Adsorption removal of mercury from flue gas by metal selenide: A review.

Mercury (Hg) pollution has been a global concern in recent decades, posing a significant threat to entire ecosystems and human health due to its cumulative toxicity, persistence, and transport in the atmosphere. The intense interaction between mercury and selenium has opened up a new field for studying mercury removal from industrial flue gas pollutants. Besides the advantages of good Hg° capture performance and low secondary pollution of the mineral selenium compounds, the most noteworthy is the relatively low regeneration temperature, allowing adsorbent regeneration with low energy consumption, thus reducing the utilization cost and enabling recovery of mercury resources. This paper reviews the recent progress of mineral selenium compounds in flue gas mercury removal, introduces in detail the different types of mineral selenium compounds studied in the field of mercury removal, reviews the adsorption performance of various mineral selenium compounds adsorbents on mercury and the influence of flue gas components, such as reaction temperature, air velocity, and other factors, and summarizes the adsorption mechanism of different fugitive forms of selenium species. Based on the current research progress, future studies should focus on the economic performance and the performance of different carriers and sizes of adsorbents for the removal of Hg0 and the correlation between the gas-particle flow characteristics and gas phase mass transfer with the performance of Hg0 removal in practical industrial applications. In addition, it remains a challenge to distinguish the oxidation and adsorption of Hg0 quantitatively.

Recent Focuses in the Syntheses and Applications of Magnetic Metal-Organic Frameworks.

In this article, we examine the recent uses of magnetic metal-organic frameworks (MMOFs). MMOFs can be used in various fields such as water purification, laboratory, food, environment, etc. Their materials can be composed of different metals and ligands, each of which has its own properties. Also, the presence of a magnetic property in these absorbents adds good features such as easy separation, faster absorption, and better interaction with other particles, which improves their application and performance. In recent years, various types of these compounds have been made, and, in this article, while classifying them, we will discuss the structure and application of some MMOFs.

Behaviour and mechanics of phenolic sorption by novel bio-based graphene derivatives as adsorbents.

Phenolic compounds, notorious for their environmental and health hazards, demand efficient removal from wastewater. Our research leads in synthesizing bio-based graphene derivatives from biomass-derived lignin, such as graphene oxide (bGO) and reduced graphene oxide (brGO), and these materials show promise in effectively removing hydrophobic pollutants like phenol and tannic acid. Hence, this study investigated the mechanical and dynamical aspects of their sorptions by bGO and brGO. Both adsorbents demonstrated a comparable adsorption pattern, with enhanced efficiency observed at higher adsorbent dosage, prolonged contact time, neutralized pH solutions, and elevated temperatures. Of note, phenol is removed at a much greater rate (>94%) than tannic acid (>84%) by both adsorbents at a dosage of 180 mg L-1, pH 6.5, 900 min, and 25 °C. The Freundlich model provided the best fit for the isotherm data of both phenol (R2 = 0.99) and tannic acid (R2 = 0.98), while the pseudo-second-order model effectively described the adsorption kinetics of phenol (R2 = 0.99) and tannic acid (R2 = 0.99). The determined activation energy exceeds 5.88 kJ mol-1, affirming the prevalence of physisorption as the dominant mechanism in the adsorption process. Thermodynamic analysis confirmed that the adsorption process is endothermic (ΔH) and occurs spontaneously (ΔG), indicating a random (ΔS) nature. However, the percentage removal plunged considerably after five consecutive adsorption-desorption cycles, attributed to the alterations of active sites on bGO and brGO.

Activated carbon co-modified by chitosan and SDS for targeted removal of aflatoxins from fragrant peanut oil.

