Pests and diseases are prevalent on food commodities such as maize, sorghum, millet, and cassava in the field and during storage. Toxigenic fungi such as Aspergillus, Fusarium, and Penicillium create mycotoxins, which are secondary metabolites. Both people and animals are susceptible to their mutagenic, teratogenic, and carcinogenic effects. Aspergillus flavus and Aspergillus parasitic generate the most potent mycotoxins, which are found in agricultural products such as peanuts, maize grains, cereals, and animal feed. The most common incidence and stability of these mycotoxins to physical and chemical variables during food and feed processing offer substantial health risks to humans and animals. As a result, the best way to deal with this condition is to use both natural and synthetic detoxification methods. The goal of this review is to look at how natural and synthetic chemical approaches can be used to control aflatoxins contamination and how they can be reduced. Antioxidants are compounds that help prevent or reduce cell damage caused by free radicals, which are unstable molecules produced by the body in response to environmental and other stresses. Oxidative stress, which causes DNA, protein, and lipid damage at the cell level, is one of AFB1's harmful mechanisms. Antioxidants have been used as food additives to defend against oxidative deterioration since they are known to prevent fungal formation. Among the various options, antioxidants are one of the control methods of mycotoxin and which are regulated as dietary supplements and food consumption components. To reduce the effect of toxicity, the best way to prevent aflatoxin prevalence in agricultural products is to make suitable harvesting and storage conditions, but if that is not possible, it is better to eat fermented foods (yogurt or dairy drinks) or take probiotics, which are available as capsules, tablets, or powders.
Natural gas plays a growing role in the energy mix by displacing coal due to its relative economic and/or environmental advantages A process of natural gas liquid (NGL) recovery utilizing internally generated energy to achieve energy efficiency was designed. The process utilizes heat generated from the compressor end of the turbo-expander to provide heat energy required to maintain the appropriate operating conditions at the intermediate and bottom sections of the demethanizer column, rather than utilizing dedicated steam generators that requires additional construction, installation, operations and maintenance cost. Simultaneously, the temperature of the hot residue gas is also dropped to the required range for export, rather than utilizing dedicated process gas coolers. The various unit operations such as heat exchangers, liquid separators, Joules Thompson Valve coefficient, demethanizer column, reflux condenser, and bottom reboiler were designed, and cost evaluation performed for each unit, while models were solved using MatLab software. The quality and composition of NGL and residue gas produced are consistent with industrial process plant data. In addition, condenser and reboiler showed that the heat removed from the condenser is 3.180.5kW and 1.65m 2 area was exchanged, while the heat for the reboiler is 474.5kW at 47.25m 2 exchanged area. Also, the temperature profile of the demethanizer column is not uniform as lower temperature is required for the rectifying section (cryogenic absorption). Thus, temperature of -90 o C to – 95 o C favours the production of sales gas as the top product stream, while a temperature range of 30 o C to 36 o C at the bottom favours the recovery of NGL product as the bottom stream. The height and diameter of demethanizer column for distillation and absorption sections are 28m and 1.55m and 7.24m and 3m respectively. Keywords: Natural Gas Liquid, Heat Exchanger, Separator, J-T Valve, Demethanizer Column, DOI: 10.7176/CPER/64-04 Publication date: January 31 st 2022
