Lingcheng Su

Four non-saleable grade (NSG) plant spices, including Cymbopogon nardus (citronella), Rosmarinus officinalis (rosemary), Thymus vulgaris (thyme), and Coriandrum sativum (coriander) seeds were extracted using hydro-distillation. The chemical compositions of essential oils were analyzed using gas chromatography coupled with mass spectrometry (GC-MS) and the antimicrobial activities were tested to against the microbes of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans). Four essential oils are corresponding to the main functional substances of citronellal (29.562%), 1, 8- Cineole (62.267%), thymol (42.579%), and linalool (76.512%). Both the chemical constituents and antimicrobial activity of NSG essential oils were similar to both commercial products and those reported in previous studies, some of NSG essential oils even present better antimicrobial activity than commercial ones. This new approach of using NSG spices can help to reduce agricultural waste and increase the revenue of spice farmers.

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.

This article studies the enhancement of methyl orange (MO) adsorption by Mongolian montmorillonite (MMt) modified by the intercalation of the Keggin Al₁₃ complex, followed by calcination during the pillaring process. The properties of MMt, Al-intercalated MMt (P-MMt), and Al-pillared MMt (P-MMt-C) were determined using X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface-area analysis, and a field emission scanning electron microscope (FE-SEM). The MO adsorption by modified MMt was subsequently evaluated. The XRD basal distance (d₀₀₁) and the specific surface area (SSA) increased after the modification of MMt. The TGA results revealed that P-MMt and P-MMt-C had better thermal stability than MMt. The Al-pillared MMt obtained after calcination (e.g., P-MMt-C400) showed a larger basal distance and surface area than that without pillaring. The MO adsorption process of P-MMt-C400 was supposed to be dominated by chemisorption and heterogeneous multilayer adsorption, according to the kinetic and isotherm studies. The maximum adsorption capacity of P-MMt-C400 is 6.23 mg/g. The MO adsorption ability of Al-pillared MMt was contributed by the Keggin Al₁₃ complex attracting MO and the increase in the surface area of macro-, meso- and micro-pores (>1.2 nm). The Al-pillared MMt in this study could be applied as an adsorbent in a water purification system to remove MO or other dye elements.