Aqua System Research Articles

Gastropod shell column reactor as on-site system for phosphate capture and recovery from aqua system

Gastropod shell (GS), whose distribution is worldwide and mineralogical assemblage is aragonite, was packed in a glass column and evaluated for phosphate capture and recovery from aqua system. The column reactor was operated in a batch-continuous mode, considered as a close approximation to a practical water treatment system, for 30 days. The time–concentration profile parameters were derived at different influent phosphate concentrations and hydraulic residence time (HRT) to determine the performance efficiency of the reactor column. The mechanism of phosphate removal was investigated and phosphate fractionation protocol was employed to elucidate the form and pattern of phosphate distribution in the spent reactor. Variations in influent phosphate concentration and HRT had minimal influence on the time–concentration profile parameters and the performance efficiency of the column reactor within the process variables studied. The first order rate constant (k1) showed that increase in the HRT of the influent in the SS column reactor does not enhance the phosphate removal. The value of the saturation index (SI) obtained over the 30 days period were all positive and the thermodynamic parameter (ΔG) was <0 which is an indication of supersaturation, the significant role of precipitation as a mechanism of phosphate removal in the reactor and spontaneity of the precipitation reaction. The order of distribution of each fraction of P, relative to the total phosphorus (T-P) in the phosphate laden SS, is as follows: dicalcium phosphate (Ca2-P) (42.5%)>ten-calcium phosphate (Ca10-P) (40.50%)>octacalcium phosphate (Ca8-P) (16.65%)>occluded phosphate (O-P) (0.35%). The simple appraisal of the fertilizer value of the spent reactor showed that it would preferentially serve as a soil conditioner cum fertilizer in acidic soil.

Synthesis of nano-sized hydrocalumite from a Gastropod shell for aqua system phosphate removal

Material with high affinity for oxyanions, Hydrocalumite (HC), was synthesized using a waste biogenic resource as a precursor and its ability to remove phosphate from aqua system was studied. The synthesis of HC samples with particle sizes that ranged between 116 and 135nm was confirmed by XRD analysis. High correlation coefficient values (r2 = 1.000) were obtained when the time–concentration profile data were fitted to the pseudo second order kinetic model. The formation of supersaturated Ca and Al phosphate salts were confirmed by the positive saturation index values and the feasibility of precipitate formation by the supersaturated salts were confirmed by the thermodynamic parameters (i.e. ΔG < 0). Process variables optimization (pH, ionic strength and organic load) had nominal influence on the magnitude of phosphate removal. The fractionation of the phosphate laden HC (PHC2) showed that the greater percentage (>99%) of the phosphate was distributed within the calcium matrix. Comparison of the EDAX spectra of the virgin HC with the PHC2 showed that anion exchange could also be a player in phosphate removal by the HC.

Appraisal of Cassava Starch as Coagulant Aid in the Alum Coagulation of Congo Red from Aqua System

Cassava starch (CS) was evaluated as coagulant aid in the alum coagulation of an acid dye, Congo red (CR), from aqua system. The use of CS, as coagulant aid reduced the value of the optimum alum dose, required for coagulation of CR, by 50%. The abilities of alum and CS were assessed, separately, on the coagulation of varying concentrations of CR contaminated water by method of continuous variation of the alum and CS dosages. Alum coagulated the CR while the CS performed poorly. Varying dosages of the CS were combined with half the optimum alum dose, for each concentration, and reduction in the aqua CR concentration was observed. The percentage of CR removed was appreciable at all the pH studied and the amount of CR removed increased with increase in the flocculation time. The kinetics of the flocculation process was studied by fitting the data obtained to a kinetic model and the flocculation rate constant increased with increase in the initial CR concentration.

