Optimization of process variables for a biosorption of nickel(II) using response surface method

Equilibrium Biosorption of Zn2+ and Ni2+ Ions from Monometallic and Bimetallic Solutions by Crab Shell Biomass

This work explored the technical feasibility of using crab shell (CS) as a promising, low-cost biosorbent to individually and simultaneously remove Zn2+ and Ni2+ from aqueous solutions. It was found that in both monometallic and bimetallic systems, Zn2+ and Ni2+ biosorption by CS was strongly dependent on the solution pH, with the optimum biosorption occurring at a pH of 6.0 for both heavy metals. The obtained isotherms for Zn2+ and Ni2+ biosorption onto CS in monometallic and bimetallic systems demonstrated that CS has a higher affinity for Zn2+ than for Ni2+. The experimental equilibrium data for the bimetallic system revealed that when one heavy metal is present in the system, there is a decrease in the equilibrium biosorption capacity for the other heavy metal; therefore, the combined action of Zn2+ and Ni2+ was antagonistic. The Sips and Redlich–Peterson isotherm models best fitted the equilibrium biosorption data for Zn2+ and Ni2+ in the monometallic systems, while the modified Sips model best fitted the binary biosorption equilibrium data. DRIFTS analyses indicated that carbonate ion, chitin, and proteins are mainly involved in the biosorption of Zn2+ and Ni2+ by CS from aqueous solutions, as confirmed using a range of analytical techniques.

Adsorptive of Nickel in Wastewater by Olive Stone Waste: Optimization through Multi-Response Surface Methodology Using Desirability Functions

Pollution from industrial wastewater has the greatest impact on the environment due to the wide variety of wastes and materials that water can contain. These include heavy metals. Some of the technologies that are used to remove heavy metals from industrial effluents are inadequate, because they cannot reduce their concentration of the former to below the discharge limits. Biosorption technology has demonstrated its potential in recent years as an alternative for this type of application. This paper examines the biosorption process for the removal of nickel ions that are present in wastewater using olive stone waste as the biosorbent. Kinetic studies were conducted to investigate the biosorbent dosage, pH of the solution, and stirring speed. These are input variables that are frequently used to determine the efficiency of the adsorption process. This paper describes an effort to identify regression models, in which the biosorption process variables are related to the process output (i.e., the removal efficiency). It uses the Response Surface Method (RSM) and it is based on Box Benken Design experiments (BBD), in which olive stones serves as the biosorbent. Several scenarios of biosorption were proposed and demonstrated by use of the Multi-Response Surface (MRS) and desirability functions. The optimum conditions that were necessary to remove nickel when the dosage of biosorbent was the minimum (0.553 g/L) were determined to be a stirring speed of 199.234 rpm and a pH of 6.369. The maximum removal of nickel under optimized conditions was 61.73%. Therefore, the olive stone waste that was investigated has the potential to provide an inexpensive biosorbent material for use in recovering the water that the nickel has contaminated. The experimental results agree closely with what the regression models have provided. This confirms the use of MRS since this technique and enables satisfactory predictions with use of the least possible amount of experimental data.