Characterization and Physicochemical Properties of Wood Sawdust in Niger Area, Nigeria

Investigation was carried out to examine the characterization and physicochemical properties of some wood sawdust obtained from Niger Delta Area of Nigeria limited for the purpose of usage as an absorbent for remediation of contaminant in soil environment. Experimental examination was conducted on value, moisture content, bulk density and porosity, iodine number and ash content for the various wood sawdust samples from Obuba and Abura, Opepe/mahogany. The result obtained revealed that the pH value of Obuba red (soft wood) is 5.48, Abura (hard wood) 6.18, opepe/mahogany (hard wood) 5.75 and iroko (soft wood) 5.29, whereas the moisture content value opepe/mahogany and iroko. The result further revealed that the bulk density and the porosity value are as presented, grain volume value are 2.910, 2.475, 1.931, and 2.959, bulk density value are 1.0317, 0.884, 0.2190, 0.4306, 0.5490, and 0.3499 for obuba red, abura, opepe/mahogany and iroko. The iodine number tested demonstrates the following value of 10.20, 6.90, 13.90 and 5:9 and 6.6 for obuba red, abura, opepe/mahogany and iroko. Finally, it was demonstrated that the usefulness of characterization and examination of physicochemical properties of functional components that control and improve the monitoring, predicting and determination of the kinetics values.


INTRODUCTION
Oil spill is a challenge that is common to oil producing areas; as a result several clean -up methods have been suggested by many researchers to curb this menace. This work is therefore focused on exploring the suitability of applying natural adsorbent(sawdust) for oil clean up to achieve an effective environmental recovery. The predominantly used adsorbents are expensive hence the use of readily available materials that are inexpensive and renewable will be advantageous. This research seeks to study the adsorption capability of www.bosaljournals/chemint/ editorci@bosaljournals.com sawdust from selected local woods. Sawdust is a waste generated from various sawmills across the country, it is mostly disposed of in the environment thereby causing pollution (Braz et al., 2019;Kebibeche et al., 2019;Raheem and Ige, 2019;Tiuc et al., 2019;. Hence using sawdust as an adsorbent for hydrocarbon clean up could enhance the eradication of the menace associated with saw dust waste in the long run and help to sustain the ecosystem (Mohsen, 2007;Idris et al., 2014., Ikenyiri and Ukpaka, 2014). It is of great importance to explore the capability of natural adsorbent (sawdust) for the adsorption process in clean -up operations of oil spilled environment. A better understanding of the mechanism of adsorption of crude oil on this adsorbent( sawdust materials) will require investigation into the particle size of the adsorbent and the critical factors that affect its rate of adsorption in terms of adsorbent characteristics (adsorption capacity) will be valuable in ascertaining the suitability or otherwise of these materials for oil spill cleanup. It will also involve the determination of the physical and chemical properties of the sawdust. These will entail carrying out experimental works to determine the rate of adsorption (Gatoki et al., 2002., Jiang et al., 2002., Hussein et al., 2011., Kingston, 2002. This work shall explore different kinds of locally available wood sawdust for the purpose adsorbents and examine the challenges associated with their use for any given process. The study will include examining their characteristics, evaluating their effectiveness and feasibility for application as remediation materials (Hussein et al., 2009). Suggestions will be made based on findings from experimental results and appropriate characterization as well as the physicochemical properties was examined to describe the rate of adsorption (Leiviska 2014;John, 2007;Ikenyiri and Ukpaka, 2016;Hussein et al., 2008) Oil introduced into environment can cause gross biological damage, physiological effects on the biotic and a broad range of ecological changes. All aquatic biota are permeable to oil constituents and accumulate them from their environment either directly from the water column, or through their food. Oil can affect and cause changes in many organisms at all levels: cellular, organismic and ecosystem (Karan et al., 2011;Horisawa et al., 1999;Garg et al., 2004). Crude oil exposure, even at very low concentrations can cause deleterious effect, whether lethal or sub lethal, to an organism, population or community. It can also enhance genetic effects and a wide range of deleterious effects on metabolism Haussard et al. (2003). The effects of oil on aquatic life can be considered as being caused by either its physical nature or by the chemical components of the oil. Aquatic life may also be affected by clean-up operations or indirectly through physical damage to the habitat in which they live. Populations of plants and animals in the sea are subject to considerable natural fluctuations in numbers brought by changes in climatic and hydrographic conditions and availability of food. Thus, the species composition and age structure of the various populations within a particular aquatic habitat are far from constant but instead are in a state of dynamic. In view of this, it is usually extremely difficult to assess the effects of an oil spill and to distinguish changes by the oil from those due to natural variability (Karan et al., 2011).
The different life stages of a species may show widely different tolerance and reaction of oil pollution. Usually, the egg, larval and juvenile stages will be more susceptible than the adults. However, many aquatic species produce very large number of eggs and larval stages to overcome natural losses. This will normally result in less than one in 100,000 eggs or larval surviving to maturity but the extreme losses due to adverse local conditions. These facts make it unlikely that any localized losses of eggs or larva caused by an oil spill will a discernible effect on the size or health of future adult populations (Ho et al., 2005). The ability of animal and plant populations to recover from an oil spill and the time taken for normal balance in the habitat to be re-established depends upon the severity and the duration of the disturbance and recovery potential of the individual species. Abundant organisms with highly mobile young stages produced regularly in large numbers may repopulate an area rapidly when pre spill conditions are restored, whereas populations of long-lived, slowly maturing species with low reproductive rates may take several years to recover their numbers and age structure (Garg et al., 2004).
Whilst it may be possible to restore the physical characteristics of an oiled habitat to near its pre-spill conditions, the extent to which its biological recovery can be enhanced is severely limited. Although the cleaning of mangroves and salt marshes, and replanting with seedlings, may be feasible in some situations, care needs to be taken to ensure that the area is not physically damaged since this may be more destructive in the longer term than the loss of the vegetation (Horisawa et al., 1999). Present investigation was carried out to examine the physicochemical properties of some wood sawdust obtained from Niger Delta Area of Nigeria limited for the purpose of usage as an absorbent for remediation of contaminant in soil environment.

