Aloysius U. Baes

Isolation and characterization of coagulant extracted from Moringa oleifera seed by salt solution

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.

Improvement of extraction method of coagulation active components from Moringa oleifera seed

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 950f the 50 NTU initial kaolin turbidity using only 4 ml l-1, while 32 ml l-1 of MOC–DW could only remove about 781023440400f 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.

Coagulation mechanism of salt solution-extracted active component in Moringa oleifera seeds

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.

Preparation of agricultural residue anion exchangers and its nitrate maximum adsorption capacity

Anion exchangers were prepared from different agricultural residues (AR) after reaction with epichlorohydrin and dimethylamine in the presence of pyridine and N,N-dimethylformamide (EDM method). Agricultural residues anion exchangers (AR-AE) produced by the EDM method were inexpensive and showed almost the same NO3- removal capacities as Amberlite IRA-900. AR-AE produced from AR with higher hemicelluloses, lignin, ash and extractive contents resulted in the lower yields. Sugarcane bagasse with the highest alpha-cellulose contents of 51.2% had the highest yield (225%) and lowest preparation cost. The highest maximum adsorption capacity (Qmax) for nitrate was obtained from rice hull (1.21 mmol g(-1)) and pine bark natural exchangers (1.06 mmol g(-1)). No correlation was found between Qmax and alpha-cellulose content in the original AR. AR-AE produced from different AR demonstrated comparable Qmax due to the removal of non-active compounds such as extractives, lignin and hemicelluloses from AR during the preparation process. Similar preparation from pure cellulose and pure alkaline lignin demonstrated that the EDM method could not produce anion exchangers from pure lignin due to its solubilization after the reaction with epichlorohydrin.

A new procedure to produce lignocellulosic anion exchangers from agricultural waste materials.

Two lignocellulosic agricultural waste materials (LCM), sugarcane bagasse (BG) and rice hull (RH), were converted into weak-base anion exchanger and evaluated for their exchanger capacity for nitrate. Pure cellulose (PC) and pure alkaline lignin (PL) were also used as reference materials to elucidate possible reactivity in LCM. Epoxy and amino groups were introduced into BG, RH, PC and PL substrates after the reaction with epichlorohydrin and dimethylamine in the presence of pyridine and an organic solvent N,N-dimethylformamide (DMF). Amino group incorporation into cellulose decreased with the presence of water in the reaction mixture and increased with the reaction time and presence of a catalyst (pyridine). The highest maximum nitrate exchange capacity (Qmax) and yields of the prepared exchangers was obtained from PL (1.8 mmol g(-1) and 412.5%), followed by BG (1.41 mmol g(-1) and 300%), PC (1.34 mmol g(-1) and 166%) and RH (1.32 mmol g(-1) and 180%). The proposed synthetic procedure was effective in modifying PL, PC and LCM chemically resulting in a higher yield and nitrate removal capacity.

Transformation of Dissolved Organic Matter During Ozonation: Effects on Trihalomethane Formation Potential

Transformation of dissolved organic matter (DOM) during ozonation results in a higher reduction in trihalomethane formation potential (THMFP) relative to dissolved organic carbon (DOC). This study was conducted to determine the effect of DOM transformation after ozonation on THM formation and to elucidate the difference in THMFP and DOC removal. Changes in DOC, THMFP, reactivities of the hydrophilic and hydrophobic DOC, and phenolic-OH were determined to explain the difference in THMFP and DOC removal after ozonation. Higher reduction in THMFP (24-46%) relative to DOC (10-16%) was obtained and was attributed to the following: transformation of DOM from a more reactive hydrophobic DOC (microg THM produced per mg organic carbon) to a less reactive hydrophilic DOC and to the decrease in the reactivities of both the hydrophobic and hydrophilic DOC after ozonation. The results also showed decrease in phenolic-OH indicating the oxidation of some reactive sites like resorcinol or meta-dihydroxy benzene ring structures, which are prone to chlorine substitution, consequently decreasing the reactivity of the organic carbon to form THM. These changes in DOM led to a significant decrease in THMFP with no remarkable removal in DOC.

Adsorption and ion exchange of some groundwater anion contaminants in an amine modified coconut coir

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 SeO 4 2− remained as a divalent anion, while monovalent species H 2 AsO 4 − and HCrO 4 − 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), NO 3 − 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 NO 3 − , 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.

Chemical properties of anion-exchangers prepared from waste natural materials

Abstract Waste natural materials (WNM) were converted into anion-exchangers through consecutive chemical reactions with thionylchloride, N,N-Dimethylformamide (DMF), dimethylamine and formaldehyde as crosslinking agents. The final products obtained were weak-base anion-exchangers with tertiary amines as major functional exchange groups. WNM containing small amounts of extractives gave higher yields. Also, anion-exchangers produced from WNM with higher lignin content gave higher maximum nitrate adsorption capacity (Qmax). Moringa oleifera (M. oleifera) hull with the highest lignin content of 30.4% showed the highest Qmax of 0.20 mmol NO3− per g of resin, followed by coconut husk, sawdust of lauan and rice hull. Anion-exchangers produced from WNM and mixtures of pure lignin and pure cellulose demonstrated that lignin is the major reactive component responsible for the anion-exchanger and cellulose seems to be a supporting material for the exchangers.

Preparation of chelating agents from sugarcane bagasse by microwave radiation as an alternative ecologically benign procedure

Microwave radiation was utilized to produce neutral chelating agents (BCA) from sugarcane bagasse. BCA were prepared by reaction of urea with reactive sites present in bagasse such as hydroxyl and carboxylic groups. BCA prepared through microwave radiation had slightly lower yield (83%) compared to the conventional oven-drier process (87%). BCA demonstrated maximum chelating adsorption capacity (Qmax) of 1.2 mmol g−1 for Cu(II) at pH of 5.5 and 1.4 mmol g−1 for Hg(II) at pH 6.0. These results could be comparable with the Qmax of 1.46 mmol g−1 for Cu(II) and 2.4 mmol g−1 for Hg(II) obtained from Duolite GT-73, a commercial chelating resin, macroreticular with tiol (S–H) functional groups.

Trihalomethane formation potential prediction using some chemical functional groups and bulk parameters

Abstract This study was conducted to determine the influence of some chemical functional groups (COOH, phenolic-OH and organic nitrogen) and bulk parameters (UV 260 and DOC) on the trihalomethane formation potential (THMFP) of various treated industrial wastewaters. The samples were analyzed for UV 260, DOC, and THMFP. They were further fractionated into hydrophobic (humic) and hydrophilic (nonhumic) fractions using the XAD-8 resin, then bulk and specific chemical functional groups were determined on both fractions. Regression analyses were carried out among the parameters analyzed with THMFP as the dependent variable. The hydrophilic fractions contained higher DOC and had larger contribution to the bulk THMFP compared to the hydrophobic fractions. Simple regression analysis showed that although UV 260 and DOC correlated better with THMFP, the correlation values obtained were not statistically significant. Correlations using bulk parameters as well as chemical functional groups taken one at a time could not predict THMFP. The parameters that influenced the formation of THMs based on a stepwise and multiple regression analyses were UV 260, organic nitrogen, and phenolic-OH in the nonhumic fractions (hydrophilic) and UV 260 and organic nitrogen in the humic fractions (hydrophobic). The estimated THMFP obtained from the equation derived from the statistical analyses correlated significantly with the observed values at 99% level of confidence.