Modelling adsorption of acid orange 7 dye in aqueous solutions to spent brewery grains

Design and preliminary techno-economic assessment of a pilot scale pharmaceutical wastewater treatment system for ammonia removal and recovery of fertilizer

Recovery of nutrients from wastewater has a paramount importance for a sustainable and safe environment. In this study removal of ammonia and recovery of resources in the form of struvite from a complex pharmaceutical acidic wastewater having high concentration of ammoniacal nitrogen (NH₄-N > 40 g/L) and other co-existing contaminants (magnesium, phosphorous, phenol etc.) was explored. Response Surface Methodology (RSM) was employed for design of experiments and process optimization. RSM results revealed that removal of ammoniacal nitrogen, i.e., struvite precipitation was found to be maximum in alkaline pH (10.5-11.0) at a N:Mg molar ratio (1:0.030 to 1:0.035) and N:P molar ratio (1:0.025 to 1:0.030). X-Ray diffraction, thermo-gravimetric analysis and Fourier transform-infrared spectroscopy confirmed the presence of struvite crystals in the obtained precipitate. Techno-economic assessment (TEA) based on mass energy balance principle and market equipment specifications revealed that a pilot-scale plant set up would have a break-even period of 1.06 years with a return on investment as 94.28%. This clearly elucidated the economic viability of the developed process for industrial applications for management of high ammonia laden pharmaceutical wastewater. While further specific technological improvements are needed for reduction of cost, this study will guide researchers and industries for careful selection of target markets to reduce the cost for successful implementation.

Novel Fe3O4-poly(methacryloxyethyltrimethyl ammonium chloride) adsorbent for the ultrafast and efficient removal of anionic dyes

The removal of anionic dyes from wastewater has attracted global concern. In this work, a novel Fe₃O₄-poly(methacryloxyethyltrimethyl ammonium chloride) (Fe₃O₄-pDMC) adsorbent for the efficient removal of anionic dyes from wastewater was successfully synthesized by grafting methacryloxyethyltrimethyl ammonium chloride (DMC) on the surfaces of Fe₃O₄. Various characterization analyses confirmed that the obtained Fe₃O₄-pDMC possessed numerous functional groups on its surfaces and retained good magnetic separation properties. Fe₃O₄-pDMC showed ultrafast removal for acid orange 7 (AO7, 58.6%, 1 min) and direct blue 15 (DB15, 98.1%, 1 min), and the maximum adsorption capacity was high (266.8 and 336.5 mg g^-1 for AO7 and DB15, respectively). In addition, the adsorption process was in accordance with pseudo-second-order kinetics and the Langmuir isotherm. The mechanism underlying the adsorption of Fe₃O₄-pDMC on anionic dyes was mainly dependent on electrostatic interaction. This study illustrated that Fe₃O₄-pDMC has great potential applications as an environmentally friendly, desirable adsorbent for the efficient removal of anionic dyes from wastewater.

Prickly pear cactus cladodes powder of Opuntia ficus indica as a cost effective biosorbent for dyes removal from aqueous solutions

The textiles manufacturing is one of the core industries that release a huge amount of dyes during the dyeing process. As a result, the growing demand of an efficient and low-cost treatment has given rise to alternative adsorbents. In the present study, prickly pear cactus cladodes powder (PPCP) of Opuntia ficus indica was investigated as an ecofriendly and low-cost biosorbent of Acid orange 51 (AO51) and Reactive Red 75 (RR75) dyes commonly used in dyeing. The FTIR spectroscopic characterization of PPCP showed the heterogeneity in surface structure and functional groups which confers to the biosorbent its capability to interact with acidic (AO51) and reactive (RR75) dyes molecules. Effects of pH, temperature, initial dye concentration and adsorbent dose on adsorption yield were investigated. The dyes uptake process was closely fitted to the pseudo-second order kinetic for both dyes. Experimental data were analyzed by applying the Langmuir, Freundlich, Dubinin-Raduskevich, Temkin, Redlich-Peterson, and BET isotherms equations. The models of BET and Langmuir were considered as the best isotherms models fitting experimental data, respectively, of RR75 and AO51. The maximum Langmuir monolayer biosorption capacities were of 198.9 and 45 mg g^-1, respectively for RR75 and AO51.

