By-product Glycerol Research Articles

Critical Review on Production of Glycerol Carbonate from Byproduct Glycerol through Transesterification

The biodiesel obtained from nonedible and waste-cooking oils through the transesterification process has been recognized as a renewable energy source. This transesterification process produces glyc...

Valorization of biodiesel byproduct glycerol to glycerol carbonate using highly reusable apatite-like catalyst derived from waste Gastropoda Mollusca

Predominantly, calcium oxide from the calcined waste Gastropoda Mollusca (Achatina fulica sp.) was post-functionalized and stabilized using trisodium phosphate to obtain an apatite-like catalyst (snail shell apatite, SNS-AP) to tailor the synthesis of glycerol carbonate (GC) from abundant biodiesel byproduct glycerol. Textural properties, crystal structure, and morphology were characterized by different techniques. The turnover frequency (TOF) and E-factor green metrics were determined, and plausible reaction mechanisms elucidated. The results show that the transformation of the crystalline phases of the snail shell consisting of aragonite and dolomite phases to apatite-like glaserite after functionalization with trisodium phosphate promoted stability and enhanced basicity of the catalyst to tailor the transesterification reaction. Thus, about 94.3% glycerol conversion and 96.5% GC yield were achieved under best reaction conditions of 80 °C, 90 min, DMC/glycerol molar ratio of 4, and 4 wt% catalyst weight. The TOF and E-factor were 12.533 h−1 and 0.5322, respectively. Also, the catalyst was stable over eight successive cycles of reuse sustaining about 80.34% GC yield. The results show the potential of this environmentally friendly strategy to prepare stable heterogeneous catalyst from natural wastes to promote the upgrading of oversupplied glycerol. Graphical abstract

Strategic biorefinery platform for green valorization of agro-industrial residues: A sustainable approach towards biodegradable plastics

The production of cellulose reinforced bio-composites has emerged as an efficient bio-sustainable alternative for high-quality functional polymeric materials to replace the presently dominated petroleum-based plastics. Also because, lignocellulose biorefinery from waste agro-industrial residues has attracted widespread attention for combating increasing environmental pollution caused by incineration of such wastes. In this prospect, the fractionation of tender coconut husks (TCH) to yield cellulose, hemicellulose and lignin fractions has been investigated by different pretreatment methodologies using conventional and novel reaction media. Excellent outcomes were obtained with the use of the deep eutectic solvent composed of choline chloride and oxalic acid dihydrate that led to the dissolution of 95.5% of the initial lignin in TCH to yield a cellulose fractional recovery of 87.5% at the optimal conditions attained by parametric variations. Interestingly, the same eutectic mixture also functionalized the obtained cellulose to cellulose nanocrystals (CNC) with 69% yield, crystallinity index of 88.6% and average particle size of 146 nm. Further, isolated starch from waste tamarind seeds was used as the polymer matrix wherein the CNC was added as a suitable bio-filler to cast bioplastic films using biodiesel byproduct glycerol as a plasticizer. The characterization of the biodegradable films revealed a tensile strength of 21.8 MPa along with outstanding thermal and moisture barrier properties. The results elucidate that the huge dependence for petro-plastics could be reduced with the integrated valorization of solid wastes that can aid wide-ranging industries and align with the rising motto of a bioeconomy.

Renewable hydrogen production from chemical looping steam reforming of biodiesel byproduct glycerol by mesoporous oxygen carriers

Abstract The selection of metal oxides and supports to improve catalytic activity and stability of oxygen carriers (OCs) is crucial for chemical looping steam reforming (CLSR) to hydrogen production. In this study, the Ni-based MCM-41 and SBA-15 OCs with and without CeO2 promoter were prepared by direct synthesis and impregnation methods. The BET, XRD, TEM, ICP-AES, H2-TPR and DSC-TGA were used to analyze the synthesized OCs. Hydrogen production by CLSR using biodiesel byproduct glycerol was studied in a fixed-bed reactor with fuel and air stages. The DSC-TGA experiments were carried out to determine the thermal decomposition of biodiesel byproduct glycerol and the results indicated the exothermic and/or endothermic reactions as a result of secondary reactions and, the main degradation with the mass loss of 85.5 wt% occurred in the stages of 150–500 °C. The mesoporous OCs presented high specific surface area, large pore volume, and uniform pore size. It was found that the NiO and CeO2 in the mesoporous OCs were first reduced by fuels and the reduced OCs was responsible of steam reforming and water gas shift (WGS) to hydrogen production, and hydrogen selectivity was up to 90% using CeNiO/SBA-15. The mesoporous OCs with Ce promoter greatly shortened ‘dead time’ (the reduce time of OCs), and effectively suppressed carbon deposited on OCs. High loading of NiO and CeO2 on SBA-15 improved oxygen transfer and achieved excellent cyclic stability. These findings provide the fundamental understanding and principle of design on the conventional Ni-based OCs with room for further developments in chemical looping process.