In this study, the effect on the mineral content of eggs from local and exotic breed hens was investigated. For this study, random samples were collected from the Ethiopian Institute of Agricultural Research, Debrezeit Agricultural Research Center, and Fresh Corner Poultry Farming Debrezeite, Ethiopia for the exotic and local breed eggs respectively. Eggshells and edible portion of the egg were analyzed for Calcium (Ca), Potassium (K), Phosphors (P), Sodium (Na), Magnesium (Mg), Iron (Fe), Zinc (Zn), Manganese (Mn), and Copper (Cu) contents. The Phosphors and Zinc contents of the edible egg portion were higher in the local breed eggs than in exotic breed eggs. Calcium and Magnesium content of the eggshell was higher in local breed eggs while Zn content showed a marked decrease. As far as Potassium, Magnesium, Sodium Phosphors, and Copper values were concerned, these did not differ between the eggs from local and exotic breed types. The present finding provides sizeable differences in mineral content between the eggs from the local and exotic breed hens. The results afford a point of departure measurements of major and trace mineral contents of eggs and suggest quantifiable differences amid eggs from hens in different husbandry systems, and hens breed types. The physiological significance of those differences is discussed. But, future studies should elucidate differences observed by crossbreed types, diet effect, and husbandry system. Drying eggs can be a workable food systems intervention that can mend the wellbeing and eminence of diets in low-income countries like Ethiopia. Keywords: Egg, Hen, Mineral Content, Local breed, Exotic breed, Food System, Low-income DOI: 10.7176/CPER/64-01 Publication date: January 31 st 2022
Zero tillage straw retained with optimum K is an important strategy to increase cotton ( Gossypium hirsutum L.) yield and K efficiency in wheat ( Triticum aestivum L.)-cotton system. A 2 years field experiment was conducted during 2018, and 2019 to study the impact of [zero tillage straw as such on soil surface (ZT SAS ) and zero tillage straw burnt (ZT SB )] and five K rates were 0, 20, 40, 60 and 80 kg ha -1 on cotton yield and K use efficiency. Results indicated that bolls/plant –1 , weight per boll, seed cotton yields, ginning out turn and K agronomic efficiency were highest with 60-80 kg K ha –1 . Interactions revealed that ZT SAS with 60-80 kg K ha –1 had higher bolls/plant, bolls weight, seed cotton yields and ginning out turn compared to ZT SB . K agronomic efficiency indices decreased with increasing K rate. ZT SAS with 20 kg K ha –1 gave greater K agronomic efficiency than other combinations. ZT SAS with 60-80 kg potassium per hectare may be a sustainable and environmentally safe strategy to enhance cotton yield and soil fertility . from combined input of ZT with straw retained and k fertilizer application at 60 kg K ha -1 . This shows that retention of crop residues has led to the increase in the K contents of soil and microbial activity which is clear indication of an improvement in soil health (Pankhurst et al. 2002; Nie et al. 2007). In the present study, we tried to optimize K management under zero tillage methods in order to improve cotton yield in wheat-cotton system.
Leaf spring is a component that accept dynamic loads and provide driving comfort. Leaf springs that have been used for a long time will experience a decrease in the quality that causes fracture. The test of leaf spring includes chemical composition, hardness, fractography and metallography. The results show leaf spring is medium carbon steel of 0.47% C, the average hardness value of broken leaf springs is 419.7 means does not experience significant changes, the microstructure of broken leaf springs was tempered martensitic, has corrosion attack, trans granular cracking, secondary crack and crevice corrosion, and the fracture first occurred in the upper position of the middle leaf springs, while the remaining fractures were at the edges, there was also a corrosion attack on the bottom of the leaf springs, forming rough holes. The initial fracture is marked by the presence of a beach mark. This shape is a characteristic of fatigue fracture. Keywords: chemical composition, hardness, metallography, fractography DOI: 10.7176/CPER/63-04 Publication date: October 31 st 2020
