Low-calcium fly ash (LC-F) and high-calcium fly ash (HC-F) were used to synthesize corresponding zeolites (LC-Z and HC-Z), then for adsorption of Se(IV) in water. The results showed that c zeolites can effectively adsorb Se(IV). The optimal adsorption conditions were set at contact time = 360 min; pH = 2.0; the amount of adsorbent = 5.0 g·L−1; temperature = 25 °C; initial Se(IV) concentration = 10 mg·L−1. The removal efficiency of HC-Z was higher than the LC-Z after it had fully reacted because the specific surface area (SSA) of HC-Z was higher than LC-Z. The adsorption kinetics model of Se(IV) uptake by HC-Z followed the pseudo-second-order model. The Freundlich isotherm model agreed better with the equilibrium data for HC-Z and LC-Z. The maximum Se(IV) adsorption capacity was 4.16 mg/g for the HC-Z and 3.93 mg/g for the LC-Z. For the coexisting anions, barely affected Se(IV) removal, while significant affected it. Regenerated zeolites still had high capacity for Se(IV) removal. In conclusion, zeolites synthesized from fly ashes are a promising material for adsorbing Se(IV) from wastewater, and selenium-loaded zeolite has the potential to be used as a Se fertilizer to release selenium in Se-deficient areas.

Modified natural zeolites (MNZ) are widely used in pollutant removal, but how to address these MNZ that have adsorbed pollutants must be considered. Selenium is an essential trace element for metabolism and is also a water pollutant. Selenium is adsorbed in the water by MNZ in this study first. Then the Brassica chinensis L. was planted in the soil which contains the MNZ loaded with selenium (MNZ-Se) to explore selenium uptake. MNZ-Se release tests in water and soil were also considered. The results showed the following: (1) The maximum adsorption capacity of MNZ for selenium is 46.90 mg/g. (2) Water release experiments of MNZ-Se showed that regardless of how the pH of the aqueous solution changes, the trend of the release of selenium from MNZ-Se in aqueous solution is not affected and first decreases before stabilizing. (3) Soil release experiments of MNZ-Se showed that the selenium content in the soil increased and reached the concentration in the standard of selenium-rich soil. Addition amount and soil pH value will affect the release ratio. The release ratio of MNZ-Se in the water was higher than that in the soil. (4) With an increase in the soil MNZ-Se content, the selenium content in the soil and B. c increases. Above all, MZN can be a good medium for water pollutant removal and soil improvement.

Diagram showing a systematic approach to preparing zeolites using the hydrothermal approach with the coal mine water and tap water as dissolution solvents.

This study aims to make adsorption-capable zeolite from coal fly ash, a waste product from coal-fired power plants (CFA). When it comes to commercializing sorbent, the total cost and efficiency of the adsorbent material are critical. This work used tap water instead of distilled water (DW) to synthesis zeolite from fly ashes at 90°C crystallization temperatures. The discovery lays the door for a cost-effective but easy technique of synthesizing viable zeolitic materials for adsorption applications using waste products like coal fly ash. According to the comprehensive characterization, the support for the use of TP to make zeolites is based on its larger particle size, and lower carbon impurities. The generated zeolite was homogenous and A-type, and applied as an adsorbent to remove traces of heavy metals contaminants. During a 25-minute agitation period, the zeolites produced with TP had a greater adsorption capacity. In principle, the proposed approach permits the synthesis of low-cost, high-efficiency zeolite-based adsorbent materials for environmental remediation without the use of harmful or expensive chemicals.

The direct electrochemical detection of cancer biomarkers using single single‐component platforms is challenging. Herein, we propose constructing an efficient screen‐printed electrode (SPE) based platform for selective detection of CD44 proteins, a non‐kinase transmembrane glycoprotein. A sensing platform, MB‐MX/HA/SPE, was developed by incorporating few‐layered Ti3C2Tx nanosheets pre‐loaded with methylene blue (MB) dye. The nanosheets were subsequently immobilized with hyaluronic acid (HA), which served as a ligand for the specific recognition of CD44. The simple electrode configuration and the highly conductive Ti3C2Tx facilitated the electrochemical oxidation of MB, generating a reference SWV signal that declined proportionally with the increasing concentration of CD44 owing to ligand (HA)‐protein interaction. The sensor could register a sensitive inhibition response in the concentration range of 0.1 to 7.25 ng.mL−1 with a detection limit of 1.2×10−2 ng.mL−1 for CD44 proteins. Moreover, the synergistic combination of the highly conductive/adsorptive Ti3C2Tx nanosheets and hyaluronic acid (HA) led to strong antifouling characteristics even in the presence of other common proteins, such as bovine serum albumin (BSA), haemoglobin (Ig), immunoglobulin G (IgG), prostate‐specific antigen (PSA), and neuron‐specific enolase (NSE). The proposed strategy eliminates the need for additional components in the electrode modification procedure. In addition, incorporating MXenes as electrode material paves the way for developing sensitive biosensors with prospective applications in cancer diagnosis.