Algerian Journal of Engineering and Technology (AJET)
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Experimental and quantum chemical investigation for the single and competitive adsorption of cationic dyes onto activated carbon.
No full textSingle and competitive adsorption studies were performed to scrutinize the removal of two cationic dyes, namely, crystal violet (CV) and malachite green (MG) by adsorption onto activated carbon (BAC) derived from Balanites aegyptiaca seed shell. The BAC was characterized via scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and pH of point of zero charge (pHpzc) analysis. The physicochemical parameters influencing the adsorption process, namely, pH, contact time, adsorbent weight, initial concentration, temperature and ionic strength were examined. Moreover, Density Functional Theory (DFT) studies were performed to investigate the chemical reactivity of the dye molecules. Experimental results indicated that maximum adsorption of both dyes was achieved at pH 8.0 and equilibrium was attained after contact time of 50 min for MG and 60 min for CV. The competitive adsorption results showed lower adsorption capacities as compared to the single adsorption results indicating antagonistic interaction. Isotherm and kinetic models were employed for fitting the experimental data. The sorption kinetics was found to obey the pseudo second order model. The equilibrium data suggests that Freundlich model could represent the dyes uptake onto the adsorbent. Thermodynamic analysis revealed that the adsorption is a spontaneous and endothermic process. The quantum chemical investigation performed on the tested dyes using DFT method have affirmed that the MG molecules are more reactive (∆E = 1.236 eV), electrophilic and have the capacity to adsorb strongly on the BAC surface compared to the CV (∆E = 1.476 eV). The results attested that BAC has great potential for cationic dyes adsorption from aqueous environment
 
Geotechnical properties of some selected lateritic soils stabilized with cassava peel ash and lime
Get PDFThis study presents the influence of cassava peel ash (CPA) and lime on some geotechnical properties of three lateritic soils. This is with a view to the use of locally available agricultural waste in stabilising lateritic soils. Soil samples (termed A, B, and C) were collected from three different locations in Osun state, South West, Nigeria. Some properties such as particle size distribution, liquid limit (LL), plastic limit (PL), Compaction properties (optimum moisture content, OMC and Maximum dry density, MDD), California bearing ratio (CBR) and unconfined compressive strength (UCS) of the soil samples were determined. Cassava peel collected from a cassava processing factory was calcined at 700oC and CPA produced was sieved through sieve No. 40. Different percentages, 2, 4, 6, 8% (by weight of dry soil) of CPA and a fixed percentage (4%) of lime were mixed with the lateritic soil. Lime was added to supply calcium ion (Ca2+) needed for formation of Calcium Silicate stabilising compounds. The LL, PL, OMC, MDD, CBR and UCS of the stabilised soil samples were determined. There was a general improvement in the geotechnical properties of the soil (especially samples A and B) with about 20% reduction in LL, 38% increase in CBR, 120% increase in UCS. The study revealed that a combination of CPA and lime has the potential of improving the geotechnical properties of fine grained lateritic soil.
 
Hexavalent chromium removal from simulated wastewater using biomass-based activated carbon: kinetics, mechanism, thermodynamics and regeneration studies
No full textIn this study, activated carbon (ACBA) was fabricated from Balanites aegyptiaca seed shell (BASS) using a two-step H3PO4 activation approach and was tested for the adsorption of toxic hexavalent chromium [Cr(VI)] from simulated wastewater. The surface properties, morphology, and elemental composition of the prepared ACBA were examined via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface area analyses. The influence of various operating conditions such as pH, adsorbent amount, contact time and temperature was investigated. Kinetic studies indicated that the pseudo second order model was able to provide a realistic description of the adsorption kinetics and that film diffusion was the dominating mechanism of the sorption process. The adsorption activation energy evaluated using kinetic data suggested physical nature of Cr(VI) adsorption onto the carbon surface. Thermodynamic investigation confirmed that the adsorption was spontaneous and endothermic in nature. Regeneration tests demonstrated that 0.2 M NaOH can appreciably desorb Cr(VI) from Cr(VI)-loaded ACBA and the regenerated adsorbent can be used for six successive adsorption-desorption cycles while sustaining an adsorption efficiency of 80.10%. Altogether, the ACBA showed high adsorptive performance, fast kinetics and reuse potential, indicating the suitability of its application in wastewater treatment.
 
