Low-cost Adsorbent Research Articles

Green synthesis of iron (III) oxide (Fe3O4) Nanoparticles Using Citrus sinensis Peel Extract for the Removal of Ciprofloxacin in Water

Ciprofloxacin is a widely used antibiotic that can contaminate water sources and pose environmental and health risks. Therefore, the objective of this paper is to explore the green synthesis of iron (III) oxide nanoparticles using Citrus sinensis peel extract for the removal of ciprofloxacin in water using standard techniques. The adsorption of ciprofloxacin on the nanoparticles was investigated under different conditions, such as pH, initial concentration of adsorbate, contact time, and different adsorbent doses. The adsorption data were fitted to different isotherm and kinetic models to understand the adsorption mechanism and parameters. The results of characterization revealed the particles to be of nanocrystalline structure with a cubic crystal shape, negative surface charge, and a high thermal stability with elemental composition primarily of Fe and O; it has z- average of 42.60, with Fe-O bond at 693.30cm-1 and UV-Visible absorbance at 221nm. The maximum adsorption capacity with ciprofloxacin was 29.21 mg/g (97.45%) at pH of 7 and room temperature of 25 °C. The results of the adsorption data indicated that the adsorption followed the Langmuir isotherm model and the pseudo-second-order kinetic model, suggesting a monolayer adsorption on a homogeneous surface with a finite number of identical sites. The synthesized nanoparticles showed a high efficiency and selectivity for the removal of ciprofloxacin from water, demonstrating it potential as an eco-friendly and low-cost adsorbent for water purification.

A low-cost water hyacinth-based adsorbent for free fatty acids removal from waste cooking oil: kinetic, isotherm, and thermodynamic studies

A low-cost water hyacinth-based adsorbent for free fatty acids removal from waste cooking oil: kinetic, isotherm, and thermodynamic studies

Efficient phosphate adsorption in aqueous solution using nano-zirconia impregnated spent coffee grounds and preliminary application as a slow-release fertilizer

ABSTRACT In this study, the development of a nano-biocomposite adsorbent based on spent coffee grounds (SCG) and nano-Zirconia (n-ZrO2) was presented to meet the increasing demand for effective and low-cost phosphate adsorbents and contribute to sustainable development goals (SDGs). The adsorption performance of raw SCG and SCG modified with n-ZrO2 (n-ZrO2-mSCG) was tested. The characterization of materials was performed by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), BET surface area analysis, thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), Dispersive X-ray spectroscopy (EDS), and Transmission electron microscopy (TEM). The n-ZrO2-mSCG exhibited superior adsorption capacity compared to SCG. The influences on the adsorption of factors such as initial concentration, pH, stirring time, temperature, and coexisting ions were evaluated. The results showed the maximal adsorption capacity of modified SCG was 15.8 mg/g at pH 2, using a stirring time of 150 mins. Among investigated coexisting anions, sulfate (SO4 2-) and bicarbonate (HCO3 −) affected the phosphate adsorption performance of n-ZrO2-mSCG, when they existed in aqueous solution at predominant levels. The n-ZrO2-mSCG displayed high selectivity toward phosphate and sustained efficacious phosphate adsorption after three successive cycles of adsorption/desorption, proposing a prospective low-cost and reusable adsorbent material for phosphate removal and a potential alternative to conventional fertilizers.

A graphene oxide based composite granule for methylene blue separation from aqueous solution: Adsorption, kinetics and thermodynamic studies

Graphene oxide and chitosan composite material using as a high-efficiency and low-cost granular adsorbent for methylene blue removal was fabricated via self-assembling method. The effects of pH value, contact time, initial concentration, adsorbent dose, temperature, and recyclic stability on the adsorption performance of methylene blue in aqueous solution were investigated in detail. Desorption process with the effects of solvents, contact time, and temperature were also conducted carefully in this study. The adsorption kinetics and adsorption isotherm of dye adsorption process showed that dye adsorption process was fitted to the pseudo-second-order kinetic model and the Freundlich adsorption isotherm, indicating a physical adsorption process with multilayer adsorption. The intra-particle diffusion model indicated that the dye adsorption by the granular adsorbent was strongly happened during the first 4 h. The thermodynamic study showed that the adsorption was a spontaneous and exothermic process and dye ions were condensed onto the surface of adsorbent. The maximum adsorption capacity of dye on the granular adsorbent was calculated as 951.35 mg/g and the adsorbent could maintain its adsorption performance after six cycles. In general, this study provided an efficient, cost-effective, and recyclable the granular adsorbent for dye separation from aqueous solution.