Solid phase extraction of hazardous metals from aqua system by nanoparticle-modified agrowaste composite adsorbents

This study reports for the first time the adsorption of Cd(II) and Hg(II) ions from simulated wastewaters onto Nauclea diderrichii agrowaste (NDS) modified with mesoporous SiO2 (MND) and mesoporous SiO2+graphene oxide (GND). Modification of NDS with mesoporous SiO2 and graphene oxide improved its adsorption capacity for Cd(II) and Hg(II) in aqueous solution with surface area increasing from 5.4m2/g (in NDS) to 209m2/g (in MND) and 267m2/g (in GND) respectively. The modification of NDS also improved its rate of uptake of both metal ions with uptake rate of Hg(II) being more than that of Cd(II). Kinetic data obtained gave better fit to the pseudo-second order kinetic model than to pseudo-first order, Elovich, modified pseudo-first order, ion exchange or Weber–Morris intraparticle diffusion kinetic models. Data obtained from the Weber–Morris intraparticle diffusion model suggests that pore diffusion mechanism may have played a significant role in the adsorption process. Thermodynamic data showed negative and positive values for ?G° and ?H° respectively for the adsorption systems, which supports the fact that the adsorption of both Cd(II) and Hg(II) by MND and GND adsorbents was feasible, spontaneous and endothermic in nature.

Gastropod shell as a precursor for the synthesis of binary alkali-earth and transition metal oxide for Cr(VI) Abstraction from Aqua System

The synergies of binary metal oxides, habitual in natural system, in sequestrating metal ions were the premise on the synthesis of binary alkali earth and transition metal oxides (ATM) for possible environmental remediation. Gastropod shell (GS) was used as a precursor for alkali earth metal generation in the perspective of wastes recycling and cost minimization in material synthesis. ATM of different combination ratios of Ca: Fe, were synthesized and characterized (XRD, SEM, EDAX, TGA and PZC) and the potential for Cr(VI) attenuation in aqua system was appraised. The Langmuir sorption capacities (mg/g) of the ATM (112.36–117.65) were higher than that of the respective metal ion constituents (101.01–105.26). Kinetic modeling showed that the pseudo second order gave the best description of the process. pH had nominal effect on the extent of Cr(VI) sorption while the magnitude of Cr(VI) sorbed reduced with increase in molar concentrations of anions and ionic strength. The spent ATM stability, determined via the toxicity characteristic leaching procedure (TCLP), was higher in acidic medium than the alkaline medium. SEM and EDAX elucidation, confirmed the presence of Cr(VI) on the sorbent while the formation of complexes of Cr ions with metal-O functional groups was confirmed via FTIR analysis.

Performance of Prosopis africana peel powder (PAPP) as a novel sorbent for remediating malachite green contaminated aqua system

This study was designed to investigate Prosopis africana peel powder (PAPP) as a potential, local, cost-effective, readily-available coagulant for remediating dye-contaminated water and compare it with activated charcoal (a standard coagulant).PAPP was prepared and characterized using standard procedures. Preliminary characterization of the malachite green (MG) contaminated water was carried out before and post- treatment with PAPP and activated charcoal, respectively, in terms of turbidity, pH, salinity, temperature, electrical conductivity, total solid (TS), total suspended solid (TSS) and total dissolved solid (TDS). The concentration of the MG adsorbed by both coagulants were determined and compared. Results showed that the percentage of MG removed increased proportionally with theconcentration of the coagulants. With PAPP, the pH of the solution was 4.67, the salinity and TSS were zero while TS and turbidity were only pronounced at higher concentrations; whereas with activated charcoal, the pH was 6.37, the turbidity, TSS, TS and salinity were zero but TDS and conductivity were concentration dependent. This study has shown that PAPP could be employed as a potential adsorbent in the treatment of MG contaminated water. A study is currently in progress to activate PAPP and compare its dye removal efficiency with activated charcoal. Key words: Malachite green, coagulant property, contaminated water, activated charcoal, Prosopis africana peel powder (PAPP).

