The feasibility of preparing activated carbon (JPAC) from jackfruit peel, an industrial residue abundantly available from food manufacturing plants via microwave-assisted NaOH activation was explored. The influences of chemical impregnation ratio, microwave power and radiation time on the properties of activated carbon were investigated. JPAC was examined by pore structural analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption isotherm, elemental analysis, surface acidity/basicity and zeta potential measurements. The adsorptive behavior of JPAC was quantified using methylene blue as model dye compound. The best conditions resulted in JPAC with a monolayer adsorption capacity of 400.06 mg/g and carbon yield of 80.82%. The adsorption data was best fitted to the pseudo-second-order equation, while the adsorption mechanism was well described by the intraparticle diffusion model. The findings revealed the versatility of jackfruit peels as good precursor for preparation of high quality activated carbon.
The feasibility of langsat empty fruit bunch waste for preparation of activated carbon (EFBLAC) by microwave-induced activation was explored. Activation with NaOH at the IR ratio of 1.25, microwave power of 600 W for 6 min produced EFBLAC with a carbon yield of 81.31% and adsorption uptake for MB of 302.48 mg/g. Pore structural analysis, scanning electron microscopy and Fourier transform infrared spectroscopy demonstrated the physical and chemical characteristics of EFBLAC. Equilibrium data were best described by the Langmuir isotherm, with a monolayer adsorption capacity of 402.06 mg/g, and the adsorption kinetics was well fitted to the pseudo-second-order equation. The findings revealed the potential to prepare high quality activated carbon from langsat empty fruit bunch waste by microwave irradiation.
Filamentous fungi are able to accumulate significant amount of metals from their environment. The potential of fungal biomass as agents for biosorption of heavy metals from contaminated sediments is currently receiving attention. In the present study, a total of 41 isolates of filamentous fungi obtained from the sediment of the Langat River, Selangor, Malaysia were screened for their tolerance and uptake capability of copper (Cu) and lead (Pb). The isolates were identified as Aspergillus niger, A. fumigatus, Trichoderma asperellum, Penicillium simplicissimum and P. janthinellum. A. niger and P. simplicissimum, were able to survive at 1000 mg/L of Cu(II) concentration on Potato Dextrose Agar (PDA) while for Pb, only A. niger survived at 5000 mg/L concentration. The results showed that A. niger, P. simplicissimum and T. asperellum have a better uptake capacity for Pb compared to Cu and the findings indicated promising biosorption of Cu and Pb by these filamentous fungi from aqueous solution. The present study was also determined the maximum removal of Cu(II) and Pb(II) that was performed by A. niger. The metal removal which occurred at Cu(II) 200 mg/L was (20.910 +/- 0.581) mg/g and at 250 mg/L of Pb(II) was (54.046 +/- 0.328) mg/g.
The main objective of this work was to determine the effectiveness of various biofouling reducers (BFRs) to operational condition in hybrid membrane bioreactor (MBR) of palm oil mill effluent (POME). A series of tests involving three bench scale (100 L) hybrid MBR were operated at sludge retention times (SRTs) of 30 days with biofouling reducer (BFR). Three different biofouling reducers (BFRs) were powdered actived carbon (PAC), zeolite (Ze), and Moringa oleifera (Mo) with doses of 4, 8 and 12 g L(-1) respectively were used. Short-term filtration trials and critical flux tests were conducted. Results showed that, all BFRs successfully removed soluble microbial products (SMP), for PAC, Ze, and Mo at 58%, 42%, and 48%, respectively. At their optimum dosages, PAC provided above 70% reductions and 85% in fouling rates during the short-term filtration and critical flux tests.
