Adsorption Research Articles

Experimental and Mathematical Investigation of Hydrogen Absorption in LaNi5 and La0.7Ce0.1Ga0.3Ni5 Compounds

In the present study, the hydrogen-absorption properties of the LaNi5 and the La0.7Ce0.1Ga0.3Ni5 compounds were determined and compared. This work is therefore divided into two parts: an experimental part that presents and discusses the kinetics and isotherms of hydrogen absorption in the two compounds at two different temperatures (298 K and 318 K). In addition, the temperature variations inside the hydride bed were determined. In the second section, the experimental isotherms were compared to a numerical model processed using statistical physics. Following that, thanks to the perfect agreement between the experimental data and the proposed model, the stereographic and energetic parameters associated with the hydrogen absorption reaction, such as the number of hydrogen atoms per receptor site (n1, n2), the densities of the sites (Nm1, Nm2), the half-saturation pressures (P1, P2) and the absorption energies (ΔE1, ΔE2) for each receptor site, were calculated. All of these parameters are acquired by making numerical adjustments to the experimental data. Thermodynamic functions, such as internal energy and Gibbs energy, which regulate the absorption process, were then identified using these parameters. For both compounds, all of the aforementioned were compared and discussed in relation to initial temperature and pressure. The results demonstrated that the hydrogen-storage properties in LaNi5 are enhanced by more than 30% of stored mass and kinetics when Ce and Ga are substituted at the La sites.

Hydrothermally Produced Activated Carbon Impregnated with ZnO for the Adsorptive Removal of Toxic Pharmaceutical Contaminants from Aqueous Solution

This research explores the adsorption (AD) of diclofenac sodium (DS) onto a Hydrothermally produced activated carbon impregnated with ZnO (HTC-AC/ZnO) surface, considering various factors such as initial concentration (IC), adsorbent dose, contact time, and pH. The characterization of HTC-AC/ZnO was performed using X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and nitrogen physisorption spectroscopy (BET). Tests were conducted with different adsorbent doses (0.5–4 g/L) at 303 K and various initial diclofenac concentrations (ranging from 50 mg/L to 250 mg/L) to observe their effects. Additionally, pH values were altered from 2 to 12 to study their influence on AD. Kinetic studies, thermodynamic studies, and AD isotherm models were examined. The Temkin isotherm model (TIM) was found to be the most accurate for DS-AD on HTC-AC/ZnO. For DS-AD on HTC-AC/ZnO, pseudo-first-order models (PFOM), intraparticle diffusion model (IPDM), and pseudo-second-order models (PSOM) were applied, with a correlation coefficient of 0.945, indicating a good fit for PFOM. The kinetics suggested rapid adsorption. Notably, the HTC-AC/ZnO composite exhibited consistent AD characteristics across four consecutive cycles, with a removal efficiency exceeding 99.38%. This suggests that HTC-AC/ZnO is an appropriate and economically viable adsorbent for the elimination of DS from water-based solutions. The investigation provides compelling evidence that HTC-AC/ZnO is a viable adsorbent for the effective elimination of DS from water sources.

Performance assessment and optimization of adsorption-assisted air gap membrane distillation process for remediation of chromium-contaminated groundwater

Chromium contamination in groundwater is becoming a significant concern due to its potential contribution to the global cancer burden. Membrane distillation (MD) is a promising method known for producing high-quality water, yet issues namely temperature and concentration polarizations should be addressed. To overcome these issues, adsorption (ADS) is proposed to reduce Chromium concentration in the concentrated feed and enhance water production and resource recovery. This study assesses the performance optimization considered parameter effects of the process individually and subsequently executes it into a combined process. Slow sand filtration (SSF) is performed to eliminate particles and thus mitigate fouling. A novel Fe3O4@C-SiO2 is introduced in the ADS process. The technical and economic performances of single MD, hybrid systems (ADS-MD and SSF-MD), and an integrated SSF-ADS-MD system are compared. The results showed the integrated process outperformed various scenarios, achieving significant water recovery almost a 2-fold increase in a single process, and notable reductions in Chromium mass (485.3 gr) and abatement (31.4 mg/h). The economic analysis indicated that the benefit-cost ratio of the integrated process is slightly higher compared to hybrid ADS-MD primarily because of the lower costs in SSF. Ultimately, the results underscored the process of SSF and ADS in boosting MD performance, particularly in water production and Chromium reduction, with prudent economic considerations.

