Abstract: Ultrasound-aided adsorption of phenol by Granular Activated Carbon (GAC) was investigated at different frequencies ranging from 35 kHz, 58 kHz, and 192 kHz. Other factors influencing adsorption such as Adsorbent dosage (g/L), the initial concentration of the phenol solution (ppm) and RPM was also considered along with the frequency variable. However, this study involved calorimetric measurements which helped is determining the effect of frequency on the % removal of phenol from the power dissipated to the system was normalized. It was found that low frequency (35 kHz) cavitation effects had a profound influence on the % removal of phenol per unit power. This study also had cavitation mapping of the ultrasonic baths, and it showed that the effect of cavitation on the adsorption system is irrespective of the position of the vessel. Hence, the vessel was placed at the center of the bath. In this study, novel temperature control and monitoring system to make sure that the system is under proper condition while operations. From the BET studies, it was found that there was only 5% increase in the surface area and hence it was concluded that ultrasound doesn’t profoundly alter the equilibrium value of the adsorption system. DOE studies indicated that adsorbent dosage has a higher influence on the % removal in comparison with other factors.
Abstract: The textile industry produces high amount of colored effluent each year. The management or treatment of these discharges depends on the applied techniques. Adsorption is one of wastewater treatment techniques destined to treat this kind of pollution, and the performance and efficiency predominantly depend on the nature of the adsorbent used. Therefore, scientific research is directed towards the development of new materials using different physical and chemical treatments to improve their adsorption capacities. In the same perspective, we looked at the effect of the heat treatment on the effectiveness of diatomite, which is found in abundance in Algeria. The textile dye Orange Bezaktiv (SRL-150) which is used as organic pollutants in this study is provided by the textile company SOITEXHAM in Oran city (west Algeria). The effect of different physicochemical parameters on the adsorption of SRL-150 on natural and modified diatomite is studied, and the results of the kinetics and adsorption isotherms were modeled.
Abstract: The present study presents, firstly, to characterize the physicochemical quality of brackish groundwater of the Terminal Complex (TC) from the region of Eloued-souf and to investigate the presence of fluoride, and secondly, to study the comparison of adsorbing power of three materials, such as (activated alumina AA, sodium clay SC and hydroxyapatite HAP) against the groundwater in the region of Eloued-souf. To do this, a sampling campaign over 16 wells and consumer taps was undertaken. The results show that the groundwater can be characterized by very high fluoride content and excessive mineralization that require in some cases, specific treatment before supply. The study of adsorption revealed removal efficiencies fluoride by three adsorbents, maximum adsorption is achieved after 45 minutes at 90%, 83.4% and 73.95%, and with an adsorbed fluoride content of 0.22 mg/L, 0.318 mg/L and 0.52 mg/L for AA, HAP and SC, respectively. The acidity of the medium significantly affects the removal fluoride. Results deducted from the adsorption isotherms also showed that the retention follows the Langmuir model. The adsorption tests by adsorbent materials show that the physicochemical characteristics of brackish water are changed after treatment. The adsorption mechanism is an exchange between the OH- ions and fluoride ions. Three materials are proving to be effective adsorbents for fluoride removal that could be developed into a viable technology to help reduce the salinity of the Saharan hyper-fluorinated waters. Finally, a comparison between the results obtained from the different adsorbents allowed us to conclude that the defluoridation by AA is the process of choice for many waters of the region of Eloued-souf, because it was shown to be a very interesting and promising technique.
Abstract: In this study, Pb2+ uptake by the hydroxyapatite nanopowders (n-Hap) from aqueous solutions was investigated by using batch adsorption techniques. The adsorption equilibrium studies were carried out as a function of contact time, adsorbent dosage, pH, temperature, and initial Pb2+ concentration. The results showed that the equilibrium time of adsorption was achieved within 60 min, and the effective pH was selected to be 5 (natural pH). The maximum adsorption capacity of Pb2+ on n-Hap was found as 565 mg.g-1. It is believed that the results obtained for adsorption may provide a background for the detailed mechanism investigations and the pilot and industrial scale applications.