1666P - Utility of a Novel Quantitative EGFR Mutated Protein Analysis Using Aqua System for EGFR-TKI Treatment in Non-Small Cell Lung Cancer Patients

ABSTRACT Background Lung cancer carrying EGFR mutation (muEGFR) expresses good response to EGFR tyrosine kinase inhibitors (TKIs). However, not all patients (pts) with mutation showed similar clinical benefits from EGFR-TKIs. Heterogeneity of tumor cells is considered to be one plausible reason. MuEGFR was usually genotyped in qualitative manner in present clinical practice. In addition, new technology of AQUA system enables us to measure protein levels objectively with considering expression heterogeneity in tissues. Here we investigated the correlation between AQUA score obtained from each specimen and the response and the response duration by EGFR-TKIs. Methods Slice sections from genotyped 105 pts with muEGFR and 33 pts with wild-type EGFR were stained by E746-A750 deletion (6B6)- and L858R (43B2)-specific antibodies. Homo- or heterogeneous staining and muEGFR protein levels of these specimens were evaluated with AQUA system. Results Concordance rate between genotypes and AQUA-based phenotypes (deletion and L858R), with cut-off values based on ROC curve, were 60% and 82%. Low sensitivity of 6B6 was due to lucking of reactivity for other deletion variants. Alternatively, specificities of both antibodies were 96% and 92%, indicating highly selectivity to muEGFR protein. The AQUA score of 28 pts treated with EGFR-TKIs were varied (5.4 – 798.5) but the falls plot analysis indicated that pts with high AQUA score showed better objective response. Specimens of partial response (PR) had significantly higher AQUA score than those of progression disease (67.4 vs 9.6, p = 0.025). However, there were no differences of AQUA score between specimens of PR and stable disease. When divided pts into two groups based on median AQUA score, the pts with high AQUA score showed a tendency of longer treatment duration (24 mo vs 15 mo, p = 0.210). Especially, the high AQUA score with low intratumoral deviation pts showed longer treatment duration in compared to others. These results indicate that AQUA-based analysis can classify pts carrying genotyped muEGFR into susceptible and less susceptible ones to EGFR-TKIs. Conclusions We observed that pts with high AQUA score were more sensitive to EGFR-TKIs. It is important for predicting sensitivity to EGFR-TKIs to examine not only genotyping but also muEGFR protein levels by using AQUA system. Disclosure All authors have declared no conflicts of interest.

Utility of a novel quantitative EGFR-mutated protein analysis using AQUA system for EGFR-TKI treatment in non-small cell lung cancer.

e18064 Background: Lung cancer carrying EGFR mutation (muEGFR) expresses good response to EGFR tyrosine kinase inhibitors (TKIs). However, not all patients (pts) with mutation showed similar clinical benefits from EGFR-TKIs. Heterogeneity of tumor cells is considered to be one plausible reason. MuEGFR was usually genotyped in qualitative manner in present clinical practice. In addition, new technology of AQUA system enables us to measure protein levels objectively with considering expression heterogeneity in tissues. Here we investigated the correlation between AQUA score obtained from each specimen and the response and the response duration by EGFR-TKIs. Methods: Slice sections from genotyped 105 pts with muEGFR and 33 pts with wild-type EGFR were stained by E746-A750 deletion (6B6)- and L858R (43B2)-specific antibodies. Homo- or heterogeneous staining and muEGFR protein levels of these specimens were evaluated with AQUA system. Results: Concordance rate between genotypes and AQUA-based phenotypes (deletion and L858R), with cut-off values based on ROC curve, were 60% and 82%. Low sensitivity of 6B6 was due to lucking of reactivity for other deletion variants. Alternatively, specificities of both antibodies were 96% and 92%, indicating highly selectivity to muEGFR protein. The AQUA score of 27 pts treated with EGFR-TKIs were varied (8.7 – 907.4) but the falls plot analysis indicated that pts with high AQUA score showed better objective response. Specimens of partial response (PR) had significantly higher AQUA score than those of progression disease (136.5 vs 9.8, p=0.014). When divided pts into two groups based on median AQUA score, the pts with high AQUA score showed a tendency of longer treatment duration (21 mo vs 14 mo, p=0.162). These results indicate that AQUA-based analysis can classify pts carrying genotyped muEGFR into susceptible and less susceptible ones to EGFR-TKIs. Conclusions: We observed that pts with high AQUA score were more sensitive to EGFR-TKIs. It is important for predicting sensitivity to EGFR-TKIs to investigate not only genotyping but also muEGFR protein levels by using AQUA system.