The pore size structure and surface structure of activated carbon (AC) may be ameliorated using the hydrophobic groups and negative surface charge of sodium dodecyl sulfate (SDS), along with the abundant hydroxyl and amine groups of chitosan (CS). In this study, a composite adsorbent (CS/SDS/AC) created through co-modification of AC with CS and SDS was employed to remove aflatoxins from fragrant peanut oil. CS/SDS/AC exhibited a superior adsorption capacity (89.9 %) for adsorbing aflatoxins. More significantly, CS/SDS/AC improved the retention of sterols (64-99.3 %), tocopherols (61.4-82.7 %), and volatile flavor compounds (68.4-82.3 %) in the treated oil. CS/SDS/AC composite adsorbent emerged as a promising candidate characterized by high detoxification efficiency and low preparation costs but also helped retain nutrients and flavors in the fragrant oil. This development could present a novel strategy for oil industry to address aflatoxins.

Competitive adsorption behavior and adsorption mechanism of limestone and activated carbon in polymetallic acid mine water treatment.

Acid mine water (AMD) can cause significant environmental hazards due to its high concentration of metal ions, so the development of effective treatment methods is essential to mitigate its impact. In this study, adsorption experiments were conducted using limestone (LS) and activated carbon (AC) to explore the adsorption efficiency for different concentrations of metal ions. Adsorption was evaluated by static and competitive batch tests. The adsorbent mechanism was investigated using analytical techniques such as SEM, FTIR and XRD. The efficacy of LS and AC for competitive adsorption of Fe, Mn, Zn and Cu ions from AMD was evaluated. The study analyzed the effect of environmental conditions such as initial concentration and ionic strength on the adsorption efficiency. The results showed that LS showed high adsorption capacity for Fe and Cu, but was less effective in competitive adsorption of Mn. AC showed superior adsorption performance for Fe and Cu under competitive conditions due to its high surface area and functional groups. Both adsorbents showed selective efficacy influenced by the physicochemical properties of metal ions. This study helps to guide the optimization of adsorbents in AMD treatment and highlights the importance of selecting suitable materials based on specific metal ion properties.

Recycling of Sewage Sludge: Synthesis and Application of Sludge-Based Activated Carbon in the Efficient Removal of Cadmium (II) and Lead (II) from Wastewater.

The limited supply of drinking water has aroused people's curiosity in recent decades. Adsorption is a popular method for removing hazardous substances from wastewater, especially heavy metals, as it is cheap, highly efficient, and easy to use. In this work, a new sludge-based activated carbon adsorbent (thickened samples SBAC1 and un-thickened samples SBAC2) was developed to remove hazardous metals such as cadmium (Cd+2) and lead (Pb+2) from an aqueous solution. The chemical structure and surface morphology of the produced SBAC1 and SBAC2 were investigated using a range of analytical tools such as CHNS, BET, FT-IR, XRD, XRF, SEM, TEM, N2 adsorption/desorption isothermal, and zeta potential. BET surface areas were examined and SBAC2 was found to have a larger BET surface area (498.386 m2/g) than SBAC1 (336.339 m2/g). While the average pore size was 10-100 nm for SBAC1 and 45-50 nm for SBAC2. SBAC1 and SBAC2 eliminated approximately 99.99% of Cd+2 and Pb+2 out the water under all conditions tested. The results of the adsorption of Cd+2 and Pb+2 were in good agreement with the pseudo-second-order equation (R2 = 1.00). Under the experimental conditions, the Cd+2 and Pb+2 adsorption equilibrium data were effectively linked to the Langmuir and Freundlich equations for SBAC1 and SBAC2, respectively. The regeneration showed a high recyclability for the fabricated SBAC1 and SBAC2 during five consecutive reuse cycles. As a result, the produced SBAC1 and SBAC2 are attractive adsorbents for the elimination of heavy metals from various environmental and industrial wastewater samples.

Innovative Adsorbents for Pollutant Removal: Exploring the Latest Research and Applications.

