A new method for the extraction of the active coagulation component from Moringa oleifera seeds was developed and compared with the ordinary water extraction method (MOC-DW). In the new method, 1.0 mol l-1 solution of sodium chloride (MOC-SC) and other salts were used for extraction of the active coagulation component. Batch coagulation experiments were conducted using 500 ml of low turbid water (50 NTU). Coagulation efficiencies were evaluated based on the dosage required to remove kaolinite turbidity in water. MOC-SC showed better coagulation activity with dosages 7.4 times lower than that using MOC-DW for the removal of kaolinite turbidity. MOC-SC could effectively coagulate more than 95% of the 50 NTU initial kaolin turbidity using only 4 ml l-1 , while 32 ml l-1 of MOC-DW could only remove about 78% of the same kaolin turbidity. The improvement of coagulation efficiency by NaCl is apparently due to the salting-in mechanism in proteins wherein a salt increases protein-protein dissociations leading to increasing protein solubility as the salt ionic strength increases. There was no difference in the coagulation efficiency observed for extracts using any of four 1:1 salts (NaCl, KNO3, KCl and NaNO3) in our study. Purification and isolation of the active component confirmed that the active component of MOC-SC was mainly protein.

The infrared spectra of a humic and a fulvic acid from a peat were obtained using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and were compared with transmission Fourier transform infrared (FTIR) spectra using KBr pellets. The DRIFT spectra showed similar resolution to KBr pellet transmission spectra. Elimination of interference due to water bands is easy with DRIFT and possible changes in the spectra due to modification of H bonding and ionization of carboxylate groups in the KBr pellet is avoided. Comparison of the DRIFT spectra of humic substances with the DRIFT spectra of some reference compounds suggests that phenolic OH groups in fulvic acids are more H‐bonded than those in humic acids, but the COOH groups are similarly H‐bonded. Comparison of the C=O stretching band with those of the reference compounds suggests that either intramolecular H‐bonding between COOH and phenolic OH is not significant in humic substances or alkyl COOH groups contribute considerably in the 1720 cm−1 band. The DRIFT spectra of Na and Cu(II) forms of humic acid powders show the capability of the method for metal‐ion binding studies. The possibility of using DRIFT spectroscopy for quantitative and semiquantitative evaluation is suggested by the similarity in the Kubelka‐Munk transformed DRIFT spectra and absorbance spectra using KBr pellets.

It is known that M. oleifera contains a natural coagulant in the seeds. In our previous research, the method using salt water to extract the active coagulation component from M. oleifera seeds was developed and compared with the conventional method using water. In this research, the active coagulation component was purified from a NaCl solution crude extract of Moringa oleifera seeds. The active component was isolated and purified from the crude extract through a sequence of steps that included salting-out by dialysis, removal of lipids and carbohydrates by homogenization with acetone, and anion exchange. Specific coagulation activity of the active material increased up to 34 times more than the crude extract after the ion exchange. The active component was not the same as that of water extract. The molecular weight was about 3000 Da. The Lowry method and the phenol-sulfuric acid method indicated that the active component was neither protein nor polysaccharide. The optimum pH of the purified active component for coagulation of turbidity was pH 8 and above. Different from the conventional water extracts, the active component can be used for waters with low turbidity without increase in the dissolved organic carbon concentration.

This study focuses on the coagulation mechanism by the purified coagulant solution (MOC-SC-PC) with the coagulation active component extracted from M. oleifera seeds using salt solution. The addition of MOC-SC-PC tap water formed insoluble matters. This formation was responsible for kaolin coagulation. On the other hand, insoluble matters were not formed when the MOC-SC-PC was added into distilled water. The formation was affected by Ca2+ or other bivalent cations which may connect each molecule of the active coagulation component in MOC-SC-PC and form a net-like structure. The coagulation mechanism of MOC-SC-PC seemed to be an enmeshment of Kaolin by the insoluble matters with the net-like structure. In case of Ca2+ ion (bivalent cations), at least 0.2 mM was necessary for coagulation at 0.3 mgC l-1 dose of MOC-SC-PC. Other coagulation mechanisms like compression of double layer, interparticle bridging or charge neutralization were not responsible for the coagulation by MOC-SC-PC.

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The adsorption of nitrate, chromium (VI), arsenic (V) and selenium (VI) anions in an amine modified coconut coir (MCC-AE : with secondary and tertiary amine functionality) were studied to determine the capability of this easily prepared and low-cost material in removing typical groundwater anion contaminants. Batch adsorption-ion exchange experiments were conducted using 200 mg MCC-AE, initially containing chloride as the resident anion, and 50 ml of different anion-containing water of varying concentrations. It is presumed, at this low pH, that only SeO42− remained as a divalent anion, while monovalent species H2AsO4− and HCrO4− predominated in their respective exchanging ion solutions. The adsorption data were fitted using the Freundlich equation and maximum adsorption for each anion was estimated using their respective Freundlich equation constants. MCC-AE exhibited preference for divalent Cr (VI) and Se (VI) anions compared with the Cl− resident ion. Maximum As (V) adsorption was 0.086 mmol/g, while maximum adsorption of Cr (VI), NO3− and Se (VI) anions was 0.327 mmol/g, 0.459 mmol/g, and 0.222 mmol/g, respectively. The ion exchange capacity of MCC-AE is estimated, based on its exchange capacity for nitrate, to be within 0.46 mmol of positive charges per gram. Similar adsorption experiments were conducted for comparison using commercial chloride-form Amberlite IRA-900 strong base (quaternary amine functionality) anion exchanger, with an exchange capacity of 4.2 meq/g. Maximum adsorption of the different ions in IRA-900 was about 3 times higher for NO3−, 9 times higher for Se (VI), 10 times higher for As (V) and 9 times higher for Cr (VI), than that in MCC-AE. Differences in the ion exchange behavior of MCC-AE and IRA-900 were probably due to the different amine functionalities in the two exchangers. The results suggest that MCC-AE may be used as a low-cost alternative adsorbent/ion exchanger for treatment of anion contaminants in groundwater.

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The ultraviolet‐visible spectra of three fulvic acids from a Mollisol (FA1), a Histosol (FA2), and a Spodosol (FA3) were determined using four solvents: 0.05 M NaHCO3, distilled water, 95% (v/v) ethanol, and absolute ethanol. Light scattering was evaluated by varying the distance of the sample cell from the detector. This test, which gave positive results for a dilute milk sample, showed no light scattering effects for the fulvic acids. The ratios of 465 to 665 nm absorbances (E4/E6 ratios) determined in 0.05 M NaHCO3 were 16.7 for FA1, 16.8 for FA2, and 18.5 for FA3. The ultraviolet spectra in water showed only slight inflections for FA1 and FA3, but the FA2 spectrum had a pronounced shoulder centered at about 280 nm. In ethanol, the shoulder was shifted towards the red and absorbance decreased. Similar red shifts were shown to occur in 2,3‐; 2,4‐; and 2,6‐dihydroxybenzoic acids (DHB). The absorbance of bands in the range of 26 to 290 nm obeyed the Beer‐Lambert law. Estimates of molar absorptivities ranged from 2300 to 4500 L mol−1 cm−1, which is within the range of molar absorptivities of the electron transfer (ET) bands of carboxyphenols. Shifts in the position of the shoulders with pH, in both water and 95% ethanol, resembled that of carboxyphenols. Absorbance at visible wavelengths was not consistent with the behavior of simple quinones but might be due to chromophores with extended conjugation, possibly polyaromatic structures. Another possibility considered was intramolecular electron donor‐acceptor complexes.