Biosorption of Ni2+ and Cr3+ in synthetic sewage: Adsorption capacities of water hyacinth (Eichhornia crassipes)

Abstract

Water hyacinth (Eichhornia crassipes) is an aquatic weed that is causing numerous adverse effects on freshwater bodies. Developing countries are still battling on how to control the growth of this weed without damaging other aquatic lives important to man. Literatures have revealed that most developing countries are still discharging untreated sewage containing heavy metals into waterbodies due to economic and technical constraints in handling conventional methods of treating heavy metals. Hence, the research investigated the possibility of using water hyacinth to adsorb heavy metals (Ni 2+ and Cr 3+ ) from sewage before discharging into waterbodies in order to solve two major problems faced in the aquatic environment, at minimal cost. This was achieved by using the said weed (water hyacinth) to treat Ni 2+ and Cr 3+ solutions prepared in the lab. Results showed that the adsorption process for both ions occurred on heterogeneous surfaces while the mechanism of adsorption followed Pseudo 2 nd -order kinetics. The Freundlich, Langmuir and Temkin adsorption capacities for Ni 2+ are 19.6925l/g, 0.7470l/mg and 1.1093l/mg respectively while for Cr 3+ are 16.814l/g, 0.7011l/mg and 0.9623l/mg respectively. However, the heat of sorption for Ni 2+ is 96.906KJ/mol while that of Cr 3+ is 98.749KJ/mol. Furthermore, FT-IR analysis identified seven functional groups involved in the binding sites with more of hydroxyl group (O-H) from alcohol and carboxylic acid. It was concluded that water hyacinth could be used as a potential bio-adsorbent of metal ions.

Removal of Ni(II) and Cu(II) in Aqueous Solutions Using Treated Water Hyacinth (Eichhornia crassipes) as Bioadsorbent

“…In comparison, the adsorption capacities of water lily treated with water were between 27.88 and 44.3 mg/g. Notably, these values were lower and the models that described the adsorption process were Freundlich [41] and Langmuir [54], respectively.…”

“…In the case of WLN, the percentage of removal decreased from 58% to 37% for Ni and from 37% to 30% for Cu. This was due to the effect that occurred when the concentration of sites for the adsorption of metal ions remained constant, resulting in greater ease of disposition at these sites at low metal concentrations but preventing further metals from being removed from solution when the available sites became saturated [39][40][41][42][43][44][45].…”

“…It was observed that the percentage of adsorption increased rapidly due to the increase in the surface area of the bioadsorbent and the concentration of available sites. This may also have been due to the electrostatic forces present on the surface of WL [34,36,38,41,44,[46][47][48][49][50]. Taking the parameter of bioadsorbent quantity into account is important because an insufficient amount of bioadsorbent may not effectively remove metals from the solution.…”

“…The parameters of the different adsorption models were obtained using the Sigmaplot ® v12 program, as shown in Table 3, taking as criteria the deterministic coefficient (R 2 ) and the normalized standard deviation (∆q%) to establish the best adjustment to the experimental data. and the models that described the adsorption process were Freundlich [41] and Langmuir [54], respectively. In other studies that have used different adsorbents, the adsorption capacity has been found to be between 0.256 and 190.38 mg/g using CoFeO2/SO2 nanoparticles [54], magnetized graphene [56], magnetite-bentonite nanocomposites [57], sapropel humic acids [58], calcium carbonate in bacterial magnetosomes [36], hydroxyapatite [59], lemon peel [60], bamboo modified with mercaptoacetic acid and carbon disulfide [61], wheat and rice biochar [46], charred bones [62], and charcoal [63].…”

Design of waste stabilisation ponds for municipal effluent treatment in sobi cantonment, ilorin, nigeria

“…Untreated wastewater or sewage discharged into the environment (rivers, streams, creeks, etc.) has long been identified of causing adverse effects on humans and aquatic life [1,2]. This is because such sewage contains high concentrations of biodegradables, which could reduce the dissolved oxygen content of the receiving water bodies due to the high oxygen demand usually needed to oxidize the biodegradables either biologically or chemically.…”