Application of Locally Produced Activated Carbon from Waste Nigerian Bamboo Dr Awajiogak Ujile Department of Chemical/Petrochemical Engineering Rivers State University of Science and Technology Port Harcourt, Rivers State Nigeria

Scope of the presentation Introduction Effects of untreated effluents Methodology –i) Activated carbon preparation, ii) Carbonization process, iii) chemical activation Analysis of the results obtained: Physicochemical properties and effect on heavy metals in the waste water Conclusions

Introduction Waste bamboo is the unavoidable by-product of construction activities of high rise buildings. The use of Bamboo for the production of activated carbon for this process is relatively cheap as Bamboo is in abundance in Nigeria. Bamboo waste generated from construction (building and furniture making) processes used for this process is in itself a remediation process. Activated carbon (AC) is widely used in decontamination of air and wastewater.

Fig 1: Bamboo scaffolding on building construction site

Fig 2: Construction site showing use of Nigerian bamboo as props

Methodology Materials The materials/Equipment/Reagent/Solutions used for the work include: 1 dm3 measuring cylinder, 100ml measuring cylinder Weighing Balance (AE ADAM AAA 250LE Grade) Beakers Bunsen burner gas cylinder Reactor with condenser pH meter Crucibles

Desiccators Muffle furnace Atomic Absorption Spectrophotometer (AAS) Model 71024 A 25% KOH Solution, 25% NaOH Solution, 5% HCl solution, Iodine Solution, 0.1M Sodium thiosulfate solution Wastewater Sample (collected from discharge outlet of Port Harcourt Refinery Company) for characterisation and treatment with the produced activated carbon from waste bamboo.

Activated Carbon Preparation Nigerian bamboo logs were obtained from the construction site of the new Chemical/ Petrochemical Engineering Laboratory at the Rivers state University of Science and Technology. The logs were reduced to sizes of 7cm long, 2cm width and 2cm thickness. The sized Bamboo pieces were washed with distilled water, air dried and oven dried at 105oC for 6 hours. The dried bamboo was divided into two batches and labelled “A” and “B” accordingly.

Carbonization Process 2.08Kg of dried Bamboo precursor “A” and 1.96Kg of dried bamboo precursor “B” was charged into the reactor and ignited to initiate the carbonization process. The heating continued until the final temperature between 300oC and 400oC is reached. The AC product was cooled overnight to room temperature and weighed again. A known quantity of the dried bamboo was measured (between 1kg to 2kg) into a reactor.

Condenser hose was fitted to the reactor which was placed on a heating mantle for pyrolysis at the temperature between 300 - 400OC in the absence of air. The pyrolysis period was about 4 - 6 hours within which charring of the bamboo occurred. The charred bamboo was allowed to cool at room temperature and later charged into a 1liter beaker for chemical activation. It was observed that 1kg of bamboo produced 300mg of carbon.

Chemical Activation The charred bamboo (carbon) were crushed into granular form and sieved using sieve meshes. This separated the product into uniform particle sizes and later weighed into a beaker. The batch “A” Bamboo precursor was soaked in KOH solution (25% by Vol.) and batch “B” Bamboo precursor in NaOH solution (25% by Vol.) at a weight ratio of bamboo precursor to reagent solution of 2. The mixtures were labelled accordingly and allowed to soak for 4hours.

The cooled AC was washed in a Hydrochloric acid (HCl) aqueous solution (5% by weight), The AC was washed in water until the pH of the washing solution became neutral. The final step in this unit is the Drying of the washed AC at 1050C for 4hr and ground to required particle size. Each batch had two different particle sizes and labelled as: A1 (212-180µm); A2 (180-150 µm); B1 (212-180µm); B2 (180-150µm)

Results and Discussion The results of the physicochemical properties and heavy metals in wastewater before and after treatment with the activated carbon obtained from waste bamboo are shown in tables 1 and 2 respectively.