Produksi Biodiesel tanpa Gliserol dari Minyak Kelapa Sawit dengan Variasi Massa Co-solvent dan Waktu Reaksi

Petroleum fuels are increasingly reduced in line with the increasing industry and population. A potential alternative renewable energy source to replace fuel is biodiesel. The process of making biodiesel that is commonly done is the process of transesterification with glycerol byproducts which is difficult to separate. The method used in this study is the method of interesterification, namely by replacing the methyl alcohol group with a methyl group from methyl acetate with triacetin byproducts. The operating conditions of the process are 250 grams of palm oil mass, 1% wt KOH catalyst mass. oil, reaction temperature 60 ⁰C, stirring speed 800 rpm, mass of co-solvent methyl ester (0, 5, 10, 15, 20% wt. oil) and reaction time (30 minutes, 60 minutes, 90 minutes). The results of the research have been obtained the highest yield with the addition of co-solvent methyl ester of 20% by weight of oil in the reaction time of 30 minutes is 92.43 %.The biodiesel product produced meets SNI 7182:2015 which is an acidic value <0.5 mg-KOH/g.

Preliminary study on the economic assessment of culturing Nannochloropsis sp. in Egypt for the production of biodiesel and high-value biochemicals

The economic feasibility of growing Nannochloropsis sp. at the commercial scale was evaluated for the production of biodiesel and co-products. A local isolate of Nannochoropsis was grown in (6) 200-L raceway ponds at Alexandria University wherein cultures reached maximum cell concentrations ~ 4–6 × 107 cells/mL (0.63–0.88 g/L dry weight) and a peak biomass productivity of 0.09 g/L/day during mid- to late-log growth. Areal productivity was estimated at 17.65 g/m2/day when ponds were operated on a semi-batch schedule, harvesting 50% every 2 days and recycling 60% of the media. Areal productivity was estimated around 10.3 g/m2/day for batch schedules. Late-log cultures harvested from all ponds yielded 10 kg of wet algal paste, which was reduced to 1.05 kg of dried algal powder. The biomass was composed of valuable co-products approx. 14.0% carbohydrate, 37.3% protein, 0.01% chlorophyll-a, and 0.02% carotenoids (w/w). Total lipid made up 38% of the biomass (w/w); 34% of the biomass was determined to be neutral lipid which are transesterified to biodiesel and 4% are polar lipid. Fatty acids from glycerolipids were quantified by gas chromatography-flame-ionization detector (GC-FID) as fatty acid methyl esters (FAMEs) revealing carbon-chain lengths from C6 to C22. A preliminary economic evaluation was conducted to determine the feasibility of constructing commercial-scale algae biodiesel production facilities in Egypt. The return on investment (ROI) of the current economic feasibility study for biofuel production alone was 22% after considering the market prices of the biodiesel, cake, and glycerol by-products. Based on this assessment, additional high-value products are needed to improve the ROI. Noting that the valuable co-products are considered as added cost in the biomass left after biodiesel production.

Significant impact of casein hydrolysate to overcome the low consumption of glycerol by Klebsiella aerogenes ATCC 29007 and its application to bioethanol production