Removal of tellurium(IV) from environmental aquatic systems using metal-organic framework material MIL-100(Fe)

Abstract Metal-organic framework (MOF) materials, characterized by their porosity and large specific surface areas, exhibit excellent adsorption properties. With the aim of removing Te(IV) from environmental aquatic systems, this study is the first to propose the use of MIL-100(Fe). The material reveals a strong adsorption capacity for Te(IV), with maximum adsorption of 531.9 mg/g, superior to other adsorbent materials. Adsorption isotherm and kinetic models indicate that the adsorption process primarily involves monolayer chemical adsorption. According to the thermodynamic parameters, the adsorption reaction is endothermic. The experiment individually examined factors affecting the material's adsorption performance, including adsorbent dose, initial concentration of Te(IV), pH, adsorption time, and coexisting ions. Even under high ion strength conditions and high concentrations of coexisting ions, the material's adsorption efficiency for Te(IV) still reached over 94%. The material has been successfully applied to remove Te(IV) from lake water, river water, and seawater, yielding satisfactory results. Due to the high salinity and ionic strength of the solution, the removal efficiency of Te(IV) in the seawater matrix was slightly lower than that in freshwater (river and lake water). Thus, this material shows promise for the removal of Te(IV) from complex aquatic systems.

OPTIMIZATION AND COLUMN STUDY ON HEXAVALENT CHROMIUM REMOVAL USING HYDROXYAPATITE BEADS DERIVED FROM MOSAMBI FRUIT PEEL

This study elaborates on the preparation of hydroxyapatite particles from mosambi fruit peels by precipitation method. This hydroxyapatite was used as an adsorbent (AB) for the removal of Cr (VI) ion particles from wastewater. The adsorption was performed and optimized by desirability function to be pH 4, initial chromium concentration 200 mg/L, adsorbent dosage 0.425 g, and contact time 32.5 min, respectively using Response Surface Methodology (RSM). The Langmuir adsorption isotherm, pseudo-2nd-order, and Elovich model are well explained. Column experiments gave better results in the removal of Cr (VI) and this method is very effective for the treatment of industry effluent.

Experimental and numerical study of hydrogen absorption in the MmNi5−xMx compound

In this paper, the hydrogen storage properties of the MmNi4.6Al0.4 and MmNi4.6Fe0.4 compounds are compared experimentally and theoretically. The experimental curves of the activation process, experimental isotherms of absorption and the Van't Hoff's plot were first investigated. Following that, a theoretical model is contrasted with the experimental data. The mathematical equations of this model contain parameters, such as the number of hydrogen atoms per site (n1, n2), the densities of the receiving sites (N1m, N2m), and the energy parameters (P1, P2). All these parameters are obtained by numerically adjusting the experimental data. Depending on the applied temperature, the relevant parameters of the suggested model were identified and described. Entropy, internal energy, and other thermodynamic variables that govern the absorption reaction were all calculated and displayed as a function of pressure and temperature.

