Search

Biochar is an interesting adsorbent material due to its use is correlated with biomass waste utilization and also minimize environmental pollution from high amount of biomass by-product. Regarding to improve the biochar ability in water treatment, several surface modifications have been developed, one of them is modification using surfactant. In this study, sodium dodecylbenzene sulfonate (SDBS) was used to modify the surface of biochar prepared from pyrolysis of cassava peels (Manihot utilissima). Its performance in biochar modification to remove methylene blue (MB) dyes was compared with sodium dodecyl sulphate (SDS) surfactant for observing the important of – interactions mechanisms. The analysis of biochar and biochar-SDBS were conducted by using Fourier transform infrared (FTIR), CHNS elemental analysis, and scanning electron microscope (SEM). Furthermore, the adsorption experiments were conducted using UV-Vis spectrophotometer. It is known that modification using SDBS could increase the adsorption capacity of biochar not only from electrostatic interaction but also through – interactions mechanisms. In this respect, as the amount of SDBS mass increased, the adsorption capacity was also improved due to the modification produced more active cites on biochar. The maximum MB adsorption onto biochar-SDBS occurred at adsorbent mass of 15 mg with optimum pH value of 10. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The activation of carbon from Manihot Esculenta (cassava) peels as a sustainable biomass precursor was explored for application in supercapacitors (SCs); demonstrating a cheap and sustainable environmental friendly source of carbon materials for potential application as electrode materials for SC. The activation was carried out with three different activating agents namely potassium hydroxide (KOH), potassium bicarbonate (KHCO3) and potassium chloride in sodium thiosulphate (KCl–Na2S2O3). The obtained activated carbon (AC) material exhibited SSA up to 828 ​m2 ​g−1 for the KOH activation and the electrodes fabricated revealed a specific capacitance (CSP) (300 ​F ​g−1 at 0.5 ​A ​g−1), excellent rate capability and cycling stability (98% capacitance retention after 5000 cycles) in 6 ​M KOH aqueous solution. The study demonstrated an efficient and sustainable approach for high performance SCs by using biomass as a viable source of the carbon material for SC applications.

Supercapacitors are conventional devices in electrical circuits that produce electrical pulses at high power levels in short periods. Electrodes for supercapacitors were prepared with activated carbon. Activated carbon was obtained from cassava peels treated by chemical activation with potassium hydroxide (KOH) and phosphoric acid (H3PO4), each at two different concentrations and at one carbonization temperature. The electrochemical performance of the prepared electrodes was obtained by means of cyclic voltammetry and galvanostatic charge-discharge in a 3-electrode system with an electrolytic solution of sulfuric acid (H2SO4) 1 M. Cyclic voltammetry allowed identifying the behavior of supercapacitors in a potential window of -0.4V to 0.6V. Activated carbon derived from cassava peel with the highest specific surface area (398.46 m2/g) has exhibited the maximum specific capacitance of 64.18 F/g. RESUMEN Los supercondensadores son dispositivos eléctricos, comunes en circuitos eléctricos, que producen pulsos eléctricos de alta potencia en cortos periodos de tiempo. Los electrodos para los supercondensadores, de este trabajo, fueron preparados con carbón activado. Los carbones activados fueron obtenidos a partir de cáscara de yuca, la cual se trató mediante activación química con hidróxido de potasio (KOH) y ácido fosfórico (H3PO4), cada uno a dos diferentes concentraciones y a una temperatura de carbonización. El desempeño electroquímico de los electrodos preparados fue obtenido por medio de pruebas de voltametría cíclica y ensayos de carga-descarga galvanostática, en un sistema de tres electrodos con ácido sulfúrico (H2SO4) 1 M como solución electrolítica. La voltametría cíclica permitió identificar el comportamiento capacitivo en una ventana de potencia de -0,4V a 0,6V. Los carbones activados, derivados de cáscara de yuca, con la mayor área superficial específica (398,46 m2/g) exhibieron la mayor capacitancia específica, alrededor de 64 F/g.

In this study, cellulose and cellulose nanofibers (CNF) were extracted and prepared from cassava peels (CPs). The method of the cellulose extraction was performed by alkali treatment followed by a bleaching process. The CNF were prepared by mechanical disruption procedure (homogenization and ultrasonication), and the results were compared with a common acid hydrolysis procedure. The resulting cellulose and CNF from both procedures were then analyzed using FTIR, SEM, TEM, XRD, and TGA. The results show that cellulose and CNF were successfully prepared from both procedures. The physical properties of the produced CNF were different, however, they hadsimilar chemical properties.