Abstract: In this study, pomegranate skin, a material suitable for the conditions in Algeria, was chosen as adsorbent material for removal of lead in an aqueous solution. Biosorption studies were carried out under various parameters such as mass adsorbent particle, pH, contact time, the initial concentration of metal, and temperature. The experimental results show that the percentage of biosorption increases with an increase in the biosorbent mass (0.25 g, 0.035 mg/g; 1.25 g, 0.096 mg/g). The maximum biosorption occurred at pH value of 8 for the lead. The equilibrium uptake was increased with an increase in the initial concentration of metal in solution (Co = 4 mg/L, qt = 1.2 mg/g). Biosorption kinetic data were properly fitted with the pseudo-second-order kinetic model. The best fit was obtained by the Langmuir model with high correlation coefficients (R2 > 0.995) and a maximum monolayer adsorption capacity of 0.85 mg/g for lead. The adsorption of the lead was exothermic in nature (ΔH° = -17.833 kJ/mol for Pb (II). The reaction was accompanied by a decrease in entropy (ΔS° = -0.056 kJ/K. mol). The Gibbs energy (ΔG°) increased from -1.458 to -0.305 kJ/mol, respectively for Pb (II) when the temperature was increased from 293 to 313 K.
Abstract: Environmental contamination is a major problem being faced by the society today. Industrial, agricultural, and domestic wastes, due to the rapid development in the technology, are discharged in the several receivers. Generally, this discharge is directed to the nearest water sources such as rivers, lakes, and seas. While the rates of development and waste production are not likely to diminish, efforts to control and dispose of wastes are appropriately rising. Wastewaters from textile industries represent a serious problem all over the world. They contain different types of synthetic dyes which are known to be a major source of environmental pollution in terms of both the volume of dye discharged and the effluent composition. From an environmental point of view, the removal of synthetic dyes is of great concern. Among several chemical and physical methods, adsorption is a promising technique due to the ease of use and low cost compared to other applications in the process of discoloration, especially if the adsorbent is inexpensive and readily available. The focus of the present study was to assess the potentiality of Brahea edulis (BE) for the removal of synthetic dye Yellow bemacid (YB) from aqueous solutions. The results obtained here may transfer to other dyes with a similar chemical structure. Biosorption studies were carried out under various parameters such as mass adsorbent particle, pH, contact time, initial dye concentration, and temperature. The biosorption kinetic data of the material (BE) was tested by the pseudo first-order and the pseudo-second-order kinetic models. Thermodynamic parameters including the Gibbs free energy ΔG, enthalpy ΔH, and entropy ΔS have revealed that the adsorption of YB on the BE is feasible, spontaneous, and endothermic. The equilibrium data were analyzed by using Langmuir, Freundlich, Elovich, and Temkin isotherm models. The experimental results show that the percentage of biosorption increases with an increase in the biosorbent mass (0.25 g: 12 mg/g; 1.5 g: 47.44 mg/g). The maximum biosorption occurred at around pH value of 2 for the YB. The equilibrium uptake was increased with an increase in the initial dye concentration in solution (Co = 120 mg/l; q = 35.97 mg/g). Biosorption kinetic data were properly fitted with the pseudo-second-order kinetic model. The best fit was obtained by the Langmuir model with high correlation coefficient (R2 > 0.998) and a maximum monolayer adsorption capacity of 35.97 mg/g for YB.
Abstract: The proposed method for speciation, preconcentration and determination of Fe(II) and Fe(III) in pharmaceutical products was developed using of alumina-coated magnetite nanoparticles (Fe3O4/Al2O3 NPs) as solid phase extraction (SPE) sorbent in magnetic mixed hemimicell solid phase extraction (MMHSPE) technique followed by flame atomic absorption spectrometry analysis. The procedure is based on complexation of Fe(II) with 1, 10-phenanthroline (OP) as complexing reagent for Fe(II) that immobilized on the modified Fe3O4/Al2O3 NPs. The extraction and concentration process for pharmaceutical sample was carried out in a single step by mixing the extraction solvent, magnetic adsorbents under ultrasonic action. Then, the adsorbents were isolated from the complicated matrix easily with an external magnetic field. Fe(III) ions determined after facility reduced to Fe(II) by added a proper reduction agent to sample solutions. Compared with traditional methods, the MMHSPE method simplified the operation procedure and reduced the analysis time. Various influencing parameters on the speciation and preconcentration of trace iron, such as pH, sample volume, amount of sorbent, type and concentration of eluent, were studied. Under the optimized operating conditions, the preconcentration factor of the modified nano magnetite for Fe(II) 167 sample was obtained. The detection limits and linear range of this method for iron were 1.0 and 9.0 - 175 ng.mL−1, respectively. Also the relative standard deviation for five replicate determinations of 30.00 ng.mL-1 Fe2+ was 2.3%.
