Desorption Efficiency Research Articles

Effective removal and immobilization of radioactive iodate from aqueous solution by iron-gallic acid@palygorskite nanohybrid

Here, we developed a new low-cost and high-efficiency adsorbent, iron-gallic acid@palygorskite nanohybrid, for removing and immobilizing radioactive IO3- from wastewater. The results show that the key factor affecting the adsorption performance of the hybrid is the reaction time, which determines the degree of coating of GA-Fe(II) nanoparticles on the palygorskite. These nanoparticles are very randomly distributed on the surface of palygorskite rod-shaped crystals or combined with a large number of rod-shaped accumulations of palygorskite. In addition to the GA-Fe(II) complex formed at a molar ratio of 1:1, there are also iron elements in the hybrid that may be fixed to the surface and lattice of the palygorskite by ion exchange and isomorphic substitution. The adsorption process conforms to the pseudo-second-order kinetic model and Langmuir isotherm model, with a maximum adsorption capacity of 78.37 mg/g. It is also a spontaneous, endothermic, and disorder-increasing process. The extremely low desorption efficiencies confirm that the GA-Fe(II) complex exhibits strong chemical adsorption with the iodate, and the positively charged sites such as ferrous and iron ions presented in the palygorskite can also be fixed to the iodate through electrostatic attraction. Therefore, this adsorbent exhibits good application potential in the treatment of radioactive iodate wastewater.

Adsorption behavior of Methylene Blue and Rhodamine B on microplastics before and after ultraviolet irradiation

The accumulation of microplastics (MPs) and dyes has attracted extensive attention because of their environmental effects, which will be exacerbated especially after the aging of MPs. This study aimed at investigating the significance of Methylene Blue (MB) and Rhodamine B (RhB) adsorption behavior by PLA (polylactic acid) and PA66 (Polyamide 66) MPs after UV aging. After aging, there was an observed increase in the hydrophilicity, specific surface area, and oxygen content of MPs. The results indicate that aging enhances the adsorption capacity of both PLA and PA66. Furthermore, it is noteworthy that PLA undergoes more significant changes in its physicochemical properties compared to PA66 following aging. The adsorption process conformed the pseudo-second order (PSO) kinetic model and Langmuir isotherm well, and the adsorption capacity followed the sequence of aged-PLA > aged-PA66 > pristine-PA66 > pristine-PLA. Besides, the adsorption of dyes onto the MPs was studied across four variables (pH, salinity, surfactants, and dissolved organic matter). The aforementioned findings collectively demonstrate that the aged MPs still exhibit a higher adsorption capacity than the pristine MPs. In desorption experiments, the desorption efficiency of MB (PLA) was reduced from 35.29 % (P-PLA) to 32.76 % (A-PLA), and the similar trend was observed on other aged MPs. These findings suggest that aged MPs could have a more pronounced ability for dye transportation. These results would contribute to a deeper understanding of the adsorption and desorption behavior of dyes on MPs and their potential health risks.

Sodium alginate/polyvinyl alcohol for the recovery of rare earth elements from mining wastewater: Mechanism and properties

With the demand for rare earth elements (REEs) increasing in the high-tech sector, the recovery of REEs from secondary sources is becoming very critical. In this study, sodium alginate/polyvinyl alcohol (SA/PVA) beads obtained by cross-linking alginate with polyvinyl alcohol were used to recover REEs from real rare-earth wastewaters. The results showed that SA/PVA beads are less affected by temperature and exhibited adsorption selectivity for REEs. The efficiency of adsorbing REEs ranged from 27.6% to 52.6%, but was significantly higher than that of 9.2% Mn. Meanwhile, among the observed REEs, SA/PVA beads revealed a preference for light REEs (44.3% − 52.6%). The adsorption process was investigated utilizing advanced characterization methods, namely Scanning Electron Microscope, Fourier Transform Infrared Spectrometer, and X-ray Diffraction Spectra. Combined with the results of Pearson correlation analysis, we proposed that the adsorption process involves the combined effects of ion exchange, complexation, electrostatic interaction and pore filling. As well, a desorption efficiency of more than 76.9% can be achieved with sodium citrate, which makes possible the effective recovery of REEs. In summary, this study provides a promising green, environmentally friendly and sustainable material for the enrichment and recovery of REEs from mining wastewater.

