Magnetite-impregnated biochar of parthenium hysterophorus for adsorption of Cr(VI) from tannery industrial wastewater

Abstract

The tannery industry inevitably generates toxic and catastrophic wastewater, which results in a huge threat to public health and water resources. Therefore, this work aimed to synthesize parthenium hysterophorus-based biochar–Fe3O4 composite for removal of Cr(VI) from tannery wastewater under 34 full factorial experimental designs of the Box–Behnken, which was analyzed using response surface methodology under four independent factors of pH (3, 6, and 9), initial Cr(VI) concentrations (40, 70, and 100 mg/L), contact times (30, 60, and 90 min), and adsorbent doses (20, 60, and 100 mg/100 mL). This composite adsorbent was described by a high BET surface area of 237.4 m2/g, XRD prominent peaks, SEM morphology corroborate and FTIR multifunctionalities of O–H at 3296 cm−1, the vibration of ketone C–OH at 1240 cm−1, and the vibration of C–O–C at 1147 cm−1 and Fe–O stretching at 542 cm−1. The maximum Cr(IV) removal efficiency of 91.8% was recorded at an initial Cr(VI) concentration of 40 mg/L, pH of 3, adsorbent dose of 100 mg/100 mL, and a contact time of 90 min, whereas the minimum Cr(VI) removal of 17.3% was observed at an initial Cr(VI) concentration of 100 mg/L, 20 mg/100 mL of adsorbent dose, pH of 9, and contact time of 30 min. The concentration of Cr(VI) in real wastewater was determined to be 85.13 mg/L and its remediation was found to be 81.8%. Langmuir’s model was the best fit with experimental data at R2 0.99 and qmax 400 mg/g, showing that the adsorption process was homogenous and monolayer. In conclusion, the adsorption results were encouraging, and biochar–Fe3O4 appears to be a potential candidate for Cr removal from wastewater.

Adsorption of methylene blue from textile industrial wastewater using activated carbon developed from Rumex abyssinicus plant

“…Then, the difference between the initial and final weight was used to calculate the moisture content. Equation ( 1 ) was used to calculate the moisture content of the adsorbent 44 . where W 1 refers to the weight of the crucible plus activated before drying, W 2 indicates the weight of the crucible plus activated after drying and MC is the moisture content of the adsorbent…”

“…The ash content of the adsorbent was determined using Eq. ( 3 ) 44 . where AC is the ash content, W 2 is the weight after ignition, and W1 is the weight before ignition.…”

“…Finally, the removal efficiency of MB and the adsorption capacity of the adsorbent were determined using Eqs. ( 5 ) and ( 6 ) respectively 27 , 44 . where %R is the MB removal percentage, Q e is the amount of MB adsorbed per unit mass of the adsorbent (mg/g), Co is the initial MB concentration (mg/L), C f is the final MB concentration (mg/L), Ce is the concentration of MB at equilibrium, V is the volume of the aqueous solution (mL) and M is the dry mass (g)…”

“…As per the Temkin isotherm model, the surface coverage resulting from the interaction of adsorbent and adsorbent will result in the linear decrease of the heat of adsorption. The Temkin isotherm is presented by (12) 44 . …”

“…Then, the difference between the initial and final weight was used to calculate the moisture content. Equation ( 1) was used to calculate the moisture content of the adsorbent 44 .…”