The growing presence of diverse pollutants, including heavy metals, organic compounds, pharmaceuticals, and emerging contaminants, poses significant environmental and health risks. Traditional methods for pollutant removal often face limitations in efficiency, selectivity, and sustainability. This review provides a comprehensive analysis of recent advancements in innovative adsorbents designed to address these challenges. It explores a wide array of non-conventional adsorbent materials, such as nanocellulose, metal-organic frameworks (MOFs), graphene-based composites, and biochar, emphasizing their sources, structural characteristics, and unique adsorption mechanisms. The review discusses adsorption processes, including the basic principles, kinetics, isotherms, and the factors influencing adsorption efficiency. It highlights the superior performance of these materials in removing specific pollutants across various environmental settings. The practical applications of these adsorbents are further explored through case studies in industrial settings, pilot studies, and field trials, showcasing their real-world effectiveness. Additionally, the review critically examines the economic considerations, technical challenges, and environmental impacts associated with these adsorbents, offering a balanced perspective on their viability and sustainability. The conclusion emphasizes future research directions, focusing on the development of scalable production methods, enhanced material stability, and sustainable regeneration techniques. This comprehensive assessment underscores the transformative potential of innovative adsorbents in pollutant remediation and their critical role in advancing environmental protection.

Biochar and biosorbents derived from biomass for arsenic remediation.

Global groundwater contamination by Arsenic (As) presents a grave danger to the health of living beings and wildlife, demanding comprehensive remediation strategies. This review delves into the complex landscape of arsenic remediation, encompassing its chemical forms, occurrences, sources, and associated health risks. Advanced techniques, notably biomass-derived adsorbents, emerge as promising and cost-effective solutions. The exploration spans preparing and modifying biomass-derived adsorbents, unraveling their adsorption capacity, influencing factors, isotherms, kinetics, and thermodynamics. Noteworthy attention is given to plant-agricultural waste, algal-fungal-bacterial, and iron-modified biomass-derived adsorbents. The comprehensive discussion of the adsorption mechanism highlights the efficacy of low-cost biomass, particularly from plant, animal, and agricultural residues, offering a sustainable remedy for arsenic removal. This insightful review contributes to the understanding of evolving technologies essential for addressing arsenic contamination in wastewater, emphasizing the potential of renewable biomaterials in advancing efficient remediation practices.

Scalable mesoporous biochars from bagasse waste for Cu (II) removal: Process optimisation, kinetics and techno-economic analysis.

As the world faces the brink of climatological disaster, it is crucial to utilize all available resources to facilitate environmental remediation, especially by accommodating waste streams. Lignocellulosic waste residues can be transformed into mesoporous biochar structures with substantial pore capacity. While biochars are considered a method of carbon dioxide removal (CDR), they are in fact an environmental double-edged sword that can be used to extract metal ions from water bodies. Biochars possess high chemical affinities through chemisorption pathways that are tuneable to specific pH conditions. This work demonstrates how biochars can be enhanced to maximise their surface area and porosity for the removal of Cu (II) in solution. It was found that bagasse derived mesoporous biochars operate preferentially at high pH (basic conditions), with the 1.18 mKOH/mSCB material reaching 97.85% Cu (II) removal in 5 min. This result is in stark contrast with the majority of biochar adsorbents that are only effective at low pH (acidic conditions). As a result, the biochars produced in this work can be directly applied to ancestral landfill sites and carbonate-rich mine waters which are highly basic by nature, preventing further metal infiltration and reverse sullied water supplies. Furthermore, to assess the value in the use of biochars produced and applied in this way, a techno-economic assessment was carried out to determine the true cost of biochar synthesis, with possible routes for revenue post-Cu being removed from the biochar.

Sustainable application of modified Luffa cylindrica biomass for removal of trimethoprim in water by adsorption with process optimization.