As the demand for biodiesel increases, the by-product glycerol is increasing. Biodiesel-derived glycerol is expected to be applied in bioindustries. However, major limitation of industrial fermentation is that the rate of substrate consumption is significantly slower than conventional process. In this study, in order to improve the consumption of refined crude glycerol in Klebsiella aerogenes, casein hydrolysate was supplemented in main medium. As a result, the substrate consumption rate, cell and ethanol concentration were improved about 2.6-fold, 2.5-fold and 3.0-fold, respectively, compared with the control group. In addition, four components of the main medium (peptone, ammonium sulfate, casein hydrolysate, refined crude glycerol) were statistically optimized. The consumption of glycerol was achieved about 89%, and the productivity of bioethanol was found to be 0.83 g/(L h) under the optimized medium. Also, the bioethanol concentration and yield were 15.89 g/L and 0.487 (g/g), respectively. The supplementation of casein hydrolysate had a significant effect on fermentation. It was proved by analyzing the concentration of free amino acids contained in casein hydrolysate. As a result, it was found that glycerol consumption and bioethanol production were promoted by the abundant supply of essential amino acids contained in casein hydrolysate for cell growth. Therefore, these results will be the basis for sustainable development by providing the opportunity to reuse crude glycerol for industrial applications.

Glycerolysis of free fatty acid in vegetable oil deodorizer distillate catalyzed by phosphonium-based deep eutectic solvent

Abstract Esterification of free fatty acids in a low-grade oil with glycerol, the by-product of transesterification, has been proposed as one possible method to reduce the cost of raw materials for biodiesel production. The glycerolysis reaction recycles the byproduct glycerol to create a much more efficient and cost-effective process. However, the glycerolysis reaction involves challenges, including its requirement of high temperature. This study is the first to apply the deep eutectic solvent (DES) as a catalyst for glycerolysis reaction to convert free fatty acid (FFA) in vegetable oil deodorizer distillate (VODD) being a waste product from the oil refining process into glycerides. The effects of temperature, catalyst dosage, and time on the esterification efficiency of fatty acid conversion were explored. The reaction progress and product solubility were studied by FT-IR and GC. The results revealed that the reaction reached equilibrium at an approximate free fatty acid (FFA) conversion of 90%. The reaction was a second-order reversible reaction, using 8 wt% catalyst loading lowered activation energy to 58.80 J/mol. The optimum condition was determined as 160 °C, 5 wt% DES loading, and 10 min reaction time.

Valorization of Biodiesel Byproduct Crude Glycerol for the Production of Bioenergy and Biochemicals

The rapid growth of global biodiesel production requires simultaneous effective utilization of glycerol obtained as a by-product of the transesterification process. Accumulation of the byproduct glycerol from biodiesel industries can lead to considerable environment issues. Hence, there is extensive research focus on the transformation of crude glycerol into value-added products. This paper makes an overview of the nature of crude glycerol and ongoing research on its conversion to value-added products. Both chemical and biological routes of glycerol valorization will be presented. Details of crude glycerol conversion into microbial lipid and subsequent products will also be highlighted.

Hydrophobic pore space constituted in macroporous ZIF-8 for lipase immobilization greatly improving lipase catalytic performance in biodiesel preparation

BackgroundDuring lipase-mediated biodiesel production, by-product glycerol adsorbing on immobilized lipase is a common trouble that hinders enzymatic catalytic activity in biodiesel production process. In this work, we built a hydrophobic pore space in macroporous ZIF-8 (named as M-ZIF-8) to accommodate lipase so that the generated glycerol would be hard to be adsorbed in such hydrophobic environment. The performance of the immobilized lipase in biodiesel production as well as its characteristics for glycerol adsorption were systematically studied. The PDMS (polydimethylsiloxane) CVD (chemical vapor deposition) method was utilized to get hydrophobic M-ZIF-8-PDMS with hydrophobic macropore space and then ANL (Aspergillus niger lipase) was immobilized on M-ZIF-8 and M-ZIF-8-PDMS by diffusion into the macropores.ResultsANL@M-ZIF-8-PDMS presented higher enzymatic activity recovery and better biodiesel production catalytic performance compared to ANL@M-ZIF-8. Further study revealed that less glycerol adsorption was observed through the hydrophobic modification, which may attribute to the improved immobilized lipase performance during biodiesel production and ANL@M-ZIF-8-PDMS remained more than 96% activity after five cycles’ reuse. Through secondary structure and kinetic parameters’ analysis, we found that ANL@M-ZIF-8-PDMS had lower extent of protein aggregation and twice catalytic efficiency (Vmax/Km) than ANL@M-ZIF-8.ConclusionsHydrophobic pore space constituted in macroporous ZIF-8 for lipase immobilization greatly improved lipase catalytic performance in biodiesel preparation. The hydrophobic modification time showed negligible influence on the reusability of the immobilized lipase. This work broadened the prospect of immobilization of enzyme on MOFs with some inspiration.

