Surveying the efficiency of Platanus orientalis bark as biosorbent for Ni and Cr(VI) removal from plating wastewater as a real sample

Heavy metals make up one of the most important pollutants in industrial wastewater. For wastewater, adsorbent materials developed from suitable biomass can be effective in removing the heavy metal ions. In this study, the powder of the bark of Platanus orientalis was used as a biosorbent to remove Cr(VI) and Ni from a nickel-chromium plating wastewater as a real sample for the first time. Two different adsorbents were used in analyzing the data: modified and non-modified bark. The extent of adsorption was dependent on the pH (in the range of 1.5, 3, 5, 7, and 9), the time of contact (in the range of 30, 60, 90, 120 min), and the adsorbent dosage (different doses of 0.5, 1, 1.5, 2 g L^-1). The concentration of unabsorbed metals was measured by inductively coupled plasma-optical emission spectroscopy (ICP-OES, Model Thermo iCAP 6000). The maximum removal of Cr(VI) was obtained 89.6% for non-modified bark and 90.7% for modified bark both at pH of 5 in 2 g L^-1 of adsorbent dosage in 300 min. While, the maximum Ni removal was obtained 74.5 and 56.5% for non-modified and modified bark, respectively, at pH 3 in 2 g L^-1 adsorbent dosage in 90 min. Based on the results, Freundlich isotherm appears better fitted in adsorption with a better correlation coefficient (R² = 0.998) than that of Langmuir model with a correlation coefficient of R² = 0.996. The q_max for Ni₁ and Ni₂ were 126.58 and 285.714 mg g^-1 and the q_max for Cr₁ and Cr₂ were 13.423 and 19.920 mg g^-1, respectively. The FTIR studies indicated that S-O stretching group from sulfonate, surface O=H stretching, and also aliphatic C-H stretching are responsible for the adsorption. The SEM results obviously show the difference between the biomass surface before and after loading of ions. Ultimately, the present study concluded that P. orientalis could be a cheap and efficient biosorbent to adsorb and remove Cr(VI) and Ni from the plating wastewater; however, it seems more efficient for Cr(VI) with an average removal power of 90.15% than Ni with an average removal power of 65.75%.

New Sustainable Biosorbent Based on Recycled Deoiled Carob Seeds: Optimization of Heavy Metals Remediation

In this study, an efficient biosorbent was developed from deoiled carob seeds, a agroindustrial waste. The biosorption efficiency was evaluated for cadmium and cobalt ions removal from aqueous solution under various parameters such as treating agent, solution pH, biosorbent dosage, contact time, initial metal ions concentration, and temperature. The effect of some major inorganic ions including Na+, K+, Ca2+, Mg2+, and Al3+ on the biosorption was also established. Based on this preliminary study, four independent variables including solution pH, biosorbents dosage, initial metal concentration, and treating agent were chosen for the optimization of the process using full-factorial experimental design. It was found that chemical pretreatment of the raw deoiled carob seeds with NaOH strongly enhances its biosorption potential. Thus, the optimal conditions for high biosorption of cadmium(II) and cobalt(II) were achieved at pH of 6, biosorbent dosage of 1 g/L, and initial metal concentration of 50 mg/L. The biosorbents were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Boehm titration, and the point of zero charge (pHPZC).

Biosorption of Cu2+ and Ni2+ Ions from Synthetic Waters

In this study, biosorption of Cu²⁺ and Ni²⁺ ions to tobacco stalks was investigated under different operational conditions. The effects of the initial pH, ion concentrations, temperature, and duration of contact and adsorbent dosage were determined in the batch experiments. Chemical oxygen demand (COD) analyses were also performed to identify the possible negative effects of the sorbent throughout biosorption process. The sorption capacities of this sorbent were predicted by use of the equilibrium and kinetic models. Within the scope of kinetic study, it was observed that biosorption fitted to second-order pseudo kinetic rate expression. The highest R ² value in isotherm studies was obtained from Freundlich isotherm (R ² = 0.9940-0.9929) for the inlet concentration. FTIR, SEM, and EDX analyses were performed to investigate the surface characteristics and chemical structure of the biosorbent. Under optimum conditions, qe value for Cu²⁺ was determined as 7.18 mg/g and removal efficiency was 86.24%; qe value for Ni²⁺ was determined as 6.45 mg/g and removal efficient was 77.4%. Sorbent recovery process was also performed within the scope of this study with 0.1 M H₂SO₄, 0.1 M HCl, and distilled water. A significant decrease was observed in efficiency when the recovered sorbent was reused.

Comparative study of raw and chemically treated mangrove leaf for remediation of 304 Methyl Violet 2B dye from aqueous solution: thermo-kinetics aspect

The adsorption process is the most attractive alternative way for the treatment of industrial effluents. The main objective of the study is to compare the efficacy of adsorption by raw and chemically treated forms of mangrove plant leaf powder. It acts as adsorbent, and would not only be economical but also help to reduce pollution. The adsorbent was characterized by Fourier transform infra-red spectroscopy and scanning electron microscopy. Results showed that percent removal of dye was higher by chemically treated mangrove leaf (98%) than by raw mangrove leaf (75%) under all determined conditions. The equilibrium and kinetics adsorption data were analyzed by the Langmuir isotherm and the pseudo second order model. They were found to be the best fit to interpret the present data. The thermodynamic parameters were calculated by using the Langmuir equilibrium constant. Results suggested that dye adsorption on mangrove leaf was a spontaneous and exothermic process with enthalpy change = -15.26 kJ/mol, and there was decrease in disorder with entropy change = -5.089 kJ/mol K.