The present study describes a set of methodological procedures (seldom applied together), including (i) development of an alternative adsorbent derived from abundant low-cost plant biomass; (ii) use of simple low-cost biomass modification techniques based on physical processing and chemical activation; (iii) design of experiments (DoE) applied to optimize the removal of a pharmaceutical contaminant from water; (iv) at environmentally relevant concentrations, (v) that due to initial low concentrations required determination by ultra-performance liquid phase chromatography coupled to mass spectrometry (UPLC-MS/MS). A central composite rotational design (CCRD) was employed to investigate the performance of vegetable sponge biomass (Luffa cylindrica), physically processed (crushing and sieving) and chemically activated with phosphoric acid, in the adsorption of the antibiotic trimethoprim (TMP) from water. The optimized model identified pH as the most significant variable, with maximum drug removal (91.1 ± 5.7%) achieved at pH 7.5, a temperature of 22.5 °C, and an adsorbent/adsorbate ratio of 18.6 mg µg-1. The adsorption mechanisms and surface properties of the adsorbent were examined through characterization techniques such as scanning electron microscopy (SEM), point of zero charge (pHpzc) measurement, thermogravimetric analysis (TGA), specific surface area, and Fourier-transform infrared spectroscopy (FTIR). The best kinetic fit was obtained by the Avrami fractional-order model. The hypothesis of a hybrid behavior of the adsorbent was suggested by the equilibrium results presented by the Langmuir and Freundlich models and reinforced by the Redlich-Peterson model, which achieved the best fit (R2 = 0.982). The thermodynamic study indicated an exothermic, spontaneous, and favorable process. The maximum adsorption capacity of the material was 2.32 × 102 µg g-1 at an equilibrium time of 120 min. Finally, a sustainable and promising adsorbent for the polishing of aqueous matrices contaminated by contaminants of emerging concern (CECs) at environmentally relevant concentrations is available for future investigations.

Designed synthesis of demethylated-hydroxymethylated lignin-based adsorbent for removal of Cr(VI) ions from wastewater.

Lignin-based adsorbents for the removal of Cr(VI) ions have attracted intensive attention due to the advantages of renewability, biodegradablity, low cost and environmental friendliness. However, there are still a lot of challenges such as poor adsorption capacity, low lignin content in adsorbents, and harsh preparation conditions. Here, a tandem hydroxymethylation-demethylation method is proposed for preparing an excellent lignin-based Cr(VI) adsorbent (DHKL), which features with high lignin content (>85 wt%) and high hydroxyl content (up to 6.26 mmol/g) under milder conditions. The prepared DHKL exhibits an adsorption capacity reaching up to 1040.9 mg/g and can maintain this capacity even in the presence of other metal ions in the solution. Model analyses indicate that chemisorption occurring in a monolayer is the main process, which is spontaneous and endothermic. Structural changes of DHKL before and after adsorption indicated that Cr(VI) ions are mainly reduced to Cr(III) ions by hydroxyl groups with some of the absorbed Cr ions dispersed into the inner part of DHKL. Based on these results, the detailed possible adsorption mechanism is deduced, providing guidance for designing, producing and utilizing lignin-based adsorbents.

Using ligand regulation, metal replacement, and ligand doping strategies on Zr-FUM to improve methane separation from coalbed gas.

Developing adsorbents suitable for industrial applications that can effectively enhance the separation of methane (CH4) from nitrogen (N2) in coalbed gas is crucial to improve energy recovery and mitigate greenhouse gas emissions. In this study, three modification strategies were implemented on Zr-FUM, including ligand regulation, metal replacement, and ligand doping, to synthesize Zr-FDCA, Al-FUM, and Zr-FUM-FA, with the aim of improving the performance of CH4/N2 separation under humid conditions. The results demonstrated that the promotion of robust orbital overlap and strengthened electrovalent bonding on adsorbents can selectively enhance CH4 adsorption. As a result, Zr-FUM-FA achieved a saturated CH4 adsorption capacity of 1.37 mmol/g, a CH4 working window of 307 s, and a CH4/N2 sorbent selection parameter (Ssp) of 47.31, exceeding the performance of most reported adsorbents. Analyses of the pore structure, surface morphology, and functional groups revealed that the presence of an ultramicropore proximity to CH4, reduced static resistance, and enhanced electrovalent bond were key factors for CH4 separation. Grand Canonical Monte Carlo and Density Functional Theory studies indicated that the introduction of -C-H- in FA played a crucial role in enhancing CH4 adsorption. Optimization of adsorption parameters using the Aspen adsorption package showed that in a dual-adsorbent bed system, the recovery and purity of CH4 in Zr-FUM-FA reach 99.5% and 97.3%, respectively, providing important theoretical support for the improvement of CH4 recovery in the pressure swing adsorption process from coalbed gas.