PH-Responsive Biocompatible Fluorescent Hydrogel for Selective Sensing and Adsorptive Recovery of Dysprosium.

The elevated accumulation of electronic wastes, especially containing Dysprosium ion [i.e., Dy(III)], is emerging as a potential environmental threat. To overcome the deleterious effects of Dy(III), detection and removal of Dy(III) is crucial. Moreover, recovery of high-value Dy(III) is economically beneficial. However, the availability of a single material, capable of sensing Dy(III) in nanomolar concentration and simultaneously adsorbing it with high adsorption capacity (AC), is rare. Therefore, to solve this problem, a pH-responsive fluorescent amino graphene oxide-impregnated-engineered polymer hydrogel (AGO-EPH) has been synthesized, suitable for selective sensing of Dy(III) in nanomolar concentration and adsorbing it from wastewater at ambient temperature. This terpolymeric hydrogel is synthesized from two nonfluorescent monomers, propenoic acid (PNA) and prop-2-enamide (PEAM), along with an in situ generated comonomer (3-acrylamidopropanoic acid/AAPPA) through N-H activation during polymerization. Surface properties and structural details of AGO-EPH are established using NMR, FTIR, XRD, TEM, SEM, EDX, Raman, MALDI-mass, and DLS studies. The AGO-EPH exhibits blue fluorescence with selective turn-off sensing of Dy(III) with the detection limit of 1.88 × 10-7 (M). The maximum AC of AGO-EPH is 41.97 ± 0.39 mg g-1. The developed AGO-EPH shows consistent adsorption-desorption property over five cycles, with more than 90% desorption efficiency per cycle, confirming significant recovery of the valuable Dy(III). From Logic gate calculations, complexation of Dy(III) and AGO-EPH may be the reason behind fluorescence quenching. The AGO-EPH also shows antibacterial action against ∼3 × 108 cells mL-1 of E. coli solution. Overall, the developed pH-responsive engineered hydrogel can be used as a potential low-cost sensing device and reusable adsorbent for Dy(III).

Removal of a model reactive azo dye from aqueous solution by a bioadsorbent in batch and fixed-bed column modes: Application of the developed technology to a textile wastewater

Sugarcane bagasse (SB) was used to produce a new bioadsorbent (STEA), drawing on circular economy concepts. STEA was synthesized using a two-step one-pot reaction, employing epichlorohydrin and triethylamine in the presence of N,N-dimethylformamide, without the use of a petroleum-based catalyst. The structure and surface of STEA were characterized by elemental C, H, N, and Cl analysis, X-ray diffraction, infrared spectroscopy, 13C solid-state nuclear magnetic resonance spectroscopy, thermogravimetric analysis, specific surface area and pore size distribution determination, and point of zero charge measurement. Batch adsorption and desorption tests were performed with the model dye Remazol Golden Yellow (RGY) RNL, a reactive anionic azo dye widely used in textile industry, to evaluate the potential reuse and application of STEA in a fixed-bed column for wastewater treatment. For batch adsorption, the best dose and agitation speed were 0.2 g L−1 and 50 rpm, respectively. STEA effectively removed RGY over a wide range of pH (2.00–10.00). The equilibrium time, maximum adsorption capacity (Qmax), and desorption efficiency (Edes) were 720 min, 369 mg g−1 (0.71 mmol g−1), and 49.5 %, respectively. The fixed-bed column fed with a spiked aqueous RGY solution could be operated for 415 min, with Qmax of 422 mg g−1 (0.81 mmol g−1) and Edes of 58.9 %. Batch and continuous experiments using real textile industry wastewater containing reactive azo dyes showed high color removal efficiency by STEA, with no interference of other compounds present in wastewater on adsorption of the reactive azo dyes (overshooting effect). The technology was validated in a relevant environment and achieved technology readiness level 5, showing potential to be upscaled. Therefore, STEA proved to be an efficient bio-based technology for application in tertiary treatment of real textile plant wastewater to remove reactive anionic azo dyes.

Role of Chalcogenides in Sensitive Therapeutic Drug Monitoring Using Laser Desorption and Ionization.