Abstract: The aim of this work is to present a low cost adsorbent
for removing toxic heavy metals from aqueous solutions. Therefore,
we are interested to investigate the efficiency of natural clay minerals
collected from south Tunisia and their modified form using sulfuric
acid in the removal of toxic metal ions: Zn(II) and Pb(II) from
synthetic waste water solutions. The obtained results indicate that
metal uptake is pH-dependent and maximum removal was detected to
occur at pH 6. Adsorption equilibrium is very rapid and it was
achieved after 90 min for both metal ions studied. The kinetics results
show that the pseudo-second-order model describes the adsorption
and the intraparticle diffusion models are the limiting step. The
treatment of natural clay with sulfuric acid creates more active sites
and increases the surface area, so it showed an increase of the
adsorbed quantities of lead and zinc in single and binary systems. The
competitive adsorption study showed that the uptake of lead was
inhibited in the presence of 10 mg/L of zinc. An antagonistic binary
adsorption mechanism was observed. These results revealed that clay
is an effective natural material for removing lead and zinc in single
and binary systems from aqueous solution.
Abstract: Textile industries cater to varied customer preferences and contribute substantially to the economy. However, these textile industries also produce a considerable amount of effluents. Prominent among these are the azo dyes which impart considerable color and toxicity even at low concentrations. Azo dyes are also used as coloring agents in food and pharmaceutical industry. Despite their applications, azo dyes are also notorious pollutants and carcinogens. Popular techniques like photo-degradation, biodegradation and the use of oxidizing agents are not applicable for all kinds of dyes, as most of them are stable to these techniques. Chemical coagulation produces a large amount of toxic sludge which is undesirable and is also ineffective towards a number of dyes. Most of the azo dyes are stable to UV-visible light irradiation and may even resist aerobic degradation. Adsorption has been the most preferred technique owing to its less cost, high capacity and process efficiency and the possibility of regenerating and recycling the adsorbent. Adsorption is also most preferred because it may produce high quality of the treated effluent and it is able to remove different kinds of dyes. However, the adsorption process is influenced by many variables whose inter-dependence makes it difficult to identify optimum conditions. The variables include stirring speed, temperature, initial concentration and adsorbent dosage. Further, the internal diffusional resistance inside the adsorbent particle leads to slow uptake of the solute within the adsorbent. Hence, it is necessary to identify optimum conditions that lead to high capacity and uptake rate of these pollutants. In this work, commercially available activated carbon was chosen as the adsorbent owing to its high surface area. A typical azo dye found in textile effluent waters, viz. the monoazo Acid Orange 10 dye (CAS: 1936-15-8) has been chosen as the representative pollutant. Adsorption studies were mainly focused at obtaining equilibrium and kinetic data for the batch adsorption process at different process conditions. Studies were conducted at different stirring speed, temperature, adsorbent dosage and initial dye concentration settings. The Full Factorial Design was the chosen statistical design framework for carrying out the experiments and identifying the important factors and their interactions. The optimum conditions identified from the experimental model were validated with actual experiments at the recommended settings. The equilibrium and kinetic data obtained were fitted to different models and the model parameters were estimated. This gives more details about the nature of adsorption taking place. Critical data required to design batch adsorption systems for removal of Acid Orange 10 dye and identification of factors that critically influence the separation efficiency are the key outcomes from this research.