Croton macrostachyus which is called ‘rush foil’ or ‘broadleaved croton is a multipurpose, medium sized, drought-deciduous pioneer tree. It is a tall tree found in tropical regions of Africa. The genus Croton belongs to the family Euphorbiaceae, which commonly known as the ‘spurge’ family, and it is known as ‘Bisana’ (in Amharic). Traditionally, C. macrostachyus used for treatment of malaria, rabies, gonorrhea, wound, diarrhea, hepatitis, jaundice, scabies, toothache, abdominal pain, cancer, typhoid, pneumonia and gastrointestinal disorders and as ethno-veterinary medicine. The air dried and powdered plant material (400g) was first soaked with 500mL n-hexane for 48hours and yielded 2g of n-hexane extract. Marc was soaked with 500mL of chloroform for 36hours and afforded 3.5g of chloroform extract. Finally, Marc was soaked with 500mL of methanol and yielded 18g of methanol extract. The chloroform extract of the stem bark of C. macrostachyus afforded a compound coded as EO . Its Structural determination was accomplished by means of spectroscopic techniques, namely IR, 1 H NMR, 13 C NMR and DEPT-135. The compound, EO was isolated and characterized from the stem bark of C. macrostachyus . Generally, more advanced chromatographic techniques are required to isolate more compounds from stem bark of C. macrostachyus . Also MS and 2D NMR spectroscopic techniques are needed to fully characterize the isolated compound. Keywords: C. macrostachyus; ethno-veterinary; characterization; chromatographic techniques; spectroscopic techniques. DOI: 10.7176/CPER/63-01 Publication date: October 31 st 2020
Science laboratory is a very important resource input for teaching science. Learning science is enhanced and the understanding level is improved when students are engaged in science laboratory for practical experiments. Since chemistry is a branch of science, it should be also assisted with practical activities. The current study aimed to assess the status of chemistry laboratory and practical activities in secondary and preparatory schools of East Gojjam zone. A random sampling technique was employed to collect data from students and chemistry teachers of the study area. Structured and semi-structured questionnaires and observation of laboratories was used. Both teacher’s and student’s response in the study area agree on the significance of practical laboratory works to learn chemistry is very high. The result shows as Grade 9 and grade 10 students never do practical work in the lab but grade 11 and grade 12 students sometimes conduct practical work in the lab. This may be one of the reasons why only 8,688 (11.5%) students have joined the natural science field according to the 2009E.C. East Gojjam Zone Educational Bureau report. Preparatory school students also conduct only few experimental activities among the experiment listed in their own chemistry text book. As teachers give the reasons on why laboratory work is not used to teach chemistry is because of lack of chemicals and apparatuses, fear of chemicals, lack of administration support, the lab is poorly organized, no time is allotted for practical lab work, practical lab work is not considered as a teaching load for teachers and lack of laboratory training on how to use laboratory to teach chemistry in high and preparatory schools. Generally the above problem hinders practical activities in the laboratory and makes students at secondary schools of the study area lack interest to join science class. Keywords: Laboratory, secondary and preparatory school, practical activity, chemistry. DOI: 10.7176/CPER/63-02 Publication date: October 31 st 2020
In this study, polyvinyl alcohol (PVA) polymer and Cloisite 15A, a modified form of organo Montmorillonite nanoclay, are used to produce nanofibrous mats via electrospinning technique. Pure PVA nanofibrous mats from mechanically stirred polymeric solutions at 8, 10 and 12 wt % PVA percents; and nanoclay added PVA nanofibrous mat samples are produced at increased nanoclay weight/ polymer weight ratios (1/13, 1/11, 1/9 and 1/6) using several mechanically stirred nanoclay-PVA solutions at various proportions of nanoclay and PVA polymer wt % in solutions. The viscosities, surface tensions and electrical conductivities of solutions were measured. FESEM (Field Emission Scanning Electron Microscopy) analysis, fiber diameter distribution with Image J software analysis and tensile testing was applied to nanofibrous samples. Increased polymer concentration led to bead-free nanofibrous PVA mats. EDX analysis approved nanoclay is present in samples produced from nanoclay added PVA solutions. Mechanical stirring for nanoclay dispersion enabled smooth nanofibrous structures only in low (1/13) nanoclay weight/ polymer weight ratios and showed very little tensile increase from 1 wt % clay loading to 2 wt % addition. A direct increase in tensile strength wasn’t achieved with nanoclay content increase in PVA nanofibrous mats; this might be due to the effect of poor nanoclay distribution adversely affecting tensile results. Morphological analysis proved that nanofibrous structures were far away from smooth fiber structures as they transformed from smooth nanofibers into non-uniform fibrous structures at increased nanoclay weight/ polymer weight ratios in nanoclay added PVA samples. Keywords: nanofibrous mat, electrospinning, polyvinyl alcohol (PVA), nanoclay, mechanical dispersion DOI : 10.7176/CPER/62-08 Publication date: May 30 th 2020