This study investigates the applicability of six transition metal dichalcogenides to efficient therapeutic drug monitoring of ten antiepileptic drugs using laser desorption/ionization-mass spectrometry. We found that molybdenum ditelluride and tungsten ditelluride are suitable for the sensitive quantification of therapeutic drugs. The contribution of tellurium to the enhanced efficiency of laser desorption ionization was validated through theoretical calculations utilizing an integrated model that incorporates transition-metal dichalcogenides and antiepileptic drugs. The results of our theoretical calculations suggest that the relatively low surface electron density for the tellurium-containing transition metal dichalcogenides induces stronger Coulombic interactions, which results in enhanced laser desorption and ionization efficiency. To demonstrate applicability, up to 120 patient samples were analyzed to determine drug concentrations, and the results were compared with those of immunoassay and liquid chromatography-tandem mass spectrometry. Agreements among these methods were statistically evaluated using the Passing-Bablok regression and Bland-Altman analysis. Furthermore, our method has been shown to be applicable to the simultaneous detection and multiplexed quantification of antiepileptic drugs.

Ionic liquids functionalized chitosan: An effective, rapid and green adsorbent for gold recovery

Thiosulfate has been considered as a more environmentally-friendly alternative to cyanide salts for the extraction of gold from gold ores and the development of affordable, green and efficient adsorbents for the isolation of gold-thiosulfate complex (Au(S2O3)23−) from the leaching solution remains a significant challenge. To address this issue, chitosan, a natural macromolecule, was selected as a carrier and chemically modified with ionic liquids. The ionic liquids modified chitosan showed greater adsorption capacity towards Au(S2O3)23− compared with pristine chitosan. The adsorption of Au(S2O3)23− on ionic liquid modified chitosan followed Freundlich isotherm and pseudo-second order kinetic models, involving an anion-exchange mechanism with liquid film diffusion as the rate-limiting step. The chitosan modified with butylimidazolium-based ionic liquid had an adsorption capacity of 5.0 mg g−1 for gold (10 mg L−1 of gold, pH 6, 2 g L−1 of adsorbent dosage), outperforming other reported adsorbents. The ionic liquid modified chitosan showed a high adsorption efficiency of up to 96.7 % for Au(S2O3)23− in an actual thiosulfate leaching solution with a desorption efficiency of 98.4 %, suggesting that the ionic liquid modified chitosan has the potential to be a eco-friendly, biocompatible and effective adsorbent for the recovery of Au(S2O3)23−.

ZnO/TiO2 hetero-structured nanosheets for effectively detecting formaldehyde at room temperature

In this study, ZnO/TiO2 nanosheets were synthesized using a hydrothermal method followed by annealing. The resulting hierarchical ZnO–TiO2 heterostructures exhibited improved gas-sensing performance compared with pure ZnO. We demonstrated that tuning the ratio of Zn to Ti components in the heterostructure allowed us to adjust the sensor stability, with the best- performing sample having a Zn:Ti ratio of 2:1. A notable reduction was observed in both the sensor response and recovery times, down to 22 and 17 s, respectively, by utilizing nanosheet- structured ZnO/TiO2 heterojunctions. To gain insight into the interaction between the sensing materials and formaldehyde (HCHO) molecules, we performed first-principles calculations to examine the density of states, charge transfer, and energy of adsorption. Our approach to constructing heterogeneous structures contributes to overcoming the low desorption efficiency and slow response-recovery time of pure ZnO for gas-sensing applications.

Revealing the potential of cyclic amine morpholine (MOR) for CO2 capture through a comprehensive evaluation framework and rapid screening experiments