Materials and equipment used for the investigation
The material and equipment used in this study are: Adsorbent (sawdust), crude oil, beakers, cylindrical flask, sampling containers(cans), pH meter, electronic balance, reagents ,filter paper, funnels, water (fresh and saline), digital water and soil analysis kit, desiccators, oven, sieves mechanical shaker, UV spectrophotometer.

Sample collection and characterization
The sawdust used for this investigation was collected from a sawmill located in Mile 3 Diobu, Port Harcourt, Rivers State, Nigeria (Fig. 1). The fresh water was obtained from the chemical/petrochemical laboratory environment.

Moisture content
The moisture content was obtained by measuring the weight reduction of the sample when the samples were subjected to drying. The initial weights of the samples were measured and thereafter, experimental investigation were made on the samples when it was subjected to drying at environmental temperature ranging from 15 0 C-37 0 C.The difference in samples weight before and after drying gives exact information on the moisture contentASTMD2016-74 (1983) and ASTMD 4442-07 (2007

Sieve analysis
The selected sawdust samples were weighed using the electronic balance. The samples were screened with the mechanical shaker to obtain various particle sizes. The particle sizes are presented in this work.(ASTM C136/C136M-14 and ASTMD 2862-10).

pH determination
The pH of the Sawdust sample was measured using a microprocessor pH meter.20gm of sawdust was sieved through a 2mm sieve and transferred into 100ml beaker and 5ml of distilled water was added and stirred for 30 minutes with a glass rod. The electrode of a standardized pH meter was inserted into it and the sawdust pH in water was measured when the digital display reading was stable. Thereafter, the pH of the sawdust water mixture were recorded. APHA 4500H (1992)(2).