Experimental analysis on hybrid adsorption and open air cycle humidification dehumidification (AD–OHD) desalination system

In the current status, an Adsorption Desalination System (ADS) has been found to have lower water production capacity than conventional desalination technologies. This study proposes a hybrid desalination system integrating the Adsorption (AD) and Open air cycle Humidification-Dehumidification (OHD) process to overcome the challenge of lower water production capacity in ADS. This hybrid system known as AD-OHD system comprises of a single bed ADS and a Humidification-Dehumidification (HDH) unit. The main objective of this work is to analyse the performance of the hybrid AD-OHD system based on parameters such as Gain Output Ratio (GOR) and amount of desalinated water production. The performance of the hybrid AD-OHD system is studied under three different operating conditions of switching (tswt) and sorption time (tspt), namely, tswt > tspt, tswt = tspt, and tswt < tspt. The results indicate that the optimal working condition is achieved when the hybrid AD-OHD system operates at condition tswt < tspt. The amount of desalinated water and GOR under the optimal condition is found to be 1.12 l/h and 0.78, respectively. The study also conducts experimental investigations to evaluate the GOR of the hybrid AD-OHD system under different operating conditions, including the temperature of the water entering the evaporator and the temperature of the hot and cooling water input to the adsorbent bed. Experimental data indicates a positive correlation between GOR and hot water temperatures, while increased cooling water temperature reduce GOR due to reduced adsorption behaviour. Although the evaporator inlet water temperature initially boosts GOR, it declines as the adsorption capacity diminishes. The study highlights the superior performance of the hybrid AD-OHD system compared to both the standalone single-bed ADS and open cycle HDH desalination systems. The hybrid AD-OHD desalination system exhibits an 80 % improvement over the single-bed ADS system and a 50 % improvement over the open cycle HDH system in desalinated water production. Additionally, a theoretical model of the adsorption desalination cycle is developed and validated, demonstrating the viability of the AD-OHD system for desalination applications.

Development of Hybrid Systems by Integrating an Adsorption Process with Natural Zeolite and/or Palygorskite into the Electrocoagulation Treatment of Sanitary Landfill Leachate

The effectiveness of a hybrid approach comprising electrocoagulation (EC) and adsorption (AD) (using natural zeolite and/or palygorskite) processes to treat raw sanitary landfill leachate (SLL) was investigated in terms of color, dissolved chemical oxygen demand (d-COD), nitrate nitrogen (NO3−-N) and ammonium nitrogen (NH4+-N) removal. Optimal EC conditions were found with a current density of 30 mA cm−2, Fe electrode material and pH 8. Implementation of the AD process using zeolite (ADzeo) as pre- or post-treatment for EC significantly increased the NH4+-N removal efficiency. The ADzeo-EC sequential treatment showed considerably higher color removal compared to the EC-ADzeo sequential treatment and was therefore determined to be the optimal sequential treatment. Integration of the AD process using palygorskite (ADpal) into the first or middle stage of the ADzeo-EC treatment system enhanced the overall NO3−-N removal efficiency. The hybrid ADzeo-ADpal-EC treatment system exhibited the highest simultaneous removal efficiencies of color, d-COD, NO3−-N and NH4+-N, corresponding to 95.06 ± 0.19%, 48.89 ± 0.89%, 68.38 ± 0.93% and 78.25 ± 0.61%, respectively. The results of this study indicate that the ADzeo-ADpal-EC hybrid system is a promising and efficient approach for treating raw landfill leachate.

Crucial role of Ce particles during initial hydrogen absorption of AB-type hydrogen storage alloys

The hydrogen storage behavior and the microstructural features of AB-type Ti50Fe48V2 hydrogen storage alloys containing a small amount of cerium (Ce) were investigated to understand the effect of Ce addition during initial hydrogen absorption. The initial hydrogen absorption kinetics of the alloys improved significantly at room temperature with Ce addition, which exhibited no significant influence on the pressure-composition isotherms for hydrogen absorption and desorption. Fine spherical particles containing Ce, which were determined to be γ-Ce mixed with cerium oxide, were dispersed in the ordered body-centered cubic TiFe matrix. During the early stage of hydrogen absorption, small cracks were initiated around the Ce particles, likely caused by the volume expansion owing to the formation of ε-CeH2. Subsequently, many large cracks, believed to have formed owing to the hydrogenation of the TiFe matrix, propagated during further hydrogen absorption. Therefore, these Ce particles appear to play a crucial role by providing starting points for the initial hydrogenation, with this mechanism explaining the significant increase in the primary hydrogen absorption kinetics after Ce addition. Notably, some small pits were observed after partial hydrogen absorption, possibly attributed to the hydrogenation of Ce particles underneath the alloy surfaces.