Miscibility and mass transfer in biodiesel production observed by LCD digital microscope

The mutual solubilities of multiple components in the transesterification reaction are among the key factors affecting biodiesel production. In the experiments, refined palm oil (RPO) and fatty acid methyl ester (FAME) were the main reactants, and methanol was added. Sodium methoxide and sulfuric acid were used as alkaline and acid catalysts, respectively. The co-solvent, tetrahydrofuran (THF), was used to improve solubility. Visual observations with an LCD digital microscope were done at room temperature to eliminate methanol loss. A concave slide glass was employed as a micro-reactor for observing mass transport in the reaction zone. The imaging results showed that the multi-component reactions in biodiesel production were of heterogeneous liquid-liquid type. The by-products glycerol and soap play significant roles as reaction barrier and suspension component in the system, while the added THF did not induce complete solubility. The kinetics of heterogeneous liquid-liquid transesterification or esterification reactions should be revised to properly account for both mass transfer and chemical reactions. Multistage combinations of separation of the alcohol phase and of new alcohol intake should be employed to reduce mass transfer resistances by glycerol and soap, to speed up overall kinetics.

Interesterification of rapeseed oil with methyl acetate in the presence of potassium tert-butoxide solution in tetrahydrofuran

Production of biodiesel (FAME) via transesterification of triglycerides with methanol in the presence of basic catalysts has largely increased over time despite the low value of the by-product glycerol. Interesterification of the same feedstock with methyl acetate allows to obtain biofuel with higher yield, as the by-product of this reaction, i.e. triacetin, can be included into the fuel composition. Investigation of interesterification with methyl acetate to oil molar ratio 18 at 55 °C during 1 h in presence of potassium tert-butoxide solution in tetrahydrofuran shows that after catalyst to oil molar ratio 0.1 slow increase of FAME and a decrease of triacertin content occur. Variation of catalyst to oil molar ratio does not allow to lower the content of intermediates below 19 wt%. An increase of methyl acetate to oil molar ratio from 18 to 65 reduces the mass fraction of intermediates to 9.5% and FAME to triacetin mass ratio to 5.2. The fuel characteristics of obtained products are close to or comply with the requirements of LVS EN 14214, excluding the requirements for FAME and intermediate content and density. The optimal region of methyl acetate to oil molar ratio as the reasonable compromise between the yield of the target products and removable excess of reactant could be from 24 to 40.

Net energy and techno-economic assessment of biodiesel production from waste cooking oil using a semi-industrial plant: A Malaysia perspective

To promote the growth of the biodiesel industry, many countries have started allocating initial inducements to start-up companies to set up the infrastructure for its production facilities. Thus, comprehensive economic assessments are vital to keeping businesses on the right track in the long run. In this present study, net energy ratio (NER) and macroeconomic assessment are investigated using actual data obtained from biodiesel production from waste cooking oil (WCO) by using a semi-industrial plant. The fuel quality produced has complied with the European Biodiesel Standard (EN 14214) and the net energy ratio (NER) calculated was positive, which, in other words, epitomized a competent-designed production practice. Concerning mass balance, 74.3% of biodiesel, 24.0% of by-product glycerol and 8.9% soap were measured. By applying these as baseline values for scale-up production of 3.68 kt per annum, projected values of total production costs, selling price of B10 fuel, net present value (NPV) and internal rate of return (IRR) were USD 1.78 million, USD 0.47/kg, USD 1.43 million and 60%, respectively. In summary, these projected values are suggestively lucrative, offering strong business growth for 10 years and capable of withstanding the variations of plant capacity and raw material price.

Physiochemical properties evaluation of Calophyllum inophyllum biodiesel for gas turbine application

The devastating phenomenon of depletion of fossil fuel and environmental pollution have caught global concern to explore for alternative fuel resources that could meet human demand. Due to the properties that match diesel fuel properties, biodiesel appears to be one of the plausible resources due to the many advantages it provides compared to the conventional petroleum-diesel. Recently, non-edible oil receives worldwide attention compared to edible feedstock in producing biodiesel. Among the many privileges provided by non-edible Calophyllum inophyllum plant include useful by-products (glycerol), environmental friendly, ability to reduce the competition for food and more economical feedstock. Besides the application in the diesel engine, biodiesel could be a promising substitute to distillate fuel for power generation sector. Gas turbine develops steady flame during its combustion and this feature gives the flexibility of wide range of fuel selection including biodiesel for gas turbine. Therefore, the use of biodiesel in gas turbine seems a viable solution for the problems. This paper aims to evaluate the physiochemical properties of C. inophyllum (CI) biodiesel for gas turbine application. The properties of C. inophyllum methyl ester was obtained to evaluate its potential in gas turbine application according to the fuel selection standard for gas turbine; ASTM D2880. The evaluation result show that C. inophyllum biodiesel may be pursued as an alternative fuel in gas turbine.

