Sorption kinetic studies of medical grade activated carbon prepared from papaya seeds

The aim of this investigation was to determine the adsorption behavior and kinetics of methylene blue in aqueous solution on activated carbons prepared from papaya seeds by way of the two stage activation method in self-generated atmosphere using a muffle furnace. The optimised activated carbon, AK7, had a sorption kinetic that complied with the pseudo-second order kinetics and was fitted well to Langmuir isotherm model. The highest adsorption capacity of 97.09 mg g-1was obtained when the samples (AK7) were subjected to activation temperature of 500oC for 60 minutes with the percentage of methylene blue removal efficiency of 99.5%

Carbon Dioxide Sequestration: A Review on the Current Techniques and the Way Forward

The effects of CO2 released from the combustion of fossil fuel and the ensuing global warming have caused a noticeable climate change throughout the world. The resulting efforts have been geared to reducing and removing atmospheric CO2. One of the most prominent efforts undertaken by researchers worldwide is to capture and store CO2 or carbon dioxide capture and sequestration (CCS) using various methods and techniques. Post-combustion capture seems promising in terms of design, but more importantly, it can be easily integrated into existing plants thus providing a cheap and instant improvement. Activated carbon adsorption method seems to be the most cost efficient for post-combustion capture as its precursors are cheap and abundant, even though zeolite and ZIF counterparts show better selectivity and adsorption but are more expensive. In this paper, different ideas of CCS are reviewed individually and discussed with the sole aim of presenting the next step for achieving a sustainable method for the removal of atmospheric CO2

Textural and chemical characterization of activated carbons prepared from rice husk (Oryza Sativa) using a two-stage activation process

Activated carbons from agro-industrial wastes; rice husk; were prepared by physical and chemical activation using phosphoric acid as the dehydrating agent. A two-stage activation process method was used; with semi-carbonisation stage at 200oC for 15 minutes as the first stage followed by an activation stage at 500oC for 45 minutes as the second stage. The precursor material with the impregnation agent was exposed straightaway to semi-carbonization and activation temperature unlike the specific temperature progression as reported in the literature. All experiments were conducted in a laboratory scale muffle furnace under static conditions in a self generated atmosphere covering process parameters such as impregnation ratios. We found that by using this method, the AC5 had the highest iodine number and methylene blue adsorption capacity which was 506.6 mg/g and 319.0 mg/g respectively

Carbon dioxide removal by adsorption

Carbon dioxide (CO2) among other air pollutants is a major culprit to the greenhouse gases that is fueling global warming. To mitigate global warming, Kyoto Protocal urges 37 industrialized nations and European Union to reduce their greenhouse gas emissions to a level of 5.2% on average lower than those of 1990 during the period of 2008-2012. It is therefore essential to develop the CCS technologies to cope with the global demand of CO2 reduction. In this study the technologies of CO2 removal are reviewed

Preparation and characterization of activated carbon derived from waste rubber tire via chemical activation with ZnCl2: surface area and morphological studies

Turning waste to wealth is an important aspect in promoting green technology. In this study, activated carbon from waste rubber tire was prepared using chemical activation (ZnCl2) by way of two-stage activation in self-generated atmosphere method. The preparation parameters examined and compared in this study were activation time, activation temperature, and impregnation ratio. The adsorption of the target pollutant, 2,4-dichlorophenol (DCP), was used to evaluate the efficiency of adsorption capacity of the prepared activated carbon. Results from the experimental work showed that the activated carbon prepared satisfied the Freundlich isotherm and complied with the pseudo-second-order kinetics (not presented here). Other parameters studied, such as the percentage yield of activated carbon, ash, and moisture content and the morphology structure, are presented in this chapter. This study showed that waste rubber tire dehydrated with ZnCl2 with an impregnation ratio of 1:1 and activated at a temperature of 500 °C for 120 min gave the best result (AC5)

Parametric and adsorption kinetic studies of reactive black 5 removal from textile simulated wastewater using oil palm (Elais guineensis) empty fruit bunch

The potential of using Empty Fruit Bunch (EFB), an agrowaste material, as a low-cost biosorbent for the removal of Reactive Black 5 (RB5) from aqueous solution was investigated in this study. The influences of solution pH, contact time, initial concentration and biosorbent dosage were studied in batch experiments at room temperature. Adsorption equilibrium was achieved after 30 min of agitation. The maximum adsorption uptake of RB5 dye occurred at pH 2, resulting in a rapid adsorption (more than 50% RB5 uptake) for the first 5 min of contact. Lower solution pH values showed better adsorption because the dye molecules tend to adsorb on positively charged adsorbent sites. Furthermore, higher biosorbent dosages increased the dye uptake by up to 90% due to the availability of more active adsorption sites. Both the pseudo-second-order kinetic model and the Langmuir model indicated that monolayer coverage on the adsorbent was dominant and that chemisorption was the rate-determining ste

