Airborne hexavalent chromium has been classified as a human respiratory carcinogen and long term exposure has been known to cause ulceration and perforation of the nasal septum, bronchitis, asthma, and liver and kidney damage. Chromium electroplating plants are the major sources of atmospheric chromium and packed-bed scrubbers are the common control devices used to reduce emission of chromic acid mist from electroplating bathes.The feasibility of a new method to remove this pollutant using alginate beads as a biomass derivative was investigated by one factor at a time approach and Taguchi experimental design. Polluted air with different chromium mist concentrations (10-5000 mg/m3) was contacted to alginate beads (3.3-20 g/L), floating in distilled water with adjusted pH (3-7), using an impinger at different temperatures (20 and 35oC), and various velocities (1.2 and 2.4 m/s).Although there were no statistical significant differences between factor levels, the higher ions removal efficiencies were achieved at lower levels of air velocities, pollution concentrations, higher levels of pHs, temperatures, and sorbent concentrations.

Tree bark is among the widely available and low-cost sorbents for metal adsorption in aqueous environments. A state-of-the-art review is compiled carrying out a comprehensive literature search on the biosorption of heavy metals in solution onto different bark species, including a characterization of bark structure and chemistry. The results indicate that biosorption has been gaining importance for bark valorization purposes. Promising heavy metal uptake values have already been attained using different bark species. These values are comparable to those obtained with commercial activated carbons. Bark has a cost advantage over activated carbon and can be used without any pretreatment. Thus, bark offers a green alternative to remove heavy metals from industrial waters. A brief survey of the chemical composition and structure of different bark species is presented. Suggestions are made to improve screening of bark species for specific heavy metal ions sorption.

Unfertilizable fruiting buds of mango plant Mangifera Indica L, an agrowaste, is used as a biomass in this study. The efficacy of the BIOSORBENT was tested for the removal of lead, copper, zinc and nickel metal ions using batch experiments in single and binary metal solution under controlled experimental conditions. It is found that metal sorption increases when the equilibrium metal concentration rises. At highest experimental solution concentration used (150 mg/L), the removal of metal ions were 82.76 % for lead, 76.60 % for copper, 63.35 % for zinc and 59.35 % for nickel while at lowest experimental solution concentration (25 mg/L), the removal of metal ions were 92.00% for lead, 86.84 % for copper, 83.96 % for zinc and 82.29 % for nickel. Biosorption equilibrium isotherms were plotted for metal uptake capacity (q) against residual metal concentrations (Cf) in solution. The q versus Cf sorption isotherm relationship was mathematically expressed by Langmuir and Freundlich models. The values of separation factor were between zero and one indicating favourable sorption for four tested metals on the BIOSORBENT. The surface coverage values were approaching unity with increasing solution concentration indicating effectiveness of BIOSORBENT under investigation. The non-living biomass of Mangifera indica L present comparable biosorption capacity for lead, copper, zinc and nickel metal ions with other types of BIOSORBENT materials found in literature and is effective to remove metal ions from single metal solutions as well as in the presence of other co-ions with the main metal of solution.

In present study the potential of a new BIOSORBENT obtained from mangosteen peel was investigated for the removal of hexavalent chromium and trivalent chromium from the aqueous solutions. The BIOSORBENT was modified by using concentrated sulphuric acid as the crosslinking reagent. Various batch experiments were carried out testing different values of several parameters such as pH, contact time, adsorbent dosages, and metal ion concentration to identify the optimum conditions. The effect of these parameters on the adsorption capacity and selectivity was studied. Results showed that optimum pH for hexavalent chromium adsorption was 3.0 and adsorption equilibrium was attained in 120 min. The adsorption data were found to fit Langmuir model and pseudo-second-order equation. The adsorption mechanism for hexavalent chromium was found to be a complex process involving esterification, reduction and ion exchange, while cation exchange is the main route for trivalent chromium adsorption. From the above results, the crosslinked mangosteen peel gel appears to be a potential low-cost and effective adsorbent for hexavalent chromium and trivalent chromium removal from the waste water.

Azo dyes are a group of hardly degradable dyes characterized by existence of azo group in their structure. The purpose of present study is the isolation of capable fungi for azo dyes biosorption. Fungi strains isolation was performed by enrichment method. The ability of selected fungal isolate in bio-decolorization was examined using different concentrations of dye. The best dye removal with a rate of 90% at concentration of 1000 mg/l was achieved after 5 days. This fungal isolate is capable to grow in 100 g/L NaCl. Molecular identification revealed 99% similarity to Neosartorya fischeri. Investigation of dye desorption showed that acetone is the best solvent for desorption. It is worth mentioning that, this strain has high ability for biosorption of dyes from textile wastewater. To our knowledge, this is the first report regarding the biosorption potential of Neosartorya sp., and it can be a potent biological agent for treatment of textile effluent.

