Zeolites P in sodium (NaP) and potassium (KP) forms were used as adsorbents for the removal of calcium (Ca2+) and zinc (Zn2+) cations from aqueous solutions. Zeolite KP was prepared by ion exchange of K+ with Na+ which neutralizes the negative charge of the zeolite P framework structure. The ion exchange capacity of K+ on zeolite NaP was determined through the Freundlich isotherm equilibrium study. Characterization of zeolite KP was determined using infrared spectroscopy and X-ray diffraction (XRD) techniques. From the characterization, the structure of zeolite KP was found to remain stable after the ion exchange process. Zeolites KP and NaP were used for the removal of Ca and Zn from solution. The amount of Ca2+ and Zn2+ in aqueous solution before and after the adsorption by zeolites was analysed using the flame atomic absorption spectroscopy method. The removal of Ca2+ and Zn2+ followed the Freundlich isotherm rather than the Langmuir isotherm model. This result also revealed that zeolite KP adsorbs Ca2+ and Zn2+ more than zeolite NaP and proved that modification of zeolite NaP with potassium leads to an increase in the adsorption efficiency of the zeolite. Therefore, the zeolites NaP and KP can be used for water softening (Ca removal) and reducing water pollution/toxicity (Zn removal).
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification
Meranti (Philippine mahogany) sawdust, an inexpensive material, showed strong scavenging behaviour through adsorption for the removal of methylene blue (MB) from aqueous solution. Batch studies were performed to evaluate and optimize the effects of various parameters such as contact time, pH, initial dye concentrations and adsorbent dosage. Langmuir, Freundlich and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The experimental data fitted well with the Langmuir adsorption isotherm, indicating thereby the mono layer adsorption of the dye. The monolayer sorption capacity of meranti sawdust for MB was found to be 120.48, 117.64, 149.25 and 158.73 mg/g at 30, 40, 50 and 60 degrees C, respectively. Thermodynamic calculations showed that the MB adsorption process is endothermic and spontaneous in nature. Kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model. The results indicated that the meranti sawdust could be an alternative material in place of more costly adsorbents used for dye removal.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The enzymatic reduction of Cr(VI) to Cr(III) by Cr(VI) resistant bacteria followed by chemical precipitation constitutes the ChromeBac system. Acinetobacter haemolyticus was immobilized onto carrier material inside a 0.2m(3) bioreactor. Neutralized electroplating wastewater with Cr(VI) concentration of 17-81 mg L(-1) was fed into the bioreactor (0.11-0.33 m(3)h(-1)). Complete Cr(VI) reduction to Cr(III) was obtained immediately after the start of bioreactor operation. Together with the flocculation, coagulation and filtration, outflow concentration of less than 0.02 mg Cr(VI)L(-1) and 1mg total CrL(-1) were always obtained. Performance of the bioreactor was not affected by fluctuations in pH (6.2-8.4), Cr(VI) (17-81 mg L(-1)), nutrient (liquid pineapple waste, 1-20%v/v) and temperature (30-38 degrees C). Standby periods of up to 10 days can be tolerated without loss in activity. A robust yet effective biotechnology to remove chromium from wastewater is thus demonstrated.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The effects of polyethyleneimine (PEI) impregnation on the Pb(2+) adsorption kinetics of palm shell-activated carbon and pH profile of bulk solution were investigated. Adsorption data were fitted to four established adsorption kinetics models, namely, pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion. It was found that PEI impregnation at 16.68 and 29.82 wt% PEI/AC increased the Pb(2+) uptake rate while the opposite was observed for PEI impregnation at 4.76 and 8.41 wt% PEI/AC. The increased uptake rates were due to higher concentration of PEI molecules on the surface of clogged pores as well as varying pore volumes. The adsorption kinetics data fitted the pseudo-second-order model better than the pseudo-first-order model, implying chemisorption was the rate-controlling step. The bulk solution pH generally showed an increasing trend from the use of virgin to PEI-impregnated activated carbon.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The aim of the present work was to investigate the feasibility of grass waste (GW) for methylene blue (MB) adsorption. The adsorption of MB on GW material was studied as a function of GW dose (0.05-1.20 g), solution pH 3-10, contact time and initial concentration (70-380 mg/L). The influence of these parameters on the adsorption capacity was studied using the batch process. The experimental data were analyzed by the Langmuir and Freundlich isotherms. The adsorption isotherm was found to follow the Langmuir model. The monolayer adsorption capacity was found to be 457.640 mg/g. The kinetic data were fitted to the pseudo-first-order and pseudo-second-order models, and were found to follow closely the pseudo-second-order kinetic model. The results revealed that GW adsorbent is potentially low-cost adsorbent for adsorption of MB.