Association of advanced oxidative and adsorptive processes for dye treatment in the sanitizer industry: kinetic, equilibrium and toxicity evaluation

The presence of dyes in wastewater can cause several damages to the environment. Aiming at its removal, advanced oxidative processes (AOP) and adsorption (ADS) have been used. In this work, the removal of acid blue dye 80 (AA80) by AOP (photoperoxidation (PP) and photo-Fenton (PF)) and by ADS was evaluated, individually and combined. The use of the PP/UV-C system led to degradations of 72.7 and 83.8% for the λ of 334 and 622 nm, respectively. The PP/LED system did not degrade. For the PF process, &gt; 90% degradation was obtained for both radiations. The [Fe] (1 mg.L-1) and [H2O2] (90 mg.L-1)were optimized for the PF/LED system. As for the PF/UV-C system, the optimal [H2O2] was 60 mg.L-1. The experimental data fit well with the Chan and Chu (2003) kinetic model with R2&gt;0.94. The kinetic data showed a better fit to the pseudo-second order model (R2&gt;0.90), while equilibrium was reached in 30 min with removal of 62.45 (λ=334 nm) and 83.22% (λ=622 nm), being well represented by the Langmuir and Sips models. Finally, the combined study promoted a 7% increase in AA80 removal, achieving an improvement in the final toxicity of the treated matrix when compared to isolated AOP systems.

The tunable anisotropic Rashba spin-orbit coupling effect in Pb-adsorbed Janus monolayer WSeTe.

The spin-splitting properties of Pb-adsorbed monolayer Janus WSeTe are investigated based on first-principles calculations. The adsorbed system shows large Rashba splitting (the Rashba parameter is up to 0.75 eV Å), and we find that different adsorption layers (Te/Se adsorption layers) exhibit different significant features under spin-orbit coupling. Zeeman splitting and Rashba splitting co-exist at the high symmetry Γ point of the Te adsorption layer, while the Se adsorption layer exhibits anisotropic Rashba spin-orbit coupling. It was determined using k·p perturbation theory that Pb atom adsorption reduces the initial symmetry of the 2H-WSeTe monolayer and induces a strong spin-orbit coupling effect, so as to induce the anisotropic Rashba effect. Furthermore, the tunability of Rashba splitting was demonstrated by varying the adsorption concentration, adjusting the adsorption distance, and applying biaxial strain. This predicted adsorption system has potential value in spintronic devices.

Microwave-assisted MOF@biomass layered nanomaterials: Characterization and applications in wastewater treatment

MOF@Biomass layered hybrids were designed through in situ growth from rice husk (RH) and microwave-assisted synthesized MIL-53(Al) particles that enable the reduction of reaction times. The synthesis process included steps to pretreat RH, Al adsorption on RH, and then MIL-53(Al) in-situ growth reaction at 125 °C for 60 min and 200 W irradiation power. The resulting hybrid (MIL-53(Al)@RH) and its parent separate materials were characterized using TGA, SEM, FTIR, XRD, among others. MIL-53(Al)@RH showed high crystallinity in the hybridized MOF particles, thermal decomposition phases, and functional groups (Al–O, O–H, CO, and CC). The hybrid particles allow an easy separation during heterogeneous processing due to their 400 times larger size compared to MIL-53(Al) crystals. The properties of the layered hybrids for removal of Oxytetracycline (OTC), Diclofenac (DCL), and Glyphosate (GLY) in aqueous solutions, were tested by adsorption (ADS) and advanced oxidation processes (AOP). The high ADS capacities (162 mg g−1 GLY, 139 mg g−1 OTC, 93 mg g−1 DCL) and % removal in AOP (97% GLY, 91% OTC, 80% DCL) demonstrated that MIL-53(Al) maintained its properties after hybridization.