The kinetic and thermodynamic adsorption and adsorption isotherms of Pb(II) and Cu(II) ions onto H(2)SO(4) modified chitosan were studied in a batch adsorption system. The experimental results were fitted using Freundlich, Langmuir and Dubinin-Radushkevich isotherms; the Langmuir isotherm showed the best conformity to the equilibrium data. The pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were employed to analyze the kinetic data. The adsorption behavior of Pb(II) and Cu(II) was best described by the pseudo-second order model. Thermodynamic parameters such as free energy change (DeltaG degrees ), enthalpy change (DeltaH degrees ) and entropy change (DeltaS degrees ) were determined; the adsorption process was found to be both spontaneous and exothermic. No physical damage to the adsorbents was observed after three cycles of adsorption/desorption using EDTA and HCl as eluents. The mechanistic pathway of the Pb(II) and Cu(II) uptake was examined by means of Fourier transform infrared (FTIR) and Energy dispersive X-ray (EDX) spectroscopy. The equilibrium parameter (R(L)) indicated that chitosan-H(2)SO(4) was favorable for Pb(II) and Cu(II) adsorption.
Rice husk is a base adsorbent for pollutant removal. It is a cost-effective material and a renewable resource. This study provides the physicochemical characterization of chemically and thermally treated rice husk adsorbents for phenol removal from aqueous solutions. We revealed new functional groups on rice husk adsorbents by Fourier transform infrared spectroscopy, and observed major changes in the pore structure (from macro-mesopores to micro-mesopores) of the developed rice husk adsorbents using scanning electron microscopy. Additionally, we studied their surface area and pore size distribution, and found a greater enhancement of the morphological structure of the thermally treated rice husk compared with that chemically treated. Thermally treated adsorbents presented a higher surface area (24-201 m2.g-1) than those chemically treated (3.2 m2.g-1). The thermal and chemical modifications of rice husk resulted in phenol removal efficiencies of 36%-64% and 28%, respectively. Thus, we recommend using thermally treated rice husk as a promising adsorbent for phenol removal from aqueous solutions.
Chitosan/PVA/Na-titanate/TiO2 composite was synthesized by solution casting method. The composite was analyzed via Fourier Transform Infrared Spectroscopy, X-ray diffraction, Field Emission Scanning Electron Microscopy, Thermal gravimetric analysis and water stability test. Incorporation of Na-titanate shown decrease of crystallinity for chitosan but increase water stability. However, the composite structure was deteriorated with considerable weight loss in acidic medium. Two anionic dyes, methyl orange and congo red were used for the adsorption test. The adsorption behavior of the composites were described by pseudo-second-order kinetic model and Lagergren-first-order model for methyl orange and congo red, respectively. For methyl orange, adsorption was started with a promising decolorization rate. 99.9% of methyl orange dye was removed by the composite having higher weightage of chitosan and crystalline TiO2 phase. On the other hand, for the congo red the composite having higher chitosan and Na-titanate showed an efficient removal capacity of 95.76%. UV-vis results showed that the molecular backbone of methyl orange and congo red was almost destroyed when equilibrium was obtained, and the decolorization rate was reaching 100%. Kinetic study results showed that the photocatalytic degradation of methyl orange and congo red could be explained by Langmuir-Hinshelwood model. Thus, chitosan/PVA/Na-titanate/TiO2 possesses efficient adsorptivity and photocatalytic property for dye degradation.
Multi-walled carbon nanotubes (MWCNTs) were prepared via chemical vapor deposition (CVD) using a series of different catalysts, derived from FeCoNiAl, CoNiAl and FeNiAl layered double hydroxides (LDHs). Catalyst-active particles were obtained by calcination of LDHs at 800 °C for 5 h. Nitrogen and hexane were used as the carrier gas and carbon source respectively, for preparation of MWCNTs using CVD methods at 800 °C. MWCNTs were allowed to grow for 30 min on the catalyst spread on an alumina boat in a quartz tube. The materials were subsequently characterized through X-ray diffraction, Fourier transform infrared spectroscopy, surface area analysis, field emission scanning electron microscopy and transmission electron microscopy. It was determined that size and yield of MWCNTs varied depending on the type of LDH catalyst precursor that is used during synthesis. MWCNTs obtained using CoNiAl-LDH as the catalyst precursor showed smaller diameter and higher yield compared to FeCoNiAl and FeNiAl LDHs.
