RESUMO
A hydrothermal technique was employed to synthesize Ni/Mg/Al ternary L.D.H.s modified with montmorillonite (NMA-MMT-LDHs). Many characterization methods, including X-ray diffraction (XRD), scanning electron microscopy (S.E.M.), Fourier transform infrared (FTIR), and Brunauer, Emmett, and Teller (B.E.T.), were used to assess the physiochemical properties of the produced analytes. Congo red and methylene blue were utilized as model dyes to treat textile waste with the synthesized analytes. The batch adsorption model was utilized to conduct the adsorption experiments under varying contact time, adsorbent dosage, and solution pH conditions. A pseudo-second-order kinetics and the Langmuir adsorption model control the adsorption process. The maximum monolayer adsorption capacities of C.R. and M.B. were determined to be 344 and 200 mg/g, respectively. As the quantity of dosage increased from the 0.01-0.04 g, the percent removal efficiency (%) increased from 75 to 87 % for S2-LDH, 84-88 % for S2-MMT, 86-93 % for S3-MMT, and 95-97% for S4-MMT for C.R. dye and 82-85 % for S2-LDH, 83-89 % for S2-MMT, 83-91 % for S3-MMT, and 84-92 % for S4-MMT for M.B. dye. The removal percentage of C.R. dye for adsorbents S2-LDH, S2-MMT, S3-MMT, and S4-MMT were 75 %, 84 %, 86 %, and 95 %, respectively and 82 %, 83 %, 83 %, and 85 %, respectively for the M.B. dye removal. The presence of MMT significantly increases the affinity of Ni/Mg/Al-LDHs (NMA-LDHs), and the designed production technique can be used to produce a variety of compositionally distinct adsorbent materials.
RESUMO
Analytical method for the monitoring of residues of multiclass pesticides (variable chemical structure and chromatographic behavior) in honey has been optimized and in-house validated in the present study. Chemical confirmation of 35 selected pesticides (in-hive-treated pesticides and pesticides applied for agricultural practices in vicinity of apiaries) has been successfully achieved with the acetonitrile extraction/partitioning and cleanup by modified US EPA solid-phase extraction (SPE) protocol following analysis on the GC/MS DRS Pesticide Screener. The applied extraction procedure has given acceptable recoveries with an associated precision (RSD) for selected pesticides within the range as suggested by SANTE at MQL of 10 µg kg-1. Potential matrix effect for selected analytes was calculated by using honey from five different floral sources. The optimized method was used to determine levels of pesticide residues in honey samples randomly collected from 26 different apiaries in Pakistan. Residues of nine selected pesticide (dichlorvos, mevinphos, ethalfluralin, trifluralin, lindane, chlorpyrifos-methyl, dieldrin, profenofos, 4,4-DDE) were frequently detected in the ranges of 3-48.8 µg kg-1 in 26.9% of analyzed samples (n = 26) and 15.3% of the studied samples exceeded maximum residue limits (MRLs). In-hive-treated acaricides, i.e., coumaphos, tau-fluvalinate, and malathion, were not detected in any of the analyzed honey samples.