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The adsorption characteristics of 2,4,6-trichlorophenol (TCP) on activated carbon prepared from oil palm empty fruit bunch (EFB) were evaluated. The effects of TCP initial concentration, agitation time, solution pH and temperature on TCP adsorption were investigated. TCP adsorption uptake was found to increase with increase in initial concentration, agitation time and solution temperature whereas adsorption of TCP was more favourable at acidic pH. The adsorption equilibrium data were best represented by the Freundlich and Redlich-Peterson isotherms. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The mechanism of the adsorption process was determined from the intraparticle diffusion model. Boyd plot revealed that the adsorption of TCP on the activated carbon was mainly governed by particle diffusion. Thermodynamic parameters such as standard enthalpy (DeltaH degrees ), standard entropy (DeltaS degrees ), standard free energy (DeltaG degrees ) and activation energy were determined. The regeneration efficiency of the spent activated carbon was high, with TCP desorption of 99.6%.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The synthesized zeolite NaY from rice husk ash (RHA) and the commercial zeolite NaY both modified with surfactants in amounts equal to 50%, 100% and 200% of their external cation exchange capacity (ECEC) were used to remove chromate and arsenate anions from aqueous solutions. While the unmodified zeolite Y had little or no affinity for the Cr(VI) and As(V) anionic species, the surfactant-modified zeolite Y (SMZY) showed significant ability to remove of these anions from the aqueous solutions. The highest chromates and arsenates adsorption efficiency was observed from solutions of pH values 3 and 8, respectively because of the dominance of the univalent species of both anions. The adsorption equilibrium data were best fitted with the Langmuir isotherm model with the highest removal capacities observed for the SMZY initially prepared considering the hexadecyltrimethyl ammonium (HDTMA) amount equal to the 100% of the ECEC of zeolite Y. Synthesized SMZY remove Cr(VI) and As(V) more than the corresponding commercial one due to its lower silica to alumina ratio. Thus, the HDTMA-covered modified zeolite Y synthesized using RHA can be used to remove Cr(VI) and As(V) from water.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
This study investigated the adsorption potential of oil palm shell-based activated carbon to remove 2,4,6-trichlorophenol from aqueous solution using fixed-bed adsorption column. The effects of 2,4,6-trichlorophenol inlet concentration, feed flow rate and activated carbon bed height on the breakthrough characteristics of the adsorption system were determined. The regeneration efficiency of the oil palm shell-based activated carbon was evaluated using ethanol desorption technique. Through ethanol desorption, 96.25% of the adsorption sites could be recovered from the regenerated activated carbon.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The potential of garlic peel (GP), agricultural waste, to remove methylene blue (MB) from aqueous solution was evaluated in a batch process. Experiments were carried out as function of contact time, initial concentration (25-200mg/L), pH (4-12) and temperature (303, 313 and 323 K). Adsorption isotherms were modeled with the Langmuir, Freundlich, and Temkin isotherms. The data fitted well with the Freundlich isotherm. The maximum monolayer adsorption capacities were found to be 82.64, 123.45, and 142.86 mg/g at 303, 313, and 323 K, respectively. The kinetic data were analyzed using pseudo-first-order and pseudo-second-order models. The results indicated that the garlic peel could be an alternative for more costly adsorbents used for dye removal.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
Coagulation-flocculation is a relatively simple physical-chemical technique in treatment of old and stabilized leachate which has been practiced using a variety of conventional coagulants. Polymeric forms of metal coagulants which are increasingly applied in water treatment are not well documented in leachate treatment. In this research, capability of poly-aluminum chloride (PAC) in the treatment of stabilized leachate from Pulau Burung Landfill Site (PBLS), Penang, Malaysia was studied. The removal efficiencies for chemical oxygen demand (COD), turbidity, color and total suspended solid (TSS) obtained using PAC were compared with those obtained using alum as a conventional coagulant. Central composite design (CCD) and response surface method (RSM) were applied to optimize the operating variables viz. coagulant dosage and pH. Quadratic models developed for the four responses (COD, turbidity, color and TSS) studied indicated the optimum conditions to be PAC dosage of 2g/L at pH 7.5 and alum dosage of 9.5 g/L at pH 7. The experimental data and model predictions agreed well. COD, turbidity, color and TSS removal efficiencies of 43.1, 94.0, 90.7, and 92.2% for PAC, and 62.8, 88.4, 86.4, and 90.1% for alum were demonstrated.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
Endocrine disrupting chemicals (EDCs) are the focus of current environmental issues, as they can cause adverse health effects to animals and human, subsequent to endocrine function. The objective of this study was to remove a specific compound of EDCs (i.e. pentachlorophenol, C(6)OCL(5)Na, molecular weight of 288 g/mol) using low pressure reverse osmosis membrane (LPROM). A cross flow module of LPROM was used to observe the effects of operating parameters, i.e. pH, operating pressure and temperature. The design of the experiment was based on MINITAB(TM) software, and the analysis of results was conducted by factorial analysis. It was found that the rejection of pentachlorophenol was higher than 80% at a recovery rate of 60 to 70%. The rejection was subjected to increase with the increase of pH. The flux was observed to be increased with the increase of operating pressure and temperature. This study also investigated the interaction effects between operating parameters involved.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