The present study comprehensively evaluates the CO2 capture performance of morpholine (MOR) at concentrations of 2 M, 5 M, and 7 M, comparing its effectiveness against conventional amines, monoethanolamine (MEA) and 2-(methylamino)ethanol (MAE). The assessment criteria include CO2 absorption rate, desorption rate, cyclic capacity, regeneration energy consumption, and relative economic cost. Utilizing 13C Nuclear Magnetic Resonance (NMR) technology, we analyzed the variations in ion concentration of the amine solvents under different CO2 loadings to reveal the reaction mechanisms of MOR with CO2. Our results demonstrate that MOR outperforms MEA and MAE in CO2 capture performance, particularly excelling in desorption efficiency. At a concentration of 7 M, MOR exhibited a 357.86% increase in average desorption rate and a 46% larger cyclic capacity compared to MEA. Additionally, MOR showed a 33.33% reduction in regeneration energy consumption and a 7.89% decrease in relative economic cost. The comprehensive evaluation method developed in this study indicates that MOR, with its high thermal stability and low corrosivity, maintains excellent CO2 capture performance at high amine concentrations, suggesting it as a promising absorbent for industrial applications. The findings contribute to the optimization of amine-based CO2 capture technologies and provide a robust framework for the selection and assessment of amine solvents, paving the way for more sustainable and cost-effective carbon capture solutions.

Highly selective recovery of rare earth elements from mining wastewater using phyto-synthesized biochar dispersed iron nanoparticles

Recovery of rare earth elements (REEs) from secondary sources such as mining wastewater has attracted much recent attention due to the rising global demand for REEs and the need to environmentally protect potentially contaminated mine sites. One significant issue it that most adsorbents proposed for removal and/or recovery of REEs are not generally selective for REEs. In this study, biochar dispersed iron nanoparticles synthesized using a plant extract (BC-FeNPs) were successfully used for the selective recovery of REEs from mining wastewater, where the Kd values were Nd(III) (918 mL∙g−1), Eu(III) (1253 mL∙g−1), Tb(III) (1119 mL∙g−1), Dy(III) (1032 mL∙g−1), Lu(III) (1898 mL∙g−1), compared to only 23.9 mL∙g−1 for Zn(II). The maximum adsorption efficiency of REEs for the composite was higher than the constituent parts being 88.4 % for BC-FeNPs, but only 8.72 % for biochar and 82.4 % for FeNPs, respectively. FTIR, XPS and Zeta potential analysis suggested that the observed selective adsorption of REEs, involved interactions of REEs with O and N, as well as ion-exchange with H+ from the biochar and capping layer, as well as electrostatic interactions. The desorption efficiency of bound REEs from BC-FeNPs was > 85 % when using acetic acid, and was attributed to efficient competitive ion exchange. Pearson correlation analysis further demonstrated that the adsorption mechanism included ion complexation, ion exchange and electrostatic adsorption, while the desorption mechanism was mainly via ion exchange. Overall, BC-FeNPs has significant potential to practically recover REEs from mining wastewater having demonstrated excellent reusability after five adsorption–desorption cycles.

Performance of a new water lean absorbent composed of EHA and DEGDEE in CO2 capture and regeneration

Previous work has shown that non-aqueous absorbent composed of dimethyl sulfoxide (DMSO) and 2-ethylhexylan-1-amine (EHA) is superior to commercial monoethanolamine (MEA) in both absorption of CO2 and desorption. However, the price of DMSO is too high, which leads to the high cost of reagents. It is worthwhile to choose a cheap solvent instead of DMSO, which can also achieve satisfactory absorption and desorption performance. Around this goal, we selected diethylene glycol diethyl ether (DEGDEE) to form a non-aqueous absorbent with EHA and investigated the absorption and desorption performance. The desorption efficiency of 70 wt% EHA +30 wt% DEGDEE was 99 % at 373 K. The desorption efficiency was 89.4 %, and the desorption energy consumption was only 45.1 % of MEA when the water content was 10 wt%. DEGDEE can achieve similar or even better performance than DMSO, while the cost of DEGDEE (12000–31000 RMB/ton, technical grade purity 99 %) is lower than DMSO (40000–48000 RMB/ton, technical grade purity 99 %). In addition, it also has a good recycling capacity. These advantages will certainly endow this newly developed absorbent with great application prospects in the field of CO2 capture.