Bulk density
After sieving with a 5mm sieve .A known weight of sawdust samples of 5g each were prepared. The bulk density was determined using the core sampler method. The finest sawdust samples of 0.40mm particle size was then weighed and kept in a core. In this case, the core was prepared with a nickel foil and stainless mesh made in a cylindrical shape. Alternatively, the core sample can be taken by driving the metal core, that is the cylindrical material into the sawdust sample at the desired depth and horizon. The bulk density is the mass of the sample divided by the total volume of the sample (BS 1377-2(1990)) pb =Ms/Vt Ms = mass of oven dried sawdust (g) Vt = total sawdust volume (cm 3 )assumed to be equal to volume of a cylinder

Porosity determination
The porosity was determined by first measuring these quantities: bulk volume, pore volume and grain volume of the selected woody samples. These quantities which are related to porosity as expressed in the equation. The pore volume of the core samples were measured using the gravimetric method. A 5g of each sample was taken and saturated with water. After the air in the pore of the material had been displaced, the sample was superficially dried and weighed again. The increase in weight divided by the density of water gives the pore volume. The grain volume was measured by crushing a dry and clean core sample. The volume of the crushed sample was determined by immersing in water. Also the bulk volume was measured by observing the volume of fluid displaced by the sample. The fluid displaced can be measured volumetrically or gravimetrically. Though the gravimetric determination of bulk volume was employed, the sample was immersed in a fluid and the loss in weight of the sample was noted. Thereafter, % porosity was determined by calculation, by substituting the values of bulk volume, pore volume or grain volume. ASTMD7263-09(2018)e2.

Carbon contents
Sawdust samples were weighed 5g eachand sieved with 0.5mm mesh. This was done in duplicate before being transferred to 25ml Erlenmeyer flask. 10ml of 1N(K2Cr2O7) solution was pipetted into each flask and was stirred gently to disperse the sawdust sample. This was followed by the addition of 20 ml concentrated H2SO4 using a graduated cylinder, taking a few seconds only in the operation. The flask was stirred gently until sawdust sample and reagents were mixed, then vigorously for one minute, to effect more complete oxidation and it was allowed to stand for 30 minutes. The contents were diluted with water at about 250ml. Thereafter,25ml of 0.5N ferrous ammonium sulphate was then added and titrated with 0.4N potassium permanganate under a strong light. ASTM D5373-16 (2016)

Iodine number
Sawdust sample was measured (5g) and placed in a 250ml beaker. 20ml of carbon tetrachloride (CCl4) and 25 ml of Wiji's reagent were also added. Then 9g of iodine in 1 litre of glacial acetic acid was pipetted into beaker and 10 ml of C3was added into the 250 ml beaker. It was shaken vigorously for 1minute.The mixture was allowed to stand for 30 minutes in a dark locker. Thereafter, 20ml of potassium iodide (KI) solution and 100 ml of distilled water into the solution was added. The solution was titrated against 0.1 N Na2S2O3. Furthermore 0.5 ml of starch solution was added at end point of the titration. Titration was continued again with 0.1NNa2S2O3. The procedure was repeated for blank with only distilled water. The test method adopted was the A.O.C.S and ASTM D4607-14 method. The Iodine number was calculated using the formula.

Characterization and physicochemical properties of sawdust
Results obtained from the research work are presented in Tables 1-5. Figure 1 illustrates the relationship between pH value and the various wood samples. Increase in pH values were observed in the order of magnitude as: Abura > Opepe/MA > Obuba > Iroko. The variation in the pH values can be attributed to the variation in the wood specie sampled. Table 4 demonstrates the relationship between the porosity with respect to the identity of the various wood sawdust .The variation in the porosity can be attributed to the variation in the wood specie.Increase in porosity was observed in the following order of magnitude Opepe/Ma > Abura > Iroko > Obuba. Porosity and bulk density has been reported to play an important role in assessing the adsorptive capability of an adsorbent. One of the parameters determined on characterization of the material is porosity. The result presented shows high percent porosity of 55% for Opepe sawdust (naucleadiderrichii) while Obuba (Berlinagrandiflora) has 22% porosity, Abura (HalleaLedermannii) has 43% and Iroko(chlorophora) with 35% porosity. The porosity values are displayed in Table 4.The wood sample and coding procedure is represented in Table 1.

