S. M. Anisuzzaman

Parametric and adsorption kinetic studies of methylene blue removal from simulated textile water using durian (Durio zibethinus murray) skin

In this study, durian (Durio zibethinus Murray) skin was examined for its ability to remove methylene blue (MB) dye from simulated textile wastewater. Adsorption equilibrium and kinetics of MB removal from aqueous solutions at different parametric conditions such as different initial concentrations (2-10 mg/L), biosorbent dosages (0.3-0.7 g) and pH solution (4-9) onto durian skin were studied using batch adsorption. The amount of MB adsorbed increased from 3.45 to 17.31 mg/g with the increase in initial concentration of MB dye; whereas biosorbent dosage increased from 1.08 to 2.47 mg/g. Maximum dye adsorption capacity of the durian skin was found to increase from 3.78 to 6.40 mg/g, with increasing solution pH. Equilibrium isotherm data were analyzed according to Langmuir and Freundlich isotherm models. The sorption equilibrium was best described by the Freundlich isotherm model with maximum adsorption capacity of 7.23 mg/g and this was due to the heterogeneous nature of the durian skin surface. Kinetic studies indicated that the sorption of MB dye tended to follow the pseudo second-order kinetic model with promising correlation of 0.9836 < R(2) < 0.9918.

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 °C for 1 h and then impregnated with ZnCl2 before activation at 500 °C 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.

Decolorization of Low Molecular Compounds of Seaweed by Using Activated Carbon

Commercially available carrageenan powder which is extracted from seaweed possesses yellowish color and off-odor that deter their usage in human food, pharmaceutical and cosmetic industries. The objective of this study was to investigate of decolorization of low molecular compounds of seaweed using activated carbon (AC). The effects of changes on AC dosage, temperature and contact time were investigated. The effect of color concentration was analysed using Hunter Laboratories ColorFlex® Colorimeter. Colors were measured in reflectance mode using the Hunter L a b system, with D65 as the illuminant and a 10 o standard observer angle. It was observed that an increase in activated carbon dosage decreases color. UV VIS Spectrophotometer was used to investigate whether adsorbed sample gives an effect to the molecular compounds before and after AC addition. In conclusion, the treatment using AC gives complete decolorization of carrageenan solution. This study also confirms contact time not really affected on bleaching process.

Spray Drying of Morinda Citrifolia L. and Beta Vulgaris L. Fruit Extract and Its Synergistic Effect

 Abstract—This study was to examine the antioxidant potential of Morindacitrifolia L. and Beta vulgaris L. fruits and its synergistic effect. The bioactive components of these fruits were extracted and then microencapsulated by spray drying technique. The antioxidant activities of these fruits were analyzed, before and after the spray drying process through DPPH radical scavenging activity, total phenolic content and total flavonoid content. The encapsulation yield of the spray drying process was also quantified. Among the spray drying samples encapsulation yield was found maximum 8 % for the mixed fruit extract. Similarly, synergistic effect between the two fruits showed the highest antioxidant activity of 30% and the individual fruit extract also exhibited significant antioxidant activity.

Wax inhibitor based on ethylene vinyl acetate with methyl methacrylate and diethanolamine for crude oil pipeline

Wax precipitation and deposition is one of the most significant flow assurance challenges in the production system of the crude oil. Wax inhibitors are developed as a preventive strategy to avoid an absolute wax deposition. Wax inhibitors are polymers which can be known as pour point depressants as they impede the wax crystals formation, growth, and deposition. In this study three formulations of wax inhibitors were prepared, ethylene vinyl acetate, ethylene vinyl acetate co-methyl methacrylate (EVA co-MMA) and ethylene vinyl acetate co-diethanolamine (EVA co-DEA) and the comparison of their efficiencies in terms of cloud point¸ pour point, performance inhibition efficiency (%PIE) and viscosity were evaluated. The cloud point and pour point for both EVA and EVA co-MMA were similar, 15°C and 10-5°C, respectively. Whereas, the cloud point and pour point for EVA co-DEA were better, 10°C and 10-5°C respectively. In conclusion, EVA co-DEA had shown the best % PIE (28.42%) which indicates highest percentage reduction of wax deposit as compared to the other two inhibitors.

Adsorption isotherm of non-azeotropic solution onto porous adsorbents

Adsorption isotherm is essential component in the understanding of the adsorption process. Several methods of the measurements, analysis and interpretation of adsorption from solution have been reported in the literature. Most of the measurements of adsorption isotherm from solution were involved the measurement of excess isotherm conducted at low region of sorbates concentration. Direct interpretation of excess adsorption isotherm as adsorption isotherm is always been practice. Therefore, in this work a study on the measurement of the adsorption isotherm from solution of non-azeotropic organic solvent mixture onto porous adsorbents for whole range of liquid concentration was conducted. The study included the measurement of excess adsorption isotherm using conventional technique. Theoretical analysis and interpretation of adsorption isotherm from the excess isotherm were conducted using Pseudo Ideal Adsorption, Gibbs Dividing Plane Model and Langmuir-Fruendlich binary isotherm model. For organic solvents, acetone and propanol were chosen as the adsorbates due to the non-azeotropic properties in the mixture. Activated carbon and silicalite were chosen as adsorbents due to the different in their porosity such as macro porous and micro porous structure. The result of the study has revealed that the adsorption isotherm of non-azeotropic mixture onto activated carbon and silicalite can be interpreted as monolayer type of adsorption.

Solid–liquid mass transfer coefficients in an ultrasound-irradiated extraction of iota-carrageenan

A 20-kHz intensity ultrasound was used in the extraction of iota-carrageenan from Eucheuma denticulatum seaweed by using water as solvent. In a simplified extraction procedure, the seaweed particle size of 0.7125E-03 m, 1.2E-03 m, and 1.7E-03 m diameter were studied at different ultrasonic amplitude levels, ranging from 2.08E-06 to 6.4E-06 m and the temperatures from 30 to 60 °C. The maximum iota-carrageenan yield obtained was 57.2 %. This study suggested that ultrasound intensity employed reduced the extraction time required and improved the yield of iota-carrageenan by 6 %. The particle diameter variation during the extraction was found to be a linear equation. The solid–liquid mass transfer coefficient was correlated for ultrasound extraction of iota-carrageenan in terms of operating conditions employed in this investigation as

Chlorinated phenol removal from aqueous media by tea (Camellia sinensis) leaf waste tailored activated carbon

k_{L} = 0.0027 A^{0.866} D_{p}^{ - 0.533} \left( T \right)^{0.133}