Treatment of raw sanitary landfill leachate using a hybrid pilot-scale system comprising adsorption, electrocoagulation and biological process

The effectiveness of a three-stage pilot approach using adsorption (AD), electrocoagulation (EC) and biological (BIO) processes for the treatment of raw sanitary landfill leachate (SLL) was investigated. SLL is loaded with hazardous substances such as organic load and heavy metals with high ammonium nitrogen (NH4+-N) concentrations and is also produced in large quantities, causing serious risks to both living organisms and the environment. In this study, column adsorption experiments were initially performed to examine the removal of toxic NH4+-N using different initial NH4+-N concentrations and recirculation flow rates. The adsorption process was then examined as a pre-treatment step in two sequential treatment scenarios, i.e., AD-EC-BIO and AD-BIO-EC, to determine which achieved the highest removal of pollutants and leachate toxic potential, thus ensuring the biosafety of these processes during the release of the respective effluents into surface waters. The overall removal efficiencies of NH4+-N, color, dissolved chemical oxygen demand (d-COD), manganese (Mn), nickel (Ni), zinc (Zn) and iron (Fe) achieved after the application of the AD-EC-BIO system were 95.5 ± 0.1%, 98.8 ± 0.1%, 85.7 ± 0.8%, 100 ± 0.1%, 71.4 ± 1.7%, 63.8 ± 1.9% and 94.2 ± 0.2%, respectively, while the values for the AD-BIO-EC system were 98.5 ± 0.2%, 98.7 ± 0.1%, 85.7 ± 0.4%, 98.9 ± 1.2%, 67.7 ± 1.7%, 76.1 ± 1.6% and 94.8 ± 0.1%, respectively. In accordance with the latter, the assessment of leachate toxic potential using a Thamnocephalus platyurus bioassay revealed that the AD-EC-BIO system could be considered a promising treatment strategy for the purification of raw SLL.

Response surface modeling of ceftriaxone removal from hospital wastewater.

In recent decades, an emerging concern of widespread antimicrobial resistance has been raised due to the existence of pharmaceutical samples such as antibiotics in an aqueous medium. Herein, antibiotic ceftriaxone (CTX) removal from hospital wastewater employing a hybrid process of electrocoagulation (EC) and adsorption (AD) was investigated. The response surface methodology (RSM) was employed to study the influences of main operating variables, including initial CTX concentration, pH, current density, reaction time, and chitosan dosage, on the removal efficiency of the treatment process. Under the optimum condition of the employed EC/AD hybrid treatment process, where initial CTX concentration, pH solution, the current density, adsorbent dosage, and reaction time were set at 20.0mg L-1, 7.5, 6.0mAcm-2, 0.75g L-1, and 12.5min, respectively, the removal efficiency of 100% was achieved. Analysis of variance (ANOVA) confirmed that the developed quadratic treatment model is highly significant. The applied EC/AD hybrid treatment process revealed the electrical energy consumption of 0.84 kWh m-3 and 0.2168 kWh (g Al)-1 per cubic meter of hospital wastewater and gram of consumed aluminum electrode, respectively. The second-order kinetic model with R2 of 0.9514 and the Langmuir isotherm model with R2 of 0.973 best fit the developed EC/AD hybrid treatment process, and qm was found to be 111.1mgg-1. The obtained experimental results confirmed that the CTX concentration of the hospital wastewater was reduced to zero after applying the EC/AD hybrid process.