Removal of chlorinated phenol from aqueous solution utilizing activated carbon derived from papaya (carica papaya) seeds

Activated carbons (ACs) were prepared from papaya seeds with different dry weight impregnation ratios of zinc chloride (ZnCl2) to papaya seeds by using a two-stage self-generated atmosphere method. The papaya seeds were first semi-carbonized in a muffle furnace at 300 oC for 1 h and then impregnated with ZnCl2 before activation at 500 oC for 2 h. Several physical and chemical characteristics such as moisture, ash, pH, functional groups, morphological structure and porosity of prepared ACs were studied and presented here. AC2, with the impregnation ration of 1 : 2 (papaya seeds: ZnCl2), yielded a product that had the highest adsorption capacity, 91.75%, achieved after 180min contact time. The maximum Brunauer, Emmett and Teller (BET) surface area of AC2 was 546m2/g. Adsorption studies indicated that AC2 complied well with the Langmuir isotherm (qm=39.683mg g-1) and the pseudo-second-order (qe=29.36mg g-1). This indicated that chemisorption was the primary adsorption method for AC2. The intraparticle diffusion model proved that the mechanism of adsorption was separated into two stages: the instantaneous stage and the gradual adsorption stage. Overall, this work demonstrated the suitability of using papaya seeds as a precursor to manufacture activated carbon

Parametric and adsorption kinetic studies of Methylene blue removal from Aqueous Solution using Bornean Rambutan (Nephelium lappaceum L.)skin

In this study, methylene blue (MB) dye removal from water sample by adsorption onto rambutan skin, was examined. The adsorption studies using batch experiments were carried out under different parametric conditions of initial dye concentrations(3.0 mg/l – 15.0 mg/l), solution pH 2 – 12 and solution temperature 30°C – 60°C. MB adsorption uptake was found to increase with the increase in initial dye concentration and solution temperature and was also favourable at higher pH. Langmuir, Freundlich and Temkin isotherm models were used to examine the experimental isotherms and their corresponding constants. The equilibrium data obtained were best represented by Freundlich isotherm model with a high R2 value of 0.898. The adsorption kinetic rates complied with the pseudo-second-order model indicated that chemisorption might be the rate-limiting step that controlled the overall adsorption process. Thermodynamic data analysis indicated that the adsorption process was endothermic in nature. The data presented above suggest that the rambutan skin could be an alternative low-cost biosorbent for the removal of cationic dye from textile industrial effluent

Low-Cost Electronic Microwave Calibration for Rapid On-Line Moisture Sensing of Seedcotton

In order to improve rapid on-line moisture sensing of seedcotton in cotton gins, a means by which to establish a reliable low-cost wide-band electronic calibration is critically needed. This calibration is needed to center the circuit due to changes in the internal signal delays and attenuation drift caused by temperature changes in the various system components and circuit elements. This research examines a hardware technique for use in conjunction with microwave reflective sensing probes having an extended bandwidth from 500 MHz through 2.5 GHz. This new technique was validated experimentally against known electrical propagation delay standards. Results of the measured propagation delay with this type of automatic electronic calibration method was found to agree with results using a vector network analyzer with a traditional S11 single port error correction calibration methodology to within 4% of the measurement, 95% confidence, with a standard error of +/− 18.6 ps for the delay measurements. At this level of performance, the proposed low-cost technique exhibits superior performance, over the typical geosciences time-domain reflectometer “TDR”, instruments in common use in soil moisture testing and is suitable for use in cotton gin moisture sensing

Removal of Chlorinated Phenol from Aqueous Media by guava seed (Psidium Guajava) Tailored Activated Carbon

In this study, the activated carbons (ACs) were prepared from guava seeds via two stages activation. The dried guava seeds were semi-carbonized at 300 °C for 1 h, and then the carbonized samples were impregnated with zinc chloride (ZnCl2). The ZnCl2: sample impregnation ratios (w/w) were altered from 1:1 to 5:1. The ACs were characterized by the yield percentage, ash content, moisture content, pH value, adsorption quality of 2,4-dichlorophenol (2,4-DCP) and surface functional groups. The surface area of the best produced AC3 was found to be 919.40 m2 g-1. It was found that AC3 had highest 2,4-DCP adsorption capacity, which was 20.9 mg g-1. The 2,4-DCP adsorption kinetic of prepared AC3 was pseudo-second order with correlation value of 0.995. In addition, the 2,4-DCP adsorption capacity of AC3 was fitted to the Langmuir model with correlation coefficient value of 0.977, indicating that chemisorption was a major contributor to the adsorption process