Produced water (PW) during oil and gas production operations contains various hazardous substances including heavy metals (HM) with adverse impact on the environment. Disposal of PW interferes with environmental sustainability, making PW treatment obligatory prior to discharge into the environment. Among previously available treatments of PW, environmentally sustainable methods using low-pore space bio-adsorbents require further development. This study investigated the efficacy of chemically-modified activated carbon (cMAC) of Luffa cylindrica (LC) and Banana Peel (BP) for the treatment of PW obtained from Niger-Delta oilfield, treated (2, 4, and 6 h) with finely ground (425 μm) carbonized LC and BP impregnated separately with phosphoric-acid and sodium hydroxide. The derived cMAC was characterized by proximate analysis and FTIR spectroscopy. Treated PW was analysed for HM using AAS, Langmuir, and Freundlich isotherms. Obtained values of the surface area for the cMAC from LC were 880 (NaOH), 830 (H3PO4) m2/g and BP was 810 (NaOH), and 920 (H3PO4) m2/g. The existence of active functional groups is revealed on the FTIR spectra. Results revealed a substantial drop in HM concentrations (Zn: 30-86%, Cu: 78-88%, Ni: 33-55%, Fe: 17-52%) in PW after treatment with cMAC at varying contact times. All metals (Zn, Cu, Ni) in the treated PW except Fe were below WHO and USEPA guideline limits. Treatment of Niger Delta oilfield PW was effectively improved with acid-modified carbonized L. cylindrica.
Key words: Activated carbon, adsorption, bio-adsorbent, heavy metals, oil-produced water, treatment
AAS, Atomic absorption spectrophotometer; BP, banana peel; CBP, carbonized banana peel; CBPN, sodium hydroxide impregnated carbonized banana peel; CBPP, phosphoric acid impregnated carbonized banana peel; CLC, carbonized Luffa cylindrical; CLCN, sodium hydroxide impregnated carbonized Luffa cylindrical; CLCP, phosphoric acid impregnated carbonized Luffa cylindrical; Cu, copper; cMAC, chemically modified activated carbon; Fe, iron; FTIR, Fourier transform infrared; HM, heavy metals; LC, Luffa cylindrical; MBP, modified banana peel; MLC, modified Luffa cylindrical; Ni, nickel; PW, produced water; TDS, total dissolved solids; TSS, total suspended solids; UN, United Nations; Zn, zinc.
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