Enhancing U(VI) removal from highly acidic wastewater through the synergistic effect of diethylenetriaminepenta(methylenephosphonic) acid and meso-SiO2 on nanosized γ-Fe2O3

Wastewater from uranium mining activities is highly acidic and contains uranium, thereby posing severe risks to the ecological environment and human health. Accordingly, uranium purification is extremely crucial. Herein, we delicately designed a novel adsorbent of diethylenetriaminepenta(methylenephosphonic) acid (DTPMP) and meso-SiO2 modified γ-Fe2O3 (γ-Fe2O3@SiO2@DTPMP, denoted as FSD), and found that the adsorbent can remarkably boost the removal performance of U(VI) under highly acidic conditions. The removal efficiencies of U(VI) by FSD are 90.26 % and 99.81 % in strong acidic solutions of pH = 1.0 and pH = 2.0, respectively, which are much higher than most of the reported adsorbents. Importantly, FSD exhibits high adsorption capacity (51.45 mg/g) and excellent anti-interference, even the wastewater stream contained a lot of organic substances (e.g., fulvic acid), cations (e.g., K+, Na+, Mg2+, NH4+, Zn2+, Co2+, etc.), radioactive nuclides (e.g., Cs+ and Sr2+). After five cycles, the adsorption efficiency and desorption efficiency of FSD only reduced by 8.83 % and 9.61 %, respectively, which are mainly attributed to the unique structures and good chemical stability of FSD. The removal of U(VI) by FSD is a heterogeneous adsorption process which is dominated by chemical adsorption, mainly involving surface coordination complexation. Multiwfn wavefunction and VMD programs based on density functional theory (DFT) further analyzed and visualized the interaction sites and relative strengths of reactions. The results of detailed characterization analysis and theoretical calculations confirmed that the highly efficient U(VI) removal by FSD is mainly ascribed to the strong coordination of the phosphate groups and amino nitrogen atoms in DTPMP with UO22+. Therefore, this study provides a promising strategy for the removal of U(VI) in strongly acidic wastewater.

State-of-the-art fabrication of crystalline zinc oxide for carbamate adsorption: Experimental, optimization, and molecular dynamics simulation

The widespread use of hazardous chemicals in residential and agricultural activities has given rise to a significant global concern regarding pesticide pollution. Present research highlighted the adsorption of carbaryl (CBRL), a carbamate-type insecticide, using zinc oxide nanoparticles (ZnONPs) synthesized from Helianthus annuus flower petals. The study involved synthesizing ZnONPs through a sol-gel process using flower petal extracts, followed by characterization of the nanoparticles. The ZnONPs were then applied for adsorption of CBRL, with mechanisms explored through isotherms, kinetics, thermodynamics insights into CBRL-ZnONPs interactions. The Box–Behnken Design (BBD) of the Response Surface Methodology (RSM) was conducted to optimize the settings for CBRL removal during the batch method adsorption studies. Additionally, molecular dynamic simulation, and density functional theory (DFT) techniques provided deeper insights into the adsorption mechanism. The adsorption process is most precisely fitted linearly as Freundlich isotherm (R2 = 0.9934). By using the Langmuir isotherm, the adsorption demonstrated a noteworthy CBRL adsorption capacity of 158.34 mg/g. The kinetic analysis indicated that the process followed the pseudo-second-order model (R2 = 0.9978). The thermodynamic parameters suggested an endothermic (ΔHo = 36.279 kJ/mol), entropy-driven, and non-spontaneous adsorption process. Nevertheless, the RSM optimization reveals that 99.983% of the CBRL was removed. Furthermore, throughout the process of adsorbent stability via regeneration, ethanol appears to be the most effective eluting agent, exhibiting the 58.33% desorption efficiency. The DFT analyzes combined visual and energetic insight into the molecular dynamics of the CBRL-ZnONPs system, revealed complex interactions and higher binding energies in complex-I. With the support of nanoparticle-based adsorbent, this research presents an in-depth overview of the adsorption of CBRL by ZnONPs, and important insights for creating efficient pollution mitigation strategies.

