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Adsorbent from agricultural waste has become a popular alternative method for heavy metal removal from aqueous solutions. The purpose of this study was to look into the feasibility of employing jackfruit peel (JP) (Artocarpus heterophyllus), a solid waste that is abundant in Malaysia, for the adsorption of Cu (II) and Zn (II) from an aqueous solution. In this work, jackfruit peels were investigated as an adsorbent with no chemical modification (JP), acidified (HJP), and base modified (NaJP) for Cu(II) and Zn(II) removal from aqueous solution by using batch-adsorption modes. Spectroscopic and electron microscopic methods were used to analyze the presence of surface functional groups such as -COOH and -OH and the morphologies of the adsorbent. Adsorption investigations were carried out by adjusting adsorbent dosage (0.10–0.50 g), solution pH (3−8), initial metal ion concentrations (20–250 mg/L), temperature (298–328 K), and contact time (0–360 min). Sorption equilibrium is quickly reached within 60 min, with a higher percentage of Cu(II) and Zn(II) removal for NaJP. Regarding the effect of initial concentration on JP, the maximum adsorption for Cu(II) and Zn(II) is at 50 mg/L and 30 mg/L, respectively. Meanwhile, for HJP, the maximum adsorption for Cu(II) and Zn(II) is at 230 mg/L and 30 mg/L, respectively. For NaJP, the maximum adsorption for Cu(II) and Zn(II) is at 20 mg/L. The pseudo-second-order model best characterized the kinetic data for both metal ions using JP, HJP, and NaJP. The experimental findings fit well with the Langmuir model in explaining the adsorption process, dominated by electrostatic interaction between the adsorbent and adsorbates, showing monolayer adsorption at the binding sites on the adsorbent's surface. It was proven that with the increase of adsorbent dosage, the percent of heavy metals removal was increased due to the increasing adsorption capability of the adsorbent. In conclusion, our findings show that jackfruit peel has the potential to remove Cu(II) and Zn(II) from an aqueous solution. The adsorption process for Cu(II) and Zn(II) was favourable in acidic conditions. Under the experimental conditions, the adsorption of Cu(II) and Zn(II) onto the surface of JP, HJP, and NaJP was exothermic and non-spontaneous. The results showed that the jackfruit peel, a waste material, has a high potential as an adsorbent for removing harmful metals such as copper and zinc from water. • The surface of the jackfruit peel was modified and characterized. • Copper(II) and Zinc (II) are removed efficiently using modified Jack fruit peel as adsorbent material. • Sodium hydroxide modified jack fruit peel (NaJP) exhibits high adsorption capacity. • Adsorption of Cu(II) and Zn(II) can be described by the Langmuir isotherm and pseudo-second-order kinetic model. [ABSTRACT FROM AUTHOR]

Six Malaysian hardwoods, chengal (Neobalanocarpus heimii), kapur (Dryobalanops spp.), keruing (Dipterocarpus spp.), ramin (Gonystylus spp.), acacia (Acacia mangium) and sesendok (Endospermum malaccense) were studied to determine their sorption kinetics behaviour using a dynamic vapour sorption (DVS) apparatus. Experimental data fitted well to the parallel exponential kinetics (PEK) model. The PEK model expresses the sorption kinetics as fast and slow sorption processes, but interpretation of how these can be related to physical phenomena is not yet understood. The Hailwood-Horrobin model was also used to examine the relationship between sorbed monolayer water and polylayer water at different relative humidities. Comparison between the two models was used to verify if the fast and slow sorption processes could be linked to monolayer or polylayer water formation in the cell wall. Characteristic times at various relative humidities showed differences between adsorption and desorption in the slow process for all the species. However, using mass change criterion, sorption hysteresis was found to occur in both the slow and fast processes. [ABSTRACT FROM AUTHOR]

The feasibility of using papaya seeds (PS), abundantly available waste in Malaysia, for the cationic dye (methylene blue) adsorption has been investigated. Batch adsorption studies were conducted to study the effects of contact time, initial concentration (50–360mg/L), pH (3–10) and adsorbent dose (0.05–1.00g) on the removal of methylene blue (MB) at temperature of 30°C. The equilibrium data were analyzed by the Langmuir, the Freundlich and the Temkin isotherms. The data fitted well with the Langmuir model with a maximum adsorption capacity of 555.557mg/g. The pseudo-second-order kinetics was the best for the adsorption of MB by PS with good correlation. The results demonstrated that the PS is very effective to remove methylene blue from aqueous solutions. [Copyright &y& Elsevier]

Abstract: This study aimed at investigating the feasibility of using jackfruit peel (JFP), a solid waste, abundantly available in Malaysia, for the adsorption of methylene blue, a cationic dye. Batch adsorption studies were conducted to evaluate the effects of contact time, initial concentration (35–400mg/L), pH (2–11), and adsorbent dose (0.05–1.20g) on the removal of dye at temperature of 30°C. The experimental data were analyzed by the four different types of linearized Langmuir isotherm, the Freundlich isotherm and the Temkin isotherm. The experimental data fitted well with the type 2 Langmuir model with a maximum adsorption capacity of 285.713mg/g. Pseudo-first and pseudo-second-order kinetics models were tested with the experimental data, and pseudo-second-order kinetics was the best for the adsorption of MB by JFP with coefficients of correlation R 2 ≥0.9967 for all initial MB concentrations studied. The results demonstrated that the JFP is very effective for the adsorption of methylene blue (MB) from aqueous solutions. [Copyright &y& Elsevier]

Bamboo, an abundant and inexpensive natural resource in Malaysia was used to prepare activated carbon by physiochemical activation with potassium hydroxide (KOH) and carbon dioxide (CO2) as the activating agents at 850°C for 2h. The adsorption equilibrium and kinetics of methylene blue dye on such carbon were then examined at 30°C. Adsorption isotherm of the methylene blue (MB) on the activated carbon was determined and correlated with common isotherm equations. The equilibrium data for methylene blue adsorption well fitted to the Langmuir equation, with maximum monolayer adsorption capacity of 454. 2mg/g. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equation were selected to follow the adsorption processes. The adsorption of methylene blue could be best described by the pseudo-second-order equation. The kinetic parameters of this best-fit model were calculated and discussed. [Copyright &y& Elsevier]

In this study, papaya stem, an agricultural biomass abundantly available in Malaysia, was utilized as low-cost adsorbent for removing methylene blue from the aqueous solution. The textural and functional characterization was evaluated using the scanning electron microscopy and Fourier transform infrared analysis. The adsorption data were simulated using the nonlinear Langmuir, Freundlich and Temkin isotherm models. Kinetic modeling and adsorption mechanism were fitted to the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Thermodynamic parameters, enthalpy, entropy, and Gibb free energy changes were established. Equilibrium data were best described by the Langmuir isotherm equation, with a monolayer adsorption capacity of 260.95 mg/g. The results supported the potential use of papaya stem as an efficient adsorbent for the treatment of cationic dye. [ABSTRACT FROM AUTHOR]