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As deep eutectic solvents (DESs) became a prevalent category of materials, reporting their physical and chemical properties turned to be urgent. In this work, a database of the thermal conductivity of 39 DESs was experimentally investigated in a temperature range of 25°C to 60°C, since this property was not broadly reported yet. Knowing the thermal conductivity is a significant approach to obtain the fluids’ heat transfer coefficients, which are essential for fluid heat transfer applications and equipment design. The selection of the reported DESs was based on their liquid phase status at room temperature and commonness. Herein, the thermal conductivity was studied as a function of temperature and compositions. Also, the data were fit with the conventional equations to predict the thermal conductivity value at a certain temperature. The highest R2 was selected to identify the best behavior with the common types of equations. It was found that the thermal conductivity reduced by raising the temperature, which was attributed to the enhancement that occurred in electrons’ randomness and reduction in electrons’ free motion. Furthermore, as the temperature rises up, the density decreases, and molecular distance increases. DESs contained choline chloride showed higher thermal conductivity stability than other DESs. While an opposite scenario was noticed for glycerol and ethylene glycol DESs due to the possibility of generating water.

A mathematical model was used to design four modes of two-bed pressure swing adsorption (PSA) process to investigate argon presence in the feed mixture. The effect of operating parameters such as cycle time, pressure equalization, adsorption pressure, and purging flow rate was investigated. The model was validated with experimental data of nitrogen separation from the air by a single bed adsorber on carbon molecular sieve (CMS). A good agreement with experimental data is obtained. In the PSA process, higher purity of nitrogen (99.7%) was detected by mode 4 when the feed mixture was free of argon (O2: 21%, N2:79%). While the nitrogen purity was only 98.0% in the state of argon presence in the feed mixture (O2: 21%, N2: 78%, Ar: 1%). The results showed that the cycle time had insignificant effect whereas the pressure equalization and purging at low vacuum pressure had a significant effect on the process performance. ABSTRAK: Model matematik digunakan bagi membina empat mod terdiri daripada tekanan dua-turus proses penyerapan buai (PSA) bagi menyiasat kehadiran argon dalam campuran pakan. Kesan parameter beroperasi seperti masa kitaran, penyamaan tekanan, tekanan penyerapan, dan kadar aliran penyingkiran disiasat. Model matematik tersebut disiasat melalui data eksperimen pemisahan nitrogen dari udara melalui penyerapan turus tunggal pada penapis molekular karbon (CMS). Data eksperimen yang bagus diperoleh. Dalam proses PSA, mod keempat menghasilkan ketulenan nitrogen (99.7%) lebih tinggi apabila campuran pakan bebas argon (O2: 21%, N2:79%). Sementara itu, ketulenan nitrogen hanya 98.0% apabila terdapat kehadiran argon dalam campuran pakan (O2: 21%, N2: 78%, Ar: 1%). Kajian menunjukkan masa kitaran memberi kesan tidak signifikan sementara penyamaan tekanan dan penyingkiran pada tekanan vakum rendah mempunyai kesan signifikan terhadap prestasi proses.

The application of sustainable materials for wastewater treatment can provide a better water quality, by eliminating toxic metals and also organic contaminants. In this study, we demonstrate a simple method to synthesize chitosan/diatomaceous earth composed (CSDE) as an adsorbent for simultaneous adsorption of Amido Black 10B (AB10B), Cd(II), and Cu(II) ions from aqueous solution. The synthesis is based on a surface physical modification of diatomaceous earth by chitosan as a binder. The effects of adsorbent dosage, initial ions concentration, contact time, and pH on the AB10B, Cd(II), and Cu(II) adsorption rate were investigated. Fourier transform infrared spectroscopy confirmed the successful preparation of the CSDE. Under optimal conditions, the adsorption isotherm of AB10B, Cd(II), and Cu(II) onto CSDE fitted the Langmuir model and the adsorption kinetics was well-correlated with the pseudo-second-order model. The CSDE composite exhibited excellent adsorption capacity toward AB10B, Cd(II), and Cu(II) in both single and multicomponent system with removal capacity of 132.8 mg/g—single; 115.3 mg/g—multicomponent (pH 2), 108 mg/g—single; 96.9 mg/g—multicomponent (pH 7), and 97 mg/g—single; 88.27 mg/g—multicomponent (pH 7), respectively, suggesting selective binding capacity and high adsorption efficiency of CSDE composite. The prepared adsorbent could be reused at least ten consecutive adsorption–desorption cycles with marginal decrease in the total adsorption capacity of both metals and AB10B. The prepared adsorbents showed a significant potential for AB10B, Cd(II), and Cu(II) ions recovery in industrial applications.