Structure and hydrogen sorption properties of Mg-Mg2Ni nanoparticles prepared by gas phase condensation

The aim of this work is to investigate the hydrogen sorption kinetics and thermodynamics of Mg-Ni nanoparticles at relatively low temperature in relation to their microstructure. To this purpose, Mg-Ni nanoparticles (20 at% Ni) were prepared by gas phase condensation employing two thermal vapour sources. In the as-prepared state, Mg and Ni are mixed within individual nanoparticles, but the intermetallic Mg2Ni compound is not fully formed. After keeping the nanoparticles at 150 °C for two hours under high vacuum or at a mild hydrogen pressure of 0.15 bar, the formation of a Mg-Mg2Ni or MgH2-Mg2NiH0.3 nanocomposite is observed. Subsequently, fast kinetics of hydrogen sorption are recorded at 150 °C with activation energy of 80±8 kJ/mol (absorption) and 60±6 kJ/mol (desorption). However, the maximum hydrogen storage capacity is limited to 2.5 wt% because the transformation from Mg2NiH0.3 to Mg2NiH4 does not take place at 150 °C even at pressures well above the expected thermodynamic equilibrium. Therefore, only the transformation Mg↔MgH2 contributes to the reversible storage capacity. The corresponding equilibrium pressure determined by pressure-composition isotherms of absorption and desorption at 150 °C is 7.5 mbar, very close to the extrapolated value for bulk Mg. The partial replacement of Ni with Fe does not significantly alter the thermodynamics and kinetics of hydrogen sorption. The structure and hydrogen sorption properties of Mg-Ni nanoparticles are compared to those of Mg-Ti nanoparticles prepared by a similar procedure.

Highly Efficient Removal of Nitrate and Phosphate to Control Eutrophication by the Dielectrophoresis-Assisted Adsorption Method.

The removal of excessive amounts of nitrate and phosphate from water sources, especially agricultural wastewater, has been of high significance to control eutrophication in aquatic systems. Here, a new method is reported for the removal of nitrate and phosphate simultaneously from wastewater based on the combination of the solution-phased adsorption (ADS) and dielectrophoresis (DEP) techniques. The plant ash was first selected as the adsorbent by screening tests, followed by a systematic investigation of using the adsorbent to remove nitrate and phosphate from wastewater under various experimental conditions, including the testing of adsorbent dosage, pretreatment time, water flow rate, and electrode voltage. The analysis of the adsorbent particles was also performed by scanning electron microscope (SEM) analysis, the energy dispersive X-ray spectroscopy (EDX) test, and the measurement of Zeta potentials. Compared with the ADS method alone, the introduction of DEP into the purification process has greatly increased the removal rate by 66.06% for nitrate and 43.04% for phosphate, respectively. In the meantime, it is observed that the processing time has been greatly reduced by 92% with the assistance of DEP.

Rational Design of Catalytic Surfaces for Fuel Cell Technologies by Selective Molecular Patterning

Current green technologies demand for deep and fundamental research. In this sense it has been reported that selective molecular patterning can be employed for the development of highly active electrocatalysts[1,2]. Pt is the most active single-component catalyst for many surface reactions and modifying it with other elements can improve its catalytic performance and stability.Here selective molecular patterning of Pt surfaces with adatoms of Bi and Te at coverages varying from 1/16 ML to 1/4 ML has been studied using DFT to explore changes in the electronic properties of both the adatom and Pt, the sum of which affects catalytic performance of the resulting system.The obtained results indicate that both adatoms are very stable on low-index platinum surfaces at all coverages. The work function of pristine Pt surfaces depends on the exposed plane, and decreases in order (111) > (100) > (110) [4]. In good agreement with experimental data [3] the presence of the adatoms lowers the work function and results in a new trend: (100) > (110) > (111). Further lowering of the model surfaces’ work function with increasing adatoms’ coverage (Table1) also agrees well with the tendencies observed in experimental study of Pt(111) interaction with Bi [3].Table 1. Adatom-Pt(111) WF values. Experimental data for Bi/Pt from ref. [3] is included as well System Coverage Δ WF / eV Experimental value Bi/Pt(111) 0.06 0.73 0.77 0.12 1.26 1.15 0.18 1.65 1.53 0.25 1.96 1.75 Te/Pt(111) 0.06 0.47 — 0.12 0.88 — 0.18 1.22 — 0.24 1.50 — Bi and Te adsorption leads to the charge transfer to the surfaces and the electron density, remaining on the adatoms, gets reorganized to assure the maximal distance from the neighboring Pt atoms, leading to the polarization of the adatom-Pt bond.The adatom-induced changes in the fundamental properties of platinum, such as work function and position of the d-band center, have been observed for both species on all studied surfaces. Even at low 1/16ML coverage Bi and Te not only may block active sites on platinum, but also have a more fundamental impact on its catalytic properties.