Hierarchically Porous Structured Adsorbents with Ultrahigh Metal-Organic Framework Loading for CO2 Capture.

Metal-organic frameworks (MOFs) have emerged as promising candidates for CO2 adsorption due to their ultrahigh-specific surface area and highly tunable pore-surface properties. However, their large-scale application is hindered by processing issues associated with their microcrystalline powder nature, such as dustiness, pressure drop, and poor mass transfer within packed beds. To address these challenges, shaping/structuring micron-sized polycrystalline MOF powders into millimeter-sized structured forms while preserving porosity and functionality represents an effective yet challenging approach. In this study, a facile and versatile strategy was employed to integrate moisture-stable and scalable microcrystalline MOFs (UiO-66 and ZIF-8) into a poly(acrylonitrile) matrix to fabricate readily processable, millimeter-sized hierarchically porous structured adsorbents with ultrahigh MOF loadings (∼90 wt %) for direct industrial carbon capture applications. These structured composite beads retained the physicochemical properties and separation performance of the pristine MOF crystal particles. Structured UiO-66 and ZIF-8 exhibited high specific surface areas of 1130 m2 g-1 and 1431 m2 g-1, respectively. The structured UiO-66 achieved a CO2 adsorption capacity of 2.0 mmol g-1 at 1 bar and a dynamic CO2/N2 selectivity of 17 for a CO2/N2 gas mixture with a 15/85 volume ratio at 25 °C. Furthermore, the structured adsorbents exhibited excellent cyclability in static and dynamic CO2 adsorption studies, making them promising candidates for practical application.

Deep Cleaning of Crystal Violet and Methylene Blue Dyes from Aqueous Solution by Dextran-Based Cryogel Adsorbents.

Polysaccharides have recently attracted growing attention as adsorbents for various pollutants, since they can be extracted from a variety of renewable sources at low cost. An interesting hydrophilic and biodegradable polysaccharide is dextran (Dx), which is well-known for its applications in the food industry and in medicine. To extend the application range of this biopolymer, in this study, we investigated the removal of crystal violet (CV) and methylene blue (MB) dyes from an aqueous solution by Dx-based cryogels using the batch technique. The cryogel adsorbents, consisting of cross-linked Dx embedding a polyphenolic (PF) extract of spruce bark, were prepared by the freeze-thawing approach. It was shown that the incorporation of PF into the Dx-based matrix induced a decrease in porosity, pore sizes and swelling ratio values. Moreover, the average pore sizes of the DxPF cryogels loaded with dyes further decreased from 42.30 ± 7.96 µm to 23.68 ± 2.69 µm, indicating a strong interaction between the functional groups of the cryogel matrix and those of the dye molecules. The sorption performances of the DxPF adsorbents were evaluated in comparison to those of the Dx cryogels and of the PF extract. The experimental sorption capacities of the DxPF cryogel adsorbents were higher in comparison to those of the Dx cryogels and the PF extract. The DxPF cryogels, particularly those with the highest PF contents (sample DxPF2), demonstrated sorption capacities of 1.2779 ± 0.0703 mmol·g-1, for CV, and 0.3238 ± 0.0121 mmol·g-1, for MB. The sorption mechanisms were analyzed using mathematical models, including Langmuir, Freundlich, Sips and Dubinin-Radushkevich isotherms, and kinetic models, like pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich and intra-particle diffusion (IPD). The sorption process was best described by the Sips isotherm and PSO kinetic models, indicating chemisorption as the dominant mechanism. This study outlines the importance of developing advanced renewable materials for environmental applications.

Insights into the environmental benefits of using apple pomace for biosorption of lead from contaminated water.