Tri‐component coupling transesterification for efficient no‐glycerol biodiesel production using methyl acetate as methyl reagent

AbstractBACKGROUNDConventional transesterification of vegetable oil with methanol for biodiesel production leads to the separation of glycerol and relatively low reaction efficiency. Methyl acetate is a more common solvent being less toxic and less soluble in water. In the presence of bases the transesterification of methyl acetate with glycerol can easily proceed at refluxing temperature.RESULTSA yield of fatty acid methyl ester (FAME) of 98.0% can be obtained with oil/methyl acetate/methanol molar ratio of 1:1:8 and 10% dosage of KCl/CaO at 65 °C after reaction for 1 h. Furthermore, results of water resistance experiments indicated that trace water gave a promoting effect on FAME yield. Recycling experiments were conducted for four cycles and a greater than 90% yield of FAME indicated the high stability of KCl/CaO.CONCLUSIONSEfficient biodiesel production with no glycerol byproduct has been developed using a tri‐component (canola oil, methyl acetate and methanol) coupling chemical reaction with calcium oxide‐supported chloride as catalyst. Various characterization techniques revealed that the unique catalytic activity of KCl/CaO was related to its high degree of crystallinity, relatively high surface basicity and large pore size. © 2019 Society of Chemical Industry

Conversion of Crude Glycerol from by-Product Biodiesel into Bio-additive of Fuel through Acetylation Reaction based on Modified Zeolite Catalyst

<p class="BodyAbstract">Biodiesel is one of the alternative fuels produced from the transesterification reaction between triglycerides and alcohols with glycerol by-products. So far, the resulting crude glycerol has not been maximally utilized because of its low purity. So, it is necessary to purify glycerol before turning it into a more useful compound. The purified glycerol can be reacted with acetic acid within esterification reaction (acetylation process) using an acid catalyst to produce glycerol triacetate (triacetin). One of the uses of triacetin as an additive in gasoline and biodiesel. The purpose of this study is to utilize glycerol from by-products from biodiesel production to bio-additive materials that can improve fuel quality and are environmentally friendly. The method used in this study begins with the purification of crude glycerol, modification of zeolite catalyst with impregnated of nickel metal followed by an acetylation reaction which held on temperature of 100°C for 60 min. The experimental results are analyzed using base titration to determine the remaining unreacted acids and are applied as bio-additives by adding them to commercial fuels and measured the increasing octane numbers. The result shows that the reaction conversion increases with increasing mole ratio of reactants and catalysts with the best results in the mole ratio of acetic acid and glycerol is 9:1 and catalyst 5% by weight of acetic acid with a conversion of 66.02%. As bio-additives the reaction product could increase the octane number of commercial fuel by 6.5 up to 8.5%.</p><p> </p>Keywords: glycerol, acetylation reaction, mofified zeolite, bio-additive

Delignification of softwood by glycerol from biodiesel by-product I: model reaction using glycerol and fatty acid sodium soap mixture for pretreatment on bioethanol production

This study investigated the use of glycerol–fatty acid sodium soap mixtures to delignify woody biomass as a model for utilization of crude glycerol by-product from biodiesel manufacture. Lignin-bearing glycerol was also produced. Delignification was carried out using glycerol mixed with sodium salts of laurate, stearate, oleate, or linoleate at 100–250 °C for 0.5–3 h. Oak, beech, bamboo, and rice straw were easily delignified by 20% sodium oleate dissolved in glycerol at around 150 °C for 1 h. For softwood (Japanese cedar and spruce), delignification did not occur below 200 °C. However, the lignin content decreased from 37.5% in untreated Japanese cedar to 10.6% and from 29.4% in untreated spruce to 11.2% by treatment at 250 °C. Japanese cedar was not delignified in glycerol mixtures with oleic acid or sodium acetate. It is suggested that the surfactant activity of soap assists delignification, but the alkaline action of sodium acetate was not effective. Enzymatic saccharification of delignified Japanese cedar (9.3% lignin) and oak (3.6% lignin) samples gave glucose yields of 0.55–0.67 g/g after 72 h and these yields were comparable with that from pure cellulose (0.77 g/g). Lignin dissolution also increased the calorific value of the collected glycerol fraction from 20 to 25 MJ/kg. The results suggest that a waste-free delignification method can be achieved based on the combined processes of biodiesel and bioethanol production.