Adsorption of Scandium and Yttrium from Aqueous Solutions by Purolite C100Na Resin: Equilibrium and Kinetic Modeling

ABSTRACT: Adsorption of Sc from single and bi-component Sc-Y solutions by Purolite C100Na was studied experimentally and kinetic and thermodynamic characteristics are described. The extended Freundlich isotherm was found to be successful in validating the experimental results. Moreover, curve fitting the time-dependent data into different kinetics mechanisms showed a satisfactory correlation with the pseudo-second-order model. Binary system results show a decrease in Sc adsorption capacity of the absorbent in the presence of secondary ions because of competition for adsorption sites. Furthermore, thermodynamic parameters indicate similarity of reaction mechanisms for both single and binary systems, with Sc absorption adversely affected by temperature. Data from experiments on synthetic electrolytes with Y/Sc ratio of 5 found in actual mining copper leach solution were used for extracting scandium by circulating mine-leach solution through a resin column. The results demonstrate a preferential collection of Sc ions despite the fivefold concentration of Y over Sc. The elusion studies showed that the yttrium desorption peak occurs before that of Sc which, corroborates the adsorption isotherm findings. This results in a 180 mgL-1 Sc rich solution or 60:1 concentration ratio over the original copper leach solution.

Comparative Study of CO2 Capture by Adsorption in Sustainable Date Pits-Derived Porous Activated Carbon and Molecular Sieve.

The rising CO2 concentration has prompted the quest of innovative tools to reduce its effect on the environment. A comparative adsorption study using sustainable low-cost date pits-derived activated carbon and molecular sieve has been carried out for CO2 separation. The adsorb ents were characterized for surface area and morphological properties. The outcomes of flow rate, temperature and initial adsorbate concentration on adsorption performance were examined. The process effectiveness was investigated by breakthrough time, adsorbate loading, efficiency, utilized bed height, mass transfer zone and utilization factor. The immensely steep adsorption response curves demonstrate acceptable utilization of adsorbent capability under breakthrough condition. The adsorbate loading 73.08 mg/g is achieved with an 0.938 column efficiency for developed porous activated carbon at 298 K. The reduced 1.20 cm length of mass transfer zone with enhanced capacity utilization factor equal 0.97 at 298 K with Cin = 5% signifies better adsorption performance for date pits-derived adsorbent. The findings recommend that produced activated carbon is greatly promising to adsorb CO2 in fixed bed column under continuous mode.

Solid - phase extraction of Lead in saline matrix using by GF- AAS with multivariate optimization

This work presents a novel method investigated in the pre-concentration of lead ion as well as the matrix effect eliminated in high salinity medium using solid phase extraction by graphite furnace Atomic Absorption spectroscopy (GFAAS). Fe 3 O 4 -graphene was used as the sorbent while 1M HNO 3 was used as the extraction solvent. Parameters such as: pH, amount of sorbent, time of adsorption, time of desorption and, stirring rate affecting the extraction efficiency of the method were studied and optimized by utilizing two decent optimization methods; factorial design and central composite design (CCD). The limit of detection and limit of quantification were 4.4 and 14.8 ng/mL, respectively The accuracy of the method was evaluated by analyzing a spiked real sample. Good spiked recoveries over the range 98.8-103.6 % were obtained. Under the optimum conditions, the calibration graph was linear over the range 5-50 ng/mL. The relative standard deviation was 4.4 % for four repeated determinations at a concentration of 20 ng/mL.