The apple processing industry generates large quantities of organic waste, presenting a major source of organic contamination. Consequently, finding an effective solution for valorizing this waste has become a pressing issue. This study aims to address two key concerns: (i) solving an agricultural problem by efficiently using agri-food residue, and (ii) removing lead, an extremely toxic element, from contaminated waters to mitigate environmental pollution. Two biosorbents were tested: raw apple waste (RA), obtained from a mixture of apple varieties, and the same material after extracting valuable bioactive and reusable components, extracted apple (EA). The study evaluated the influence of pH, initial biosorbent mass, adsorption kinetics, and equilibrium isotherms. The results are very promising, showing a lead removal efficiency of 82 % for RA and 100 % for EA at a low initial concentration of the solution of 20 mg Pb2⁺/L and an optimal pH of 5 ± 0.5. The Langmuir model predicted a maximum adsorption capacity of 44.6 mg/g for RA and 48.6 mg/g for EA. These findings demonstrate that apple waste, even after selective extraction of valuable bioactive components, can be effectively used for environmental remediation on a practical scale.

Synthesis of Highly Porous Lignin-Sulfonate Sulfur-Doped Carbon for Efficient Adsorption of Sodium Diclofenac and Synthetic Effluents.

Herein, a novel sulfur-doped carbon material has been synthesized via a facile and sustainable single-step pyrolysis method using lignin-sulfonate (LS), a by-product of the sulfite pulping process, as a novel carbon precursor and zinc chloride as a chemical activator. The sulfur doping process had a remarkable impact on the LS-sulfur carbon structure. Moreover, it was found that sulfur doping also had an important impact on sodium diclofenac removal from aqueous solutions due to the introduction of S-functionalities on the carbon material's surface. The doping process effectively increased the carbon specific surface area (SSA), i.e., 1758 m2 g-1 for the sulfur-doped and 753 m2 g-1 for the non-doped carbon. The sulfur-doped carbon exhibited more sulfur states/functionalities than the non-doped, highlighting the successful chemical modification of the material. As a result, the adsorptive performance of the sulfur-doped carbon was remarkably improved. Diclofenac adsorption experiments indicated that the kinetics was better described by the Avrami fractional order model, while the equilibrium studies indicated that the Liu model gave the best fit. The kinetics was much faster for the sulfur-doped carbon, and the maximum adsorption capacity was 301.6 mg g-1 for non-doped and 473.8 mg g-1 for the sulfur-doped carbon. The overall adsorption seems to be a contribution of multiple mechanisms, such as pore filling and electrostatic interaction. When tested to treat lab-made effluents, the samples presented excellent performance.

Adsorption of ionic contaminants from complex water matrices by versatile chitosan-based beads.

Most adsorbents are currently restricted by their single function in pollutant removal from complex wastewater. Herein, we constructed a versatile chitosan-based adsorbent (MC-DA) by grafting amphoteric copolymers with high pH-responsiveness property, aiming at the removal of multiple ionic contaminants. Specifically, the surface charge and hydrophobicity/hydrophilicity of MC-DA can be finely tuned under different pH conditions. As a result, the effective adsorption of cationic methylene blue (MB) and anionic Acid Orange 7 (AO7) with capacities of 627.4 mg/g and 1146.8 mg/g were achieved respectively, superior to most reported materials. Regarding the characterization results, the adsorption mechanisms for MB adsorption were electrostatic and hydrophobic interactions, while the electrostatic attraction was the main driving force for AO7 adsorption. Apart from the versatile adsorption performance, high acid resistance (pH ≥ 2.0), good reusability and rapid separation property under an external magnetic field suggested MC-DA's promising environmental benefits and practical application potential in water remediation.

Fabrication of electrospun ion exchanger adsorbents with morphologies designed for the separation of proteins and plasmid DNA.