Abstract: This paper describes the use of by-products as
adsorbents for removing heavy metals from aqueous effluent
solutions. Products of almond skin, walnut shell, saw dust, rice bran
and egg shell were evaluated as metal ion adsorbents in aqueous
solutions. A comparative study was done with commercial adsorbents
like ion exchange resins and activated carbon too. Batch experiments
were investigated to determine the affinity of all of biomasses for,
Cd(ΙΙ), Cr(ΙΙΙ), Ni(ΙΙ), and Pb(ΙΙ) metal ions at pH 5. The rate of
metal ion removal in the synthetic wastewater by the biomass was
evaluated by measuring final concentration of synthetic wastewater.
At a concentration of metal ion (50 mg/L), egg shell adsorbed high
levels (98.6 – 99.7%) of Pb(ΙΙ) and Cr(ΙΙΙ) and walnut shell adsorbed
high levels (35.3 – 65.4%) of Ni(ΙΙ) and Cd(ΙΙ). In this study, it has
been shown that by-products were excellent adsorbents for removal
of toxic ions from wastewater with efficiency comparable to
commercially available adsorbents, but at a reduced cost. Also
statistical studies using Independent Sample t Test and ANOVA Oneway
for statistical comparison between various elements adsorption
showed that there isn’t a significant difference in some elements
adsorption percentage by by-products and commercial adsorbents.
Abstract: Bisphenol A (BPA) is an organic synthetic compound that has many applications in various industries and is known as persistent pollutant. The aim of this research was to evaluate the efficiency of bone ash and banana peel as adsorbents for BPA adsorption from aqueous solution by using Response Surface Methodology. The effects of some variables such as sorbent dose, detention time, solution pH, and BPA concentration on the sorption efficiency was examined. All analyses were carried out according to Standard Methods. The sample size was performed using Box-Benken design and also optimization of BPA removal was done using response surface methodology (RSM). The results showed that the BPA adsorption increases with increasing of contact time and BPA concentration. However, it decreases with higher pH. More adsorption efficiency of a banana peel is very smaller than a bone ash so that BPA removal for bone ash and banana peel is 62 and 28 percent, respectively. It is concluded that a bone ash has a good ability for the BPA adsorption.
Abstract: Heavy metals have a damaging impact for the environment, animals and humans due to their extreme toxicity and removing them from wastewaters is a very important and interesting task in the field of water pollution control. Biosorption is a relatively new method for treatment of wastewaters and recovery of heavy metals. In this study, a continuous fixed bed study was carried out by using Bacillus thuringiensis as a biosorbent for the removal of Cu and Mn ions from Sarcheshmeh Acid Mine Drainage (AMD). The effect of operating parameters such as flow rate and bed height on the sorption characteristics of B. thuringiensis was investigated at pH 6.0 for each metal ion. The experimental results showed that the breakthrough time decreased with increasing flow rate and decreasing bed height. The data also indicated that the equilibrium uptake of both metals increased with decreasing flow rate and increasing bed height. BDST, Thomas, and Yoon–Nelson models were applied to experimental data to predict the breakthrough curves. All models were found suitable for describing the whole dynamic behavior of the column with respect to flow rate and bed height. In order to regenerate the adsorbent, an elution step was carried out with 1 M HCl and five adsorption-desorption cycles were carried out in continuous manner.
