Remediation of Cr(VI) via combined self-reduction and adsorption bychemically modified carbon sorbents

Abstract

Hexavalent chromium, Cr(VI), is a highly toxic species, while trivalent chromium, Cr(III), is an essential trace element for humans and other organisms. In the present work, a simple, rapid, and efficient procedure for water treatment of Cr(VI) is described. Active carbon (AC) was chemically treated with HCl and NaOH for the formation of surface modified Acidic-AC and Basic-AC sorbents, respectively. In addition, AC sorbent was treated with HNO 3 as an oxidizing agent and sodium sulfite as a reducing agent for the formation of Ox-AC and Rd-AC sorbents, respectively. The modified AC sorbents were tested to identify their potential applications in removal of Cr(VI) under various controlling factors using the batch technique. The results indicated that these sorbents can be used in water treatment due to their excellent and efficient reduction of Cr(VI) into Cr(III) with percentage transformation values in the range of 90%-100%. Acidic-AC was found to be the superior sorbent in the reduction process of Cr(VI). The produced Cr(III) was removed from aqueous solutions via adsorption on the surface of these sorbents. The reduction and adsorption processes of Cr(VI)-Cr(III) were evaluated and optimized under different experimental parameters. The potential applications of these sorbents in real water treatment were also explored.

Synthesis and characterization of clay-based ultrafiltration membranes supported on natural zeolite for removal of heavy metals from wastewater

“…Moreover, Cr (VI) is included in the list of the US environmental protection agency for prioritizing control of its application. According to the World Health Organization standards, the acceptable level of chromium in drinking water is 0.05 mg/L for Cr (VI) and 0.1 mg/L for total Cr (Mahmoud et al,2016).…”

Evaluation of TiO2/smectite nanoparticles as an alternative low-cost adsorbent for chromium removal from industrial wastewater

“…Moreover, Cr(VI) is included in the list of the US Environmental Protection Agency (EPA) as one of the most toxic heavy metals requiring prioritized control. According to the World Health Organization (WHO) standards, the acceptable level of chromium ion in drinking water is 0.05 mg/L for Cr(VI) and 0.1 mg/L for total Cr [13].…”

Preparation and characterization of nano-galvanic bimetallic Fe/Sn nanoparticles deposited on talc and its enhanced performance in Cr(VI) removal

“…Technologies based on adsorption techniques have been known as adequate and straightforward approaches for Cr(VI) elimination, due to their wide adaptability and cost-effectiveness 14 , 15 . Various classes of adsorbents are utilized in Cr(VI) sequestration, including activated carbon 16 , 17 , carbon nanotube based materials 18 , graphene-based materials 19 , layered double hydroxide 20 , 21 , polymers and biopolymers 22 – 24 , Silica 25 , 26 and biosorbents 27 , 28 . Among different adsorbent for heavy metal remediation, nanoscale zero-valent iron (nZVI) particles which have combined large specific surface area, high reactivity, abundant surface binding sites, low toxicity, and absence of secondary pollution, has been proved as an efficient and environmental-friendly materials.…”