Biochar-based geopolymer nanocomposite for COD and phenol removal from agro-industrial biorefinery wastewater: Kinetic modelling, microbial community, and optimization by response surface methodology

Nickel augmented biochar for sustaining produced water treatment to decarbonize oil and gas industrial waste using anaerobic-aerobic granular cylindrical periodic discontinuous batch reactors

This study assessed the efficacy of granular cylindrical periodic discontinuous batch reactors (GC-PDBRs) for produced water (PW) treatment by employing eggshell and waste activated sludge (WAS) derived Nickel (Ni) augmented biochar. The synthesized biochar was magnetized to further enhance its contribution towards achieving carbon neutrality due to carbon negative nature, Carbon dioxide (CO2) sorption, and negative priming effects. The GC-PDBR1 and GC-PDBR2 process variables were optimized by the application of central composite design (CCD). This is to maximize the decarbonization rate. Results showed that the systems could reduce total phosphorus (TP) and chemical oxygen demand (COD) by 76-80% and 92-99%, respectively. Optimal organic matter and nutrient removals were achieved at 80% volumetric exchange ratio (VER), 5 min settling time and 3000 mg/L mixed liquor suspended solids (MLSS) concentration with desirability values of 0.811 and 0.954 for GC-PDBR1 and GC-PDBR2, respectively. Employing four distinct models, the biokinetic coefficients of the GC-PDBRs treating PW were calculated. The findings indicated that First order (0.0758-0.5365) and Monod models (0.8652-0.9925) have relatively low R2 values. However, the Grau Second-order model and Modified Stover-Kincannon model have high R2 values. This shows that, the Grau Second Order and Modified Stover-Kincannon models under various VER, settling time, and MLSS circumstances, are more suited to explain the removal of pollutants in the GC-PDBRs. Microbiological evaluation demonstrated that a high VER caused notable rises in the quantity of several microorganisms. Under high biological selective pressure, GC-PDBR2 demonstrated a greater percentage of nitrogen removal via autotrophic denitrification and a greater number of nitrifying bacteria. The overgrowth of bacteria such as Actinobacteriota spp. Bacteroidota spp, Gammaproteobacteria, Desulfuromonas Mesotoga in the phylum, class, and genus, has positively impacted on granule formation and stability. Taken together, our study through the introduction of intermittent aeration GC-PDBR systems with added magnetized waste derived biochar, is an innovative approach for simultaneous aerobic sludge granulation and PW treatment, thereby providing valuable contributions in the journey toward achieving decarbonization, carbon neutrality and sustainable development goals (SDGs).

Ball milling nano-sized biochar: bibliometrics, preparation, and environmental application

Nano-sized biochar, which is a small structure prepared from biochar by grinding, has surpassed traditional biochar in performance, showing enhanced effects and potential for a wide range of environmental applications. Firstly, this paper visualizes and analyzes the literature in this field by CiteSpace to clarify the development trend of nano-sized biochar. The review intuitively shows the most influential countries, the most productive institutions, and the most concerned hot spots in the field of nano-sized biochar. Secondly, these hotspots in environment management are summarized by keywords and clustering: (1) The application of ball milling is a modification scheme that researchers have paid attention to, and it is also a key method for preparing biochar nanomaterials. It has a more dispersed structure and can support more modified materials. (2) Nano-sized biochar in the comprehensive utilization of water, soil, and plants was discussed and is a small range of application modification methods. (3) The bidirectional effects of nano-sized biochar on plants were analyzed, and the challenges in its application were listed. Finally, the economic management of nano-sized biochar and the relationship between microorganisms are the focus of the next research.