Exergoeconomic optimisation of steam power plant

The second law of thermodynamics combined with economics forms a powerful tool for systematic analysis and assessment of energy systems. This paper presents an exergoeconomic optimisation of 50 MW steam turbine power plant associated with a large fertiliser industrial unit through Thermoeconomic Evaluation and Optimisation (TEO) method, and identifies the losses in various components. As the industrial unit also operates aqua ammonia Vapour Absorption Refrigeration system (VAR) for its low temperature applications, the economy of the source of heat energy to VAR is also checked. For this, the cost of the part of bled steam at an appropriate tapping from the steam turbine originally meant for feed water heating proposed to be utilised as a heat source for VAR system is compared with the existing one. It is found that the use of heat source from bled steam is more economical than that generated in independent boiler or steam generated at HRSG of gas turbine power plant.

Synthesis of Nano Calcium Oxide from a Gastropod Shell and the Performance Evaluation for Cr (VI) Removal from Aqua System

A spongy, porous nano calcium oxide (NC) with point zero charge of 11.80 was synthesized using the shell of a Gastropod (Achatina achatina) via the sol–gel technique. The ability of the NC to adsor...

Performance Evaluation of Fixed Bed of Nano Calcium Oxide Synthesized from a Gastropod Shell (Achatina achatina) in Hexavalent Chromium Abstraction from Aqua System

The shell of a gastropod (Achatina Achatina) was used as a precursor for the synthesis of nano calcium oxide (NC) via the sol–gel technique. The NC was characterized and the performance evaluation in chromium (Cr) (VI) abstraction was assessed in a fixed bed. The operating characteristics of the NC-Cr (VI) system were analysed with the mass transfer model and the mass transfer zone parameters were found to fluctuate with changes in the initial Cr (VI) concentration. The evaluation of the equilibrium data, generated from the fixed bed studies, showed that the sorption of Cr (VI) occurred via monolayer adsorption mechanism, and the monolayer sorption capacity was 833.33 mg/g. Different kinetic models (i.e., Adams–Bohart, Thomas, Wolborska, and Yoon–Nelson models) were applied to experimental data to predict the breakthrough curves and to determine the parameters of the column useful for process design. The kinetic analysis showed that the Yoon and Nelson model had the best fitting of the experimental data. The data obtained for Cr (VI) removal, when the NC bed height was optimized, were well described by bed depth service time model.

Characterization of Mn(II) and Mn(III) binding capability of natural siderophores desferrioxamine B and desferricoprogen as well as model hydroxamic acids

Complexes formed between Mn(II) ion and acetohydroxamic acid (HAha), benzohydroxamic acid (HBha), N-methyl-acetohydroxamic acid (HMeAha), DFB model dihydroxamic acids (H2(3,4-DIHA), H2(3,3-DIHA), H2(2,5-DIHA), H2(2,5-H,H-DIHA), H2(2,4-DIHA), H2(2,3-DIHA)) and two trihydroxamate based natural siderophores, desferrioxamine B (H4DFB) and desferricoprogen (H3DFC) have been investigated under anaerobic condition (and some of them also under aerobic condition). The pH-potentiometric results showed the formation of well-defined complexes with moderate stability. Monohydroxamic acids not, but all of the dihydroxamic acids and trihydroxamic acids were able to hinder the hydrolysis of the metal ion up to pH ca. 11. Maximum three hydroxamates were found to coordinate to the Mn(II) ion, but presence of water molecule in the inner-sphere was also indicated by the corresponding relaxivity values even in the tris-chelated complexes. Moreover, prototropic exchange processes were found to increase the relaxation rate of the solvent water proton over the value of [Mnaqua]2+ in the protonated Mn(II)–siderophore complexes at physiological pH. The much higher stability of Mn(III)–hydroxamate (especially tris-chelated) complexes compared to the corresponding Mn(II)-containing species results in a significantly decreased formal potential compared to the Mn(III)aqua/Mn(II)aqua system. As a result, air oxygen becomes an oxidizing agent for these manganese(II)–hydroxamate complexes above pH 7.5. The oxidation processes, followed by UV–Vis spectrophotometry, were found to be stoichiometric only in the case of the tris-chelated complexes of siderophores, which predominate above pH 9. ESI-MS provided support about the stoichiometry and cyclic-voltammetry was used to determine the stability constants for the tris-chelated complexes, [Mn(HDFB)]+ and [MnDFC].