KINETICS AND MECHANISM MODELLING OF Pb(II) AND Ni(II) IONS SORPTION FROM AQUEOUS MEDIUM: EVALUATING THE PERFORMANCE OF Curcuma longa RHIZOME IN THE TREATMENT OF WASTE WATER.

In this research Curcuma longa Rhizome, an agricultural product, available in large quantity in northern Nigeria, were used as low-cost adsorbent for removal of Pb(II) and Ni(II) ions from aqueous medium. Batch operation was used to study the equilibrium behaviour of Curcuma longa rhizome. The effect of solution pH, and contact time on the adsorbent for the removal of Pb(II) and Ni(II) ions were evaluated. To study the adsorption kinetics of Pb(II) and Ni(II) ions onto Curcuma longa Rhizome, pseudo-first-order, pseudo-second-order as well as three diffusion models: intraparticle diffusion model (Weber and Morris model), film diffusion model (McKay model) and liquid film Models were used. The sorption kinetics can be described well by the pseudo-second-order model due to the closeness between the qexp ( 49.26 mg/g) and qcal (52.63 mg/g) for Pb(II) and qexp (57.60) and qcal (55.56 mg/g) for Ni(II) ions. Moreover, the rate limiting step are liquid film and intraparticle diffusion controlled. In addition, the results suggest that Curcuma longa Rhizomes are very effective adsorbent for the removal of Pb(II) and Ni(II) ions from aqueous medium. This will serve as an indicator to consider in the design for waste water treatment plant for heavy metal detoxification using Curcuma longa Rhizome.

The Potential of Bentonite as a Low-cost Adsorbent for the Removal of Heavy Metal Ions from Multicomponent Aqueous Systems of the Galvanic Industry

Waste water in the galvanic process contains high concentrations of heavy metals that pose a direct danger to humans and the environment. Conventional methods for their removal are quite expensive and generate a large amount of waste. The development of new and improvement of existing methods for the removal of heavy metals from galvanic wastewater are the subject of many studies. Compared to other purification methods, the adsorption is becoming an increasingly popular method of wastewater purification, especially if the adsorbent is cheap, easily available and does not require any other treatment before use. Therefore, the aim of the work was to investigate the possibility of using natural bentonite for the removal of heavy metal ions from multi-component water systems of the galvanic industry. For this purpose, the physico-chemical characterization of natural bentonite was performed, and then the influence of pH value, time and temperature on the adsorption efficiency was examined. The results of adsorption showed that natural bentonite can be used as an adsorbent for the removal of heavy metal ions from waste galvanic waters, and that at pH 5 it achieves the maximum removal efficiency for Cu(II):Cr(III):Ni(II) ions in the percentage ratio 100 : 99.990 : 99.998. The results showed that the highest removal efficiency for Cu (II) ions was achieved in the first 10 minutes, and 20 minutes for Cr (III) and Ni (II) ions. The maximum efficiency of Cu (II) removal was achieved at all temperatures, while for Cr (III) 99.99% and Ni (II) 100% maximum efficiency was achieved at 35°C, which indicates that the adsorption process is endothermic. The experimental results of the adsorption of Cu (II) metal ions are in good agreement with the Langmuir and Freundlich theoretical models, while for Cr (III) and Ni (II) ions they are in better agreement with the Langmuir adsorption model.