Ni-Zn/CeO2 nanocomposites for enhanced adsorptive removal of 4-chlorophenol

Chlorophenols are one of the major organic pollutants responsible for the contamination of water bodies. This study explores the application of Ni-Zn/CeO2 nanocomposites, synthesized via the aqueous co-precipitation method, as effective adsorbents for the 4-chlorophenol removal from aqueous solutions. The nanocomposites' chemical and structural characteristics were assessed using different physical characterization methods, viz. X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, zeta potential, using a Box-Behnken design within response surface methodology, optimal conditions of pH 3, temperature 20 °C, contact time 120 min, adsorbent dosage 0.05 g, and 4-chlorophenol concentration 50 ppm are identified. Among the nanocomposites tested, NZC 20:10:70, with 20% Ni and 10% Zn, achieves enhanced performance, removing 99.1% of 4-chlorophenol within 2 h. Adsorption kinetics follow the pseudo-second-order model and equilibrium data fit the Freundlich isotherm. Thermodynamic analysis indicates an exothermic and spontaneous process. The adsorption capacity of NZC 20:10:70 shows significant enhancement, growing from 19.85 mg/g at 10 ppm to 96.33 mg/g at 50 ppm initial concentration. Physical characterization confirms NZC 20:10:70's superior properties, including a high surface area of 118.471 m2/g. Evaluating economic viability, NZC 20:10:70 demonstrates robust reusability, retaining 85% efficiency over eight regeneration cycles. These results highlight NZC 20:10:70 as a promising adsorbent for effective and sustainable chlorophenol removal in water treatment.

Optimization of syngas production from co-gasification of palm oil decanter cake and alum sludge: An RSM approach with char characterization

The study explores co-gasification of palm oil decanter cake and alum sludge, investigating the correlation between input variables and syngas production. Operating variables, including temperature (700-900 °C), air flow rate (10-30 mL/min), and particle size (0.25-2 mm), were optimized to maximize syngas production using air as the gasification agent in a fixed bed horizontal tube furnace reactor. Response Surface Methodology with the Box-Behnken design was used employed for optimization. Fourier Transformed Infra-Red (FTIR) and Field Emission Scanning Electron Microscopic (FESEM) analyses were used to analyze the char residue. The results showed that temperature and particle size have positive effects, while air flow rate has a negative effect on the syngas yield. The optimal CO + H2 composition of 39.48 vol% was achieved at 900 °C, 10 mL/min air flow rate, and 2 mm particle size. FTIR analysis confirmed the absence of C─Cl bonds and the emergence of Si─O bonds in the optimized char residue, distinguishing it from the raw sample. FESEM analysis revealed a rich porous structure in the optimized char residue, with the presence of calcium carbonate (CaCO3) and aluminosilicates. These findings provide valuable insights for sustainable energy production from biomass wastes.

Biomass - metal oxide nano composite for the decontamination of phenol from polluted environment - parametric, kinetics and isotherm studies

The contamination of aqueous environment by phenol poses a major threat due to its hyper toxic effects and removal of phenol is challenging due to its hydrophilic properties. This research study examines the surface encapsulation of iron oxide (IO) with bio-derived carbon-based date palm (DP) to make date palm-iron oxide (DP-IO) nanocomposite to potentially remediate phenol in aqueous environment. Phenol removal percentage is predominantly influenced by environmental factors, namely pH, nano sorbent loading, temperature, agitation speed, and initial phenol concentration. Under optimum conditions of 30 °C and pH 7.8, 80.30% of phenol was removed using a 0.75 g/L sorbent load with 100 mg/L initial phenol concentration. Langmuir isotherm fitted well (R2 > 0.997), supporting single-layer phenol attachment with maximum bio-sorption capacity of 72.46 mg/g. A pseudo-2nd-order (PSO) kinetic model is identified to be the most appropriate for the DP-IO sorption experiment (R2>0.999). Scanning electron microscopic images, X-ray diffraction observations, FT-IR plots, and thermogravimetric analysis have been used to characterize. The removal mechanism involves unimolecular layer and chemisorption is identified as a rate determining step. The reuse potential proved that the synthesized nanocomposite as a sustainable solution for phenolic wastewater treatment.