Mechanistic insights into the adsorption of methylene blue by particulate durian peel waste in water

A comprehensive review on the production of durian fruit waste-derived bioadsorbents for water treatment

Global water pollution by various pollutants is becoming an urgent problem. The conversion of durian fruit waste into adsorbents can help to mitigate this issue. Transforming durian waste into adsorbents can reduce pollution risk from waste discharged directly into the environment, while also effectively eliminating existing contaminants. Here, this work explores the potential of durian fruit waste and supplies insights into the synthesis and application of durian fruit waste-derived adsorbents such as biosorbents, modified-biosorbents, biochars, activated carbons, and composites. Several factors affecting the adsorption process of pollutants and the mechanism how pollutants can be adsorbed onto durian fruit waste-derived adsorbents are elucidated. This review also analyzes some aspects of limitations and prospects of biosorbents derived from durian fruit waste. It is anticipated that the promising properties and applications of durian fruit waste-derived adsorbents open up a new field for water waste treatment.

Enhanced Adsorption Performance Cross-Linked Chitosan/Citrus reticulata Peel Waste Composites as Low-Cost and Green Bio-Adsorbents: Kinetic, Equilibrium Isotherm, and Thermodynamic Studies

This study revealed the synthesis of cross-linked chitosan/Citrus reticulata peel waste (C/CRPW) composites that could be used as low-cost and green bio-adsorbents for the removal of Congo red (CR) dye from aqueous solutions. C/CRPW composites containing different amounts of Citrus reticulata peel waste (CRPW) and chitosan were prepared and cross-linked with glutaraldehyde. The composites were characterized by FESEM, EDS, FTIR, XRD, BET, and zeta potential measurements. The C/CRPW composites as a new type of bio-adsorbents displayed superior adsorption capability toward anionic CR molecules, and the adsorption capacities increased with the incorporation of CRPW. Effects of different ambient conditions, such as contact time, pH, adsorbent dosage, initial adsorbate concentration, and temperature, were fully studied. The conditions which obtained 43.57 mg/g of the highest adsorption capacity were conducted at pH 4 with an initial concentration of 100 mg/L, adsorbent dosage of 2.0 g/L, and contact time of 24 h at 328 K. The adsorption data was found to follow the pseudo-second-order kinetic model and the Freundlich isotherm model. According to the findings of this investigation, it was observed that the C/CRWP composites could be used as adsorbents due to their advantages, including the simple preparation process, being environmentally friendly, renewable, efficient, and low-cost.

Durian Waste Husks as an Adsorbent in Improving Soaking Water during the Retting Process of Piper nigrum L. (Pepper Berries)

The potential of raw durian husk and NaOH-modified durian husk as an adsorbent, using different doses, 0.5 g, 1.0 g, 1.5 g, and 2.0 g, is investigated to improve soaking water of pepper berries during the retting process. The surface area and the pore size of the durian husk were examined using Brunner Emmett and Teller analysis. The surface area of NaOH-modified durian husk is higher (2.33 m2/g) compared to the raw durian husk (1.51 m2/g). NaOH-modified durian husk has a higher porous structure than the raw durian husk, but both pore diameters are more than 50 nm, which is considered micropore raw material. The effect of the raw durian husk on pH, chemical oxygen demand (COD), dissolved oxygen (DO), and turbidity were compared to the NaOH-modified durian husk with different doses. The 2.0 g of NaOH-modified durian husk enhanced changes in the four parameters. The highest pH value using NaOH-modified durian husk was 6.10 ± 0.02, while turbidity and COD increased to 971.33 ± 1.15 NTU and 1984.67 ± 3.21 mg/L, respectively. The DO of NaOH-modified durian husk shows the lowest reduction to 1.49 mg/L with 2.0 g of NaOH-modified durian husk. The experimental data was best fitted with a first-order kinetic model. Durian husk treated with NaOH could be used as a potential adsorbent to enhance the soaking water for pepper berries.

Experimental Design, Equilibrium Modeling and Kinetic Studies on the Adsorption of Methylene Blue by Adsorbent: Activated Carbon from Durian Shell Waste

For the first time, activated carbon from a durian shell (ACDS) activated by H₂SO₄ was successfully synthesized in the present study. The fabricated ACDS has a porous surface with a specific surface area of 348.0017 m²·g^-1, average capillary volume of 0.153518 cm³·g^-1, the average pore diameter of 4.3800 nm; ash level of 55.63%; humidity of 4.74%; density of 0.83 g·cm^-3; an iodine index of 634 mg·g^-1; and an isoelectric point of 6.03. Several factors affecting Methylene Blue (MB) adsorption capacity of ACDS activated carbon was investigated by the static adsorption method, revealing that the adsorption equilibrium was achieved after 90 min. The best adsorbent pH for MB is 7 and the mass/volume ratio is equal to 2.5 g·L^-1. The MB adsorption process of ACDS activated carbon follows the Langmuir, Freundlich, Tempkin, and Elovich isotherm adsorption model, which has determined the maximum adsorption capacity for MB of ACDS as q_max = 57.47 mg·g^-1. The MB adsorption process of ACDS follows the of pseudo-second-order adsorption kinetic equation. The Weber and Morris Internal Diffusion Model, the Hameed and Daud External Diffusion Model of liquids have been studied to see if the surface phase plays any role in the adsorption process. The results of thermodynamic calculation of the adsorption process show that the adsorption process is dominated by chemical adsorption and endothermic. The obtained results provide an insight for potential applications of ACDS in the treatment of water contaminated by dyes.

Sunlight Photocatalytic Performance of ZnO Nanoparticles Synthesized by Green Chemistry Using Different Botanical Extracts and Zinc Acetate as a Precursor

In this work, the assessment of Azadirachta indica, Tagetes erecta, Chrysanthemum morifolium, and Lentinula edodes extracts as catalysts for the green synthesis of zinc oxide nanoparticles (ZnO NPs) was performed. The photocatalytic properties of ZnO NPs were investigated by the photodegradation of methylene blue (MB) dye under sunlight irradiation. UV-visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Thermogravimetric (TGA), and Brunauer-Emmett-Teller analysis (BET) were used for the characterization of samples. The XRD results indicate that all synthesized nanoparticles have a hexagonal wurtzite crystalline structure, which was confirmed by TEM. Further, TEM analysis proved the formation of spherical and hemispherical nanoparticles of ZnO with a size in the range of 14-32 nm, which were found in aggregate shape; such a size was well below the size of the particles synthesized with no extract (~43 nm). ZnO NPs produced with Tagetes erecta and Lentinula edodes showed the best photocatalytic activity, matching with the maximum adsorbed MB molecules (45.41 and 58.73%, respectively). MB was completely degraded in 45 min using Tagetes erecta and 120 min using Lentinula edodes when subjected to solar irradiation.