Affordable cellulose-based solid phase extraction adsorbent for efficient chromatographic analysis of trace contaminants in environmental waters for developing countries

The current work reports on a new low-cost solid phase extraction (SPE) material obtained by crosslinking cellulose with 4,4–methylenebisphenyldiisocyanate (CMDI-1) for the pre-concentration of two contaminants of emerging concern (CEC): Chloramphenicol (CAP) and Bisphenol-A (BPA) from water. The results obtained show good analytical performance with low Limit of Detection of 71.9 ng/L and 10 ng/L for the pre-concentration of CAP and BPA respectively, and a good linear range between 0.5 and 8 µg/L, with r2 values > 0.99. The application of the developed method for the analysis of real water samples achieved good percentage recoveries (86.8 – 96.2 %), comparable to that of an expensive commercial HLB adsorbent (89.8 – 107 %). Response Surface Methodology modelling indicates that adsorbent dose, elution volume, and sample volume had a significant influence on CAP recovery, while solution pH, elution volume, and ionic strength had a significant influence on BPA recovery. From our economic assessment, a pack of 30 SPE tubes of 500 mg CMDI-1 SPE adsorbent will cost 82 % less than a similar amount of Oasis HLB adsorbent. This study demonstrates and validates a feasible and inexpensive approach to the use of cellulose to develop low-cost SPE adsorbents for the effective pre-concentration and determination of trace contaminants in water. The CMDI-1 SPE adsorbent can be easily prepared and adopted for use by water professionals in developing countries to enhance understanding on the presence and fate of such contaminants in the environment and also in technical systems, towards developing relevant environmental protection measures for sustainability.

Low-cost eggshell-fly ash adsorbent for phosphate recovery: A potential slow-release phosphate fertilizer

Fly ash (FA) and eggshells (ES) are common solid wastes with significant potential for the recovery of phosphorus from water. This study focuses on synthesizing a low-cost and environmental-friendly phosphate adsorbent called eggshell-fly ash geopolymer composite (EFG) using eggshells instead of chemicals. The CaO obtained from the high-temperature pyrolysis of eggshells provides active sites for phosphate adsorption, and CO2 serves as a pore-forming agent. The phosphate adsorption performance of EFG varied with the eggshell-fly ash ratios and achieved a maximum of 49.92 mg P/g at an eggshell-fly ash ratio of 40 %. The adsorption process was well described by the pseudo-second-order model and the Langmuir model. EFG also exhibited a good regeneration performance through six-cycle experiments and achieved the highest phosphate desorption at pH 4.0. The results of the column experiment showed that EFG can be used as a filter media for phosphorus removal in a real-scale application with low cost. Soil burial test indicated saturated EFG has a good phosphate slow-release performance (maintained for up to 60 days). Overall, EFG has demonstrated to be a promising adsorbent for phosphorus recovery.

Oyster shell-modified lignite composite in globular shape as a low-cost adsorbent for the removal of Pb2+ and Cd2+ from AMD: Evaluation of adsorption properties and exploration of potential mechanisms

A low-cost composite adsorption material has been synthesized from fishery wastes and natural minerals to address challenges such as ecological balance destruction caused by high concentrations of Pb and Cd in acid mine drainage (AMD), unreasonable use of low-caloric lignite, and environmental pollution caused by idle accumulation of oyster shells. This new adsorbent can effectively treat AMD by improving acidity and adsorbing Pb2+ and Cd2+. In this study, oyster shell-modified lignite composite in globular shape (OSL-G) was synthesized by using pyrolyzed oyster shell and lignite, with the addition of bentonite adhesive. The adsorption properties of OSL-G on AMD were evaluated, and the potential mechanism of OSL-G repairing AMD was explored. The results showed that when the mass ratio of oyster shell to lignite was 1:1, oyster shell-modified lignite composite (OSL) was synthesized at 900 °C for 20 min. When the adhesive content was 15.50 %, the roasting temperature was 640 °C, and the roasting time was 2.35 h, OSL-G was synthesized and the adsorption effect was the best. The OSL-G could effectively treat AMD with pH 4 ∼ 5 and initial Pb2+ and Cd2+ concentrations of 10 mg/L within 600 min at a dosage of 4 g/L. The OSL-G adsorption process followed the quasi-second-order kinetic model and the Freundlich model. The maximum adsorption saturation capacities of Pb2+ and Cd2+ were 107.2821 mg/g and 8.3777 mg/g at 298.15 K, respectively. The adsorption process was a multistep controlled spontaneous endothermic process. The potential mechanism was mainly the adsorption-condensation coexistence results of electrostatic adsorption, neutralization precipitation, ion exchange, and surface complexation. The removal rates of Pb2+ and Cd2+ of the recovered OSL-G (ROSL-G) were still high, reaching 57.26 % and 50.38 % after 5 times of adsorption–desorption, respectively. The applicability of ROSL-G after adsorption–desorption for other heavy metal components in AMD proved its good application potential. This study suggested that OSL-G can be used as a promising environmentally friendly adsorbent for AMD. This study provided a broad picture of the management and reuse possibilities of fishery wastes and natural mineral resources, and addressed established, current, and potential strategic needs, particularly in terms of sustainability challenges and ecological civilization construction.