Now-a-days, Because of cost and time consuming in the design of plants chemical engineer used simulators to simulate design and operation of chemical equipment and plant, which spares a great deal of time and cash.Today, there are many number of the simulators are refreshed and utilized in the simulation of chemical equipment and plant such as ChemCad, ProII, UniSim……..etc. Among of these simulators, Aspen Hysys is the most utilized programming in all ventures because of aiding in two noteworthy fields (design & operation). Simulation of ammonia synthesis process is done on Aspen Hysys V8.8 with steady state mode making some assumptions and using hypothetical reactors ammonia. By fluctuating the distinctive parameters in this simulation environment, the impact of these parameters in the generation rate of the procedure are watched. Keywords: Ammonia, Simulation, Aspen Hysys DOI : 10.7176/CPER/62-03 Publication date: January 31 st 2020
The study was carried out to investigate the effect of process variables on the production of alumina (Al 2 O 3 ) by leaching of local clays obtained from four different locations in Nigeria – Ikot-Abasi, Enito II, Akpugo and Awgbu containing 56.00%, 8.45%, 25.28% and 14.43% of Al 2 O 3 respectively. The process variables whose effect on alumina leaching investigated were: acids concentration (2M to 10M), calcinations temperature (200 o C to 1000 o C), calcinations time (15 to 75 minutes), leaching time (20 to 100 minutes) and particles size (75 to 1000µm) with the experiment conducted at constant boiling temperatures of the acids used (Nitric and Acetic acid). The recommended leaching conditions used as obtained from literature were: 6M for the two acids concentrations, particles size of 150µm, calcinations and leaching time of one hour and calcinations temperature of 600 o C. Upon leaching of these clays under prescribed conditions, the optimal yield obtained by varying each of the process variables were noted. Calcination temperature was observed to have the highest effect on the yield of alumina extractible providing the highest yield of alumina after analysis using mass adsorption spectrophotometer. The yield of alumina presented under the variation of calcination temperature were: Ikot-Abasi clay and nitric acid – yield of 68.10% alumina; Ikot-Abasi and Acetic – yield of 38.07% alumina; Enito II and nitric acid – yield of 56.50% alumina; Enito II clay and acetic acid – yield of 43.41% alumina; Awgbu clay and nitric acid – 59.04% alumina yield; Awgbu clay and acetic acid – alumina yield of 46.55%; Akpugo clay and nitric acid – alumina yield 53.47%; Akpugo clay and acetic acid – alumina yield 43.23%. It was observed that Ikot-Abasi clay/nitric acid gave the best yield. Keywords: Local Clays, Alumina, Nitric Acid, Acetic Acid, Mass Adsorption Spectrophotometer. DOI : 10.7176/CPER/60-05 Publication date :March 31 st 2019
Nanotechnology has attained significant concern in the field of Environmental Protection, Health Risk Energy, Material Science, Biotechnology, Information Technology, Pharmaceuticals, Tissue Engineering, Cosmetics, Food and Agriculture, and others. In this research the preparation of indigenous copper oxide Nanoparticles (Cu 2 O NPs) were prepared by the bottom up approach in the presence of Sodium do Decyl Sulfate (SDS). Material properties of Copper oxide NPs such as Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Fourier Transforms Infrared (FTIR) spectroscopy were also studied. The SEM demonstrated the surface of indigenous Copper Oxide NPs was non-agglomerated powders with irregular ball resembling particles. The X-ray Diffraction (XRD) analysis explained that the Cu 2 O NPs were highly crystalline in nature with average size was found to be 3.5 nm ranging from 2 to 5 nm were recorded by the help of scherrer formula. The Fourier transforms infrared (FTIR) spectroscopy described the carbonyl group are responsible for formation of stable indigenous Cu 2 O NPs. These stable Indigenous cuprous oxide nanoparticles would be applied for the desulfurization of natural Gas separation purpose. Keywords: Indigenous, Copper oxide nanoparticles (Cu 2 O NPs), chemical reduction, SDS, morphology, desulfurization and natural gas. DOI : 10.7176/CPER/61-04 Publication date : April 30 th 2019
