Adsorption of U(VI) on montmorillonite pillared with hydroxy-aluminum

Batch and Column Adsorption of Phosphorus by Modified Montmorillonite

Phosphorus pollutants are a crucial component of water eutrophication. In this study, montmorillonite modified by Keggin Al13 and hexadecyltrimethyl ammonium (Al13-O-MMt) was used as an adsorbent to remove phosphorus from solutions and thus simulate the practice of a field trial, such as in wastewater. The ammonium molybdate spectrophotometric method was used to determine the concentrations of phosphorus in samples. In the batch experiment, phosphorus was adsorbed by original montmorillonite (MMt) and Al13-O-MMt at various pH values (6–9) to identify the effect of pH during the adsorption process. The batch adsorption results demonstrate that Al13-O-MMt can adsorb up to 93% of phosphorus at pH = 8. Six graduated amounts (0.01–0.25 g) of montmorillonite were tested at three different temperatures to determine the most suitable temperature and the minimum dosage of Al13-O-MMt needed for the adsorption of 200 mg/L phosphorus in a 30 mL solution, which was 0.1 g at 25 °C. Therefore, the adsorption capacity of Al13-O-MMt was found to be 60 mg/g. Subsequently, a column experiment was conducted. The results showed that the optimized dosage of Al13-O-MMt was 6.667 g for phosphorus adsorption with a concentration of 200 mg/L in 2000 mL solution, and the breakthrough time was 4794.67 min.

NanoTafla Nanocomposite as a Novel Low-Cost and Eco-Friendly Sorbent for Strontium and Europium Ions

Now the wide use of nanooxides is attributed to their remarkable collection of properties. Nanocomposites have an impressive variety of important applications. A thermal decomposition approach provides a more optimistic method for nanocrystal synthesis due to the low cost, high efficiency, and expectations for large-scale production. Therefore, in this study a new eco-friendly nanooxide composite with sorption characteristics for europium (Eu(III)) and strontium (Sr(II)) was synthesized by a one-step thermal treatment process using earth-abundant tafla clay as a starting material to prepare a modified tafla (M-Taf) nanocomposite. The synthesized nancomposite was characterized by different techniques before and after sorption processes. Different factors that affected the sorption behavior of Eu(III) and Sr(II) in aqueous media by the M-Taf nanocomposite were studied. The results obtained illustrated that the kinetics of sorption of Eu(III) and Sr(II) by the M-Taf nanocomposite are obeyed according to the pseudo-second order and controlled by a Langmuir isotherm model with maximum sorption capacities (Q _max) of 25.5 and 23.36 mg/g for Eu(III) and Sr(II), respectively. Also, this novel low-cost and eco-friendly sorbent has promising properties and can be used to separate and retain some radionuclides in different applications.

Adsorption of deoxynivalenol by pillared montmorillonite

Deoxynivalenol (DON) is found widely in foods and feeds that are contaminated with mildew and is one of the most harmful mycotoxins, threating not only human health but also impacting animal husbandry. Various physical, chemical and biological detoxification strategies have been applied in the past to reduce mycotoxin contamination. As a practical and economic method, addition of montmorillonite (Mt) offers the potential to eliminate mycotoxins, especially aflatoxin B1 (AFB₁) and zearalenone (ZEA). Our study aimed to control DON, for the first time, using environmentally friendly Mt, modified with aluminum, iron and titanium via a pillaring effect to enlarge interlayer spacing. The materials were characterized using XRD, FTIR, SEM, EDS and BET. Spacing of the pillared Mt layers was shown to exceed that of raw Mt and could be tuned using the pillaring reagents (Al, Fe and Ti, 0.01 to 2.00 eq. relative to the cation exchange capacity of Mt). Adsorption of DON by pillared Mt was investigated using UPLC-MSMS (at pH 2.0 and 6.8). The results demonstrated that the adsorption ratios of 1.00-Al-Mt, 0.50-Fe-Mt and 1.00-Ti-Mt were 23.6%, 14.7% and 23.4%, respectively at pH 2.0 and 27.1%, 21.8%, and 27.4% correspondingly at pH 6.8 when added at 1.0 mg, which is 3-4 times higher than raw Mt (6.3-6.8% at pH 2.0 and 7.3-8.1% at pH 6.8). It was also found that with increased addition of pillared Mt (2.5 mg), the adsorption ratio approached 35%. The time for reaching equilibrium was approximately 120 min. These results demonstrated that Mt after pillaring modifications with Al, Fe and Ti can have potential for the control of DON in foods and feeds.

Improvement of the sorption behavior of aluminum silicate composite toward 134Cs and 60Co radionuclides by non-living biomass of Chlorella vulgaris

Cesium and cobalt radioactive isotopes (¹³⁴Cs and ⁶⁰Co) are dangerous to human health due to their long half-life about 2.1 and 5.3 year, respectively. Developing a new composite used as an efficient sorbent for these is an urgent requirement for radioactive waste management. Herein, preparation of different materials such as aluminum silicate (AS), cultured of Chlorella vulgaris (NCV) alga, and aluminum silicate/Chlorella vulgaris (AS/NCV) composite 3:1 were prepared by wet chemical technique and used to remove the ¹³⁴Cs and ⁶⁰Co radionuclides. Different analytical techniques were used to characterize the prepared sorbents as SEM, TEM, XRD, BET, TGA/DTA, FTIR particle size analyzer, and pore size distribution. The factors affecting the sorption process as pH, temperature, contact time, and weight of adsorbent were studied. The sorption process was found to follow a pseudo-second-order mechanism. The monolayer capacity for ¹³⁴Cs radionuclide onto the aluminum silicate, non-living Chlorella vulgaris biomass, and aluminum silicate/Chlorella vulgaris composites are 66.67, 83.54, and 90.11 mg/g, respectively, and for ⁶⁰Co radionuclide are 59.31, 91.99, and 99.24 mg/g, respectively. The values of thermodynamic parameters indicate that the sorption process is endothermic and spontaneous.