In situ hybridization of waste dyes into growing particles of calcium derivatives synthesized from a Gastropod shell ( Achatina Achatina)

The necessity to develop a benign and effectual method of water pollution control necessitated the studies on this non-conventional in situ hybridization of organic pollutant into growing particles of CaCO 3 and Ca(OH) 2. A biogenic waste, the shell of a gastropod, was used as a precursor for the synthesis of the CaCO 3 and Ca(OH) 2, via the sol–gel route, in a medium containing either methylene blue (MB) or Congo Red (CR). Similar trends were exhibited by the growing particles in the abstraction of each dye contaminant from the aqua system. The magnitude of conjugation between the growing particles and dye molecule was higher in CR than in MB medium. The dye removal efficiency was not impacted by the optimization of process variables (initial dye concentration, pH, ionic strength and interfering ion) but the sludge settling property was swayed by the change in ionic strength. Experimental and instrumental (FTIR, XRD and SEM) evidence showed that the two types of co-precipitation reaction–occlusion and surface adsorption were the controlling mechanism of this in situ hybridization process.

Synchronous attenuation of metal ions and colour in aqua stream using tannin–alum synergy

The need to ameliorate the discolouration of the aqua system by soluble phenolics, in the use of tannin and tannin rich materials as a metal ion scavenger, without reducing the efficiency of the process necessitated this study. Tannin–alum synergy was used to remove metal ions (Cu, Zn, Cd and Pb) and the imparted colour from the aqua system. At lower alum dose, higher amounts of metal ions, in addition to the imparted colour by tannin was removed by the tannin–alum combination, when compared with the use of alum alone. The removal effieciency reduced, though minimally, as the pH of the solution increased from 3 to 6 and the percentage metal ion removal, for each metal ion, reduced when all metal ions were all present in a single solution but the colour removal efficiency was not affected. The metal–tannin interactions, studied using FTIR spectrophotometer, revealed an interaction between the –OH group and the metal ions.

Preliminary Comparison between AQUA and Centralised ER/PgR Analysis within the TEAM Pathology Study.

Abstract Background: The Tamoxifen and Exemestane Adjuvant Multinational (TEAM) trial identified quantitative relationships between ER/PgR (Can Res 69:83S) and patient prognosis, and suggested that high ER expression might be predictive for benefit from aromatase inhibitors. Conventional immunohistochemical assays, even when performed centrally, appear to be more variable than fluorescent immunohistochemical assays analysed by automated image analysis such as the AQUA system. However, output from the two systems may provide subtly different results for biomarkers. We have performed analysis of ER/PgR using AQUA technology in the TEAM pathology cohort and will present data on the full anlaysis of ER/PgR by central IHC and AQUA in 4600 cases. Preliminary data on ER (using a single TMA core) are included in the current analysis.Patients &amp; Methods: TMAs from 4598 TEAM patients were analysed by AQUA and image analysis using established algorithms performed. Comparisons between IHC and AQUA were performed and outcome data will be analysed and presented.Results: Interim AQUA results from a single core were available from 2319 TEAM cases. Analysis of results suggested incremental increases in AQUA scores across conventional Allred categories (2-8). Regression analysis suggests that multiple cores may be required adequate representation of ER expression. PgR data will be presented.Conclusion: Initial comparison between AQUA and ER expression by central IHC suggests these methods are comparable. Further data is required to assess the potential value of AQUA scores and will be presented. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3045.