Aluminum-diatomite (Al-D) composite adsorbent is synthesized in one pot by heating natural diatomite in NaOH and subsequently mixed with a solution of aluminum salt. The chemical, surface, textural and structural properties of the prepared material were characterized by XRF, XRD, SEM, FTIR, and Nitrogen adsorption methods. The adsorption efficiency of the composite sample was evaluated towards Pb(II) species in batch technique and compared with the raw diatomite. The impact of operational conditions, such as pH, adsorption time, temperature, an initial concentration of adsorbate, and the adsorbent dose was also evaluated. As confirmed by XRD and FTIR, the partial dissolution of silica in NaOH leads to the formation of an alumina-silicate compound at the addition of an aluminum salt. SEM image showed that aluminum is successfully loaded both on the surface of the diatomite and on the inner surface of the meso- and macropores, which leads to the advance of the specific surface area from 19.7 m 2 /g to 80.9 m 2 /g. It was observed that the Al-Diatomite adsorbent showed a noticeable higher Pb (II) sorption capacity (67.9 mg/g) than the natural diatomite (17.2 mg/g). This result can be explained by the higher surface area, mesoporous structure and uniform deposition of small-sized Alumina particles. Keywords: Aluminum, Composite, Lead ion, Modification, Sorption DOI : 10.7176/CPER/60-02 Publication date :March 31 st 2019
Leaching by use of factorial design experiment was used to investigate the effect of process variables on the yield of alumina obtainable from four local clays from four different locations in Nigeria. Characterization of these clays obtained from previous work was observed in this order: Ikot-Abasi, Enito II, Akpugo and Awgbu containing 56.00%, 8.45%, 25.28% and 14.43% Al 2 O 3 respectively. Fractional factorial design was used to develop a mathematical model used in the investigation. The process variables whose effect on alumina leaching investigated were: acid concentration (2M and 10M), calcinations Temperature (200 o C and 1000 o C), calcinations time (15 and 75 minutes), leaching time (20 and 100 minutes) and particle size (75 and 1000µm) with the experiment conducted at constant boiling temperatures of the acids used (Nitric and Acetic acid). On optimization of the model developed from the factorial design experiment, optimal leaching conditions for each clay samples were obtained with corresponding yields of alumina presented as follows: Ikot-Abasi clay and nitric acid – yield of 78.86% alumina; Ikot-Abasi and Acetic – yield of 50.26% alumina; Enito II and nitric acid – yield of 53.14% alumina; Enito II clay and acetic acid – yield of 30.23% alumina; Awgbu clay and nitric acid – 62.74% alumina yield; Awgbu clay and acetic acid – alumina yield of 43.24%; Akpugo clay and nitric acid – alumina yield 75.43%; Akpugo clay and acetic acid – alumina yield 41.98%. The values of the yields obtained from the model optimization were validated by conducting the leaching experiment again in the laboratory under the optimized process conditions and were observed to closely match with a deviation ranging from 0.21 to 5.55%. From the results obtained, it was observed that the best yield was gotten from Ikot-Abasi clay which contained the highest percentage of alumina content. DOI : 10.7176/CPER/60-03 Publication date :March 31 st 2019