Electrospun cellulose adsorbents are an emergent class of materials applied to a variety of bioprocess separations as an analogue to conventional packed bed chromatography. Electrospun adsorbents have proven to be effective as rapid cycling media, enabling high throughput separation of proteins and viral vectors without compromising selectivity and recovery. However, there is a current lack of knowledge in relation to the manipulation and control of electrospun adsorbent structure with function and performance to cater to the separation needs of emerging, diverse biological products. In this study, a series of electrospun cellulose adsorbents were fabricated by adjusting their manufacturing conditions. A range of fiber diameters (400 to 600 nm) was created by changing the electrospinning polymer solution. Additionally, a range of porosities (0.4 to 0.7 v/v) was achieved by varying the laminating pressures on the electrospun sheets. The adsorbents were functionalized with different degrees of quaternary amine ligand density to create 18 prototype anion exchangers. Their morphology was characterized by BET nitrogen adsorption surface area, X-ray computed tomography, capillary flow porometry and scanning electron microscopy measurements. The physical characteristics of the adsorbents were used in an adapted semi-empirical model and compared to measured permeability data. Permeabilities of prototypes ranged from 10-2 to 10-4 mDarcy. The measured data showed good adherence to modelled data with possible improvements in acquiring wet adsorbent characteristics instead of dried material. Finally, the electrospun adsorbents were characterized for their binding capacity of model proteins of different sizes (diameters of 3.5 nm and 8.9 nm) and plasmid DNA. Static binding capacities ranged from 5 mg/ml to 25 mg/ml for the proteins and plasmid DNA and showed <20 % deviation from monolayer coverage based on BET surface area. Therefore, it was concluded that the electrospun adsorbents most likely adsorb monolayers of proteins and plasmid DNA on the surface with minimal steric hindrance.

Enhancing the Humidity Stability of Perovskite Films through Interfacial Modification with Differentiated Hydrophilic Organics.

Preparing high-quality perovskite films is a decisive step toward realizing highly efficient and stable perovskite solar cells (Pero-SCs). Water is a key factor affecting the stability of the Pero-SCs. Here, the widely used water adsorbents chitosan, sorbitol, and sodium hyaluronate (NaHA) were used as hydrophilic layers on the upper interface of the perovskite to form a barrier against water. The water adsorbents also passivated defects on the surface of the perovskite active layer due to their -OH and -COOH functional groups. The NaHA-modified devices showed the best power conversion efficiency (PCE) (PCE = 21.74%). Although the NaHA-modified Pero-SCs showed optimal photovoltaic performance, the stability of the modified devices decreased due to the strong water adsorption ability of NaHA, while with moderate water adsorption ability sorbitol-modified devices exhibited good stability and PCE. The devices were tested in the dark and room temperature at different humidity levels for 800 h. At low humidity (25% ± 5% RH), the PCEs of the sorbitol- and NaHA-modified devices were maintained at 80% and 71% of the initial values, respectively. At high humidity (75% ± 5% RH), the PCE was maintained at 64% and 23% of the initial values, respectively. This work provides an avenue to select adsorbents with suitable water absorption ability as the interface modification layer, thus reducing the water erosion of perovskite films and obtaining highly stable inverted Pero-SCs.

Adsorption of ciprofloxacin from aqueous solutions using cellulose-based adsorbents prepared by sol-gel method.

Ciprofloxacin (CIP) is one of the most widely used antibiotics to treat bacterial infections. Consequently, there is concern that it may contaminate water resources due to its high usage level. It is therefore necessary to monitor, trace, and reduce exposure to these antibiotic residues. In the current study, the extraction of CIP from water was performed using a green adsorbent material based on cellulose/polyvinyl alcohol (PVA) decorated with mixed metal oxides (MMO). This cellulose/MMO/PVA adsorbent was synthesized using a simple sol-gel method. The prepared adsorbent materials were then characterized using a range of methods, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, gas adsorption analysis, X-ray diffraction, and Fourier Transform infrared. The impact of pH, adsorbent dose, contact time, and CIP concentration on ciprofloxacin extraction were examined. The equilibrium and kinetic adsorption data were well described using the Freundlich model (R2 = 0.965). The optimum conditions for CIP adsorption were: pH = 4.5; adsorbent dosage = 0.55 g·L-1; contact time = 83 min; and initial CIP concentration = 2 mg·L-1. The adsorption capacity of the cellulose/MMO/PVA adsorbent for CIP removal was ∼19 mg·g-1 (CIP removal = 86.48 %). This study shows that cellulose/MMO/PVA adsorbents have potential for removing contaminants from aqueous environments.