Abstract: The discharge of dye in industrial effluents is of great concern because their presence and accumulation have a toxic or carcinogenic effect on living species. The removal of such compounds at such low levels is a difficult problem. The adsorption process is an effective and attractive proposition for the treatment of dye contaminated wastewater. Activated carbon adsorption in fixed beds is a very common technology in the treatment of water and especially in processes of decolouration. However, it is expensive and the powdered one is difficult to be separated from aquatic system when it becomes exhausted or the effluent reaches the maximum allowable discharge level. The regeneration of exhausted activated carbon by chemical and thermal procedure is also expensive and results in loss of the sorbent. The focus of this research was to evaluate the adsorption potential of the raw clay in removing rhodamine B from aqueous solutions using a laboratory fixed-bed column. The continuous sorption process was conducted in this study in order to simulate industrial conditions. The effect of process parameters, such as inlet flow rate, adsorbent bed height, and initial adsorbate concentration on the shape of breakthrough curves was investigated. A glass column with an internal diameter of 1.5 cm and height of 30 cm was used as a fixed-bed column. The pH of feed solution was set at 8.5. Experiments were carried out at different bed heights (5 - 20 cm), influent flow rates (1.6- 8 mL/min) and influent rhodamine B concentrations (20 - 80 mg/L). The obtained results showed that the adsorption capacity increases with the bed depth and the initial concentration and it decreases at higher flow rate. The column regeneration was possible for four adsorption–desorption cycles. The clay column study states the value of the excellent adsorption capacity for the removal of rhodamine B from aqueous solution. Uptake of rhodamine B through a fixed-bed column was dependent on the bed depth, influent rhodamine B concentration, and flow rate.
Abstract: Fixed bed adsorption has become a frequently used
industrial application in wastewater treatment processes. Various low
cost adsorbents have been studied for their applicability in treatment
of different types of effluents. In this work, the intention of the study
was to explore the efficacy and feasibility for azo dye, Acid Orange 7
(AO7) adsorption onto fixed bed column of NaOH Treated eggshell
(TES). The effect of various parameters like flow rate, initial dye
concentration, and bed height were exploited in this study. The
studies confirmed that the breakthrough curves were dependent on
flow rate, initial dye concentration solution of AO7 and bed depth.
The Thomas, Yoon–Nelson, and Adams and Bohart models were
analysed to evaluate the column adsorption performance. The
adsorption capacity, rate constant and correlation coefficient
associated to each model for column adsorption was calculated and
mentioned. The column experimental data were fitted well with
Thomas model with coefficients of correlation R2 ≥0.93 at different
conditions but the Yoon–Nelson, BDST and Bohart–Adams model
(R2=0.911), predicted poor performance of fixed-bed column. The
(TES) was shown to be suitable adsorbent for adsorption of AO7
using fixed-bed adsorption column.
Abstract: Flue gas desulfurization gypsum (FGD) is a waste
material arouse from coal power plants. Hydroxyapatite (HAP) is a
biomaterial with porous structure. In this study, FGD gypsum which
retrieved from coal power plant in Turkey was characterized and
HAP particles which can be used as an adsorbent in wastewater
treatment application were synthesized from the FGD gypsum. The
raw materials are characterized by using X Ray Diffraction (XRD)
and Fourier transform infrared spectroscopy (FT-IR) techniques and
produced HAP are characterized by using XRD. As a result, HAP
particles were synthesized at the molar ratio of 5:10, 5:15, 5:20, 5:24,
at room temperature, in alkaline medium (pH=11) and in 1 hour-reaction
time. Among these conditions, 5:20 had the best result.
Abstract: The present study investigates the effectiveness of
newly designed clayey pellets (fired clay pellets diameter sizes of 5
and 8 mm, and unfired clay pellets with the diameter size of 15 mm)
as the beds in the column adsorption process. The adsorption
experiments in the batch mode were performed before the column
experiment with the purpose to determine the order of adsorbent
package in the column which was to be designed in the investigation.
The column experiment was performed by using a known mass of the
clayey beds and the volume of the waste printing developer, which
was purified. The column was filled in the following order: fired clay
pellets of the diameter size of 5 mm, fired clay pellets of the diameter
size of 8 mm, and unfired clay pellets of the diameter size of 15 mm.
The selected order of the adsorbents showed a high removal
efficiency for zinc (97.8%) and copper (81.5%) ions. These
efficiencies were better than those in the case of the already existing
mode adsorption. The obtained experimental data present a good
basis for the selection of an appropriate column fill, but further
testing is necessary in order to obtain more accurate results.