Rapid industrialization is one of the major threats to water pollution worldwide, as discharge effluents contain large amounts of toxic metal ions. Heavy metals are highly toxic to the ecosystem and human even at very low concentrations. We focused on easily available, green and eco-friendly with low operational cost materials to remove heavy metals from industrial wastewater. Chitosan is considered an alternative and sustainable adsorbent due to its highly efficient adsorption capacities for heavy metals. In this particular study, chitosan was successfully modified by using diatomaceous earth and then fabricated as spherical beads using the drop-wise method. Pristine chitosan (CS) beads and chitosan coated diatomaceous earth (CSDE) beads were used to remove zinc, chromium, lead, and nickel ions from aqueous solutions in batch and continuous adsorption processes. The prepared adsorbents were characterized by using scanning electron microscopy (SEM) B Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and zeta potential. The results showed that the prepared adsorbents were porous in nature and the total surface area were increased from 1.9 m2/g for pristine chitosan to 14.4 m2/g for chitosan coated diatomaceous earth. The performance of prepared adsorbents was investigated at different temperatures, initial pH of the solution, contact times, initial metal concentrations. The pseudo-second-order kinetic model is more likely to predict the kinetic behavior of the metal ions adsorption process for the whole used contact time range, and the adsorption isotherm data of CS and CSDE beads were well fitted to Langmuir model. The maximal adsorption capacities of prepared CSDE beads were found to be pH dependent as follows: - Zinc ion - 127.4 mg/g at initial Zn(II) concentration 500 mg/L and pH 6. - Chromium ion - 84.23 mg/g at initial Cr(VI) concentration 1000 mg/L and pH 3. - Lead ion - 175.22 mg/g at initial Pb(II) concentration 400 mg/L and pH 7. - Nickel ion - 149.64 mg/g at initial Ni(II) concentration 400 mg/L and pH 6. Successful desorption and regeneration of prepared adsorbents were achieved (with common chemicals) and possessed excellent reusability (up to 10 cycles without a significant loss in adsorption capacity). The common anions and cations coexisting ions have insignificant impact on the removal capacity of prepared adsorbents. Overall, these results suggest that the environmentally friendly materials might be recognized as effective adsorbent and sustainable means for the separation of heavy metals from wastewater streams. That will lead to a new solution to water pollution required in the modern industrial society.

A novel adsorbent for an effective removing of Pb(II) and Ni(II) from aqueous systems in both noncompetitive and competitive modes was prepared by dispersion chitosan onto the diatomaceous earth (CSDE), and then was synthesized into a spherical shape by using a drop-wise method. Its chemical composition, microstructure morphology, and metal-binding mechanism were characterized by dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) techniques. Batch adsorption studies were utilized to evaluate the potential suitability of the prepared CSDE beads and to examine the impact of major adsorption parameters such as solution-pH, initial metal concentration, and contact time on the Pb(II) and Ni(II) adsorption. Under optimal conditions, the maximal adsorption capacities of the CSDE beads based on the Langmuir isotherm model were 175.22 mg/g for Pb(II) and 149.64 mg/g for Ni(II) for noncompetitive adsorption and 234.8 mg/g for both metals in competitive adsorption. The common foreign ions such as Na+, Mg2+, and Ca2+ had insignificant effect on the Pb(II) adsorption while Mg2+ and Ca2+ affected on Ni(II) adsorption. Adsorption kinetics of both metals followed a pseudo-second-order model better than pseudo-first-order model. The prepared CSDE beads could be reused at least ten consecutive adsorption-desorption cycles with marginal decrease in the total adsorption capacity of both metals.

An investigation on two processes of pressure swing adsorption (PSA) to produce oxygen and nitrogen simultaneously was conducted numerically through exploiting depressurizing and purging gas of each process by each other. Each unit included two bed six step PSA process. The first unit packed with zeolite 13X for oxygen generation, and the second unit packed with carbon molecular sieve (CMS) for nitrogen generation. Three configurations were studied, two process were operated individually, depressurizing and purging gas of each process used by other unit ( no gas vented to atmosphere), and the third configuration was similar to the second configuration except purging gas of the second unit was vented to atmosphere. Configuration three produced oxygen with purity 98% and nitrogen with purity 95% together in comparing with configuration 1, and 2. Configuration 2 produced oxygen with purity over 99% while nitrogen purity dropped dramatically to be lower than its atmospheric purity (78%). Oxygen and nitrogen purity in all configuration improved with increasing the adsorption pressure.

