Mussel-inspired polydopamine functionalized recyclable coconut shell derived carbon nanocomposites for efficient adsorption of methylene blue

Application of conventional and emerging low-cost adsorbents as sustainable materials for removal of contaminants from water

The impact of water pollution has led to the search for cost-effective and environmentally friendly treatment processes to alleviate the associated environmental hazards. Adsorption is identified as an advanced treatment technology that offers simplicity and cheap alternatives to water treatment technologies when low-cost adsorbents such as industrial by-products, waste, and agricultural waste are utilized. The utilization of these materials as low-cost adsorbents for the treatment of drinking water will bring them some value. Several practices have been done to improve the removal efficiencies of the low-cost adsorbents in order to achieve WHO standards of drinking water quality. The paper highlights some of the synthesis routes employed for the modification of low-cost adsorbents. This updated review provides information on the different applications of low-cost adsorbents in removing pollutants and their adsorption capacities in an attempt to deploy the recent sustainable low-cost adsorbents with high removal efficiencies for water treatment. Future research should focus on the fabrication of hybrid low-cost adsorbents with multifunctional and antimicrobial properties. In addition, life cycle assessment (LCA) should be conducted to reveal the environmental burdens associated with the modification of the low-cost adsorbent to improve their removal efficiencies.

Coconut shell and its biochar as fertilizer amendment applied with organic fertilizer: Efficacy and course of actions on eliminating antibiotic resistance genes in agricultural soil

Biomass amendments have numerous benefits in reducing antibiotic resistance genes (ARGs) in the soil environment. However, there are debatable outcomes regarding the effect of raw biomass and its pyrolytic biochar on ARGs, and the exploration of the influence mechanism is still in infancy. Herein, we investigated the changes in soil ARGs under the organic fertilizer application with coconut shell and its biochar. The results showed that the coconut shell biochar could effectively diminish ARGs, with 61.54% reduction in target ARGs, which was higher than that adding raw coconut shells (p < 0.05). Structural equation modeling indicated that ARGs were significantly affected by changes in environmental factors, mainly by modulating bacterial communities. Neutral community model and network analysis demonstrated that the coconut shell biochar can restrict the species dispersal, thereby mitigating the spread of ARGs. Also, coconut shell biochar exhibited strong adsorption, with a large specific surface area (476.66 m²/g) and pores (pore diameter approximately 1.207 nm, total pore volume: 0.2451 m³/g), which markedly enhanced soil heterogeneity that created a barrier to limit the resistant bacteria proliferation and ARGs propagation. The outcome gives an approach to control the development of ARGs after organic fertilizer application into soil.

Utilization of shell-based agricultural waste adsorbents for removing dyes: A review

Dye existence in the water body adversely impacts the habitat and the quality of the aquatic system. Considering different physical and chemical methods, adsorption is a propitious substitute for extracting dyes from wastewater specifically due to its performance, high selectivity, less expense, clear operation, and existence in a broad area of experimental circumstances. These benefits are directly linked to the essence of the adsorbent strength used in dye adsorption. In keeping with the principles of green chemistry, the adsorbent materials' accessibility in large amounts that involves easy preparation should boost the effectiveness of the adsorption cycle. Agricultural waste shell-based adsorbent is a novel and better alternative for the expansive adsorbent. This article focuses on the use of a raw and activated adsorbent from agricultural waste shell-based material (on the mitigation of different types of synthetic as well as natural textile dye particles) to find out adsorption capacity based on its operational conditions like pH, dosage, primary concentration of dye, equilibrium time and temperature. Oil palm empty agricultural waste bunch fiber has a maximum adsorption capacity of 393.67 mg/g of Cibacron blue 3G-A dye and Almond shell activated carbon has a maximum adsorption ability of 833.33 mg/g of Methylene Blue dye. Adsorption removal capacity of various raw agricultural wastes and activated agricultural wastes is reviewed. Agricultural waste shell-based adsorbents are a low-cost adsorbent that is a safer alternative to traditional adsorbents.