Carbon dots (C-dots) have been successfully synthesized from cassava peels using the hydrothermal method. The C-dots are further passivated using poly (ethylene glycol) (PEG) with a variation of the volume of 0.5 ml, 1.0 ml, and 1.5 ml. The properties of photoluminescence C-dots before and after PEG were characterized using photoluminescence (PL) and time-resolved photoluminescence (TRPL) spectrophotometers. PEG succeeded in influencing PL C-dots properties, such as peak wavelength, PL intensity, and electron time decay. The addition of 0.5 ml of PEG to C-dots is the optimum condition and best with the peak wavelength, the PL intensity and, time decay electron is 507.52 nm, 5302 a.u, and 3.794031133 ns, respectively.

A comparative analysis of the efficiency of activated carbon produced from fermented cassava peels (CPB), unfermented cassava peels (CPA) and commercial grade activated carbon (CAC) in the treatment of refinery wastewater was carried out. CPB was found to be 8% and 18% more efficient when compared to CPA and CAC in the removal of COD, and 14% and 3% better than CAC and CPA respectively in the removal of BOD5. The removal efficiency of Pb 2+ by CPB was 100% compared to 95% and 57% by CPA and CAC while 96% of phenol was removed by CPB against 93% and 83% by CPA and CAC respectively. This better performance of CPB over CPA and CAC is not unconnected with its higher pH resulting from the removal of cyanide from the peels during the fermentation process. However, despite the high phenol removal efficiency by CPB, the concentration of phenol in the treated effluent does not meet the environmental guidelines for disposal. It is therefore, recommended that a two-stage CPB adsorption column arranged in series is necessary to treat refinery wastewater efficiently if it is desired to totally remove phenol from the effluent or reduce the concentration to 0.005 mg/l allowed by the Federal environmental protection agency (FEPA). The equilibrium adsorption test conducted showed that the Freundlich isotherm is a better fit for the adsorption of phenol by the three activated carbons with correlation coefficients (R2) of 0.9364, 0.9383 and 0.9541 for CAC, CPA and CPB respectively. CPB was found to be a better adsorbent as it has the highest adsorptive capacity as evidenced from its better Freundlich exponent. Keyword: Cassava peels, activated carbon, adsorption, refinery wastewater, environment, pollutant. Received: 2016.01.18 Accepted: 2016.03.04 Published: 2016.04.01 before being discharged into the environment or recycled back into the plant depending on water economics [Nekoo and Shoreh, 2013; Hariz and Monser, 2014]. Since refinery wastewater pollutants is made up of both organic and inorganic sources, the treatment of such wastewater will involve chemical, physical, biological or a combination of these processes [Adeyinka and RimiRukeh, 1999; Fetter et al., 1982]. To measure the organic content of wastewater, the biological oxygen demand (BOD) and chemical oxygen demand (COD) as well as the total organic matter

The oil and gas industry faces numerous problems, from the exploration to the production phase. One of the most common problems faced by the industry is the formation of gas hydrates in the pipeline during the deep-water operation. The advancement of kinetic hydrate inhibitors (KHIs) has been rapid. However, as the natural degradation of conventional KHIs, such as polyvinylpyrrolidone (PVP) and polyvinylcaprolactam (PVCap), is challenging, there is a need to develop environmental-friendly KHIs with enhanced biodegradability to improve possible environmental risks. Thus, green inhibitors have been developed as a new class of KHIs. Research for enhancement of green hydrate inhibitors, as an alternative for existing low dosage hydrate inhibitors (LDHIs), has increased. In this paper, the effect of induction time with presence of cassava peels on the formation of methane hydrate was studied and compared with commercialized inhibitor, PVP. The performance of cassava peels as a kinetic hydrate inhibitor was investigated using high pressure micro differential scanning calorimetry (&micro, DSC). For the induction time measurement, linear cooling ramps at a constant cooling rate of 0.5 K/min were used under isobaric conditions. Aqueous solutions of 0.5 wt % and 1.0 wt % of cassava peels were prepared and the induction time of methane hydrate formation in these solutions was measured at pressure ranges from 4.0 to 10.0 MPa. One of the characteristics to be a good kinetic inhibitor is the presence of hydroxyl functional group in inhibitors, which assist to form hydrogen bonds with water molecules, thus preventing hydrates formation. Fourier transform infrared (FTIR) analysis confirms the presence of hydroxyl groups in cassava peels with wavenumber value of 3370.68 cm&minus, 1. Cassava peel solution is observed to delay the induction times at all pressure settings and it is better at 1.0 wt % concentration. However, at lower pressures of 4 and 6 MPa, the performance is less effective when compared to a commercial inhibitor, PVP. At high pressures of 8 and 10 MPa, it can be seen that the performance is as effective as PVP. This research paper shows that cassava peels have high potential to be developed as a gas hydrate green kinetic inhibitor that can be applied for industry usage in the future.