The influence of PO4 to bio-silica catalyst on synthesis benign additive fuel

Fuel additive solketal can be produced through acetalization reaction of biodiesel by-product (glycerol) and acetone. This reaction was conducted over acidified silica derived from sustainable bioresource rice husk in a batch reactor under the solvent-free condition. The chemical and structural properties of the prepared catalyst were studied by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), N2 adsorption/desorption isotherms, temperature-programmed desorption of ammonia (NH3-TPD) and scanning electron microscope (SEM). Based on this paper, the optimized conditions using 15% phosphoric acid acidified silica extracted from rice husk ash (10 wt.% PO4 loaded SiO2) are 50 °C (lower temperature) with the molar ratio of acetone: glycerol= 2. Reusability test used to examine the stability of the catalytic activity was investigated. This effort is a serious step for development and taking apart of solketal as the main product from glycerol and acetone by using waste resources.

Valorizing kitchen waste through bacterial cellulose production towards a more sustainable biorefinery

In this work, water washing pretreatment was employed on kitchen waste (KW) to integrate a multi-product biorefinery process for producing biogas, biodiesel, bacterial cellulose (BC) and biofertilizer. As a crucial stream in this biorefinery process, BC production were investigated to clarify the effects of residual salt and cooked oil. Meanwhile, glycerol, a by-product in biodiesel stream, as carbon source was attempted to produce BC. Results indicated that BC yield was significantly promoted from 0.11 g L−1 to 2.07 g L−1 as NaCl content decreased from 0.44% to 0.04%. Correspondingly, the BC crystallinity increased from 30.1% to 57.4% and the tensile strength increased from 3.30 MPa to 21.64 MPa. In addition, the residual cooked oil didn't affect the BC yield significantly, however, the crystallinity was greatly decreased from 57.4% to 34.5% as more cooked oil was remained in the medium of KW, and the tensile strength was decreased from 21.64 MPa to 4.30 MPa, correspondingly. Obviously, reducing the salt and cooked oil content in the starch fraction of KW by intensifying the water washing pretreatment will greatly benefit the BC yield and qualities. When the glycerol from biodiesel stream was employed for BC production with content of 10 g L−1–25 g L−1, 34.2%–44.0% increase on BC yield can be achieved. By contrast, extra higher glycerol content (50 g L−1) reduced the BC yield by 41%. However, the crystallinity and the tensile strength were increased by 18% and 2.2-folds, respectively. Therefore, the biodiesel stream can be well integrated in the process via producing BC with by-product of glycerol as a replaceable carbon source. Based on the results above, a more sustainable biorefinery process of KW via BC production can be achieved, which will potentially offer a new path to valorize the daily-released KW.

US FDA targets 19 chemicals in e-cigs

The US Food and Drug Administration is proposing to add 19 chemicals to its list of harmful and potentially harmful constituents (HPHCs) in tobacco products. The 19 chemicals are specific to electronic nicotine delivery systems, such as e-cigarettes and e-liquids. The substances include diacetyl, a buttery-tasting flavoring agent; ethylene glycol, sometimes used as a solvent in e-liquids; and glycidol, a thermal by-product of glycerol found in e-cigarette vapor. The agency’s initial list of HPHCs, established in 2012, contains 93 chemicals found in tobacco products or tobacco smoke. Researchers have linked the chemicals to cancer, addiction, and cardiovascular, respiratory, and reproductive diseases. The FDA did not have the authority to regulate e-cigarettes when that list was established. “As our oversight and scientific knowledge of tobacco products has evolved, so too should our requirements for manufacturers and importers,” FDA acting commissioner Ned Sharpless says in a statement. Manufacturers and ...