The molecularly imprinted polymer (MIP) based on methacrylic acid functionalized β-cyclodextrin (MAA-β-CD) monomer was synthesized for the purpose of selective recognition of benzylparaben (BzP). The MAA-β-CD monomer was produced by bridging a methacrylic acid (MAA) and β-cyclodextrin (β-CD) using toluene-2,4-diisocyanate (TDI) by reacting the -OH group of MAA and one of the primary -OH groups of β-CD. This monomer comprised of triple interactions that included an inclusion complex, π-π interaction, and hydrogen bonding. To demonstrate β-CD performance in MIPs, two MIPs were prepared; molecularly imprinted polymer-methacrylic acid functionalized β-cyclodextrin, MIP(MAA-β-CD), and molecularly imprinted polymer-methacrylic acid, MIP(MAA); both prepared by a reversible addition fragmentation chain transfer polymerization (RAFT) in the bulk polymerization process. Both MIPs were characterized using the Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Brunauer-Emmett-Teller (BET). The presence of β-CD not only influenced the morphological structure, it also affected the specific surface area, average pore diameter, and total pore volume of the MIP. The rebinding of the imprinting effect was evaluated in binding experiments, which proved that the β-CD contributed significantly to the enhancement of the recognition affinity and selective adsorption of the MIP.
This article explains recent advances in the synthesis and characterization of novel titanium-based nanocomposite materials. Currently, it is a pressing concern to develop innovative skills for the fabrication of hybrid nanomaterials under varying experimental conditions. This review generally focuses on the adsorption behavior of nanocomposites for the exclusion of organic and inorganic pollutants from industrial effluents and their significant applications in various fields. The assessment of recently published articles on the conjugation of organic polymers with titanium has revealed that these materials may be a new means of managing aquatic pollution. These nanocomposite materials not only create alternative methods for designing novel materials, but also develop innovative industrial applications. In the future, titanium-based hybrid nanomaterials are expected to open new approaches for demonstrating their outstanding applications in diverse fields.
Nine solvents, namely, n-hexane, ethanol, acetonitrile, chloroform, ethyl-ether, ethyl-acetate, petroleum ether, n-butyl alcohol, and methanol were used to extract natural dyes from Cordyline fruticosa, Pandannus amaryllifolius and Hylocereus polyrhizus. To improve the adsorption of dyes onto the TiO2 particles, betalain and chlorophyll dyes were mixed with methanol or ethanol and water at various ratios. The adsorption of the dyes mixed with titanium dioxide (TiO2) was also observed. The highest adsorption of the C.fruticosa dye mixed with TiO2 was achieved at ratio 3:1 of methanol: water. The highest adsorption of P.amaryllifolius dye mixed with TiO2 was observed at 2:1 of ethanol: water. H.polyrhizus dye extracted by water and mixed with TiO2 demonstrated the highest adsorption among the solvents. All extracted dye was adsorbed onto the surface of TiO2 based on Fourier Transform Infrared Spectroscopy (FTIR) analysis. The inhibition of crystallinity of TiO2 was likewise investigated by X-ray analysis. The morphological properties and composition of dyes were analyzed via SEM and EDX.
Indian jujuba seed powder (IJSP) has been investigated as a low-cost and an eco-friendly biosorbent, prepared for the removal of Acid Blue 25 (AB25) from aqueous solution. The prepared biomaterial was characterized by using FTIR and scanning electron microscopic studies. The effect of operation variables, such as IJSP dosage, contact time, concentration, pH, and temperature on the removal of AB25 was investigated, using batch biosorption technique. Removal efficiency increased with increase of IJSP dosage but decreased with increase of temperature. The equilibrium data were analyzed by the Langmuir and the Freundlich isotherm models. The data fitted well with the Langmuir model with a maximum biosorption capacity of 54.95 mg g(-1). The pseudo-second-order kinetics was the best for the biosorption of AB25 by IJSP, with good correlation. Thermodynamic parameters such as standard free energy change (ΔG(0)), standard enthalpy changes (ΔH(0)), and standard entropy changes (ΔS(0)) were analyzed. The removal of AB25 from aqueous solution by IJSP was a spontaneous and exothermic adsorption process. The results suggest that IJSP is a potential low-cost and an eco-friendly biosorbent for the AB25 removal from synthetic AB25 wastewater.