Production of L-lactic acid using cultures of Rhizopus oligosporus and Lactobacillus plantarum was investigated. Cassava peels were hydrolyzed by boiling for 1 h in either NaOH or HCl solutions followed by neutralization to a pH of 6.2. Reducing sugar produced from the hydrolysates increased with increasing concentrations of alkali or acid. Samples hydrolyzed with HCl produced a maximum reducing sugar concentration of 402 mg/g substrate while alkali hydrolyzed samples produced a maximum reducing sugar concentration of 213 mg/g substrate. Hydrolysates were amended with 0.5% ammonium sulphate solution and inoculated with either single or mixed cultures of Rhizopus oligosporus and Lactobacillus plantarum and incubated for 48 h for lactic acid production. The best lactic acid production of 50.2 g/100g substrate was observed in a mixed culture fermentation of acid hydrolyzed peels. Mixed culture fermentation of alkali hydrolyzed peels produced a maximum lactic acid concentration of 36.4 g/100g substrate. Un hydrolyzed cassava peels inoculated with a mixed culture of the microorganisms produced only 4.6 g/100g substrate. This work reports an efficient use of cassava peels for bio-product formation through microbial fermentation.

Mozambique is one of the largest coal exporters in Africa. Usually miningactivities generate polluted water that is discharged into the Zambezi river basin in the Moatize area without treatment, increasing the risk both to the local environment and to public health because of this water containing significant amounts of metals and metalloids. At the same time, Mozambique is one of the largest producers of cassava peels, most of which are wasted. The aim of the present investigation was to study the use of discarded cassava peels to treat the polluted mine water from Moatize by means of adsorption. The effects both of the pH and of the contact time between the adsorbent, the adsorbate and the adsorption isotherms were examined.For calcium, magnesium, cobalt, mercury and manganese, an equilibrium wasattained in less than 50 min, the removal efficiency of calcium, magnesium, and mercury being greater under alkaline conditions and being greatest for cobalt at pH 4 and for manganese at pH 7.5. The correlation coefficients of the experimental data were very high for the calcium, magnesium and manganese metals as compared with the Langmuir and Freundlich isotherms. For the Langmuir isotherms, it was found that the adsorption of calcium, magnesium, cobalt, mercury, and manganese by the cassava peels was favorable for adsorption generally, whereas for the Freundlich isotherms it was only manganese that was found to be not favorable for adsorption. (Less)

In-vitro degradation of cassava peel was carried out for 20 days with Trichoderma viride. The highest protein level attainable at the end of the 20th day was 15.95% and the least was 4.76%. Proximate and detergent fibre composition of in-vitro degraded cassava peel samples were determined. Experimental diets were formulated with graded levels of degraded cassava peels for weaned pigs. Diets 1, 2, 3, 4 and 5 contained biodegraded cassava peels at the expense of cassava flour at levels 0, 10, 20, 30 and 40%, respectively. Diet 3 was found to be the best utilized with feed conversion ratio (2.74+0.10), while diet 2 with the poorest conversion (3.20+0.07) was the least utilized. The best and least weight gain were recorded in the pigs fed diets 3 and 5, respectively. Biodegradation increased the crude protein content of the cassava peels, which was 15.95% at 20 days compared to 4.76 and 10.13% at 0 and 5th day, respectively. Phytic and tannic acid contents were also reduced by in-vitro degradation. Colonial counts of micro-organisms from faecal samples of pigs ranged between 108 – 1010 cfu/ml. Presence of Mucor spp and Pseudomonas spp. was noted in the experimental diets, while isolates of Lactobacilli spp., E. Coli, Pseudomonas spp. and yeast were the major micro-organisms in the faecal samples. It is therefore, concluded that biodegraded cassava peels should not be used in pig's production, as parameters studied were not significant (P>0.05) and cost of feed per kg live weight gain was best in control. Keywords : Microbial characterization; feed; faecal samples; weaned pigs; cassava peels; pigs performance Moor Journal of Agricultural Research Vol. 6 (1&2) 2005 pp. 36-44