Reverse osmosis is a major process that produces soft water from saline water, and its output represents the majority of the overall desalination plants production. Developing efficient membranes for this process is the aim of many research groups and companies. In this work, we studied the effect of adding cellulose micro crystals (CMCs) and cellulose nano crystals (CNCs) to the support layer and thin film nanocomposite (TFN) membrane on the desalination performance. SEM, TEM, ATR-FTIR, and contact angle measurements were used to characterize the membrane&rsquo, s properties, and membrane&rsquo, s performance were evaluated by water flux and NaCl rejection. Filling 2% of CNCs gel in the support layer improved the water flux by +40%, while salt rejection maintained almost the same, around 95%. However, no remarkable improvement was gained by adding CNCs gel to m-phenylenediamine (MPD) solution, which was used in TFN membrane preparation. Filling CMCs powder in TFN membrane led to a slight improvement in terms of water flux.

In this work, chitosan coated diatomaceous earth (CCDE) beads were synthesized by a drop-wise method and characterized by FTIR, BET, SEM, EDS, and zeta potential for Zn(II) ion removal from aqueous solution in batch and continuous processes. Several parameters have been studied such as solution-pH, initial Zn(II) ion concentration, temperature, flow rate, and contact time to investigate the Zn(II) ion uptake. The maximum adsorption capacity of Zn(II) ion onto CCDE beads was 127.4mg/g in batch studies. The adsorption followed Pseudo second order and was well fitted to Langmuir model, indicating monolayer adsorption behavior. The continuous adsorption studies showed decreasing breakthrough and exhausted time with increasing flow rate of solution. The breakthrough points were 220 and 115min at flow rate 3 and 6mL/min, respectively. Loaded CCDE beads with Zn(II) ions were successfully regenerated by 0.2M NaOH without damaging the adsorbents and up to 87% recovery in the fourth cycle. Anions in the solution had an insignificant effect on Zn(II) ion uptake by CCDE beads. Overall results suggested that the prepared adsorbents could be employed as a low-cost, sustainable, and excellent alternative material for Zn(II) ion removal from wastewater.

In order to obtain a sufficient removal of heavy metal ions from water, new resources should be exploited to design more efficient and eco-friendly adsorbents. In this work, we have demonstrated an efficient, simple, and reusable adsorbent, which can be operated at the water treatment site. The simultaneous adsorption behavior and competitive interactions between As(III) and As(V) from aqueous solution onto chitosan/diatomaceous earth composite (CSD) were investigated at different solution-pH and adsorbent dosages. The adsorption mechanism was interpreted depending on the data of X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy. Results of batch equilibrium experiments indicated that the pH and adsorbent dosages have significantly influenced the adsorption process, and the adsorption of heavy metals was better fitted with Langmuir isotherm and pseudo-second-order models. The binary maximal adsorption capacities of As(III) and As(V), as determined from the Langmuir adsorption isotherms, were 87.81 mg/g and 44.07 mg/g at a pH of 6, respectively. The presence of phosphate (PO43−) as co-existing anions has an obvious impact on the adsorption of arsenic species. Based on the obtained results, the prepared adsorbent showed a great promise to be used in arsenic species adsorption from aqueous solution.

Low-cost chitosan beads were prepared by dropping chitosan solution into an alkaline bath and then were used for Cr(VI) and Zn(II) ions adsorption from aqueous solution. Prepared chitosan beads were characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) measurements, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The effect of solution-pH, contact time, initial ion concentration, and temperature on both metal ions adsorption was investigated. The kinetics of adsorption suggested a pseudo-second-order model fits better than pseudo-first-order model for both metals. The equilibrium adsorption isotherm of both metals matches well with the Langmuir isotherm model. The maximum adsorption capacity of chitosan beads was 79.56 mg Cr(VI)/g and 109.18 mg Zn(II)/g at initial ion concentration 1,000 mg/L, and temperature 10 °C. Thermodynamic parameters showed that the adsorption of Cr(VI) and Zn(II) ions onto chitosan beads was feasible, spontaneous, and exothermic under the studied conditions. While the chitosan beads enabled a good adsorption application, further lab work and field studies are necessary before using in a practical adsorption process.