Effect of Mercerization and Acetylation on Properties of Coconut Fiber and its Influence on Modified Bitumen

Coconut fiber, one of many types of natural fibers, is an agricultural waste which is left unutilized after the coconut fruits and juice are extracted. In this research, the effect of the different chemical treatments on the morphological, chemical and physical properties of coconut fiber and its influence on the properties of the modified bitumen were studied. The mercerization effectively altered the surface morphology and reduced the diameter of the coconut fiber. The waxy layer present on the surface of the coconut fiber was significantly reduced after mercerization. Acetylation reported minor reduction on the waxy layer and did not cause any significant changes on the diameter of the coconut fiber. The chemical characterization reported that the hemicelluloses were present only on the surface of the natural coconut fiber whereas the peak of Fourier Transform Infrared spectra associated with the presence of waxes was observed for natural and chemically treated coconut fibers. The bitumen modified with chemically treated coconut fibers exhibited lower penetration values and higher softening point. From the analyses of penetration value, softening point and penetration index, the bitumen modified with 10% NaOH and 50% CH3COOH treated coconut fibers resulted in enhanced properties for paving binders to be used in warmer region

Effects of temperature on wastewater treatment in an affordable microbial fuel cell-adsorption hybrid system

Graphical abstract: A cost effective single-chamber microbial fuel cell (MFC) integrated with adsorption system was tested under different operating temperatures to observe pH profiles, organics, solids, nutrients, color and turbidity removal and power density generation. The optimum operating temperature range was found to be ∼25-35°C with majority of the removals achieved at ∼35°C. Maximum power density recorded was 74±6mW/m3 with coulombic efficiency (CE) of 10.65±0.5% when operated at 35°C. Present studies had successfully demonstrated the effectiveness of a hybrid system in removing various types of pollutants in POME at optimum temperature and able to fulfill the stringent effluent discharge limit. Chemical oxygen demand (COD), total solids (TS) and turbidity removals increase linearly with temperatures with removal efficiency of 0.5889%C−1, 1.0754%C−1 and 0.7761%C−1, respectively. The temperature coefficient (Q10) is found to be 1.06, 1.45 and 1.09, respectively. Besides, MFC-adsorption hybrid system had demonstrated superior stability over a wide range of operating temperatures in terms of COD removal as compared to the non-integrated MFC system

Development of adsorption air-conditioning technology using modified activated carbon – a review

Adsorption air-conditioning technology has attracted much attention recently due to its environmental friendly property. Some successes have been reported in the literature on the adsorption technology for air-conditioning applications. This paper presents an overview of the researches which had been carried out on adsorption refrigeration system with the commonly used adsorbent and adsorbate working pairs, solar adsorption refrigeration and adsorption technologies in automobile. Activated carbon has been widely used as the adsorbent in adsorption refrigeration system. However, one of the bottlenecks which prevent the improvement of the adsorption refrigeration technology using activated carbon is the use of the readily available commercial activated carbon without prior treatment, which has resulted in relatively lower performance as compared to the conventional absorption and vapour compression technologies. Various modification methods on activated carbon are thus discussed in this paper for future development and improvement of adsorption air-conditioning system

Encapsulated biochar-based sustained release fertilizer for precision agriculture: A review

The excessive use of conventional fertilizers leads to environmental issues associated with the loss of nutrient through leaching, volatilization, denitrification and surface run-off. Biochar-based fertilizer has gained much research interest as it can be used as a slow release fertilizer. Biochar-based fertilizer can alleviate the properties of soil to slow down the nutrient release rate. However, the sustained release mechanism of biochar-based fertilizer is still facing limitations. As a solution to mitigate this issue, the integration of encapsulating technology and biochar-based fertilizer has been introduced to improve the sustained release mechanism. This paper presents an extensive overview on the various formulations of biochar-based fertilizer and encapsulated biochar-based fertilizer. Additionally, the influence of the inorganic mineral, polymer and hydrogel-based fertilizers on the nutrient release behaviour are also critically discussed. The various methods used to synthesize the fertilizers and their effects on soil amendment are also discussed in detail. This paper could be used as a good source of information on the current advances and future perspectives of encapsulated biochar-based sustained release fertilizer for precision agriculture.The authors acknowledge the research grant provided by Universiti Malaysia Sarawak under Cross Disciplinary Research Grant [ F02/CDRG/1830/2019 ].Scopu

Mesoporous and adsorptive properties of palm date seed activated carbon prepared via sequential hydrothermal carbonization and sodium hydroxide activation