The removal of toxic herbicide from wastewater is challenging due to the availability of suitable adsorbents. The Langsat empty fruit bunch is an agricultural waste and was used in this study as a cheap precursor to produce activated carbon for the adsorption of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at different initial concentrations ranging from 50 to 400 mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65 m(2)/g with different active functional groups. The effect of shaking time, temperature and pH on 2,4-D removal were investigated using the batch technique. The adsorption capacity of 2,4-D by LEFBAC was decreased with increase in pH of solution whereas adsorption capacity increased with temperature. The adsorption data was well described by Langmuir isotherm followed by removal capacity of 261.2 mg/g at 30 °C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater.
The purpose of this work is to remove Pb(II) from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-montmorillonite was prepared through emulsion polymerization method. Fourier transform infrared spectroscopy (FTIR), Solid carbon nuclear magnetic resonance spectroscopy (CNMR)), silicon(-29) nuclear magnetic resonance spectroscopy (Si NMR)), and X-ray diffraction spectroscope ((XRD) were applied to characterize the hydrogel composite. The hydrogel composite was then employed as an adsorbent for the removal of Pb(II) from the aqueous solution. The Pb(II)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy (FTIR)), scanning electron microscopy (SEM)), and X-ray photoelectron spectroscopy ((XPS)). From XPS results, it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(II). Kinetic studies indicated that the adsorption of Pb(II) followed the pseudo-second-order equation. It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm. The maximum removal capacity of the hydrogel composite for Pb(II) ions was 430mg/g. Thus, the waste linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(II) adsorbent.
The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature.
Many industries discharge untreated wastewater into the environment. Heavy metals from many industrial processes end up as hazardous pollutants of wastewaters.Heavy metal pollution has increased in recent decades and there is a growing concern for the public health risk they may pose. To remove heavy metal ions from polluted waste streams, adsorption processes are among the most common and effective treatment methods. The adsorbents that are used to remove heavy metal ions from aqueous media have both advantages and disadvantages. Cost and effectiveness are two of the most prominent criteria for choosing adsorbents. Because cost is so important, great effort has been extended to study and find effective lower cost adsorbents.One class of adsorbents that is gaining considerable attention is agricultural wastes. Among many alternatives, palm oil biomasses have shown promise as effective adsorbents for removing heavy metals from wastewater. The palm oil industry has rapidly expanded in recent years, and a large amount of palm oil biomass is available. This biomass is a low-cost agricultural waste that exhibits, either in its raw form or after being processed, the potential for eliminating heavy metal ions from wastewater. In this article, we provide background information on oil palm biomass and describe studies that indicate its potential as an alternative adsorbent for removing heavy metal ions from wastewater. From having reviewed the cogent literature on this topic we are encouraged that low-cost oil-palm-related adsorbents have already demonstrated outstanding removal capabilities for various pollutants.Because cost is so important to those who choose to clean waste streams by using adsorbents, the use of cheap sources of unconventional adsorbents is increasingly being investigated. An adsorbent is considered to be inexpensive when it is readily available, is environmentally friendly, is cost-effective and be effectively used in economical processes. The advantages that oil palm biomass has includes the following:available and exists in abundance, appears to be effective technically, and can be integrated into existing processes. Despite these advantages, oil palm biomasses have disadvantages such as low adsorption capacity, increased COD, BOD and TOC. These disadvantages can be overcome by modifying the biomass either chemically or thermally. Such modification creates a charged surface and increases the heavy metal ion binding capacity of the adsorbent.