Crop residues are considered among the most important materials in Ethiopia especially maize stalk, bean stalk, sorghum stalk, and wheat and barley straw. There are many types and models of imported top hammer miller in Ethiopia to assist in milling the grain. Those machines which are imported have many problems such as size of mill and rusting of hammers which not advisable to human food. Therefore the machines adapted and evaluated for livestock feed process purpose in terms of crop residues like maize stalk, bean stalk and wheat straw with predetermined feed rate and hammers’ shaft speed (RPM). The research was conducted at Asella Agricultural Engineering Research Center (AAERC), Maki and Bokoji district to evaluate the machine performance in crushing maize stalk, bean stalk, and wheat straw for animal feed. In this paper, two top feed hammer mills were used. They are collected from market and Bako Agricultural Engineering Research Center (BAERC). The performance of the machine is evaluated in terms of crushing capacity, crushing efficiency and crushing loss. The output of the market top hammer miller was satisfactory. The market top hammer miller produced a highest crushing efficiency and capacity about 99.33 % and 152.54 kg/hr while the BAERC’s was produced 94% and 78.68 kg/hr, respectively. The crushing losses of the market top hammer miller were 2.67, 0.67 and 5 % on maize stalk, bean stalk and wheat straw respectively. Keywords : crushing capacity, crushing efficiency, crushing loss, RPM DOI : 10.7176/CPER/61-02 Publication date : April 30 th 2019
In this study, the effects of free quenching on mechanical physical and thermal behaviours of high density Polyethylene (PEHD) have been investigated. Three different thermal treatments were used: A first free quenching from the melt state to air, a second free quenching from 130°C to different temperatures and finally an annealing .The results have shown that an improvement of the impact strength and elongation at break can be obtained after a first quenching to air. However, a second quenching at 0°C gives better results and a correlation between the mechanical and thermal properties is observed. The improvement of these properties is obtained to the detriment of other properties like elasticity modulus, density, vicat softening temperature (VST) and heat distortion temperature (HDT). The improvement of impact strength and elongation at break after the second quenching is probably linked to the existence of a relaxation mode located around this temperature. Keywords : free quenching; polyethylene, mechanical, physical, thermal. DOI : 10.7176/CPER/59-03
Background. Gardenia ternifolia is utilized in traditional medicine of Ethiopia for malaria treatment and possessing in vitro antimalarial activity. However, no in vivo study was conducted to substantiate the claim. The aim of this study was to judge the antimalarial activity of Gardenia ternifolia extract in vivo in Plasmodium berghei‐infected mice. Methods. Plasmodium berghei was inoculated to healthy mice, and hydromethanolic crude extract and chloroform fraction of G. ternifolia leaves at 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day were administered. Percent parasitemia inhibition, percent change in bodyweight, hemoglobin level, and mean survival time were determined. Data were analyzed using one‐way ANOVA followed by post hoc Tukey HSD test with IBM SPSS software version 20.0 statistical package and P < 0.05 considered as statistically significant. Results. The chemosuppressive test of hydromethanolic crude extract at 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day ranged from 27.09% to 67.72%, and chloroform fraction had 35.21%–78.19% parasitemia suppression, respectively. For curative test on day 5, hydromethanolic crude extract at 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day ranged from 25.58% to 48.76%, chloroform fraction at 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day and chloroquine base at 10 mg/kg showed 46.36%–74.42% and 92.87% percent parasitemia inhibition, respectively, and also the results to both tests were highly significant (P < 0.001) compared to the negative control. Maximum effects on chemosuppressive, curative, prevention of weight loss, and reduction in hemoglobin were observed at higher doses of the hydromethanolic crude extract and chloroform fraction. Conclusion. From this study, hydromethanolic crude extract and chloroform fraction of G. ternifolia leaves have shown promising antimalarial activity. The findings support the traditional claim of G. ternifolia leaves for malaria treatment; however, species variation could also limit such a straightforward extrapolation of the findings of this study in humans.