Easy Preparation of Liposome@PDA Microspheres for Fast and Highly Efficient Removal of Methylene Blue from Water

Mussel-inspired chemistry was usefully exploited here with the aim of developing a high-efficiency, environmentally friendly material for water remediation. A micro-structured material based on polydopamine (PDA) was obtained by using liposomes as templating agents and was used for the first time as an adsorbent material for the removal of methylene blue (MB) dye from aqueous solutions. Phospholipid liposomes were made by extrusion and coated with PDA by self-polymerization of dopamine under simple and mild conditions. The obtained Liposome@PDA microspheres were characterized by DLS and Zeta potential analysis, TEM microscopy, and FTIR spectroscopy. The effects of pH, temperature, MB concentration, amount of Liposome@PDA, and contact time on the adsorption process were investigated. Results showed that the highest adsorption capacity was obtained in weakly alkaline conditions (pH = 8.0) and that it could reach up to 395.4 mg g⁻¹ at 298 K. In addition, adsorption kinetics showed that the adsorption behavior fits a pseudo-second-order kinetic model well. The equilibrium adsorption data, instead, were well described by Langmuir isotherm. Thermodynamic analysis demonstrated that the adsorption process was endothermic and spontaneous (ΔG⁰ = −12.55 kJ mol⁻¹, ΔH⁰ = 13.37 kJ mol⁻¹) in the investigated experimental conditions. Finally, the applicability of Liposome@PDA microspheres to model wastewater and the excellent reusability after regeneration by removing MB were demonstrated.

Mussel-inspired triple bionic adsorbent: Facile preparation of layered double hydroxide@polydopamine@metal-polyphenol networks and their selective adsorption of dyes in single and binary systems

To effectively address the serious human health challenges and ecological damage caused by organic dyes in wastewater, we developed a novel bionic adsorbent (LDH@PDA@MPNs) for the selective adsorption and removal of malachite green (MG) and crystalline violet (CV). The adsorbent was prepared using a facile two-step method based on mussel-inspired chemistry and metal complexation. The physicochemical structure, surface morphology, and composition of the LDH@PDA@MPNs were characterized by scanning electron microscopy, Fourier-transform infrared spectrometry, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Adsorption of MG and CV with the LDH@PDA@MPNs was evaluated. Under optimal conditions, the maximum adsorption of MG and CV by the adsorbent was 89.608 and 40.481 mg/g, respectively. The adsorption kinetics showed that the experimental data were in good agreement with the pseudo-second-order kinetic model, and the equilibrium adsorption isotherm data fitted well with the Freundlich model. The thermodynamic results indicated that the adsorption of the dyes on LDH@PDA@MPNs was a spontaneous endothermic process. Importantly, the bionic adsorbent not only shows high removal efficiency by easy regeneration with low-cost reagents but also exhibits high selectivity for dyes in both single and binary systems. Therefore, LDH@PDA@MPNs have the potential to adsorb and remove dyes from complex wastewater solutions.

Facile Fabrication of a ZnO/Eu2O3/NiO-Based Ternary Heterostructure Nanophotocatalyst and Its Application for the Degradation of Methylene Blue

The ZnO-based ternary heterostructure ZnO/Eu2O3/NiO nanoparticles are synthesized using waste curd as fuel by a simple one-pot combustion method. The as-synthesized heterostructure is characterized by using various spectroscopic and microscopic techniques including X-ray diffraction, UV-vis, FTIR, SEM, and TEM analyses. The photocatalytic activity of the ternary nanocomposite was tested for the photodegradation of methylene blue (MB) under solar light irradiation. The results have revealed that the ternary ZnO/Eu2O3/NiO photocatalyst exhibits excellent performance toward the photocatalytic degradation of the studied dye. Optimization studies revealed that the synthesized heterostructure exhibited a pH-dependent photocatalytic activity, and better results are obtained for specific concentrations of dye and catalysts. Among the different light sources employed during the study, the catalyst was found to possess the best degradation efficiency in visible light.