective treatment of copper-contaminated wastewater can therefore, be achieved with the use of nano-adsorbents as a novel, non-toxic, and cost-effective technique of adsorption. • A decade of studies on the removal of Cu 2+ ions from water using nano-adsorbents has been reviewed. • The nano-adsorbents for Cu 2+ removal were grouped into seven different classes. • Functionalization of the nano-adsorbents with other materials increases their surface area and subsequently, their uptake capacity. • Adsorption process parameters were also discussed.

Management of surgical mask waste to activated carbons for CO2 capture

Abstract: The worldwide COVID-19 pandemic has resulted in a huge amount of face masks being used up and thrown away, resulting in increased environmental pollution and infection risks. In our work, we have developed a highly efficient process of neutralizing face mask waste into a useful carbon material. Then, the prepared activated carbon was used for CO2 adsorption studies. A series of activated carbons from face masks used as a precursor were synthesized using KOH and the activation temperature was in the range of 600-800 °C. All materials were characterized by well-developed porosity. The influence of activation temperature on the textural properties of prepared activated carbons and their adsorption abilities were investigated. The highest CO2 adsorption was received for the M_800 carbon and it was 3.91 mmol/g at the temperature of 0 °C and the pressure of 1 bar. M_800 carbon exhibited also high selectivity of CO2 over N2. Seven equilibrium isotherms were applied to the experimental data to find out the best fit (Langmuir, Freundlich, Sips, Toth, Unilan, Fritz-Schlunder and Radke-Prausnitz isotherms). The presented research provides an environmentally friendly and cost-effective method of recycling waste masks into a valuable product in the form of carbon and its potential use in the absorption of harmful CO2 influencing the greenhouse effect.

Adsorption Behavior of Heavy Metal Ions by Hybrid Inulin-TEOS for Water Treatment

Abstract: The present work reports the adsorption behavior involved in the adsorption of heavy metal ions using a hybrid inulin-tetraethoxysilane (TEOS) adsorbent produced through the sol-gel process. An aqueous multi-element solution was used in order to examine the inulin-TEOS adsorbent efficiency in removing Cd2+, Co2+, and Ni2+ ions. The effects of the contact duration, adsorbent dosage, initial concentration, and solution pH on the adsorption of the targeted metal ions in batch systems were evaluated. The optimal conditions for the removal of all targeted heavy metals were as follows: 30 mg of an adsorbent dosage at pH 4 and 5 minutes of contact time with an initial concentration of 0.5 mg/L. A one-way analysis of variance (one-way ANOVA) with a replication test showed that all parameters had significant differences at a p-value of 0.05. At the optimum condition, 92.59%, 90.27%, and 86.472% of Cd2+, Ni2+, and Co2+ were removed, respectively. Findings from kinetic studies suggest that the pseudo-second order model can successfully describe the overall adsorption process. Additionally, the adsorption process can be adequately explained using an intra-particle diffusion model with diffusion rate constants following the sequence of Kint,1 > Kint,2 for Co2+ and Ni2+ and Kint,1 > Kint,2 > Kint,3 for Cd2+ in each step. The results suggest that Ni2+ fits with the Langmuir isotherm, while Cd2+ and Co2+ better fit the Freundlich one. Finally, the adsorbent can be reused and is able to retain a good percentage of removal, with percentage difference decreases of 1.99%, 3.29%, and 4.12% for Cd2+, Ni2+, and Co2+, respectively, after the fifth cycle. The hybrid inulin-TEOS bio-sorbent has good adsorption capacity and durability, which could offer a low-cost practical cleaner production process for removing targeted analytes from wastewater. Doi: 10.28991/CEJ-2022-08-09-03 Full Text: PDF

Removal of pollutants from aqueous media using cow dung-based adsorbents

Abstract: An ideal adsorbent must be relatively cheap, abundant, easily undergo modification, and exhibit better removal efficiency. Animal wastes are much better adsorbents in comparison with activated carbon adsorbents with respect to being cost-effective and their zero regeneration process factor. The review aims to report the efficiency of utilized cow-dung based adsorbents for the sequestration of a wide spectrum of pollutants from aqueous media. It discusses the potential of utilizing cow dung as a cheap and effective adsorbent. It was observed that cow dung-based adsorbents were efficient for the removal of dyes, heavy metals, and other pollutants from aqueous solutions. The maximum reported uptake capacity of dyes and heavy metals was 501 ​mg/g and 625.26 ​mg/g for Methylene blue and lead, respectively, which were both for cow dung activated carbon. The Langmuir and Freundlich isotherm models emerged as the best-fit models for almost all studies. Based on the review outcome, a pseudo-second-order model was reported as the kinetic model of best fit in all cases. Other adsorption studies such as adsorption mechanism, thermodynamic modelling, desorption, column adsorption, and competitive adsorption were also included in this study. Finally, the study identified some knowledge gaps that could aid future investigation in this research field. Summarily, it can be deduced that cow dung-based adsorbent has exhibited good potential as an adsorbent for the mitigation of pollutants from water.

Efficiency of Activated Natural Zeolite-Based Magnetic Composite (ANZ-Fe3O4) as A Novel Adsorbent for Removal of Cr(VI) from Wastewater

Abstract: The increase of Cr(VI) ion species access in the aquatic system through anthropogenic activity has harmed the ecosystem and human health. In solving this problem, the use and development of inorganic material low-cost based as an effective adsorbent by good physico-chemical stability are one of this research's faces. The activated natural zeolite-magnetic composite (ANZ–Fe 3 O 4 ) adsorbent material was prepared by using the co-precipitated method. Several adsorptions recognize the performance of removing Cr(VI) from a water sample; parameters such as pH, contact time, adsorbent mass, and temperature were studied. The result shows that the optimum adsorption occurs in pH 2, with a mass of adsorbent are 0.20 g, for 50 min of contact time at a temperature of 298 K. The adsorption mechanism was studied by using a linear and non-linear pseudo-first order (PFO) model, four pseudo-second order (PSO) models, Elovich model, and intraparticle diffusion model. The Langmuir, Freundlich, Dubinin-Radushkevich (DKR), Temkin, Brunauer-Emmett-Teller (BET), Redlich-Peterson, Harkin-Jura and Javonovic models were use to study the isotherm adsorption. Cr(VI) adsorption on ANZ-Fe 3 O 4 followed with pseudo-second-order model (PSO) with R 2 is 0.993. The comparative of linear PSO and non-linear PSO kinetic were wholly studied. The result shows that non-linear PSO model is the best-fit expression of mechanism adsorption of Cr(VI) on ANZ-Fe 3 O 4 than the linear PSO model. The adsorption of Cr(VI) on ANZ-Fe 3 O 4 in line with the Langmuir model with Q max reaches 2.850 mg/g. The thermodynamics study shows that the adsorption process occurs exothermically and follows the physisorption process.