Rapid adsorptive removal of chromium from wastewater using walnut-derived biosorbents

Abstract

Contamination of water resources by industrial effluents containing heavy metal ions and management of solid waste from agricultural and food industries is a serious issue. This study presents the valorization of waste walnut shells as an effective and environment-friendly biosorbent for sequestrating Cr(VI) from aqueous media. The native walnut shell powder (NWP) was chemically modified with alkali (AWP) and citric acid (CWP) to obtain modified biosorbents with abundant availability of pores as active centers, as confirmed by BET analysis. During batch adsorption studies, the process parameters for Cr(VI) adsorption were optimized at pH 2.0. The adsorption data were fitted to isotherm and kinetic models to compute various adsorption parameters. The adsorption pattern of Cr(VI) was well explained by the Langmuir model suggesting the adsorbate monolayer formation on the surface of the biosorbents. The maximum adsorption capacity, qm, for Cr(VI) was achieved for CWP (75.26 mg/g), followed by AWP (69.56 mg/g) and NWP (64.82 mg/g). Treatment with sodium hydroxide and citric acid improved the adsorption efficiency of the biosorbent by 4.5 and 8.2%, respectively. The endothermic and spontaneous adsorption was observed to trail the pseudo-second-order kinetics under optimized process parameters. Thus, the chemically modified walnut shell powder can be an eco-friendly adsorbent for Cr(VI) from aqueous solutions.

Viscose Support for Assembly of Cu2O and TiO2: Antimicrobial, Photocatalytic, and Recoverable Composites for Cr(VI) Removal

“…The most applied techniques for the removal of Cr­(VI) were photocatalysis and adsorption . The removal of Cr­(VI) by adsorption process was carried out by different adsorbents, such as chitosan (153.9 mg/g), Fe 2 O 3 @chitosan (14.5 mg/g), zeolite-NaX (6.4 mg/g), modified silica (51.9–68.0 mg/g), polyaniline@SiO 2 (63.4 mg/g), walnut-derived biosorbents (64.8–75.3 mg/g), Cu–S@biomass (94.3 mg/g), and polyaniline@polystyrene beads (231.2 mg/g) . In comparison with the aforementioned adsorbents in the literature, the present work showed extensively high removal of Cr­(VI) (593.8 mg/g, 98%) by using Cu 2 O@TiO 2 @viscose.…”

Stepwise reduction of graphene oxide and studies on defect-controlled physical properties

“…The concentration of leftover dye was estimated based on the peak intensity of RhB at 554 nm in an aqueous solution. The adsorption capacity ( and the percentage of removal efficiency of different adsorbent was calculated by using the following equations 33 , 34 : where (mg.g -1 ) is the adsorption capacity at the equilibrium, (mg L -1 ), the initial concentration, (mg.L -1 ), the concentration at the equilibrium, V the volume solution in L and W the amount of adsorbent used as adsorbent.…”

Agricultural Solid Wastes Based Adsorbent Materials in the Remediation of Heavy Metal Ions from Water and Wastewater by Adsorption: A Review

“…There are various adverse health effects, such as diarrhoea, disorderedness, stomach problems, paralysis, various skin deceases, haemoglobinuria, vomiting, etc., that occur due to heavy metal ion contamination [ 3 , 10 ]. Heavy metal ions are highly toxic, hazardous to health, and non-biodegradable, and pose a high threat to the ecosystem if they are left untreated [ 3 , 11 , 12 ]. Therefore, there is an urgent need to develop ecofriendly, economically feasible technology to remove these potential pollutants from the aqueous phase [ 11 ].…”

“…Heavy metal ions are highly toxic, hazardous to health, and non-biodegradable, and pose a high threat to the ecosystem if they are left untreated [ 3 , 11 , 12 ]. Therefore, there is an urgent need to develop ecofriendly, economically feasible technology to remove these potential pollutants from the aqueous phase [ 11 ]. Detailed information on heavy metal ion classifications, sources, and their toxicity effects have been detailed in our own previous publications [ 3 ].…”