A novel environmentally-friendly adsorbents, carboxymethyl cellulose /k-carrageenan /graphene oxide (CMC/KC/GO) gel beads (GBs) was prepared via a simple method. The composition and morphology of these gel beads were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The maximum adsorption capacity of (CMC/KC/GO) GBs for Cu (II) and Co (II) was 2.85 and 1.87 mmol/g respectively at 30 o C. Factors affecting the adsorption capacity of metal ions such as CMC/KC ratios, GO ratios, pH, initial metal ions concentration, and the temperature were also explored. The kinetics studies showed that the adsorption process followed the pseudo-second-order kinetics. The analysis of the isotherm indicated that the Langmuir isotherm is in a good agreement with the sorption process. The thermodynamic parameters indicate that the adsorption process was endothermic and spontaneous. The adsorption capacity of the GBs barely declined even after six cycles of regeneration; furthermore, the GBs can be simply separated from the aqueous solution after adsorption by a simple filtration. Keywords: Carboxymethyl cellulose; k-carrageenan ;graphene oxide ; gel beads; isotherm
In this analysis the MHD stagnation point flow of Jeffrey fluid over a stretching/shrinking sheet through porous medium is studied. The governing partial differential equations are transformed into nonlinear ordinary differential equation using the similarity transformations and are solved shooting technique. The effects of governing parameters on the velocity, the temperature and the concentration while the skin friction coefficients, the rate of heat transfer are studied graphically. Keywords: MHD; Jeffrey fluid, stretching/shrinking sheet, Porous medium.
The potential of an agro-based industrial waste, dry empty oil palm bunch (DEOPB), obtained from a local oil palm processing mill was explored to treat effluent from a petrochemical plant. The adsorbent was subjected to pyrolysis and chemically activated using a 0.1mol hydrochloric acid (HCl). The adsorption behaviors of iron, copper and cadmium were found to obey Pseudo Second Order kinetic model, Brunauer, Emmet and Teller (BET) and the Langmuir isotherm models were used to fit the iron, copper and cadmium adsorption isotherm onto the DEOPB activated carbon with their equilibrium capacities agreeing with experimental data except for the lead component that showed no effect. The heavy metals contaminants investigated using this technique was found to have been removed from the wastewater stream in the following percentage efficiency: iron; 57%, copper; 99.6% and cadmium; 90% but was ineffective in the removal of the lead component as its concentration remained unchanged throughout the experiment. The locally produced activated carbon was subjected to laboratory analysis and its properties (Density; 0.369g/m 3 , Particle Size; 0.18mm, Ash Content; 5.73%ww, Porosity; 90%, Surface Area; 691.85 m 2 /g) were found to favorably compare with commercial activated carbon. Keywords : heavy metal contaminants, effluent, multi-layer adsorption, bio-adsorbent.
The effect of activation method (physical and chemical) and the concentration of the chemical activating agents on the characterization of periwinkle shell activated carbon was investigated. The periwinkle shell was pyrolysed and activated by physical activation (using an oxidizing gas - steam) and chemical activation (using base: ZnCl 2 , CaCl 2 and acid: H 2 SO 4 , HCl). The produced activated carbons were characterized to determine the bulk density, moisture content, pore volume, porosity, ash content, iodine number and surface area following standard ASTM procedures. The effects of concentration of the activating agents on these properties were also studied. Effects of activation method on activation carbon properties showed that the chemical activated carbon had higher bulk density, pore volume, porosity, ash content, iodine number, and surface area, while the physical activated carbon had higher moisture content. The effect of activating agent concentration showed that the bulk density, pore volume and porosity increased with concentration for base activated carbon and decreased with concentration for acid activated carbon. The ash content and iodine number fluctuated (initial increase then decrease and increase) for base activated carbon; while these parameters increased continuously and fluctuated (initial decrease the continuous increase) with concentration for acid activated carbon. The moisture content and surface area decreased with concentration for base activated carbon; these parameters fluctuated (initial increase, decrease then increase) and increased continuously for acid activated carbon. Periwinkle shell carbon chemically activated with ZnCl 2 was the best activated carbon with highest density, pore volume, porosity, iodine number and surface area. Keywords : Activated carbon, Physical and Chemical activation, effect of activation agent concentration.
