Isotherm and kinetics of methylene blue removal by Musa acuminata peel adsorbents

Adsorbents were derived from banana peel through chemical treatment using phosphoric acid, potassium hydroxide, and sodium hydroxide to adsorb methylene blue from water. The adsorption of methylene blue was performed at varying concentrations and contact times. The equilibrium data fitted well with Langmuir equation, with a maximum monolayer adsorption capacity of 99.28 mg/g (28%). Phosphoric acid-treated adsorbent exhibits a greater capacity despite a lower affinity than the other adsorbents. A two-stage batch adsorber model was developed to optimize the adsorbent dosage for performance evaluation. Banana peel is a promising resource of adsorbent for wastewater treatment

Solubility assessment of castor (Ricinus communis L) oil in supercritical CO<inf>2</inf> at different temperatures and pressures under dynamic conditions

A simple dynamic technique was used to obtain the solubility of castor oil in supercritical carbon dioxide. The solubility was measured at temperatures ranging from 313 to 335K and pressures from 20 to 36MPa. Under extraction conditions, the measured solubilities were in the range from 1.29×10-3 to 4.88×10-3 (g of oil)/(g of CO2). Measurements confirmed that temperature and pressure have direct effects on solubility-enhancement factors. Five semi-empirical models were tested for their ability to correlate experimental data: the Chrastil, Del Valle Aguilera (VA), Bartle, Kumar and Johnston (KJ), and Mendez-Santiago and Teja (MST) models. Over the temperature and pressure ranges studied, solubilities from these models had the following average absolute relative deviations from experimental data: Chrastil, VA, Bartle, KJ and MST models with an average absolute relative deviation percent (AARD%) of 0.05%, 0.30%, 0.38%, 5.98% and 28.4%, respectively. Thus, the Chrastil, VA and Bartle models correlated the castor oil solubility data with the lowest AARD%

The effect of conventional and microwave heating techniques on transesterification of waste cooking oil to biodiesel

This research is focused on the effect of processing parameters such as molar ratio of sample to solvent (1:3 - 1:15), catalyst loading (0.5 - 2.5 wt %), temperature (40 - 80 C) and time of reaction ( 5 - 180 min) on the transesterification yield of waste cooking oil (WCO) in conventional thermal heating and microwave heating technique s . The analysis carried out revealed that the microwave assisted transesterification produced a comparable yield to conventional heating transesterification with ~ 5 times faster in heating up the reaction mixture to a reaction temperature and reduced ~ 90% of the reaction time required . This study concludes that microwave assisted transesterification , which is a green technology, may have great potential in reducing the processing time compared to conventional thermal heating transesterification

Relationship between helium degassing of cattle-manure-compost adsorbents and copper ions removal

This work was aimed to investigate the effect of helium degassing of cattle-manure-compost (CMC) based activated carbons on the adsorptive removal of copper ions from aqueous solution. Degassing temperatures were 500°C, 800°C and 1000°C. Activated carbons were characterized according to surface chemistry and pore structures. Adsorption of copper ions was carried out using the conventional bottle-point technique to which the equilibrium data were correlated to Langmuir and Freundlich models. Results indicated that the uptake of copper ions could be well characterized by Langmuir model. It was found that the adsorption of copper ions decreased with significant decrease in surface area as a result of helium degassing at higher temperature. The increase of electron density on graphene layers offered higher affinity towards copper ions at lower equilibrium concentration. It was inferred that copper ions favorably adsorbed on mesopores at lower equilibrium concentration and switched to micropores at higher equilibrium concentration

Mass transfer kinetics and mechanisms of phosphate adsorbed on waste mussel shell

An excessive amount of phosphate (PO4 3−) released from domestic wastewater treatment plant efuent (DWTPE) may trigger eutrophication of water causing a degradation of healthy aquatic eco�system. Even though the PO4 3− ions can be removed from aqueous solution with an adsorption technique using the low-cost adsorbent, the adsorption kinet�ics of PO4 3− removal must be understood. The bed depth service time (BDST), Thomas and modifed mass transfer factor (MMTF) models were used to investigate the adsorption kinetics of PO4 3− removed from DWTPE onto the waste mussel shell (WMS) applied to hybrid plug fow column reactor (HPFCR). Dynamic adsorption capacity of WMS described by the new modifed BDST model is shown to increase with increasing of the plug fow column (PFC) bed. The analysis of mass transfer behavior described using the Thomas model is able to predict the per�formance of HPFCR at certain depths of the PFC bed. The use of the MMTF models could be useful to describe the real diference between the behav�iors of flm mass transfer and porous difusion. The resistance of PO4 3− mass transfer depending on porous difusion has been verifed to provide a contri�bution in the development of advanced WMS adsor�bent for enhancing the HPFCR performance in the future

Optimization and solubilization of interest Compounds from roselle in subcritical ethanol Extraction (see)