CO2 desorption and mass transfer characteristic study in micropacked bed reactors

The chemical desorption method with amine-based solvent have been widely applied in CO2 capture and storage (CCS) industrial. However, there is still exist mass transfer limitation and difficult to achieve packing/catalyst immobilization in conventional reactors for CO2 desorption process. In this work, micropacked bed reactors (μPBRs) with glass beads are adopted to investigate CO2 desorption performance. Effects of absorbent type, temperature, initial concentration of absorbent, liquid superficial velocity, initial loading of absorbent, particle size, and N2 superficial velocity on the desorption efficiency and desorption rate are discussed. The desorption efficiency of μPBR is 36 ∼ 81 % based on the MDEA absorbent. The value of desorption rate in μPBR is from 0.38 to 3.37 mmol/min, which is bigger than microchannel reactor. Liquid phase mass transfer coefficient of μPBR is 0.06 ∼ 1.38 s−1 for CO2 desorption process, which is 1–3 orders higher than that of packed column. Then, an empirical correlation of mass transfer coefficient is developed in μPBR. μPBR has a high mass transfer rate with an advantage of fixed packing/catalyst compared with other CO2 desorption equipment.

Enhanced capture of uranyl in simulated seawater by supramolecular PSA@PAO hydrogel through carboxyl synergistic effect

Efficient capture of uranium from seawater is of great significance for promoting the sustainable development of nuclear energy and environmental protection. The preparation of highly efficient adsorbent materials plays a key role in this process. In this study, a composite gel PSA@PAO with ultra-high uranium adsorption capacity and excellent desorption efficiency was successfully designed through the supramolecular crosslinking and synergistic effect of glutaraldehyde, hydrazine oxime, sodium alginate, and polyvinyl alcohol. The gel achieved a uranium adsorption capacity of 348 mg·g−1 in a solution with an extremely low uranium concentration (8 ppm) and exhibited ultra-high adsorption selectivity for uranium oxyanions in simulated seawater containing various metal ions. XPS analysis showed that the acylhydrazone groups and carboxylic acid ligands in the PSA@PAO gel could form more stable synergistic uranium complexes. In the desorption solution, the recovery rate of uranium by the PSA@PAO gel reached 98 %, providing a certain strategy for designing efficient adsorbent materials with multi-functional group synergistic effect.

Selective adsorption of actinides and rare earth elements from leach liquor using metal oxide-polymer nanocomposites

Utilization of actinides and rare earth elements is only possible by separating these metals with high purity. The materials used in separation must have thermal, chemical, mechanical, and radiation resistance. In the present study, separation experiments of actinides and rare earth elements (REEs) were carried out using purified H2SO4 leach liquor. Polyacrylonitrile (PAN)-supported Ti, Zr, and Si oxide nanocomposites were tested for the selective separation of Th, U, Gd, Eu, Sm, Pr, Nd, La, Ce, and Y. The effects of pH, contact time, adsorbent/solution ratio, and temperature on distribution coefficient (KD) and adsorption capacity (Q) were investigated. The synthesized nanocomposites tend to separate the elements into two main groups: Th, U, Gd, Eu and Sm, Pr, Nd, La, Ce. Notably, it was observed that the separation of Th and U from the remaining elements is promising at 15 °C. Additionally, the separation can be further improved depending on the differences in desorption efficiency.

Cobalt adsorption by Ca(OH)2 Modified quartz rock particles adsorbent: Equilibrium isotherm, kinetics, and thermodynamic studies

The presence of cobalt ions Co(II) in wastewater poses major threats to both humans and the environment. The effectiveness of the adsorption of modified quartz rock particles (MQRP) adsorbent with calcium hydroxide solution Ca(OH)2 for eliminating Co(II) from a water solution was examined. MQRP had a maximum ability to adsorb 47.112 mg g−1 for Co(II) at pH 6.0 and a contact time of 2 h. The HCl stripping agent offered the highest desorption efficiency to regenerate the adsorbent for use again for a new cycle of adsorption. The equilibrium isotherms of the adsorption characteristics were experimentally identified, and the results of adsorption aligned with the principles of the Langmuir model. Under the examined temperature conditions, thermodynamic evaluation proved that Co(II) adsorption on adsorbent vacancies was spontaneous and exothermic.The outcomes of the kinetic process demonstrated that the process closely conformed to a pseudo-second-order pattern. Therefore, the high silica content of MQRP makes it an important adsorbent, and it could be applied as a cost-effective and efficient adsorbent to control the release of Co(II) ions in industrial wastewater.

