Novel nanocomposite of biochar-zerovalent copper for lead adsorption

Catalytic degradation of carbamazepine by surface-modified zerovalent copper via the activation of peroxymonosulphate: mechanism, degradation pathways and ecotoxicity

In this research work, surface-modified nano zerovalent copper (nZVC) was prepared using a simple borohydride reduction method. The spectroscopic and crystallographic results revealed the successful synthesis of surface-modified nano zerovalent copper (nZVC) using solvents such as ethanol (ETOH), ethylene glycol (EG) and tween80 (T80). The as-synthesized material was fully characterized for morphological surface and crystal structural properties. The results indicated that EG provides an excellent synthesis environment to nZVC compared to ETOH and T80 in terms of good dispersion, high surface area and excellent catalytic properties. The catalytic efficiency of nZVC/EG was investigated alone and with peroxymonosulphate (PMS) in the absence of light. The degradation results demonstrated that the involvement of PMS synergistically boosted the catalytic efficiency of synthesized nZVC/EG material. Furthermore, the degradation products (DPs) of CBZ were determined by GC-MS and subsequently, the degradation pathways were proposed. The ecotoxicity analysis of the DPs was also explored. The proposed (nZVC/EG/PMS) system is economical and efficient and thus could be applied for the degradation of CBZ from an aquatic system after altering the degradation pathways in such a way that results in harmless products.

Effective removal and adsorption mechanism of fluoride from water by biochar-based Ce(III)-La(III)-crosslinked sodium alginate hybrid hydrogel

An eco-friendly macroparticle biochar (BC)-based Ce(III)-La(III) crosslinked sodium alginate (SA) hybrid hydrogel (BC/Ce-SA-La) was synthesized by droplet polymerization and characterized by SEM-EDS, XRD, FTIR, UV-Vis and XPS. The effects of dosage, pH, contact time, temperature and coexisting ions on the F- ions removal by hybrid hydrogel, and the adsorption performance, interaction mechanism and reusability were investigated. The results demonstrate that the composite has a fancy wrinkle structure with a particle size of about 1.8 mm and abundant porosity on the surface. The removal rate of F- ions by BC/Ce-SA-La reached 90.2 % under the conditions of pH 2.0, 200 min of contact time and 298 K. The adsorption behavior was perfectly explained by Langmuir model, and the maximum adsorption capacity reached 129 mg/g. The adsorption process was an endothermic spontaneous reaction and followed Pseudo-second-order rate model. The strong adsorption was attributed to multi-interactions including complexation, hydrogen bonding and electrostatic adsorption between the composite and F- ions. Coexisting ions hardly interfered with the adsorption of F- ions by BC/Ce-SA-La except for a slight effect of phosphate. The composite after F- ion adsorption was easily separated and could be reused at least three times. BC/Ce-SA-La is a cost-effective and promising granular biosorbent.

Qualitative and Quantitative Investigation of Biochar-Cu0 Composite for Nickel Adsorption

The current investigation deals with the treatment of water pollution that is caused by the leaching of nickel ions from the metallurgical industry and new-energy batteries. Therefore, an eco-friendly treatment of nickel through the use of a composite of cotton stalk biochar with nanozerovalent copper has been presented in this investigation signifying the impact of zerovalent copper in enhancing the adsorption capacity of biochar for nickel adsorption. Thermogravimetric analysis data showed the adsorbent to be significantly stable in the higher thermal range, whereas transmission electron microscopy analysis confirmed the particles to be 27 nm and also showed the cubic geometry of the particles. A much closer scanning electron microscopy analysis shows the morphology of particles to be cubic in shape. Batch adsorption indicated a positive influence of pH increase on adsorption due to the electrostatic attraction between positive nickel ions and post point of zero charge (pHPZC) negative surface of copper biochar composite (pH > 5.5). A high adsorption rate was observed in the first 60 min, whereas adsorption increased with the increase in temperature from 303 to 318 K. Kinetic modeling confirmed the pseudo-first-order to fit best to the data. The apparent activation energy (11.96 kJ mol-1) is indicative of the chemical nature of the process. The adsorption data fitted well to the Langmuir adsorption model. The negative values of apparent ΔG° and the positive values of apparent ΔH° indicate the spontaneity and endothermicity of the process, respectively, whereas the positive values of apparent ΔS° point toward increased randomness during the process. Postadsorption XPS suggests the adsorption of nickel on the surface of biochar composites in the form of Ni(OH)2 and NiO(OH).

A Novel Low-Cost Bio-Sorbent Prepared from Crisp Persimmon Peel by Low-Temperature Pyrolysis for Adsorption of Organic Dyes

In order to properly reuse food waste and remove various contaminants from wastewater, the development of green, sustainable and clean technologies has demonstrated potential in the efficient inhibition of secondary pollution to the environment. In this study, an economical and green method was used to prepare biochar from crisp persimmon peel (CPP) using flash-vacuum pyrolysis at different temperatures (200–700 °C; referred to as CPP200–CPP700). CPP200 has high polarity, low aromaticity and high oxygen-containing functional groups that exhibit superior MB adsorption capabilities. CPP200 that was prepared at a relatively low temperature of 200 °C exhibited a high adsorption capacity of 59.72 mg/g toward methylene blue (MB), which was relatively higher than that for alizarin yellow R (4.05 mg/g) and neutral red (39.08 mg/g), indicating that CPP200 possesses a higher adsorption selectivity for cationic dyes. Kinetics investigation revealed that the kinetic data of CPP200 for the adsorption of MB was better fitted by a linear pseudo-second-order model. Isothermal studies indicated that the linear Langmuir model was more suitable for describing the adsorption process. The adsorption thermodynamics illustrated that the adsorption of MB onto CPP200 was spontaneous and endothermic. EDS and IR analyses of CPP200 for both pre- and post-adsorption of MB showed that electrostatic interactions between oxygen-containing groups on biochar and target MB dominated the adsorption procedure, in addition to hydrogen bonding interactions. Reusability tests confirmed the excellent regeneration characteristics of CPP200, indicating that CPP200 may be used as a green, sustainable, highly efficient and recyclable adsorbent for the selective removal of cationic organic dyes.

Nanoscale zerovalent copper (nZVC) catalyzed environmental remediation of organic and inorganic contaminants: A review

Over the past decade, the nano zerovalent copper has emerged as an effective nano-catalyst for the environment remediation processes due to its ease of synthesis, low cost, controllable particle size and high reactivity despite its release during the remediation process and related concentration dependent toxicities. However, the improvised techniques involving the use of supports or immobilizer for the synthesis of Cu⁰ has significantly increased its stability and motivated the researchers to explore the applicability of Cu⁰ for the environment remediation processes, which is evident from access to numerous reports on nano zerovalent copper mediated remediation of contaminants. Initially, this review allows the understanding of the various resources used to synthesize zerovalent copper nanomaterial and the structure of Cu⁰ nanoparticles, followed by focus on the reaction mechanism and the species involved in the contaminant remediation process. The studies comprehensively presented the application of nano zerovalent copper for remediation of organic/inorganic contaminants in combination with various oxidizing and reducing agents under oxic and anoxic conditions. Further, it was evaluated that the immobilizers or support combined with various irradiation sources originates a synergistic effect and have a significant effect on the stability and the redox properties of nZVC in the remediation process. Therefore, the review proposed that the future scope of research should include rigorous focus on deriving an exact mechanism for synergistic effect for the removal of contaminants by supported nZVC.