Evaluating the performance of carbon-based adsorbents fabricated from renewable biomass precursors for post-combustion CO2 capture

The significant increase in atmospheric CO2 concentration originated mainly from fossil fuels combustion has encouraged the development and improvement of CO2 separation operations to reduce emissions and control climate change and global warming. Therefore, this work is focused on the separation of CO2 from N2 in flue gas streams under post-combustion conditions by developing low-cost adsorbents. Six carbons were fabricated from biomass resources (olive stones and almond shells) to assess their influence on CO2 adsorption capacity: One carbonized and two KOH-activated carbons with carbon/KOH ratio of 1:2 and 1:4 (w/w) for each precursor. The carbons were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), elemental analysis, nitrogen and carbon dioxide adsorption–desorption analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and point of zero charge determination. In addition, the equilibrium adsorption data of pure components for all adsorbents were measured at 0, 25 and 50 °C between 0 and 760 mmHg and CO2/N2 selectivity was determined. Activated carbons were found to have higher CO2 adsorption capacity but with a reduction in apparent selectivity. Dynamic binary adsorption simulations performed in a fixed-bed column demonstrated that the activated carbon produced from olive stones with a carbon/KOH ratio of 1:4 (w/w) can separate a mixture of 14 % CO2 and 86 % N2 at 25 and 50 °C with the highest selectivity, CO2 adsorption capacity, CO2 purity and N2 recovery factor. Reducing flow rate, the breakthrough time increased. Moreover, the breakthrough time was reduced by increasing the temperature from 25 to 50 °C owing to the exothermic nature of adsorption process.

Extraction of Uranium by a Cheap Phosphite-Derived Polymer under Light Condition.

Uranium, as the main fuel of today's nuclear energy, is crucial to the development of nuclear energy. Therefore, the development of low-cost and powerful adsorbents is very important for the removal or recovery of uranium from uranium-containing solutions. Herein, we report the synthesis of a cheap phosphite-derived polymer for such use. Under visible-light irradiation, this phosphite-derived polymer was found to enable selective adsorption of uranium with an adsorption capacity as high as 1030 mg/g, suggesting its great potential in handling nuclear waste.

Activated nanosulfur for broad-spectrum heavy metals capture

Current problems of existing heavy metal-removing technologies, especially for nanomaterials-based ones, are typically single metal ion-specific, high-cost and collected difficult. Herein, facile modification of commercial sulfur creates a versatile adsorbent platform to address challenges. The versatile adsorbent can be easily prepared through solvothermal treatment of a saturated commercial sulfur solution, followed by water precipitation on a commercial foam that eliminates the need for separation. Interestingly, the solvothermal treatment endows the resulting nanosulfur with sulfate acid groups (hard Lewis base), sulfur anions (soft base), and sulfite groups (borderline base), promising the coordination of all types of heavy metal ions (Lewis acids). As such, this versatile adsorbent with well-distributed adsorption sites exhibits highly effective heavy metal adsorption capacity towards diverse heavy metal ions for both single-component and multi-component adsorption, including soft, hard, borderline Lewis metal ions, with ultra-high adsorption ability (e.g., 903.79 mg g−1 for Cu2+). These findings highlighted the potential of this low-cost sulfur-based adsorbent to address the arising challenges in ensuring clean water.

A novel approach for adsorption of organic dyes from aqueous solutions using a sodium alginate/titanium dioxide nanowire doped with zirconium cryogel beads.