The adsorption from aqueous solution of imidazolium, pyrrolidinium and pyridinium based bromide ionic liquids (ILs) having different alkyl chain lengths was investigated on two types of microporous activated carbons: a fabric and a granulated one, well characterized in terms of surface chemistry by "Boehm" titrations and pH of point of zero charge measurements and of porosity by N2 adsorption at 77 K and CO2 adsorption at 273 K. The influence of cation type, alkyl chain length and adsorbate size on the adsorption properties was analyzed by studying kinetics and isotherms of eight different ILs using conductivity measurements. Equilibrium studies were carried out at different temperatures in the range [25-55 °C]. The incorporation of ILs on the AC porosity was studied by N2 adsorption-desorption measurements at 77 K. The experimental adsorption isotherms data showed a good correlation with the Langmuir model. Thermodynamic studies indicated that the adsorption of ILs onto activated carbons was an exothermic process, and that the removal efficiency increased with increase in alkyl chain length, due to the increase in hydrophobicity of long chain ILs cations determined with the evolution of the calculated octanol-water constant (Kow). The negative values of free energies indicated that adsorption of ILs with long chain lengths having hydrophobic cations was more spontaneous at the investigated temperatures.
In this study, pyrolysis technique was utilized for converting palm oil sludge to value added materials: bio-oil (liquid fuel) and bio-char (soil amendment). The bio-oil yield obtained was 27.4±1.7 wt.% having a heating value of 22.2±3.7 MJ/kg and a negligible ash content of 0.23±0.01 wt.%. The pH of bio-oil was in alkaline region. The bio-char yielded 49.9±0.3 wt.%, which was further investigated for sorption efficiency by adsorbing metal (Cd(2+) ions) from water. The removal efficiency of Cd(2+) was 89.4±2%, which was almost similar to the removal efficiency of a commercial activated carbon. The adsorption isotherm was well described by Langmuir model. Therefore, pyrolysis is proved as an efficient tool for palm oil sludge management, where the waste was converted into valuable products.
This paper reports on the direct ability of two positively charged organic polyelectrolytes (natural-based and synthetic) to reduce the atrazine concentration in water. The adsorption study was set up using multiple glass vessels with different polymer dosing levels followed by ultrafiltration with a 1 kDa membrane. The addition of polymers exhibited a capability in reducing the atrazine concentration up to a maximum of 60% in surface-to-volume ratio experiments. In the beginning, the theoretical L-type of the isotherm of Giles' classification was expected with an increase in the dosage of the polymer. However, in this study, the conventional type of isotherm was not observed. It was found that the adsorption of the cationic polymer on the negatively charged glass surface was necessary and influential for the removal of atrazine. Surface-to-volume ratio adsorption experiments were performed to elucidate the mechanisms and the polymer configuration. The glass surface area was determined to be a limiting parameter in the adsorption mechanism.
Cyclodextrin-ionic liquid polymer (βCD-BIMOTs-TDI) is a new class of macroporous material and has great potential to be used as an SPE adsorbent material for extraction of phenols in river water samples. Six phenols, as model analytes, were extracted on a βCD-BIMOTs-TDI SPE cartridge, and then, eluted with 2 mL of methanol containing 1% acetic acid. The optimum experimental condition was 15 mL of sample volume (sample at pH 6) and 2 mL of methanol containing 1% acetic acid as an eluent solvent. The eluent concentration was determined by using Gas Chromatography-Flame Ionization Detector (GC-FID). Under optimized condition, high sensitivity (detection limits 0.23-0.35 µg/L) and good recoveries (87-116%) were achieved with satisfactory relative standard deviation (RSD) (0.1-1.7%). The developed βCD-BIMOTs-TDI-SPE was then compared with other adsorbents, and the obtained results showed that the βCD-BIMOTs-TDI exhibited higher extraction recovery due to the unique structure and properties. Finally, the βCD-BIMOTs-TDI was applied as a solid phase extraction sorbent for phenols determination under optimized condition, in river and tap waters, prior to the GC-FID separation.