Abstract
This study indicates kaolinite clay as an effective adsorbent for the uptake of Cu (II) from wastewater. The adsorption process was studied with variation of time, temperature and adsorbent dosage at the effluent pH of 6. X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Brunauer Emmett and Teller (BET) and Scanning electron microscopy (SEM) were used to characterize the adsorbents. XRD spectra showed that modification with KH2PO4 did not significantly change the crystal spacing on the lattice structure of the clay mineral; however, there were shifts in the intensity of the peaks for the modified kaolinite clay. The FTIR spectra showed that certain functional groups are responsible for binding the metal ions from solution. SEM indicated an increase in the porosity of the modified adsorbent as compared with the unmodified kaolinite, which enhances metal ion adsorption on modified kaolinite clay. The BET indicate that acid modification increased the surface area and total pore volume of the kaolinite clay. The kinetic study revealed that the pseudo-first-order model fitted poorly to the equilibrium data, however, the pseudo-second-order model had a good fit for all reaction time at different initial concentrations. The mechanism of the sorption process was evaluated using thermodynamic properties such as enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS), which were evaluated using Van’t Hoff equations. The negative values of free energy change (ΔG), suggests spontaneity and feasibility of the process. The positive values of enthalpy change (ΔH) indicate endothermic nature of the process.
Highlights
Increasing industrial and domestic activities arising from human population growth have caused more hazardous substances to be released into the environment within the past decades (Saima et al, 2019)
The sharp and intense peaks and the presence of other weak peaks in the spectra indicate the amorphous nature of both adsorbents (Vinod et al.,2010) and the amorphous nature of the kaolinite clay suggests that Cu (II) ion can penetrate its surface for efficient adsorption which is desirable for an effective removal (Akpome and Dawodu, 2014)
The percentage adsorption increases for adsorption of Cu (II) ion with increasing temperature and adsorbent dosage, but the amount adsorbed per unit adsorbent weight decreased significantly
Summary
Increasing industrial and domestic activities arising from human population growth have caused more hazardous substances to be released into the environment within the past decades (Saima et al, 2019). There have resulted to rising global concern about water pollution because of heavy deleterious metals and great awareness on treatment of industrial wastewater that is received from. Most of these metallic ions are contained in industrial wastewater, which includes cadmium, chromium, nickel, zinc, lead, and copper occurring in various industrial activities ranging from geological activities, batteries production, paints production, leather tanning, electroplating, metal coating, and metal finishing (Omar et al, 2016). The high cost of production of activated carbon and activation process has limited their applications for wastewater treatment (Ali et al, 2012). The present study investigates the removal of copper (II) ion from industrial dye effluent using locally sourced kaolin clay
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