The presence of organic dyes in wastewater raises significant environmental and human health concerns, owing to their high toxicity. In light of this, a novel adsorbent material with porous cryogel architecture was developed and employed for the effective removal of organic dyes from an aqueous solution. Initially, a titanium dioxide nanowire doped with zirconium HZTO was synthesized by the hydrothermal process. Subsequently, the beads (SA/HZTO) of sodium alginate and HZTO were successfully prepared through a cross-linking process, employing Ca2+ ions as the crosslinking agent. Structural analysis of SA/HZTO beads was performed using FTIR, SEM, and EDX techniques. We systematically examined the impact of different conditions, including the initial dye concentration, pH, contact time, and adsorbent dosage, on the adsorption process. Batch experiments, both in signal and binary systems, were conducted to rigorously assess the dye adsorption capabilities. Kinetic modeling revealed that the adsorption process adhered to the pseudo-second-order kinetic model. Remarkably, the prepared beads exhibited impressive adsorption capacities of 26 and 29mg/g toward methylene blue (MB) and safranin (SF), respectively. SA/HZTO beads have demonstrated excellent adsorption properties, offering a promising avenue for the development of low-cost, efficient, and reusable adsorbent to remove dyes from wastewater.

Comprehensive life cycle assessment of NH2-functionalized magnetic graphene oxide for mercury removal: Carbon emissions and economic evaluation

Heavy metals contamination critically affects human health and ecosystems, necessitating pioneering approaches to diminish their adverse impacts. Hence, this study synthesized aminated magnetic graphene oxide (mGO-NH2) for the removal of mercury (Hg) from aqueous solutions. Although functionalized GO is an emerging technology at the early stages of development, its synthesis and application require special attention to the eco-environmental assessment. Therefore, the life cycle assessment and life cycle cost of mGO-NH2 were investigated from the cradle-to-gate approach for the removal of 1 kg Hg. The adsorption process was optimized based on pH, Hg concentration, adsorbent dose, and contact time at 6.48, 40 mg/l, 150 mg/l, and 35 min, respectively, resulting in an adsorption capacity of 184.17 mg/g. Human carcinogenic toxicity with a 40.42% contribution was the main environmental impact, relating to electricity (35.76%) and ethylenediamine (31.07%) usage. The endpoint method also revealed the pivotal effect of the mGO-NH2 synthesis on human health (90.52%). The most energy demand was supplied by natural gas and crude oil accounting for 70.8% and 22.1%, respectively. A 99.02% CO2 emission originated from fossil fuels consumption based on the greenhouse gas protocol (GGP). The cost of mGO-NH2 was about $143.7/kg with a net present value of $21064.8 per kg Hg removal for a 20-year lifetime. Considering the significant role of material cost (>70%), the utilization of industrial-grade raw materials is recommended to achieve a low-cost adsorbent. This study demonstrated that besides the appropriate performance of mGO-NH2 for Hg removal, it is essential that further studies evaluate eco-friendly approaches to decrease the adverse impacts of this emerging product.

Rare Earth Element Recovery and Hydrochar Evaluation from Hyperaccumulator by Acid Leaching and Microwave-Assisted Hydrothermal Carbonization

Phytomining is a sustainable approach that uses hyperaccumulators for critical element extraction from various substrates, such as contaminated soils, mine tailings, and aqueous solutions. In this study, grass seeds were fed with a solution containing Y, La, Ce, and Dy, resulting in around 510 mg/kg (dry basis) of total rare earth elements (TREEs) accumulated in grass leaves. Electron probe microanalyzer (EPMA) analysis showed that rare earth elements (REEs) in the grass leaves (GL) predominantly complexed with phosphorous (P). Around 95% of Y, 93% of La, 92% of Ce, and 93% of Dy were extracted from the GL using 0.5 mol/L H2SO4 at a solid concentration of 5 wt.%. Subsequently, microwave-assisted hydrothermal carbonization (MHTC) was used to convert the leaching residue into hydrochar to achieve a comprehensive utilization of GL biomass. The effect of temperature on the structural properties and chemical composition of the resulting hydrochar was evaluated. Scanning electron microscopy (SEM) analysis revealed that the original structure of GL was destroyed at 180 °C during MHTC, producing numerous microspheres and pores. As the reaction temperature increased, there was a concurrent increase in carbon content, a higher heating value (HHV), and energy densification, coupled with a decrease in the hydrogen and oxygen contents of hydrochar. The evolution of H/C and O/C ratios indicated that dehydration and decarboxylation occurred during MHTC. The results showed that the waste biomass of the GL after REE extraction can be effectively converted into energy-rich solid fuel and low-cost adsorbents via MHTC.

