Biosorption of Remazol Brilliant Blue R Dye onto Chemically Modified and Unmodified Yarrowia lipolytica Biomass

Remazol Brilliant Blue R (RBBR) is a widely used carcinogenic and toxic dye. This study focused on RBBR dye from aqueous solution using potassium permanganate, cetyltrimethylammonium bromide (CTAB) modified, and unmodified Yarrowia lipolytica biomass as biosorbent. RBBR dye biosorption studies were carried out as a function of pH, initial dye concentration, biosorbent dose, contact time, and temperature. The pH of the aqueous solution strongly influenced the biosorption percent of RBBR dye. The highest dye biosorption capacity yield was obtained at pH 2-3 as well as above pH 3, very low yield biosorption of RBBR was observed. No differences were found between chemically modified and unmodified biomass in terms of RBBR dye biosorption capacity. In the first 15 min, almost 50% RBBR dye was removed from the solution and reached equilibrium within,180 min at pH 2. Biosorption isotherm obeyed Langmuir isotherm model and pseudo-second-order kinetic model.

Biosorption of nickel, cobalt, zinc and copper ions by Serratia marcescens strain 16 in mono and multimetallic systems

The metallurgical industry is one of the main sources of heavy metal pollution, which represents a severe threat to life. Metals can be removed from aqueous solutions by using microbial biomasses. This paper analyses the heavy metal biosorption capacity of Serratia marcescens strain 16 in single and multimetallic systems. The results obtained show that Co(II), Ni(II) and Zn(II) biosorption in monometallic systems is two to three times higher than in the presence of bi-metallic and multimetallic solutions. Fourier transform infrared spectroscopy confirmed that carbonyl, carboxyl and hydroxyl were the main functional groups, as well as the amide bands I and II involved in metal uptake, which are present in external structures of the bacterial cell. The results obtained demonstrated the viability of S. marcescens strain 16 as a biosorbent for the design of eco-friendly technologies for the treatment of waste liquor.

Biosorption of Hexavalent Chromium Metal Ions by Lentinula Edodes Biomass: Kinetic, Isothermal, and Thermodynamic Parameters

Lentinula edodes was investigated as a biosorbent for hexavalent chromium biosorption in this study. To examine the optimum conditions of biosorption, the pH of the hexavalent chromium solution, biosorbent dosage, temperature, contact time, and initial hexavalent chromium concentration were identified. Further, to clarify the biosorption mechanism process, the isothermal, kinetic, and thermodynamic parameters were determined. The functional groups and surface morphology of the biosorbent were identified using Fourier transform infrared spectrometry and scanning electron microscopy in the absence and presence of hexavalent chromium, respectively. Based on the results, the maximum biosorption capacity was determined as 194.57 mg g–1 under acidic conditions at 45 °C. From the kinetics studies, the biosorption process was observed to follow the Freundlich isotherm and pseudo-second-order kinetic models well. Thus, L. edodes as a biosorbent has potential usage for wastewater treatment owing to its effective biosorption capacity.

Pyrolysis of Solid Digestate from Sewage Sludge and Lignocellulosic Biomass: Kinetic and Thermodynamic Analysis, Characterization of Biochar

This study investigates the pyrolysis behavior and reaction kinetics of two different types of solid digestates from: (i) sewage sludge and (ii) a mixture of sewage sludge and lignocellulosic biomass—Typha latifolia plant. Thermogravimetric data in the temperature range 25–800 °C were analyzed using Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose kinetic methods, and the thermodynamic parameters (ΔH, ΔG, and ΔS) were also determined. Biochars were characterized using different chemical methods (FTIR, SEM–EDS, XRD, heavy metal, and nutrient analysis) and tested as soil enhancers using a germination test. Finally, their potential for biosorption of NH4+, PO43−, Cu2+, and Cd2+ ions was studied. Kinetic and thermodynamic parameters revealed a complex degradation mechanism of digestates, as they showed higher activation energies than undigested materials. Values for sewage sludge digestate were between 57 and 351 kJ/mol, and for digestate composed of sewage sludge and T. latifolia between 62 and 401 kJ/mol. Characterizations of biochars revealed high nutrient content and promising potential for further use. The advantage of biochar obtained from a digestate mixture of sewage sludge and lignocellulosic biomass is the lower content of heavy metals. Biosorption tests showed low biosorption capacity of digestate-derived biochars and their modifications for NH4+ and PO43− ions, but high biosorption capacity for Cu2+ and Cd2+ ions. Modification with KOH was more efficient than modification with HCl. The digestate-derived biochars exhibited excellent performance in germination tests, especially at concentrations between 6 and 10 wt.%.

Application of Saccharomyces cerevisiae/Calcium Alginate Composite Beads for Cephalexin Antibiotic Biosorption from Aqueous Solutions

Cephalexin (CPX) is recognized as a water pollutant, and it has been listed in a number of countries with a risk factor greater than one. Herein, the present work focused on the synthesis, characterization and biosorption capacity evaluation of Saccharomyces cerevisiae immobilized in calcium alginate as a biosorbent to remove CPX from aqueous solutions. Biosorbent was characterized by SEM and FTIR techniques. Batch biosorption experiments were conducted in order to evaluate the effect of the initial pH, biosorbent dose and CPX initial concentration. The removal efficiency, in considered optimal conditions (pH = 4, CPX initial concentration = 30 mg/L, biosorbent dose = 1 g/L) was 86.23%. CPX biosorption was found to follow the pseudo–second-order kinetics. The equilibrium biosorption data were a good fit for the Langmuir model with correlation coefficient of 0.9814 and maximum biosorption capacity was 94.34 mg/g. This study showed that the synthesized biosorbent by immobilization technique is a low-cost one, easy to obtain and handle, eco-friendly, with high feasibility to remove CPX antibiotic from aqueous solution. The findings of this study indicate that the biosorbents based on microorganisms immobilized on natural polymers have the potential to be applied in the treatment of wastewater.

Enhanced cadmium removal by growing Bacillus cereus RC-1 immobilized on different magnetic biochars through simultaneous adsorption and bioaccumulation

Biosorption of cadmium by growing bacteria immobilized on the three magnetic biochars derived from rice straw (MRSB-pellet), sewage sludge (MSSB-pellet), and chicken manure (MCMB-pellet) was investigated, respectively. Total biosorption capacity of the pellets was tested under varying range of pH, culture time, and initial Cd 2+ concentration. The maximum biosorption capacity of 93.02 mg/g was obtained with MRSB-pellet, followed by MSSB-pellet (68.02 mg/g) and MCMB-pellet (63.95 mg/g). The biosorption by these immobilized bacterial pellets was more effective than free bacteria, this enhancement could be the result of simultaneous adsorption and bioaccumulation, mainly resulting from magnetic biochar carrier and active bacteria, respectively. The biosorption process by immobilized pellets was primarily driven by ion-exchange and complexation, which jointly contributed of 73.56% (MRSB-pellet) to 78.62% (MSSB-pellet) the total adsorption, while the mechanisms of chemical precipitation and physical adsorption could averagely contribute 6.91% (MSSB-pellet) and 11.24% (MRSB-pellet), respectively. Intracellular accumulation was comparably tiny among these mechanisms accounting for 4.30-5.92% of total biosorption, in turn, it would maintain intracellular Cd 2+ concentration below a toxic threshold to promote cell growth. These suggested that magnetic biochar immobilized bacteria, particularly MRSB-pellet could be used as an effective biosorbent to remove the Cd 2+ from the growth medium. This study further deepened our understanding of biosorption process by microorganism immobilized onto magnetic biochar for the metals removal.