A scientific investigation on the optimization and solubilization of anthocyanin from roselle by subcritical ethanol (SE) has not yet been conducted. Consequently, the purpose of this work is to evaluate the parameter influences on anthocyanin recovery by SE, followed by the identification of the solubilization behavior by semi-empirical modelling. The best conditions were 8.74 MPa, 383.51 K and 5.21 mL/min with responses of global yield of 0.765 g/g, anthocyanin of 921.43 mg/100 g, TPC of 40.57 mg/100 g and TFC of 559.14 mg/g. High pressure and temperature conditions are conducive to global yield, anthocyanin, flavonoid and phenolic recovery. The Del Valle Aguilera model fits the solubility of global yield and anthocyanin in SE effectively instead of Chrastil model since it has the lower average absolute relative deviation (AARD), which is 11.54 % and 7.15 %, respectively. The most influenced parameters were found to be the temperature, which gave a significant impact in enhancing the solubization power of global yield and anthocyanin

Irradiated water-activated waste tyre powder for decolourization of reactive orange 16

The present study was aimed to characterize the adsorptive properties of waste tyre powder based activated carbons for decolourization of reactive orange 16 (RO16). Waste tyre powder was activated through irradiated water environment (MAC). Comparison was made by conventional chemical activation using calcium chloride (CAC) and recovered calcium chloride from the first activation (RAC). Activated carbons were characterized according to surface area, morphology and functional groups. The values of surface area were recorded as 95.9, 111, 80.9m2/g for MAC, CAC and RAC, respectively. The decolourization of RO16 was observed to have the following order: MAC>CAC>RAC. Adsorption data for all activated carbons studied obeyed Langmuir isotherm for which the process could be described as monolayer adsorption. The kinetics data were well-fitted to pseudo-second-order model, suggesting the chemisorption proces

Giant mud crab shell biochar: A promising adsorbent for methyl violet removal in wastewater treatment

Giant mud crab (Scylla serrata sp.) shell prepared through pyrolysis at various temperatures without any modification were characterized for physicochemical properties and methyl violet (MV) removal potential. Hence, this paper investigated the performance and mechanism of biochar derived from giant mud crab shell as adsorbent in the removal of methyl violet as well as the potential for regenerating adsorbents via hot water regeneration. The results show that CSB500 (produced through pyrolysis at 500 °C) exhibits a surface area of 59.73 m2/g and mesopore size of 31.3 nm, favorable for methyl violet removal at 3139 mg/g. The equilibrium adsorption data agreed well with Langmuir and Redlich-Peterson isotherm models, indicating a monolayer adsorption of MV. The kinetics data fitted better with both pseudo-first-order and pseudo-second-order models. The intraparticle diffusion and Boyd's models revealed that both film and pore diffusion may be involved in the adsorption process. In hot water regeneration studies, CSB500 shown superior regeneration performance when using water with temperature of 70 °C rather than 30 °C for 9th regeneration cycles, with retained to achieve >90 % MV removal for 6th regeneration cycles. Biochar derived from giant mud crab shell has shown significant promise as a low-cost, effective, and ecologically friendly with reasonably good adsorption capacity and reusability for dye removal, and it can be considered as an environmental sustainability strategy in wastewater treatment

The effects of conventional and microwave heating techniques on extraction yield of orthosiphon stamineus leaves

The heating technique in a solid-liquid extraction system plays a significant role in the design and economic potential for the extraction of active components from herbs. This paper focused on the effects of extraction parameters such as ratio of sample to solvent, temperature and time of processing on the extraction yield of Orthosiphon stamineus leaves in conventional and microwave heating extraction techniques. The extracts were concentrated and dried using a rotary evaporator and freeze dryer in order to relate the yield to the processing parameters quantitatively in both heating techniques. The analysis results revealed that the processing parameters; ratio of sample to solvent, temperature and time of extraction had essential effects on the extraction yield of Orthosiphon stamineus leaves. Microwave heating extraction produced a comparable yield to conventional heating extraction with a relatively small deviation of approximately 2.8 % in average. Furthermore, microwave heating extraction reduced processing time, where this technique required about 25 % of the conventional heating time in heating up the extraction mixture to set-point temperature (60 ºC). This study concludes that microwave heating extraction, which is a green technology, has great potential in reducing the carbon foot print due to a shorter processing time and reduced energy consumption (~77 % less) compared to conventional heating extraction

Effects of zinc chloride impregnation states on specific surface and dielectric properties of activated carbons

The present work was aimed at evaluating the roles of zinc chloride impregnation states on specific surface and dielectric properties in microwave-assisted activated carbon preparation. Activated carbons were synthesized using castor shell at dry impregnation ratios of 1 and 2 (material-to-activator), and in suspensions of distilled water and zinc chloride, at power intensity of 800 W and irradiation time of 5 min. The activated carbons exhibit an improvement in dielectric properties and specific surface with increasing impregnation ratio. Palm kernel shell was employed for comparison to verify the effect of power intensity. At 800 W, the magnitudes of surface area are 1684 m2/g and 1150 m2/g for castor shell- and palm kernel shell-based activated carbons, respectively. A high specific surface brings about a greater methylene blue adsorption for possible applications in wastewater treatment