Bioinspired Stevia rebaudiana Green Zinc Oxide Nanoparticles for the Adsorptive Removal of Antibiotics from Water.

Green zinc oxide nanoparticles (ZnO NPs) synthesized using Stevia rebaudiana as a reducing agent were investigated as ecofriendly adsorbents for the removal of the antibiotics ciprofloxacin (CIP) and tetracycline (TET) from water. Green ZnO NPs were synthesized using a rapid novel approach that did not require annealing or calcination at high temperatures to produce mesoporous NPs with a size range of 37.36-71.33 nm, a specific surface area of 15.28 m2/g, and a negative surface charge of -15 mV at pH 5. The green ZnO NPs exhibited an antioxidant activity of 85.57% at 250 μg/mL and an antibacterial activity with MIC and MBC of 50 and 100 mg/mL, respectively, against both Escherichia coli and Staphylococcus aureus. The best adsorption performance was achieved using a 4 g/L dose and pH 5, yielding, respectively, 86.77 ± 0.82% removal and 27.07 ± 0.26 mg/g adsorption capacity for CIP at 10 mg/L and 67.86 ± 3.41% and 15.88 ± 0.37 mg/g for TET at 25 mg/L. The green ZnO NPs achieved 79.71% ± 0.28 and 61.55% ± 0.53 removal of 10 mg/L CIP and 25 mg/L TET, respectively, in a spiked tap water binary system of the two contaminants. Adsorption of CIP and TET occurred mainly via electrostatic interactions, whereby CIP was bound more strongly than TET by virtue of its charge and size. The synthesis and adsorption processes were evaluated by a stepwise regression statistical model to optimize their parameters. Lastly, the green ZnO NPs were regenerated and reused for 5 cycles, indicating their functionality as simple, reusable, and low-cost adsorbents for the removal of CIP and TET from wastewater, in accordance with SDGs #6 and 12 for the sustainable management of water.

Ciprofloxacin adsorption onto CNT loaded Pumice: Adsorption Modelling, kinetics, equilibriums and reusability studies

A novel CNT-derived Pumice adsorbent (P-CNT3) was successfully synthesized as an efficient adsorbent for Ciprofloxacin (CIP) removal from aqueous solutions. In present study, P-CNT3 composite synthesized by hydrothermal technique was loaded with multiwalled carbon nanotube (CNT) using sonification to remove CIP antibiotic. P-CNT3 composite were characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. Adsorption performance was studied by adjusting the pH, contact time, initial CIP concentration, temperature and adsorbent dosage in a batch reactor to obtain the maximum adsorption capacity (qm). The maximum adsorption capacity (qm) was achieved in 240 min at pH ≤ 5).The adsorption process of P-CNT3 followed the pseudo-first-order kinetic model (R2 = 0.989) and sips isotherm model (R2 = 0.991), and qm to adsorb CIP was 28.6 mg/g. The illustrated adsorption mechanism shows that hydrophobic interactions, electrostatic and non-electrostatic interactions, suggests CIP adsorption. Over the temperature range of 298–318 K, the thermodynamic parameters ΔG°, ΔS° and ΔH° were calculated. The adsorption reactions were shown to be spontaneous and endothermic. Furthermore, activation energy suggested a physisorption mechanism for P-CNT3. In addition, regeneration study shows that the P-CNT3 can be reused five times with excellent results in CIP adsorption. Based on these findings, P-CNT3 can be considered a feasible low-cost adsorbent for CIP removal. Hence, the prepared P-CNT3 composite can be used as an inexpensive and a promising adsorbent for the removal of other pharmaceutical compounds.

