Preparation and Application in Water Treatment of Magnetic Biochar

Development of a new magnetic solid-phase extraction method prior to HPLC determination of naproxen in pharmaceutical products and water samples

In this study, a new magnetic solid phase extraction based on magnetic composite modified with biochar obtained from pumpkin peel was developed for the enrichment and extraction of Naproxen in lake water, tablet and urine samples. The effects of main parameters such as pH, extraction time, amount of adsorbent and sample volume, which affect magnetic solid phase extraction, were investigated. Under optimal conditions, intraday and interday precision values for naproxen were below 5.9, with accuracy (relative error) better than 7.0 %. The detection limit and preliminary concentration factor were 12 ng/mL and 10, respectively. The method proposed here can be used for routine analysis of naproxen in lake water, urine and tablets.

A critical review on biochar for the removal of toxic pollutants from water environment

As an effort to tackle some of the most pressing ecological issues we are currently experiencing, there has been an increasing interest in employing biomass-derived char products in various disciplines. Thermal combustion of biomass results in biochar production, which is a remarkably rich source of carbon. Not only does the biochar obtained by the thermochemical breakdown of biomass lower the quantity of carbon released into the environment, but it also serves as an eco-friendly substitute for activated carbon (AC) and further carbon-containing products. An overview of using biochar to remove toxic pollutants is the main subject of this article. Several techniques for producing biochar have been explored. The most popular processes for producing biochar are hydrothermal carbonization, gasification and pyrolysis. Carbonaceous materials, alkali, acid and steam are all capable of altering biochar. Depending on the environmental domains of applications, several modification techniques are chosen. The current findings on characterization and potential applications of biochar are compiled in this survey. Comprehensive discussion is given on the fundamentals regarding the formation of biochar. Process variables influencing the yield of biochar have been summarized. Several biochars' adsorption capabilities for expulsion pollutants under various operating circumstances are compiled. In the domain of developing biochar, a few suggestions for future study have been given.

Microwave disinfection strengthened by a biochar-based microwave absorbing material for sewage resource utilization

Proper disinfection treatment is the basic guarantee for safe utilisation of sewage. However, the commonly used disinfection methods are not suitable for nutrients containing reclaimed water. In this work, the microwave disinfection method assisted by a microwave-absorbing material in recycled water samples was investigated. Magnetic corn stalk biochar (MCSB), the microwave absorbing material, was prepared by high temperature carbonisation of corn stalk particles impregnated with ferrous sulfate. Escherichia coli and fecal coliforms were selected as target microorganisms to investigate the disinfection efficiency of MCSB assisted microwave radiation (MW/MCSB). The addition of microwave absorbing materials significantly improves the disinfection effect of water samples. Compared with the microwave radiation (MW) without MCSB, the bactericidal rate by using 107 CFU/L E. coli suspension increased from 63.5% to 100% at 480 W for 30 s after adding 4 g/L MCSB. Besides, the effects of MCSB dosage, microwave power, microwave radiation time, and initial bacterial concentration on disinfection efficiency were explored. Moreover, the bactericidal efficiency for actual sewage samples was also demonstrated by treating the effluent from septic tank sewage. The residual fecal coliforms in treated water samples met China's farmland irrigation water standard (GB 5084-2021). The result indicates that the proposed method of microwave disinfection strengthened by MCSB has a promising application prospect for reclaimed water disinfection.

Simultaneous removal of Cu (II) and Cr (VI) ions from petroleum refinery wastewater using ZnO/Fe3O4 nanocomposite

The presence and removal of heavy metals such as Cu(II) as well as Cr(VI) in petroleum refinery wastewater calls for concerted efforts due to their mobility, toxicity, bioaccumulation, and non-biodegradability in the environment. In this present work, zinc oxide (ZnO), iron oxide (Fe₃O₄) nanoparticles and ZnO/Fe₃O₄ nanocomposites were synthesized via simple sol-gel and chemical reduction methods; characterized using different analytical tools and then applied as nanoadsorbent to sequester Cu(II) and Cr(VI) ions from Petroleum Refinery wastewater via batch adsorption process. Cu(II) and Cr(VI) adsorption processes were examined with respect to contact time (kinetic effect), nanoadsorbent dosage, isotherm equilibrium, and thermodynamic parameters. ZnO/Fe₃O₄ nanocomposites with higher surface area (39.450 m²/g) have a mixture of rod-like and spherical shapes as compared to ZnO and Fe₃O₄ nanoparticles with spherical shape only and surface areas of 8.62 m²/g and 7.86 m²/g) according to the high-resolution scanning electron microscopy (HRSEM) and Brunauer-Emmett-Teller (BET) analysis. The X-ray diffractometer (XRD) results revealed the formation of hexagonal wurtzite structure of ZnO and the face-centered cubic structure phase of Fe₃O₄ nanoparticles, after the formation of the ZnO/Fe₃O₄ nanocomposites the phases of the nanoparticles were not affected but the diffraction peaks shifted to higher 2θ degree. The average crystallite size of ZnO and Fe₃O₄ nanoparticles and ZnO/Fe₃O₄ nanocomposites were 20.12, 26.36 and 14.50 nm respectively. The maximum removal efficiency of Cu (II) (92.99%) and Cr (VI) (77.60%) by ZnO/Fe₃O₄ nanocomposites was higher than 85.83%; 65.19% for Cu (II) and 80.57%; 62.53 for Cr (VI) using ZnO and Fe₃O₄ nanoadsorbents individually under the following conditions: contact time (15), dosage (0.08 g) and temperature (30 °C). The experimental data for Cu (II) and Cr (VI) ion removal fitted well to the pseudo-second-order kinetic and Langmuir isotherm models. The thermodynamic study suggested that the removal of the two metal ions from petroleum wastewater was endothermic. The reusability study after the fourth adsorption-desorption cycle indicated the stability of ZnO/Fe₃O₄ nanocomposites with 85.51% and 69.42% removal efficiency of Cu (II) and Cr (VI). The results showed that ZnO/Fe₃O₄ nanocomposite achieves higher performance than ZnO and Fe₃O₄ alone in the removal of Cu (II) and Cr (VI) ions from the petroleum refinery wastewater.