Abstract: Constructed Wetland (CW) is a reasonable method to
treat wastewater. Current study was carried out to co-treat landfill
leachate and domestic wastewater using a CW system. Typha
domingensis was transplanted to CW, which encloses two substrate
layers of adsorbents named ZELIAC and zeolite. Response surface
methodology and central composite design were employed to
evaluate experimental data. Contact time (h) and leachate-towastewater
mixing ratio (%; v/v) were selected as independent
factors. Phenols and manganese removal were selected as dependent
responses. At optimum contact time (48.7 h) and leachate-towastewater
mixing ratio (20.0%), removal efficiencies of phenols and
manganese removal efficiencies were 90.5%, and 89.4%,
respectively.
Abstract: Superabsorbent polymers received much attention and
are used in many fields because of their superior characters to
traditional absorbents, e.g., sponge and cotton. So, it is very
important but challenging to prepare highly and fast-swelling
superabsorbents. A reliable, efficient and low-cost technique for
removing heavy metal ions from wastewater is the adsorption using
bio-adsorbents obtained from biological materials, such as
polysaccharides-based hydrogels superabsorbents. In this study, novel multi-functional superabsorbent composites
type semi-interpenetrating polymer networks (Semi-IPNs) were
prepared via graft polymerization of acrylamide onto chitosan
backbone in presence of gelatin, CTS-g-PAAm/Ge, using potassium
persulfate and N,N’-methylene bisacrylamide as initiator and
crosslinker, respectively. These hydrogels were also partially
hydrolyzed to achieve superabsorbents with ampholytic properties
and uppermost swelling capacity. The formation of the grafted
network was evidenced by Fourier Transform Infrared Spectroscopy
(ATR-FTIR) and Thermogravimetric Analysis (TGA). The porous
structures were observed by Scanning Electron Microscope (SEM).
From TGA analysis, it was concluded that the incorporation of the Ge
in the CTS-g-PAAm network has marginally affected its thermal
stability. The effect of gelatin content on the swelling capacities of
these superabsorbent composites was examined in various media
(distilled water, saline and pH-solutions). The water absorbency was
enhanced by adding Ge in the network, where the optimum value was
reached at 2 wt. % of Ge. Their hydrolysis has not only greatly
optimized their absorption capacity but also improved the swelling
kinetic.These materials have also showed reswelling ability. We
believe that these super-absorbing materials would be very effective
for the adsorption of harmful metal ions from wastewater.
Abstract: Due to the resultant leachate from waste
decomposition in landfills has polluter potential hundred times
greater than domestic sewage, this is considered a problem related to
the depreciation of environment requiring pre-disposal treatment.In
seeking to improve this situation, this project proposes the treatment
of landfill leachate using natural fibers intercropped with advanced
oxidation processes. The selected natural fibers were palm, coconut
and banana fiber.These materials give sustainability to the project
because, besides having adsorbent capacity, are often part of waste
discarded. The study was conducted in laboratory scale.In trials, the
effluents were characterized as Chemical Oxygen Demand (COD),
Turbidity and Color. The results indicate that is technically
promising since that there were extremely oxidative conditions, the
use of certain natural fibers in the reduction of pollutants in leachate
have been obtained results of COD removals between 67.9% and
90.9%, Turbidity between 88.0% and 99.7% and Color between
67.4% and 90.4%.The expectation generated is to continue evaluating
the association of efficiency of other natural fibers with other landfill
leachate treatment processes.
Abstract: Many water desalination technologies have been
developed but in general they are energy intensive and have high cost
and adverse environmental impact. Recently, adsorption technology
for water desalination has been investigated showing the potential of
using low temperature waste heat (50-85oC) thus reducing energy
consumption and CO2 emissions. This work mathematically
compares the performance of an adsorption cycle that produces two
useful effects namely, fresh water and cooling using two different
adsorbents, silica-gel and an advanced zeolite material AQSOA-ZO2,
produced by Mitsubishi plastics. It was found that at low chilled
water temperatures, typically below 20oC, the AQSOA-Z02 is more
efficient than silica-gel as the cycle can produce 5.8 m3 of fresh water
per day and 50.1 Rton of cooling per tonne of AQSOA-ZO2. Above
20oC silica-gel is still better as the cycle production reaches 8.4 m3
per day and 62.4 Rton per tonne of silica-gel. These results show the
potential of using the AQSOA-Z02 at low chilled water temperature
for water desalination and cooling applications.