Efficient removal of Cd(II), Cu(II), Pb(II), and Zn(II) from wastewater and natural water using submersible device

Humic Acids as a New Type of Methane Hydrate Formation Promoter and a Possible Mechanism for the Hydrate Growth Enhancement

“…Elemental analysis of the dry substance was carried out using a Euro EA 3000 analyzer (C, H, N, and S) and a GRAND spectrometer (Russia; Si, Ca, Mg, Fe, and other microelements). It provides the compositions expected for HA. − Fourier transform infrared (FTIR) spectra of these samples were recorded using a SCIMITAR FTS 2000 FTIR spectrometer (USA) in the range of 4000–400 cm –1 . The characteristics of the acid–base surface functional groups (SFGs) in the HA were determined by potentiometric titration of the protonated samples (0.05 g of the HA in 50 mL of 0.01 M KNO 3 as the background electrolyte) with 0.1 M KOH.…”

“…FTIR spectrum of the raw BC and extracted HA is shown in Figure . The spectrum of HA displays typical peaks characteristic of these substances, − such as (i) a strong and very broad band at 3500–3000 cm –1 is assigned to OH stretching of alcohol, phenol, and carboxylic groups; (ii) bands at 2922 and 2851 cm –1 are related to CH stretching of sp 3 carbon; (iii) broad bands between 1720 and 1610 cm –1 are assigned to CO of amides, ketones, ester, and carboxylic acid groups; (iv) other broad bands at 1600–1500 cm –1 are assigned to COO– symmetric stretching frequencies and CC aromatic groups; (v) the broad bands between 1410 and 1300 cm –1 attributed to CC aromatic groups, OH deformation, and COO– antisymmetric stretching are characteristic for HA molecules; (vi) broad bands between 1290 and 1100 cm –1 correspond to aromatic C and C–O stretching frequencies of phenol and aliphatic groups and also assigned to OH deformation of COOH; and (vii) peaks between 1120 and 1000 cm –1 are attributed to C–O of polysaccharides. The main absorbance bands and the corresponding assignments obtained for our sample of HA are listed in Table .…”