Grain volume
Also the grain volume of the selected samples falls within the range 1.931cm 3 to 2.959cm 3 . The grain volume of Opepe (naucleadiderrichii) was the lowest at 1.9cm 3 . Table  4 shows the various samples with respect to their grain volumes. It is shown that the grain volume varies with different species of the wood. Increase in the grain volume for the different sawdust were observed to follow the order of magnitude Iroko > Obuba >Abura > opepe/Ma. The variation in the grain volume can be attributed to the variation in the sampled specie.

Bulk density
Bulk density is one of the properties of Adsorbents. The bulk densities of these sawdust samples are: Abura sawdust sample (HalleaLedermannii), Opepe (naucleadiderrichii) and Iroko (chlorophora/miliciaexcela) obtained are: 0.88g/cm 3 , 0.90g/cm 3 and 0.84g/cm 3 respectively. The result shows that the Obuba red (Berlinagrandiflora) has high bulk density value of 1g/cm 3 . The bulk density of the sawdust samples are presented in Table 4. The variation in the bulk density can be attributed to the variation in the physicochemical properties of the wood. The magnitude of the bulk density is in this sequence Obuba > Opepe/Ma > Abura > Iroko.

Moisture content
The moisture content feature for the various wood sawdust samples are shown in Table 3. The moisture content analysis reveals that the Obuba red sawdust sample (Berlinagrandiflora) has the highest moisture content of 14.7%. The results also indicated the moisture content for Abura (HalleaLedermannii) with 9.82%, Iroko (Chlorophora/miliciaexcela) has 9.25% and Opepe (naucleadiderrichii) has 8.25%. Increase in the moisture content was observed in this sequence Obuba > Abura > Iroko > opepe/Ma wood sawdust. Obuba red wood (Berlinagrandiflora) C 4 Opepe/Mahogany wood (Naucleadiderrichi/mellaceae) D   Table 3.

Iodine number
The Iodine number of different wood sawdust is presented in Table 5. Result demonstrates the level of the iodine number with respect to wood type. The variation in the iodine number can be attributed to the variation in the physicochemical property of the wood specie. Table 5 illustrates the iodine number of various samples (obuba red, Abura, Opepe/Mahogany and Iroko). Results revealed that the iodine number is higher in the order of magnitude Iroko > opepe/Mahogany > Obuba > Abura. The result obtained indicates that the hard wood contains high iodine number than the softwood samples. Table 5 illustrates the ash content of various samples (obuba red, Abura, Opepe/Mahogany and Iroko). Results revealed that the ash content is higher in the order of magnitude Iroko > Abura > opepe/Mahogany > Obuba. It is observed that the hard wood sawdust possesses high level of ash content concentration compared to the semi and soft wood sawdust. It also indicates that the ash content of the hardwood will be more effective if used as activated carbon in water treatment mechanism.

pH values
The pH value of wood sawdust samples is determined as follows: A-obuba red (soft wood) is 5.48, B-Abura (hardwood) is 6.18, C-opepe/mahogany (hardwood) is 5.75 and D-iroko (softwood) is 5.29. From the result presented in Table 2 revealed that iroko is more acidic than other and the magnitude order of acidicity is D > A > C > B. The results of present study revealed that the characterization and examination of physicochemical properties of functional components that control is helpful in monitoring, predicting and determination quality of respected area (

CONCLUSIONS
The following conclusion was drawn; the research work revealed that wood sawdust obtained from softwood is more acidic in nature than the ones obtained from the hard wood. It is obtained that the softwood species obtained high moisture content retainable than the hardwood species. The grain volume is observed to be high in softwood sawdust than the hard wood sawdust. It is seen that the bulk density of the soft wood sawdust is higher than hardwood sawdust. The research work also revealed that the hardwood sawdust is more porous than the softwood sawdust. The research work demonstrates the iodine number of the various species of wood sawdust samples which indicates that the magnitude of the iodine number is as stated iroko > opepe/mahogany > obuba red > abura.

REFERENCES
APHA., 1992. Standard Test method for the Examination of Water and Waste Water, American Public Health Association.  6.1 C -Opepe/Mahogany 13.9