Removal of reactive black dye in water by magnetic mesoporous carbon from macadamia nutshell

The novel and intriguing role of Fe(NO3)3 as a chemical activator in carbonization of macadamia nutshell is introduced in this work. Magnetic mesoporous carbon was achieved by chemical activation of macadamia nutshell with Fe(NO3)3 under nitrogen atmosphere at 850°C (MMC-850). Porosity of MMC-850 included SBET 317 m2/g with Vmicro 0.0796 cm3/g and considerably high Vmeso 0.4318 cm3/g. Not only did MMC-850 possesses good magnetic properties with saturation magnetization and coercive force of 31.48 emu/g and 506.6 Oe, respectively, but MMC-850 also showed high-removal efficiency of reactive black dye (RB5) with maximum adsorption capacity at 123.51 mg/g. The experimental data fit the Langmuir isotherm and Elovich model. Thermal regeneration was effective in degrading RB5 and removal ability was above 90% after two regeneration cycles. RB5 removal from water by MMC-850 as an adsorbent is considered a facile and inexpensive method since macadamia nutshell is a food by-product which is a green and renewable carbon precursor. MMC-850 is a potential adsorbent because it can be separated from wastewater treatment system using magnetic force. Besides, MMC-850 particle is not brittle compared to other porous biochar/activated carbon with similar size; therefore, it is an excellent candidate for column packing or scaling up for wastewater treatment facilities in the future

Trihalomethanes in Water Supply System and Water Distribution Networks

The formation of trihalomethanes (THMs) in natural and treated water from water supply systems is an urgent research area due to the carcinogenic risk they pose. Seasonal effects and pH have captured interest as potential factors affecting THM formation in the water supply and distribution systems. We investigated THM occurrence in the water supply chain, including raw and treated water from water treatment plants (coagulation, sedimentation, sand filtration, ClO2-disinfection processes, and distribution pipelines) in the Chiang Mai municipality, particularly the educational institute area. The effects of two seasons, rainy (September–November 2019) and dry (December 2019–February 2020), acted as surrogates for the water quality profile and THM occurrence. The results showed that humic acid was the main aromatic and organic compound in all the water samples. In the raw water sample, we found a correlation between surrogate organic compounds, including SUVA and dissolved organic carbon (DOC) (R2 = 0.9878). Four species of THMs were detected, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Chloroform was the dominant species among the THMs. The highest concentration of total THMs was 189.52 µg/L. The concentration of THMs tended to increase after chlorination when chlorine dioxide and organic compounds reacted in water. The effect of pH on the formation of TTHMs was also indicated during the study. TTHM concentrations trended lower with a pH ≤ 7 than with a pH ≥ 8 during the sampling periods. Finally, in terms of health concerns, the concentration of TTHMs was considered safe for consumption because it was below the standard

Efficient Removal of Paraquat Pollutants Using Magnetic Biochar Derived from Corn Husk Waste: A Sustainable Approach for Water Remediation

Due to the widespread production of maize, the waste created by this crop has become a serious concern. This study applied the concept of waste circulation to the production of magnetic biochar from corn husk waste to remediate paraquat-contaminated water. Magnetic biochar (MB) was produced by impregnating maize husks with iron and carbonizing the residue in a nitrogen environment. Carbonized MB at the temperature of 850°C (MB-01-850) exhibited a combination of microporous and mesoporous structures (Vmeso=0.30 cm3/g, Vmicro=0.12 cm3/g), while biochar created only a microporous structure (Vmicro=0.11 cm3/g). According to the findings, Fe(NO3)3 significantly affected the increase in mesopore formation after carbonization. In addition, biochar exhibits excellent magnetic responsiveness. MB-01-850 reached equilibrium within approximately 20 min in synthetic water. Batch adsorption studies showed that MB-01-850 had maximum adsorption capacities (Q0) of 34.97 mg/g and 31.63 mg/g for synthetic and natural water, respectively. The unmodified biochar (without mesopores) had a Q0 of 4.08 mg/g. This indicates that the presence of mesopores improves the effectiveness of paraquat adsorption. Additionally, the adsorption performance of magnetic biochar exhibited no statistically significant variance when tested under natural water conditions. Furthermore, magnetic biochar demonstrates impressive regeneration capacity, allowing it to be regenerated almost entirely for a minimum of four cycles using a sodium hydroxide (NaOH) solution with a concentration equal to or greater than 0.5 M

Trihalomethanes in Water Supply System and Water Distribution Networks

The formation of trihalomethanes (THMs) in natural and treated water from water supply systems is an urgent research area due to the carcinogenic risk they pose. Seasonal effects and pH have captured interest as potential factors affecting THM formation in the water supply and distribution systems. We investigated THM occurrence in the water supply chain, including raw and treated water from water treatment plants (coagulation, sedimentation, sand filtration, ClO2-disinfection processes, and distribution pipelines) in the Chiang Mai municipality, particularly the educational institute area. The effects of two seasons, rainy (September–November 2019) and dry (December 2019–February 2020), acted as surrogates for the water quality profile and THM occurrence. The results showed that humic acid was the main aromatic and organic compound in all the water samples. In the raw water sample, we found a correlation between surrogate organic compounds, including SUVA and dissolved organic carbon (DOC) (R2 = 0.9878). Four species of THMs were detected, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Chloroform was the dominant species among the THMs. The highest concentration of total THMs was 189.52 μg/L. The concentration of THMs tended to increase after chlorination when chlorine dioxide and organic compounds reacted in water. The effect of pH on the formation of TTHMs was also indicated during the study. TTHM concentrations trended lower with a pH ≤ 7 than with a pH ≥ 8 during the sampling periods. Finally, in terms of health concerns, the concentration of TTHMs was considered safe for consumption because it was below the standard (<1.0) of WHO’s Guideline Values (GVs)