THE SEARCH FOR POLYMERS THAT MEET THE DEMANDS OF THE WATER RECOVERY PROCESS IN MINING IS A CONTINGENT CHALLENGE. BOTH THE PRESENCE OF CLAYS AND SALINE WATERS CAN IMPAIR WATER RECOVERY FROM TAILINGS WHEN CONVENTIONAL FLOCCULANTS ARE USED. IN THIS WORK, THE ADSORPTION OF POLYACRYLAMIDE (PAM), HYDROLYZED POLYACRYLAMIDE (HPAM), POLY(2-ACRYLAMIDO-2-METHYL-1-PROPANE SULFONIC ACID) (PAMPS), POLYACRYLIC ACID (PAA), POLYETHYLENE OXIDE (PEO), AND GUAR GUM (GUAR) ON A KAOLINITE SURFACE (010) WAS INVESTIGATED USING CLASSICAL MOLECULAR DYNAMICS. THE RESULTS SHOW THAT THE PRESENCE OF SODIUM CHLORIDE MODIFIES THE AFFINITIES OF THE POLYMERS WITH KAOLINITE (010). AT LOW SALT CONCEN-TRATIONS, THE PAM AND GUAR POLYMERS GENERALLY SHOW HIGHER ADSORPTION DUE TO THE FORMATION OF HYDROGEN BRIDGES. HOWEVER, THE HIGHEST ADSORPTIONS OCCUR IN SALT SOLUTIONS IN THE PRESENCE OF HPAM BY CATIONIC BRIDGING WITH SODIUM IONS AS A MEDIATOR. THIS HIGH AFFINITY OF HPAM IS NOT EFFICIENT FOR FLOCCULATION BECAUSE IT RE-DISPERSES THE PARTICLES, BUT IT IS PROMISING FOR THE DESIGN OF NEW ADDITIVES PRODUCED BY GRAFTING HPAM GROUPS ONTO ADVANCED POLYMERS.

THE MOLECULAR STRUCTURE OF THE LIQUID?VAPOR INTERFACES OF AQUEOUS SOLUTIONS OF ALKALI METAL HALIDES AND METHYL ISOBUTYL CARBINOL (MIBC, (CH3)2CHCH2COCH3) IS DETERMINED BY USING MOLECULAR DYNAMICS SIMULATIONS WITH POLARIZABLE FORCE FIELDS FOR THE FIRST TIME. THE SALTS ARE CHLORIDES, AND IODIDES, SOME OF WHICH ARE FOUND IN RAW AND PARTIALLY DESALINATED SEAWATER INCREASINGLY USED IN FLOTATION OPERATIONS IN REGIONS AFFECTED BY SEVERE AND PROLONGED DROUGHT. THE DENSITY PROFILES AT THE INTERFACES SHOW THAT ALL IONS PREFER THE INTERFACE; HOWEVER, WITH MIBC, NON-POLARIZABLE IONS, GENERALLY SMALL ONES, ARE INCREASINGLY PUSHED INTO THE LIQUID BULK. A FEW IONS OF COMPARATIVELY LESS IONIC NACL THAN KCL AND CSCL, PERSIST AT THE INTERFACE, CONSISTENT WITH SPECTROSCOPY OBSERVATIONS. ON THE OTHER HAND, STRONGLY POLARIZABLE IONS SUCH AS I? ALWAYS SHARE THE INTERFACE WITH MIBC. IN THE PRESENCE OF CHLORIDES, THE FROTHER CHAINS AT THE INTERFACE STRETCH SLIGHTLY MORE TOWARD VAPOR THAN IN FRESHWATER; HOWEVER, IN THE PRESENCE OF IODIDES, THE CHAINS STRETCH SO MUCH THAT THEY BECOME ORTHOGONAL TO THE INTERFACE, GIVING RISE TO A WELL-PACKED MONOLAYER, WHICH IS THE MOST EFFECTIVE CONFIGURATION. THE DOMINANT WATER CONFIGURATIONS AT THE INTERFACE ARE DOUBLE DONOR AND SINGLE DONOR, WITH HYDROGEN ATOMS POINTING TOWARD THE LIQUID, CONSISTENT WITH STUDIES WITH SUM-FREQUENCY GENERATION EXPERIMENTS AND EXTENSIVE AB INITIO SIMULATIONS. THIS PICTURE CHANGES RADICALLY IN THE PRESENCE OF MIBC AND SALTS. DEPENDING ON THE HALIDE AND MIBC CONCENTRATION, THE DIFFERENT MOLECULAR CONFIGURATIONS AT THE INTERFACE LEAD TO VERY DIFFERENT SURFACE TENSIONS. THE STRUCTURE AND PROPERTIES OF THESE NEW SALT-RICH INTERFACES AND THEIR IMPACT ON THE LOCATION AND ARRANGEMENT OF FROTHER MOLECULES SHOULD SERVE THE FLOTATION PRACTITIONER, ESPECIALLY IN THE SEARCH FOR THE BEST FROTHER AND DOSING IN POOR-QUALITY WATER