TABLE 1: PHYSICOCHEMICAL PROPERTIES OF WASTEWATER SAMPLES ` PARAMETER SOURCE SAMPLE A1 SAMPLE A2 SAMPLE B1 SAMPLE B2 SAMPLE 1 pH 7.12 7.55 7.49 7.51 7.45 2 Conductivity (*) 12,250 650 770 669 695 3 Total dissolved solid (mg/l) 6,440 401 423 450 4 Chlorine Cl- (mg/l) 85 31 23 29 5 Salinity as Cl- 144.5 52.7 46.5 50.3 6 Turbidity (NTU) 24.3 15.4 12.8 13.3 7 Total suspended solid (TSS) (mg/l) 19.5 10.3 11.9 11.5 8 Colour Milky Clear 9 Odour Offensive unobjectionable

TABLE 2: TEST FOR HEAVY METALS IN WASTEWATER SAMPLES Lead Platinum Cadmium Iron 1 SOURCE SAMPLE (UNTREATED) 0.542 0.0014 0.0021 0.710 2 A1(212-180µm) 0.0310 <0.001 0.0011 0.442 3 B1(212-180 µm) 0.297 0.0013 0.411 4 A2(180-150 µm) 0.261 0.398 5 B2(180-150 µm) 0.0257 0.0010 0.372

Adsorption of Lead Ions From the results of the experiments, it was observed that NaOH Activated Carbon of particle size range 180-150µm had 52.58% adsorption. It was followed by KOH Activated Carbon of 180-150µm particle. While it has been established that NaOH AC adsorbs most of Lead ions, it is adsorbed more at a reduced particle size. Reducing the particle size more will give even higher percentage adsorption.

Cadmium Ion Adsorption Cadmium ion had its highest adsorptions by KOH AC of 180-150µm particle size range. NAOH AC of 180-150µm had the next highest percentage adsorption. The same is observed here that the smaller the particle size range, the greater the adsorption. Higher adsorption percentages are promised at smaller particle size ranges.

Iron and Platinum Ion Adsorption 180-150µm particle size of NaOH AC exhibited the highest adsorptive ability for the removal of Iron (Fe) from the waste water source. On the same contact time of 30mins, 180-150µm particle size AC of KOH was next in adsorptive ability. The Platinum adsorption was one that gave results beyond traceable limit for all AC samples.

Changes in Physicochemical Properties of Water pH: KOH AC of 212-180µm had the highest effect on the pH of the waste water. It was followed by NaOH AC of 212-180µm particle size. CONDUCTIVITY: It was also observed that the 212-180µm KOH AC had the greatest effect on the conductivity of the waste water followed by the 212-180µm particle size range of NaOH AC. TOTAL DISSOLVED SOLIDS (TDS): It was also observed that the 212-180µm KOH AC had the greatest effect on the TDS of the waste water followed by the 212-180µm particle size range of NaOH AC.  

TOTAL SUSPENDED SOLIDS (TSS): It was also observed that the 212-180µm KOH AC had the greatest effect on the TSS of the waste water followed by the 212-180µm particle size range of NaOH AC. CHLORIDE AND SALINITY: 180-150µm size range KOH AC proved to be more efficient in the removal of Chloride and Salinity followed by the 180-150µm size range of NaOH AC. TURBIDITY: 180-150µm PARTICLE SIZE RANGE of KOH AC cleared the waste water more followed by the 180-150µm particle size range of NaOH AC.

The use of Nigerian Bamboo Activated Carbon (NBAC) for the adsorption of iron from borehole water has been examined Ujile and Joel, (2012). They established in their work that the percentage recovery of iron depends on the initial concentration of the ions and decreases with the adsorption rate on the adsorbent.

Conclusions From experimental results, it has been shown that the principles of adsorption can be applied to the removal of metal ions from industrial wastewater sample. The physicochemical properties of the wastewater were remediated by the Bamboo Activated Carbon, which was used as the adsorbent for this research work. The 180-150µm particle size ranges of KOH and NaOH activated carbon proved to be more efficient in the removal of wastewater contaminants, although the KOH activated carbon took the lead.

Recommendation It is however recommended that more work be done to compare the effects of: 1. Lower particle size ranges, say, 150-100µm and 100-75µm size ranges, 2. Higher activation temperature and 3. Longer contact time. The water thus treated is fit to be discharged into the water body as it has met regulatory standards on waste water disposal. 4. Pilot plant development for the pyrolysis process. 5. Commercial scale production of AC from bamboo.

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