Improved Automated Analysis of Radon (222Rn) and Thoron (220Rn) in Natural Waters

Natural radon ((222)Rn) and thoron ((220)Rn) can be used as tracers of various chemical and physical processes in the environment. We present here results from an extended series of laboratory experiments intended to improve the automated analysis of (222)Rn and (220)Rn in water using a modified RAD AQUA (Durridge Inc.) system. Previous experience with similar equipment showed that it takes about 30-40 min for the system to equilibrate to radon-in-water concentration increases and even longer for the response to return to baseline after a sharp spike. While the original water/gas exchanger setup was built only for radon-in-water measurement, our goal here is to provide an automated system capable of high resolution and good sensitivity for both radon- and thoron-in-water detections. We found that faster water flow rates substantially improved the response for both isotopes while thoron is detected most efficiently at airflow rates of 3 L/min. Our results show that the optimum conditions for fastest response and sensitivity for both isotopes are at water flow rates up to 17 L/min and an airflow rate of 3 L/min through the detector. Applications for such measurements include prospecting for naturally occurring radioactive material (NORM) in pipelines and locating points of groundwater/surface water interaction.

Predictive value of p27 for the benefit of adjuvant anthracycline-based chemotherapy in early breast cancer.

Abstract Abstract #6063 Background: p27 is a cyclin-dependent kinase (cdk) inhibitor that plays a role in cell cycle regulation. The expression of this protein, assessed by immunohistochemistry (IHC), has prognostic value for overall survival in breast cancer patients (Porter P.L., J Natl Cancer Inst., 2007). Based on this, we hypothesized that p27 could be a predictive factor for the efficacy of adjuvant anthracycline (A)-based chemotherapy in early breast cancer.&amp;#x2028; Methods: Tumor samples from 823 patients, included at Institut Gustave Roussy (IGR) in two randomized trials comparing an A-based chemotherapy with no adjuvant treatment, were used to construct a tissue microarray. We previously reported predictive values of ER, Her2 expression and molecular subclassification using the same tissue array (Conforti R., Ann Oncol., 2007). Nuclear and cytoplasmic expression of p27 was assessed by the AQUA system. A p27 ratio of nuclear and cytoplasmic expression (p27 N/C ratio) was calculated for each tumor sample. The prognostic and predictive value of the continuous value of p27 N/C ratio was assessed by a Cox regression model adjusted for treatment, age, tumor grade, stage and ER expression (IHC) and stratified by trial.&amp;#x2028; Results: p27 was assessable in 715 primary tumors. The p27 N/C ratio was significantly different according to the molecular subclasses (p=0.001) and was higher in Her2- versus Her2+ and in EGFR+ versus EGFR- tumors (p=0.0075 and p&amp;lt;0.0001 respectively). There was an almost significant interaction between p27 N/C ratio and disease-free survival in the adjusted Cox model (p=0.052). The adjusted hazard ratios (HR) of relapse or death of a unit increase in p27 N/C ratio was HR = 1.27 (95% CI = [0.58-2.81], p = 0.55) in the control arm and HR = 0.30 (95% CI = [0.12-0.77], p= 0.01) in the A-arm. For overall survival, the adjusted interaction p-value was equal to 0.08. The adjusted HR of death of a unit increase in p27 N/C ratio was HR=1.67 (95% CI = [0.61-1.73], p=0.32) in the control arm and HR=0.32 (95% CI = [0.10-0.99], p=0.05) in the A-arm.&amp;#x2028; Conclusion: p27 N/C ratio, determined by the AQUA system, was borderline predictive for the efficacy of adjuvant A-based chemotherapy. However, this study is hampered by a relatively low number of events, a low dose of anthracycline, and multi-hypotheses testing (overall 20 biomarkers tested in different studies). Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6063.