Polyamine functionalized cage hollow mesoporous SiO2 microspheres for CO2 capture over a wide temperature range

Hollow SiO2 microspheres have become attractive materials for nanotechnology applications owing to their biological inertness and high functionality. In this study, hydrophobic spherical hollow cages were formed using the soft stencil method with Pluronic F127 and cetyltrimethylammonium bromide (CTAB) as the structure-directing agent, and hollow nanoporous SiO2 microspheres (FHMS) were prepared using the soft template method. Various of amine functionalization modes were further employed to demonstrate the complexity of the relationship between pore structure/amidation mode/amine content and adsorption capacity. The hollow morphology of the porous silica was revealed using field-emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and its porous properties were revealed using nitrogen adsorption-desorption isotherm measurements. Experiments on the fixed-bed dynamic adsorption process at 15% CO2 showed that the high specific surface area, high pore volume and amine content of the carriers had a positive effect on the adsorption performance. However, the accessibility of the adsorption centre was affected at high loadings, and the amine efficiency and adsorption capacity were reduced. The dual amine functionalized FHMS-G-I60 maintained the integrity and order of the hollow mesoporous carrier structure, and overcame the dilemma of easy loss in the cycle process of the impregnation method and the low adsorption capacity of the grafting method. It possessed an adsorption capacity of 3.62 mmol/g, high adsorption cycling stability (more than 99.5% adsorption maintained after 10 cycles) and high amine efficiency (0.2852 mmol CO2/mmol N). CO2-TPD analysis (Thermal Programmed Desorption) further showed that FHMS-G-I60 had a faster desorption rate and lower regeneration energy consumption. In general, such structure-directed prepared matrices and functionalized with different amines are promising and low-cost adsorbents that can be used to capture CO2 from ambient air and flue gases under different demands.

CARBONATION OF OLIVE SEED SHELLS USING A STRONG BASE AND A STUDY OF CARBONATION PRODUCTS AND THEIR EFFECT ON THE SPECIFICATIONS OF PREPARED CARBON

Due to the large presence of plant waste of all kinds, In order to reduce them, activated carbon is prepared as a low-cost adsorbent with many uses in removing various environmental pollutants, including gases, vapors, and water-contaminating dyes, in addition to its medical uses. These wastes include olive seeds that are obtained after extracting olive oil from olive fruits. In our study, activated carbon was prepared from olive seeds, It was ground well into a very fine powder so that the interaction with the carbonated substance (potassium hydroxide) was as large as possible and thus increased the carbon content of the raw material, To obtain good results when compared with commercial activated carbon, The physical properties of the prepared activated carbon were determined, such as internal and external surface area, density, moisture content, and ash content

Wastewater Treatment Utilizing Industrial Waste Fly Ash as a Low-Cost Adsorbent for Heavy Metal Removal: Literature Review

Wastewater discharges from industrial processes typically include elevated concentrations of contaminants, which largely consist of potentially harmful chemicals such as heavy metals. These contaminants are characterized by their slow rate of decomposition. Hence, the removal of these metallic ions from effluents poses a challenge. Among different treatments, the adsorption approach has considerable potential due to its ability to effectively eliminate both soluble and insoluble pollutants from effluent, even at lower levels of concentration. Of various wastes, fly ash (FA) material has been the subject of attention because it is abundant, has favorable qualities, and contains a high percentage of minerals. This review investigates multiple facets, with a specific focus on the application of FA, an industrial byproduct, as an adsorbent in removing heavy metals. A comprehensive examination was conducted on a range of concerns pertaining to the pollution caused by metallic ions, including the underlying causes, levels of contamination, health implications of heavy metals, and removal methods. Multiple factors were found to affect the adsorption process. Of all the factors, the pH value considerably influences the elimination of heavy metals. An acidic pH range of 2.5–4.5 was found to be optimal for achieving the highest possible elimination of As(V), Cu(II), Hg(II), and Cr(VI). The latter elimination rate reached 89% at the optimal pH level. Most heavy metals’ adsorption isotherms conformed to the Langmuir or Freundlich models, while the pseudo-second-order kinetics provided a satisfactory match for their removal. Using a raw FA, adsorption capacities were achieved in the removal of metallic ions, Ni(II), Pb(II), and Cr(VI), that ranged from 14.0 to 23.9 mg g−1. Meanwhile, the FA-zeolite showed a remarkable capacity to adsorb ions Mn(II), Ni(II), Cd(II), Cu(II), and Pb(II), with values ranging from about 31 to 66 mg g−1. The cost analysis showed that the treatment of FA is economically advantageous and may result in significant cost reductions in comparison to commercial adsorbents. In summary, FA is an inexpensive waste material with potential for water treatment applications and several other purposes due to its excellent chemical and mineralogical composition.