Comparative studies of the curing and hardening process of soaps produced from locally processed saturated and unsaturated fatty acids
Get PDFThis paper presents a comparative study of the curing and hardening processes of five soaps produced from Nigerian local oils (Palm oil, Palm-kernel Oil, Groundnut oil, Shea-butter oil and Tallow oil). The curing process was investigated by drying the soap samples under natural conditions and obtaining their daily moisture loss for duration of 21 days. Hardness tests based on the Brinell Hardness Methodology was conducted using a locally improvised manual indenter with a test load of 6.585kgf or 64.553N. Graphical plots of the moisture loss versus a one day time interval showed that all the soaps exhibited similar behaviour in the curing process, characterized by exponential decay in the rate of moisture loss. Superimposition of the curves into one graph showed very close fitting between the curves, indicating that the rates of moisture loss are very close. Graphs of the hardening process of the soaps showed that there are similarities in the hardening behaviour of the soaps with the curves exhibiting two hardening regions, a region of non-linear hardening and a region of constant hardening. Results showed that the hardness of the soaps varies in this order: tallow (1.88 HN) >shea butter (0.3 HN) >palm kernel (0.25 HN >palm Oil (0.15 HN) > groundnut oil (0.13 HN).
 
A new design of square paralelipedic treatment chamber for food processing using pulsed electric field
No full textToday, the influence of pulsed electric field is one of the key components in the PEF treatment process. The manuscript focused on the design and development of new multiple square paralelipedic PEF treatment chamber (TC2) which houses several electrodes, and testing the efficacy of this chamber on beet juice extraction compared with a single square paralelipedic treatment chamber (TC1) which houses only two electrodes. The aim of this paper to mention the effect of the Electric Field distribution based on Response Surface Modeling (RSM) for identifying the set point of the juice extraction process using pulsed electric field pre-treatment using a laboratory experimental bench. Obtained results show that the TC2 of PEF treatment has significant effect not only in juice yield, but also for enhancement of the betanin concentration and saving in consumed energy.
 
Equilibrium binding constants of Tris-(3,4,7,8-Tetramethyl-1,10-phenanthroline)Iron(II) Sulphate and Tris-(4,7- dimethyl-1,10-phenanthroline)Iron(II) Perchlorate with Sodium Dodecyl Sulphate. A comparative study
Get PDFBinding constants were investigated with a double beam unicam UV-Visible spectrophotometer at maximum absorption peaks (λmax) of 500nm and 510 nm for tris– (3,4,7,8 – tetramethyl -1,10- phenanthroline)iron(II) sulphate and Tris- (4,7-dimethyl –1,10 – phenanthroline)iron(II) perchlorate, respectively and the data were analyzed using double reciprocal plots. Absorbances were taken at fixed concentration of the metal complexes and the concentrations of sodium dodecyl sulphate (SDS) were far less than the critical micelle concentration (CMC). The effect of alkaline, acid, benzoate ion and urea on binding constants were investigated. Binding between Tris-(4,7-dimethyl-1,10-phenanthroline)Iron(II) Perchlorate(Fe(Me2phen)32+ and Sodium dodecyl sulphate was accelerated at low [H+] = 1.00 10-4 mol dm-3 and decreased at higher acid concentrations. However, binding was enhanced in the presence of hydroxyl ion, benzoate ion and urea. Furthermore, binding between Tris-(3,4,7,8-Tetramethyl-1,10-phenanthroline)Iron(II) Sulphate and sodium dodecyl sulphate was accelerated at low[H+] = 1.00 10-4 mol dm-3 to reach a maximum at [H+] = 2.00 x 10-4 mol dm-3 after which it decreased at higher acid concentrations. However, binding was retarded in the presence of hydroxyl ion and urea but enhanced in benzoate ion
Comparative studies between aluminium sulphate, moringa seed and green plantain peel as coagulants
Get PDFAluminium sulphate (alum) is the most commonly and widely used coagulant in water treatment plants however, literatures have revealed that it has certain setbacks that needs to be addressed including imparting acidity and hardness to water. Hence, the coagulation capacities of the seeds of moringa (Moringa oleifera) and peels of unripe or green plantain (Musa paradisiaca) which are abundantly available and currently considered as waste in most developing countries, were investigated in comparison with alum. This was achieved by using standard methods to treat raw water at different dosages of coagulants (100-600mg/l) prepared from moringa seed and plantain peel, and comparing the performances of these coagulants with that of aluminium sulphate (alum) used in treating same raw water at same dosages. Parameters checked are turbidity, pH and hardness. Results showed that alum performed best in terms of turbidity removal followed by moringa seed solution and then plantain peel solution. This is because alum reduced the water turbidity by 99.94% at an optimum dosage of 100mg/l while moringa seed and plantain peel solutions reduced the turbidity by 80.27% at 300mg/l and 63.99% at 500mg/l respectively. Nevertheless, it was noted that at optimum dosage of alum, the water pH was reduced from 6.7 to 6.2 as against the WHO permissible limits (6.5 – 8.5), and the harness level was increased by 22.43%. On the contrary, at the optimum dosages of moringa seed and plantain peel solutions, the pH were raised to 7.3 and 7.5 respectively, which is within the permissible limits and also, the hardness levels were reduced by 13.41% and 8.52% respectively. It was concluded that moringa seed solution could replace alum successfully but plantain peel solution needs modifications in order to improve the turbidity removal capacity before replacing alum although, it could be used in the absence of other conventional coagulants
Equilibrium, kinetics and isotherm studies of Cadmium (II) adsorption from aqueous solution utilizing Cane Papyrus
Get PDFCadmium(II) ions is a very toxic element known to cause detrimental effects to human health even at very low concentrations. Cane Papyrus was prepared form the marsh in south of Iraq, as adsorbent to Cadmium(II) ions adsorption from aqueous solution. Completed the analysis by using Fourier transform infra-red and notes presence of amino (–NH), carbonyl (–C=O) and hydroxyl (–OH) functional groups. Batch experiments were performed on simulated aqueous solutions under optimized conditions of adsorbent dosage, contact time, pH and initial Cadmium(II) ions concentration at 25Co. The Freundlich isotherm model more suitably described the adsorption process than the Langmuir model with linearized coefficients of 0.986 and 0.9733, respectively. Pseudo-second order kinetic equation best described the kinetics of the reaction. Furthermore, 1M HCl was a better desorbing agent than 1M NaOH and de-ionized water. The experimental data obtained demonstrated that Cane Papyrus can be used as a suitable adsorbent for Cadmium(II) ions removal from wastewater.
 