Mesoporous activated carbon (AC) was prepared via sodium hydroxide (NaOH) activation of hydrochar from the hydrothermal carbonization (HTC) of palm date seed (PDS). The textural, morphological, and chemical properties of the produced hydrochar AC were investigated. NaOH activation enhanced the porosity and surface functionality of the hydrochar. Batch equilibration methods were performed to explore the process parameters that affected the adsorption of the prepared AC on methylene blue (MB), including initial concentration, contact time, solution pH and temperature. The Freundlich isotherm model better depicted the equilibrium data compared with the Langmuir isotherm model. Temperature was found to negatively affect the adsorption capacity of the prepared AC, which exhibited 612.1, 464.3 and 410.0 mg/g maximum MB adsorption capacities at 30, 40 and 50 �C, respectively. The pseudo-second order kinetic model best described the kinetic data. HTC and NaOH activation was proven to be an effective method in preparing highly porous AC from PDS, with good potential for cationic dye removal from liquid phase

Continuous asymmetric ketone reduction processes with recombinant Escherichia coli

The reduction of methyl acetoacetate was carried out in continuously operated biotransformation processes catalyzed by recombinant Escherichia coli cells expressing an alcohol dehydrogenase from Lactobacillus brevis. Three different cell types were applied as biocatalysts in three different cofactor regeneration approaches. Both processes with enzyme-coupled cofactor regeneration catalyzed by formate dehydrogenase or glucose dehydrogenase are characterized by a rapid deactivation of the biocatalyst. By contrast the processes with substrate-coupled cofactor regeneration by alcohol dehydrogenase catalyzed oxidation of 2-propanol could be run over a period of 7 weeks with exceedingly high substrate and cosubstrate concentrations of up to 2.5 and 2.8 mol L(-1), respectively. Even under these extreme conditions, the applied biocatalyst showed a good stability with only marginal leakage of intracellular cofactors

Obtenção e caracterização de carvão ativado de caroço de buriti (Mauritia flexuosa L. f.) para a avaliação do processo de adsorção de cobre (II) Production and characterization of the activated carbon from buriti stone (Mauritia flexuosa L. f.) to evaluate the adsorption's process of copper (II)

Na região amazônica, algumas indústrias despejam cobre nos corpos receptores que, em elevadas concentrações, é tóxico para os seres vivos. A remoção de cobre de efluentes industriais é realizada por diversos processos como a adsorção. Neste trabalho mostrou-se o resultado da adsorção de cobre (II) em carvão ativado de caroço de buriti carbonizado a 400 °C e ativado a 900 °C. O carvão ativado foi caracterizado em termos de área específica, tamanho dos poros, densidades aparente e real, porosidade, microscopia eletrônica de varredura, conteúdo de cinzas, pH, umidade, carbono fixo e grupos funcionais de superfície. O estudo de equilíbrio de adsorção avaliou a influência do diâmetro das partículas do carvão, do tempo de contato adsorvente/adsorbato, do pH e da concentração inicial da solução de cobre (II) sobre a remoção de cobre (II). Com base nos resultados, concluiu-se que há uma maior eficiência de remoção de cobre (II) para diâmetro < 0,595 mm, tempo de contato de 300 minutos, pH 4,0 e concentrações iniciais de cobre (II) de 50 e 80 mg L-1. O modelo matemático de Langmuir foi o que melhor se ajustou aos dados de equilíbrio de adsorção. A partir do tempo de contato de 15 minutos todas as concentrações de equilíbrio ficaram abaixo do máximo permitido de 1,0 mg L-1 previsto pela legislaç��o vigente para lançamento de efluentes em corpos receptores.<br>In the Amazon region some industries discharges copper into watercourse that in high concentrations is toxic to the biota. The removal of copper from industrial effluent is performed by several processes such as adsorption. This work shows the result of copper (II) adsorption on activated carbon obtained from buriti kernel, carbonized at 400 °C and activated at 900 °C. The activated carbon was characterized according to specific area, pore size, apparent and real density, porosity, scanning electron microscopy, ash content, pH, moisture, fixed carbon and surface functional groups. The study of adsorption equilibrium evaluated the influence of the coal particles diameter, contact time adsorbent/adsorbate, pH and copper (II) solution initial concentration on copper (II) remotion. The results showed a higher removal efficiency of copper (II) to the diameter D < 0.595 mm, contact time of 300 minutes, pH of 4.01 and the copper (II) initial concentrations of 50 and 80 mg L-1. The mathematical model of Langmuir was the best fit to the adsorption equilibrium data. From the contact time of 15 minutes, all the equilibrium concentrations were below the allowed maximum of 1,0 mg L-1 provided by law for discharging effluents into receiving bodies