In order to produce sufficient food supply for the ever-increasing human population, pesticides usage is indispensable in the agriculture sector to control crop losses. However, the effect of pesticides on the environment is very complex as undesirable transfers occur continually among different environmental sections. This eventually leads to contamination of drinking water source especially for rivers located near active agriculture practices. This paper studied the application of nanofiltration membrane in the removal of dimethoate and atrazine in aqueous solution. Dimethoate was selected as the subject of study since it is being listed as one of the pesticides in guidelines for drinking water by World Health Organization. Nevertheless, data on effectiveness of dimethoate rejection using membranes has not been found so far. Meanwhile, atrazine is classified as one of the most commonly used pesticides in Malaysia. Separation was done using a small batch-type membrane separation cell with integrated magnetic stirrer while concentration of dimethoate and atrazine in aqueous solution was analyzed using high performance liquid chromatography (HPLC). Four nanofiltration membranes NF90, NF200, NF270 and DK were tested for their respective performance to separate dimethoate and atrazine. Of all four membranes, NF90 showed the best performance in retention of dimethoate and atrazine in water.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
Oil palm empty fruit bunch (EFB) fibers were employed to remove dyes from aqueous solutions via adsorption approaches. The EFB fibers were modified using citric acid (CA) and polyethylenimine (PEI) to produce anionic and cationic adsorbents, respectively. The CA modified EFB fibers (CA-EFB) and PEI-modified EFB fibers (PEI-EFB) were used to study the efficiency in removing cationic methylene blue (MB) and anionic phenol red (PR) from aqueous solutions, respectively, at different pHs, temperatures and initial dye concentrations. The adsorption data for MB on the CA-EFB fitted the Langmuir isotherm, while the adsorption of PR on the PEI-EFB fitted the Freundlich isotherm, suggesting a monolayer and heterogeneous adsorption behavior of the adsorption processes, respectively. Both modified fibers can be regenerated up to seven adsorption/desorption cycles while still providing as least 70% of the initial adsorption capacity.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
A batch adsorption system was applied to study the adsorption of Fe(II) and Fe(III) ions from aqueous solution by chitosan and cross-linked chitosan beads. The adsorption capacities and rates of Fe(II) and Fe(III) ions onto chitosan and cross-linked chitosan beads were evaluated. Chitosan beads were cross-linked with glutaraldehyde (GLA), epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE) in order to enhance the chemical resistance and mechanical strength of chitosan beads. Experiments were carried out as function of pH, agitation period, agitation rate and concentration of Fe(II) and Fe(III) ions. Langmuir and Freundlich adsorption models were applied to describe the isotherms and isotherm constants. Equilibrium data agreed very well with the Langmuir model. The kinetic experimental data correlated well with the second-order kinetic model, indicating that the chemical sorption was the rate-limiting step. Results also showed that chitosan and cross-linked chitosan beads were favourable adsorbers.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The preparation of tamarind fruit seed granular activated carbon (TSAC) by microwave induced chemical activation for the adsorptive treatment of semi-aerobic landfill leachate has been attempted. The chemical and physical properties of TSAC were examined. A series of column tests were performed to determine the breakthrough characteristics, by varying the operational parameters, hydraulic loading rate (5-20 mL/min) and adsorbent bed height (15-21 cm). Ammonical nitrogen and chemical oxygen demand (COD), which provide a prerequisite insight into the prediction of leachate quality was quantified. Results illustrated an encouraging performance for the adsorptive removal of ammonical nitrogen and COD, with the highest bed capacity of 84.69 and 55.09 mg/g respectively, at the hydraulic loading rate of 5 mL/min and adsorbent bed height of 21 cm. The dynamic adsorption behavior was satisfactory described by the Thomas and Yoon-Nelson models. The findings demonstrated the applicability of TSAC for the adsorptive treatment of landfill leachate.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
