Carboxylate-functionalized dragon fruit peel powder as an effective adsorbent for the removal of Rhodamine B (cationic dye) from aqueous solution: adsorption behavior and mechanism

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.

Magnetic separation, sunlight-driven photocatalytic activity, and antibacterial studies of Sm-doped Co0.33Mg0.33Ni0.33Fe2O4 nanoparticles

Magnetic nanoparticles have emerged as a promising tool for wastewater treatment due to their unique properties. In this regard, Co0.33Mg0.33Ni0.33SmxFe2-xO4 (0.00 ≤ x ≤ 0.08) nanoparticles were prepared to examine their magnetic separation efficiency (MSE), photocatalytic, antibacterial, and antibiofilm performances. Pure nanoparticles, having the highest saturation magnetization (Ms = 31.87 emu/g), exhibit the highest MSE, where 95.6% of nanoparticles were separated after 20 min of applying a magnetic field of 150 mT. The catalytic performance of the prepared samples is examined by the photodegradation of rhodamine B (RhB) dye exposed to direct sunlight radiation. Improved photocatalytic activity is exhibited by Co0.33Mg0.33Ni0.33Sm0.04Fe1.96O4 nanoparticles, labeled as Sm0.04, where the rate of the degradation reaction is enhanced by 4.1 times compared to pure nanoparticles. Rising the pH and reaction temperature improves the rate of the photodegradation reaction of RhB. The incorporation of 15 wt% reduced graphene oxide (rGO) with Sm0.04 enhanced the rate of the reaction by 1.7 and 2.4 times compared with pure Sm0.04 sample and rGO, respectively. The antibacterial and antibiofilm activities against Escherichia coli, Leclercia adecarboxylata, Staphylococcus aureus, and Enterococcus faecium are assessed by the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) broth microdilution, the agar well diffusion, the time-kill assays, the biofilm formation, and destruction assays. The bacteria used in these assessments are isolated from wastewater. The nanoparticles exhibit a bacteriostatic activity, with a better effect against the Gram-positive isolates. Co0.33Mg0.33Ni0.33SmxFe2O4 (x = 0.00) nanoparticles have the best effect. The effect is exerted after 2-3 h of incubation. Gram-positive biofilms are more sensitive to nanoparticles.

Preparation of KHA/SA/MMT composites and their adsorption properties for Rhodamine B

Two natural adsorbent materials, potassium humate (KHA) and montmorillonite (MMT), were successfully prepared by embedding them in sodium alginate (SA) gel spheres through physical cross-linking with CaCl2. And CaCO3 was used as a porogenic agent to prepare the porous composites, KHA/SA/MMT. The materials were characterized by using XRD, TGA, SEM, and N2 adsorption/desorption equipment. The results showed that MMT and KHA were successfully embedded in the SA gel; the introduction of MMT increased the thermal stability of the composites and the embedding of MMT, and the porogenic effect of CaCO3 increased the specific surface area of the composites substantially, which provided favorable conditions for adsorption and treatment of pollutants. In addition, a one-way exploratory experiment yielded a higher removal rate of Rhodamine B (RhB) at D = 0.6 g/L, pH = 5, C0 = 100 mg/L, and t = 360 min. The adsorption kinetics and adsorption isotherm conformed to the secondary kinetic model and Langmuir model, respectively, and the maximum adsorption of RhB by KHA/SA/MMT could reach up to 884.96 mg/g at 303 K. The adsorption mechanism for RhB was shown by FT-IR and XPS analyses to be possibly bound by non-covalent bonding forces. After seven consecutive adsorption-desorption cycles, the adsorption of RhB by KHA/SA/MMT still reached 80.75%. Therefore, the prepared gel spheres have the advantages of easy regeneration and efficient reuse and great potential for application in purifying RhB from wastewater.

The Lantana camara L. stem biomass as an inexpensive and efficient biosorbent for the adsorptive removal of malachite green from aquatic environments: kinetics, equilibrium and thermodynamic studies

Plant biomass is one of the available and economic biomaterials used to remove environmental pollutants. The presence of colored compounds in aqueous solutions is one of the problems that can be solved by biological methods. Herein, the efficiency of available and inexpensive biomass obtained from Lantana camara L. stem for cationic dye uptake has been evaluated. The effect of operational factors, including dosage of L. camara L. stem biomass (LSB), pH of the solution, initial concentration of malachite green (MG), and residence time on the optimal conditions of analyte uptake was studied. The experimental data of adsorption studies fit with P-S-O kinetic (R2=0.999) and L.I.M (R2=0.998), indicating MG dye adsorption onto LSB occurred in monolayers due to its chemical affinity. The maximum uptake capacity of LSB for the removal of MG dye was 100 mg g^-1. Thermodynamic parameters, including ΔG° (from -2.13 to -2.469 kJ  mol-1), ΔH° (+2.916 kJ  mol-1), and ΔS° (+16.934 J  mol-1 K-1) suggested that the adsorption process was endothermic and spontaneous. The results revealed that LSB considerably has potential for adsorptive removal of cationic dyes such as, MG from aquatic environments.