Heteroatoms doped porous carbon derived from hydrothermally treated sewage sludge: Structural characterization and environmental application

The heteroatoms (N and S) doped porous carbons (HAPCs) were prepared from sewage sludge by hydrothermal carbonization and chemical activation for the first time. The porous structures and surface properties of HAPCs were characterized by multiple techniques including SEM-EDS, TEM, BET, XRD, Raman spectroscopy and Boehm's titration. The resultant materials were showed to be naturally N and S dual-doped porous carbons (HAPCs), especially for HAPC_HCl+HF obtained by HCl-HF-washing, which was typical 3D hierarchically porous structure with abundant mesopores as well as big pore diameter. Then the performance of HAPC_HCl+HF on AO7 removal was determined through Response surface methodology. The results showed the adsorption behavior obeyed Langmuir isotherm model and the maximum adsorption capacity was up to 440.53 mg g^-1 at 25 °C. Kinetics study revealed that the adsorption followed pseudo second-order kinetic and intra-particle diffusion was the main control step. The high removal rate of AO7 was ascribed to the unique properties of HAPC_HCl+HF. The great V_mes and big pore diameter facilitated the diffusion of AO7 into the intra surface of particle. Meanwhile, the basic groups and doping of N and S made HAPC_HCl+HF surface had positive charges, then strong π-π stacking interaction and electrostatic attraction contributed to the highly effective adsorption. This study indicated hydrothermal carbonization coupled with chemical activation was a cost-effective approach to prepare efficient heteroatoms doped porous carbon from sewage sludge towards azo dye contaminated wastewater treatment.

Removal of azo dye by a highly graphitized and heteroatom doped carbon derived from fish waste: Adsorption equilibrium and kinetics

A highly graphitized and heteroatom doped porous carbon was prepared from fish waste in the present study. The morphology and chemical composition of the resultant porous carbon were characterized by SEM-EDS, TEM, BET, XRD and Raman measurement. The prepared porous carbon was employed as an adsorbent for acid orange 7, a typical azo dye, removal from aqueous solution. The results showed that the porous carbon had ultrahigh surface area of 2146 m(2)/g, a high degree of graphitization structure and naturally doped with nitrogen and phosphorous. The maximum adsorption capacity of acid orange 7 reached 285.71 mg/g due to unique property of the prepared porous carbon. In addition, acid orange 7 adsorption onto the porous carbon well followed pseudo-second-order kinetics model and acid orange 7 diffusion in micropores was the potential rate controlling step.

Synthesis and characterization of ZnO-nanorods loaded onto activated carbon and its application for efficient solid phase extraction and determination of BG from water samples by micro-volume spectrophotometry

The applicability of ZnO-nanorods loaded onto activated carbon (ZnO-NRs-AC) for the dispersive solid phase microextraction (DSPME) of brilliant green (BG) from water samples has been described.

Efficient adsorption of Europhtal onto activated carbon modified with ligands (1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine (M) and (1E,2E)-1,2-bis(pyridin-3-ylmethylene)hydrazine (SCH-4); response surface methodology

Porous activated carbon was modified with (1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine (M) and (1E,2E)-1,2-bis(pyridin-3-ylmethylene)hydrazine (SCH-4).

Brewer's spent grain: a valuable feedstock for industrial applications

Brewer's spent grain (BSG) is the most abundant by-product generated from the beer-brewing process, representing approximately 85% of the total by-products obtained. This material is basically constituted by the barley grain husks obtained as solid residue after the wort production. Since BSG is rich in sugars and proteins, the main and quickest alternative for elimination of this industrial by-product has been as animal feed. However, BSG is a raw material of interest for application in different areas because of its low cost, large availability throughout the year and valuable chemical composition. In the last decade, many efforts have been directed towards the reuse of BSG, taking into account the incentive that has been given to recycle the wastes and by-products generated by industrial activities. Currently, many interesting and advantageous methods for application of BSG in foods, in energy production and in chemical and biotechnological processes have been reported. The present study presents and discusses the most recent perspectives for BSG application in such areas.

Biosorption of Basic Violet 5BN and Basic Green by waste brewery's yeast from single and multicomponent systems

BACKGROUND AND AIM

The biosorption of Basic Violet 5BN (BV) and Basic Green (BG) by waste brewery's yeast (WBY) from single and binary systems was investigated.