A glycine-modified persimmon powder was used as BIOSORBENT for platinum adsorption in aqueous solution. The combined effects of modifying agent amount, modifying time and temperature on Pt (IV) adsorption by persimmon BIOSORBENT were investigated, from which the optimum modification conditions with modifying agent amount of 50 %, temperature of 333 K and contact time of 4.0 h were determined. The influences of solution initial pH, solid-to-liquid ratio, contact time, temperature and initial concentration on the Pt(IV) adsorption were studied systematically by batch experiments. The optimum modification conditions were determined as follows: chemical reagent amount of 50 %, temperature of 333 K and contact time of 4.0 h. From the adsorption kinetic analysis, it was found that the adsorption kinetics of glycine-modified persimmon powder followed a pseudo-second-order kinetic model. The adsorption isotherms of the crude persimmon powder and glycine-modified persimmon powder were analyzed with the BET-type adsorption isotherm. The adsorption mechanism of Pt(IV) on the glycine-modified persimmon was considered to be adsorption-reduction mechanism. The results achieved from this study indicated that the novel persimmon adsorbent could be applied to recover trace Pt(IV) ions from a concentrated chloride solution.

Immobilized Cystoseira indica algae and Saccharomyces Cerevisiae on the silica gel were used for the biosorption of Th(IV) from aqueous solutions. Ability and capacity of bi-functionalized algae-yeast BIOSORBENT for adsorption of thorium(IV) from aqueous solutions were investigated in a batch method. The response surface methodology (RSM) based on the central composite design (CCD) was used to investigate the effect of pH (2-6), time (10-180 min), initial thorium(IV) concentration (50-300 mg/l) and adsorbent dosage (0. 5-5 g/l) on the sorption of thorium(IV) from aqueous solutions, and to optimize the biosorption of Th(IV). Variance analysis showed that the adsorbent dosage, initial Th(IV) concentration, time and pH were respectively, the most effective factors in the biosorption of thorium(IV). Under optimal conditions (pH 5, contact time 137. 5 min, initial Th(IV) concentration 237. 5 mg/l, and adsorbent dosage 1. 63 g/l) the capacity of the BIOSORBENT for Th(IV) was estimated to be 128. 82 mg/g. The kinetic data were fitted well the pseudo-second-order rate equation. The biosorption data could be well described by Langmuir isotherm in comparison to Freundlich and Temkin isotherms. The maximum sorption capacity of the BIOSORBENT for Th(IV), by Langmuir isotherm was estimated to be 142. 86 mg/g. The thermodynamic parameters indicated that the biosorption of Th(IV) on the biomass was a spontaneous, and endothermic process, at the studied temperatures and would occur via physical adsorption.

BACKGROUND AND OBJECTIVE: The overuse of antibiotics in hospitals and the entry of these pollutants into water resources is one of the major challenges to the health of the community and the environment. Removal of antibiotics from hospital wastewater and other aquatic environments is possible through the adsorption process. This study was performed to evaluate antibiotic removal using plantain wood due to being cheapn and natural. METHODS: In this in vitro study, the effect of pH (2, 4, 6, 8, 10 and 12), contact time (5, 10, 20, 40, 60, 80, 100 and 120 minutes), initial metronidazole concentration (10, 50 and 100 mg/L) and BIOSORBENT dose (0. 2, 0. 4, 0. 6, 0. 8, 1, 1. 2 and 1. 4 g) on metronidazole removal rate in synthetic solution were evaluated, and the isothermal kinetic and thermodynamic results of the adsorption process were investigated in this study. Concentration of metronidazole in aqueous solution was measured by Hach DR 5000 UV-Vis Laboratory Spectrophotometer. FINDINGS: Maximum removal of metronidazole (91%) was obtained at pH=6. 5, 60 min, initial concentration of 50 mg/l, adsorbent dose of 0. 8 g and 25 ° C and maximum adsorption capacity (11. 38 mg/g) was obtained at a dosage of 0. 1 g. In this study, the reaction rate followed the pseudo-second order and adsorption isotherm followed Langmuir equation. The adsorption thermodynamic results showed that the adsorption process is physical in nature and is a spontaneous endothermic reaction. CONCLUSION: The results of the study showed that BIOSORBENT prepared from plantain wood is a natural material and has the ability to remove metronidazole antibiotics from hospital wastewater and other aquatic environments.