Unveiling the fast adsorption and desorption of heavy metals on/off nanoplastics by real-time in-situ potentiometric sensing

Nanoplastics (<1 μm) can serve as a transport vector of environmental pollutants (e.g., heavy metals) and change their toxicities and bioavailabilities. Up to date the behaviors of adsorption and desorption heavy metals on/off nanoplastics are largely unknown. Herein, polymeric membrane potentiometric ion sensors are proposed for in-situ assessment of the real-time kinetics of heavy metal adsorption and desorption on/off nanoplastics. Results show that nanoplastics can adsorb and release heavy metals in a fast manner, indicating their superior ability in transferring heavy metals. The adsorption behaviors are closely related to the characteristics of nanoplastics and background electrolytes. Particle aggregation and increases in salinity and acidity suppress the adsorption of heavy metals on nanoplastics. The desorption efficiencies of different heavy metals are Pb2+ (31 %) < Cu2+ (40 %) < Cd2+ (97 %). Our proposed method is applicable for the detection of the plastic pollutants with size <100 nm and of the samples with high salinities (e.g., seawater). This work would provide new insights into the assessment of environmental risks posed by nanoplastics and heavy metals.

Optimization of desorption parameters using response surface methodology for enhanced recovery of arsenic from spent reclaimable activated carbon: Eco-friendly and sorbent sustainability approach

Desorption and adsorbent regeneration are imperative factors that are required to be taken into account when designing the adsorption system. From the environmental, economic, and practical points of view, regeneration is necessary for evaluating the efficiency and sustainability of synthesized adsorbents. However, no study has investigated the optimization of arsenic species desorption from spent adsorbents and their regeneration ability for reuse as well as safe disposal. This study aims to investigate the desorption ability of arsenic ions adsorbed on hybrid granular activated carbon and the optimization of the independent factors influencing the efficient recovery of arsenic species from the spent activated carbon using central composite design of the response surface methodology. The activated carbon before the sorption process and after the adsorption-desorption of arsenic ions have been characterized using SEM-EDX, FTIR, and TEM. The study found that all the investigated independent desorption variables greatly influence the retrievability of arsenic ions from the spent activated carbon. Using the desirability function for the optimization of the independent factors as a function of desorption efficiency, the optimum experimental conditions were solution pH of 2.00, eluent concentration of 0.10 M, and temperature of 26.63 ℃, which gave maximum arsenic ions recovery efficiency of 91 %. The validation of the quadratic model using laboratory confirmatory experiments gave an optimum arsenic ions desorption efficiency of 97 %. Therefore, the study reveals that the application of the central composite design of the response surface methodology led to the development of an accurate and valid quadratic model, which was utilized in the enhanced optimization of arsenic ions recovery from the spent reclaimable activated carbon. More so, the desorption isotherm and kinetic data of arsenic were well correlated with the Langmuir and the pseudo-second-order models, while the thermodynamics studies indicated that arsenic ions desorption process was feasible, endothermic, and spontaneous.

Janus structured photothermal conversion materials prepared from carbonized corn straw particles for portable air water extraction devices

The utilization of photothermal conversion materials to enhance the desorption performance of hygroscopic salt solutions through interfacial photothermal effects presents a promising approach for the continuous extraction of water from the atmosphere. To improve the desorption efficiency of hygroscopic salt solutions, the objective of this research is to employ agricultural and forestry residues, such as corn straw, in conjunction with polyurethane sponges, for the production of an innovative Janus structure carbonized biomass photothermal conversion material. Compared to single-layer structured photothermal conversion materials, the pure water evaporation rate increased from 2.42 kg m-2 h-1 to 3.20 kg m-2 h-1 when utilizing the Janus structured photothermal conversion material. Remarkably, this material demonstrates outstanding resistance to salt, allowing it to endure 8 h evaporation cycles with 30 wt% NaCl without salt crystallization. Therefore, it is well-suited for the continuous desorption of liquid hygroscopic agents. Moreover, the portable air–water extraction device, which incorporates Janus structural photothermal conversion material to enhance the performance of 30 % LiCl, has been shown to effectively extract water in practical settings. It achieves a water intake rate of 1.74 L m-2 d-1 at 50 % humidity. This approach is distinguished by its simplicity, cost-effectiveness, and efficient utilization of solar energy resources, providing a promising solution to mitigate the shortage of fresh water resources.