RESULTS AND DISCUSSION

For the single system, the adsorption of both dyes is pH-dependent and the optimum value is 5.0. At a lower initial concentration, the kinetic data agree well with both pseudo-first-order and pseudo-second-order models, while at a higher initial concentration the data fit better with the pseudo-second-order model. External diffusion is the rate-controlling step at initial fast adsorption, and then the intraparticle diffusion dominated the mass transfer process. Equilibrium data for BV and BG fit better with the Langmuir model. The maximum biosorption capacities of WBY onto BV and BG obtained at 303 K are 114.65 and 141.89 mg/g, respectively. Thermodynamic analysis reveals that the adsorption process for the two dyes is spontaneous and exothermic.

CONCLUSIONS

The hydroxyl, amino, amide, carboxyl, and phosphate groups are responsible for the biosorption based on Fourier transform infrared analysis. The presence of BV significantly affects the biosorption of BG, but not vice versa. The P-factor model and Sheindrof-Rebhun-Sheintuch equation gave a good description of the equilibrium adsorption data at the multicomponent system.

Valorization of Agroindustrial Wastes as Biosorbent for the Removal of Textile Dyes from Aqueous Solutions

The goal is to determinate the technical feasibility of using agroindustrial wastes for adsorption of dyes. The pHpzcof Brewer’s spent grains and Orange peel is 5.3 and 3.5, respectively. The equilibrium isotherms of Basic Blue 41, Reactiive Black 5, and Acid Black 1 were carried out without pHs control which ranging between 4 and 5.5. The equilibrium concentrations for both adsorbents were fitted by the Freundlich and Langmuir models. The maximum adsorption capacity measured for Basic Blue 41, Reactive Black 5, and Acid Black 1 was 32.4, 22.3, and 19.8 mg g-1for Brewer’s spent grains; and 157, 62.6, and 45.5 for orange peel, respectively. The kinetic of process was fitted by the model of pseudo-second order. The constant rate for orange peel decreased to extend the initial concentration of dye increased, obtaining 4.08 * 10−3−0.6 * 10−3(Basic Blue 41), 2.98 * 10−3−0.36 * 10−3(Acid Black 1), and 3.40 * 10−3−0.46 * 10−3 g mg−1 min−1(Reactive Black 5). The best removal efficiency was obtained in orange peel with values started from 63% to 20%. Consequently, according the results obtained there are two positive effects, the reuse of agricultural wastes and its use as low-cost adsorbent of the dyes.

NiO111 nanosheets as efficient and recyclable adsorbents for dye pollutant removal from wastewater

Semiconductor single-crystalline polar NiO(111) nanosheets with well-defined hexagonal holes have been investigated for application in dye adsorption and combustion processes. With regard to adsorption technologies, high surface area metal oxides have an advantage over activated carbon in that the adsorbed species can be combusted and the adsorbent reused in the case of metal oxides while regeneration of activated carbon remains challenging and thus the adsorbent/adsorbate system must be disposed of. Here, three typical textile dyes, reactive brilliant red X-3B, congo red and fuchsin red, were studied for removal from wastewater with two NiO systems and activated carbon. These studies revealed that the NiO(111) nanosheets exhibited much more favorable adsorptive properties than conventionally prepared nickel oxide powder (CP-NiO) obtained from thermal decomposition of nickel nitrate. The maximum adsorption capabilities of the three dyes on NiO(111) nanosheets reached 30.4 mg g(-1), 35.15 mg g(-1) and 22 mg g(-1) for reactive brilliant red X-3B, congo red and fuchsin acid, respectively, while the maximum adsorption capabilities of the three dyes on CP-NiO were only 8.4, 13.2 and 12 mg g(-1) for reactive brilliant red X-3B, congo red and fuchsin acid. To simulate the adsorption isotherm, two commonly employed models, the Langmuir and the Freundlich isotherms, were selected to explicate the interaction of the dye and NiO(111). The isotherm evaluations revealed that the Langmuir model demonstrated better fit to experimental equilibrium data than the Freundlich model. The maximum predicted adsorption capacity was 36.1 mg g(-1). In addition, adsorption kinetic data of NiO(111) followed a pseudo-second-order rate for congo red. These studies infer that NiO(111) nanosheets possess desirable properties for application in adsorption and combustion applications.