Statistical analysis and Response Surface Modelling of the compressive strength inhibition of crude oil in concrete test cubes
Get PDFThe use of crude oil contaminated fine aggregates in the production of concrete significantly affect the properties of such concrete, especially the compressive strength. In the present investigation, response surface methodology (RSM) of the Design-Expert software version 11.1.0.1 was used for the statistical analysis and predictive modelling of the compressive strength of concrete cubes made from crude oil contaminated fine aggregates at 7, 14, 28, and 56 days curing periods. The fine aggregates were mixed with varying concentrations of crude oil contamination (ranging from 0% to 5% by weight of the fine aggregates, at 1% interval). Concrete test cubes were produced for compressive strength determination and prediction phase of the modelling. A steady reduction in the compressive strength of the concrete cubes was recorded as the crude oil content increases, due to the inhibitive and surface shielding influence of crude oil molecules on the fine aggregates, thereby hindering physical bond formation between the cement paste and the aggregates. Statistical analysis of the output/response was carried out; a correlation coefficient of 0.9923 was obtained. The result of the modelling has shown that the use of RSM is adequate in the prediction of the compressive strength inhibition of crude oil in concrete made from crude oil-contaminated sand.
 
Indirect effect of Covid-19 on Vegetation Indices around the cement plant of Gabes region
No full textTo contain the Covid-19 pandemic, Tunisia imposed a national lockdown at the end of March 2020, a decision that resulted in a massive industrial complexes shutting down. The cement industry of Gabes was one of these complexes. However, to assess the impact of Covid-19 on the state of the vegetation around this industry three radiometric vegetation indices (RIs), NDVI, SAVI and EVI, were calculated from two Sentinel-2A imageries extracted at 22th December 2018 and 16th December 2020. Six plant species such as Oleo europaea, Ficus caria, Medicago sativa, Prunus persica vulgaris, Zygophyllumalbum and Helianthemum kahiricum were collected from 30 sites. Results suggest that, the period of pre-outbreak has the lowest averages of RIs. While, the after outbreak date has the higher levels of RIs presenting especially perennial species such as Oleo europaea. Then, EVI was the most higher index comparing to the rest of indices whatever the year studied. It was the most sensitive to cement dust and more susceptible to detect defoliation. Finally, through a remote application (RIs), the period of confinement allowed to improve the state of the vegetation surrounding the cement plant. It has helped the ecosystem to regenerate, especially perennial plant species.