Snail shell as coagulant aid in the alum precipitation of malachite green from aqua system

The ability of snail shell (SS) to act as coagulant aid in the alum precipitation of a basic dye (MG) was investigated. The proximate physicochemical characterization of the SS showed the pH solution to be 8.01, high fraction of the inorganic constituents (ash content = 93.76%), the presence of Ca 2+ (99.74%) as the major metal ion present and the point zero charge (PZC) found at pH 7.9. The X-ray diffractometric analysis revealed the presence of aragonite. The stability and leaching of the SS, tested in different aqua medium (acidic, basic and neutral solutions) showed that the SS was less stable in the acidic medium. Both the alum and the SS were used, differently, for the dye precipitation. The alum alone had no precipitating effect on the MG dye molecules while SS alone was able to reduce the intensity of the dye. When the SS was used as coagulant aid in alum precipitation, the percentage of the MG molecule removed was enhanced. The effects of some process variables (coagulant/coagulant aid dosage, pH and flocculation time) were optimized by method of continuous variation. The optimum pH for the MG removal was found to range between 4 and 5 but the amount of MG removed was appreciable at all the pH studied. Studies on the effect of time on the flocculation of the precipitated MG molecule showed that the problem of redispersion and restabilisation encountered in alum precipitation could be overcome using alum–SS combination. The settling characteristics of the sludge obtained from the use of SS alone and alum–SS combination was studied by measuring the sludge volume index (SVI, mg/g) over time. The value of the SVI (mg/g) showed that the sludge produced from the alum–SS combination had better settling characteristics than the sludge got from the use of SS alone.

Evaluation of Plantain Peelings Ash Extract as Coagulant Aid in the Coagulation of Colloidal Particles in Low pH Aqua System

Abstract The use of plantain peelings ash extract (PPAE) as a coagulant aid in a low pH water was evaluated in the present studies. Plantain peelings were collected, washed, dried, and ashed in a furnace. The ash was extracted using deionized water, and the chemical composition was examined using an atomic absorption spectrophotometer. Synthetic turbid water of varying turbidities (50, 100, 300 NTU) and varying pHs (2, 3, 4) were prepared by clay dispersion in deionized water. The optimum alum dosages for the coagulation of colloidal particles in different turbid waters of varying pHs were determined by method of continuous variation using the jar test procedure. The residual turbidities of the treated waters were determined, and the alum doses that gave the minimum residual turbidities were taken as the optimum dosage for the removal of colloidal particles. The use of PPAE as a coagulant aid with alum showed an improvement in the value of residual turbidities of the treated waters. Results obtained from the different studies showed that treated waters of lower residual turbidities were obtained from synthetic waters of higher initial turbidities and pHs. The pH of the treated water decreased with an increase in alum dosage, whereas an increase in the pH value was observed with the addition of PPAE as a coagulant aid. High correlation coefficient values (r2) were obtained when the changes in pH (i.e., ΔpH = pHf –pHi) of the treated waters were correlated with alum and PPAE additions, and mathematical relationships were derived from the linear graph. Studies on the effect of flocculation time on residual turbidity showed that an optimum flocculation time of 30 minutes was attained, when alum was used alone, before redistribution and redispersion of the flocs was noticed. This phenomenon did not occur when PPAE was used as a coagulant aid.

Kinetics and mechanism of catalytic oxidation of alcohols to carbonyl compounds with dioxygen in the Pd-containing aqua system

The oxidation of lower aliphatic alcohols C1–C4 with dioxygen to form the corresponding carbonyl compounds in the presence of the PdII tetraaqua complexes and FeII-FeIII aqua ions in an aqueous medium was studied at 40–80 °C. The introduction of an aromatic compound (acetophenone, benzonitrile, phenylacetonitrile, o-cyanotoluene, nitrobenzene) and FeII aqua ion instead of the FeIII aqua ion into the reaction system increases substantially the catalytic activity and the yield of the carbonyl compound. The key role of the Pd species in the intermediate oxidation state stabilized by the aromatic additive in the catalytic cycle of alcohol oxidation with dioxygen to the carbonyl compound was shown. An increase in the kinetic isotope effect with an increase in the temperature of methanol oxidation indicates a change in the rate-determining step of alcohol oxidation with dioxygen in the presence of PdII-FeII-FeIII and the aromatic compound. At temperatures below 60 °C, the catalytically active palladium species are mainly formed upon the reduction of the PdII tetraaqua complex with the FeII aqua ion, whereas at higher temperatures the reaction between the alcohol and PdII predominates. The mechanism and kinetic equation of the process were proposed.