Aquaculture activities in developing countries have raised deep concern about nutrient pollution, especially excess phosphorus in wastewater, which leads to eutrophication. NF, NF90, NF450 and XLE membranes were studied to forecast the potential of nanofiltration and low pressure reverse osmosis in the removal of phosphorus from aquaculture wastewater. Cross-sectional morphology, water contact angle, water permeability and zeta potential of these membranes were first examined. Membrane with higher porosity and greater hydrophilicity showed better permeability. Membrane samples also commonly exhibited high zeta potential value in the polyphosphate-rich solution. All the selected membranes removed more than 90% of polyphosphate from the concentrated feed (75 mg/L) at 12 bar. The separation performance of XLE membrane was well maintained at 94.6% even at low pressure. At low feed concentration, more than 70.0% of phosphorus rejection was achieved using XLE membrane. The formation of intermolecular bonds between polyphosphate and the acquired membranes probably had improved the removal of polyphosphate at high feed concentration. XLE membrane was further tested and its rejection of polyphosphate reduced with the decline of pH and the addition of ammonium nitrate.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
Oil palm shell, a waste from palm oil industry, was cleaned and utilized as adsorbent. Its particle size distribution gave the uniformity coefficient of approximately two indicating that it can be used as filter bed media for continuous operation without resting. Its measured pH(pzc) of 4.1 is below the common pH of constructed wetland water body suggesting positive adsorption for heavy metal. The effect of various parameters on its adsorption was studied via batch experiments. The adsorption of Cu(II) and Pb(II) ions by oil palm shell showed a slightly better fit with the Freundlich compared to Langmuir. Its monolayer adsorption capacities were found to be 1.756 and 3.390mg/g for Cu(II) and Pb(II), respectively. High correlation coefficient of over 0.99 given by the pseudo-second-order model suggests that the rate limiting factor may be chemisorption. These findings suggest its potential application as constructed wetland media for the removal of heavy metal.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The effects of initial concentration of lead, temperature, biomass loading and pH were investigated for an optimized condition of lead uptake from the aqueous solution. The optimization process was analyzed using Central Composite Face-Centered Experimental Design in Response Surface Methodology (RSM) by Design Expert Version 5.0.7 (StatEase, USA). The design was employed to derive a statistical model for the effect of parameters studied on the removal of lead ion from aqueous solution. The coefficient of determination, R2 was found to be 92.36%. The initial concentration of 50.0 mg/L, temperature of 60 degrees C, biomass loading of 0.2 g and pH of 5.0 had been found to be the optimum conditions for the maximum uptake of lead ions in 98.11% batch mode. Under the optimum conditions, the lead uptake was attained to be circa 8.60 mg/g.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
A novel preparation method of magnetized palm shell waste-based powdered activated carbon (MPPAC, avg. size 112 μm) was developed. The prepared MPPAC was assessed by several physicochemical analyses, and batch tests were performed for ibuprofen (IBP) removal. Field emission scanning electron microscopy (FESEM) and N2 gas isotherms revealed that magnetite and maghemite were homogeneous and deposited mostly on the surface of PPAC without a significant clogging effect on the micropores. Isotherm results showed that 3.8% Fe (w/w) impregnated PPAC [MPPAC-Fe(3.8%)] had about 2.2-fold higher maximum sorption capacity (157.3 mg g-1) and a 2.5-fold higher sorption density (0.23 mg m-2) than pristine PPAC. Both Fourier-transform infrared spectroscopy (FTIR) and isotherm data indicated that the high sorption capacity and density of IBP by MPPAC was primarily attributable to donor-acceptor complexes with the C = O group and dispersive π-π interactions with the carbon surface. Based on kinetic and repeated adsorption tests, pore diffusion was the rate-limiting step, and MPPAC-Fe(3.8%) had about 1.9~2.8- and 9.1~15.8-fold higher rate constants than MPPAC-Fe(8.6%) and palm shell-waste granular activated carbon (PGAC, avg. size 621 μm), respectively. MPPAC showed almost eight fold greater re-adsorption capacity than PPAC due to a thermal catalytic effect of magnetite/maghemite.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*
The effectiveness of combined nanofiltration and disinfection processes was studied by comparing the pre-disinfection and post-disinfection when in combination with nanofiltration. Four types of sulfonamide (sulfanilamide, sulfadiazine, sulfamethoxazole, and sulfadimethoxine) were chosen as substrates, with sodium hypochlorite as a disinfectant. A laboratory-scale nanofiltration system was used to conduct the following sets of experiment: (1) a pre-chlorination system, where the free active chlorine (FAC) was added to the membrane influent; and (2), a post-chlorination system, where the FAC was added to the membrane effluent. Overall, the pre-disinfection nanofiltration system showed higher sulfonamide removal efficiency compared to the post-chlorination nanofiltration system (>99.5% versus >89.5%). In the case of limited FAC ([FAC]0: [sulfonamide]0≤1), the removal efficiency for the post-chlorination nanofiltration system was higher, due to the prior nanofiltration process that could remove 12.5% to 80% of sulfonamide. The flux of the treated feed system was considerably higher than in the untreated feed system; however, the membrane was observed to be slightly damaged due to residual chlorine attack.
Matched MeSH terms: Water Pollutants, Chemical/isolation & purification*