EL APRENDIZAJE BASADO EN EQUIPOS O POR SUS SIGLAS EN INGLÉS CONOCIDO COMO: TEAM BASED LEARNING (TBL), ES UNA METODOLOGÍA DE APRENDIZAJE ACTIVA, DONDE EL ESTUDIANTADO CONSTRUYE EL CONOCIMIENTO A PARTIR DE TAREAS QUE DESARROLLAN EN EQUIPOS DINÁMICOS, ASUMIENDO UN ROL PARTICIPATIVO. ESTA METODOLOGÍA FUE APLICADA EN ESTUDIANTES DE PREGRADO DEL CURSO DE BALANCES DE MATERIA Y ENERGÍA PERTENECIENTES AL PROGRAMA DE INGENIERÍA CIVIL QUÍMICA DE LA UNIVERSIDAD DEL BÍO-BÍO, CHILE. TBL FUE IMPLEMENTADO CON EL PROPÓSITO DE FACILITAR EL TRABAJO EN EQUIPO, Y MEJORAR EL DESEMPEÑO DEL ESTUDIANTADO CON RESPECTO A LAS TRADICIONALES CLASES MAGISTRALES. EL TRABAJO FUE DESARROLLADO EN LA ÚLTIMA UNIDAD TEMÁTICA DEL CURSO PARA LOS AÑOS 2014 Y 2016 Y FUE CONTRASTADO CON LOS RESULTADOS ALCANZADOS EN LOS AÑOS 2015 Y 2017, AÑOS EN LOS CUALES NO SE APLICÓ LA METODOLOGÍA. LOS RESULTADOS EVIDENCIAN QUE LAS CALIFICACIONES FINALES PROMEDIO PARA EL CURSO ALCANZARON SU VALOR MÁS ALTO EN EL AÑO 2016 (4.9), AÑO EN EL CUAL SE IMPLEMENTÓ LA METODOLOGÍA POR SEGUNDA VEZ. DE IGUAL MANERA LAS CALIFICACIONES EN ESTA UNIDAD FUERON EN PROMEDIO 6.5 Y 6.6 PARA LOS AÑOS 2014 Y 2016 FRENTE A 6.0 Y 4.9 PARA LOS AÑOS 2015 Y 2017 RESPECTIVAMENTE (EN UNA ESCALA DE PUNTUACIONES QUE TIENE COMO VALOR MÍNIMO 1.0 HASTA UN MÁXIMO DE 7.0). LOS RESULTADOS DEL CUESTIONARIO DE PERCEPCIÓN REVELAN QUE LA METODOLOGÍA FACILITA EL TRABAJO EN EQUIPO, FORMANDO UN AMBIENTE COOPERATIVO DE TRABAJO, DONDE MÁS DEL 90% DEL ESTUDIANTADO MANIFESTÓ ESTAR CONFORME CON LA METODOLOGÍA.

THE EFFECT OF FOAMING AGENTS, OR FROTHERS, ON THE WATER-LIQUID-VAPOR INTERFACE IS STUDIED THROUGH MOLECULAR DYNAMICS AT DIFFERENT FROTHER CONCENTRATIONS. THE FROTHERS ARE ALIPHATIC ALCOHOL-BASED, SUCH AS HEXANOL, METHYL ISOBUTYL CARBINOL (MIBC), AND OCTANOL, AND POLYGLYCOL POLYMER-BASED, SUCH AS DF-200 AND DF-250. THE AIM IS TO DELVE INTO THE STABILITY THEY CONFER TO THE INTERFACES THEY PARTICIPATE IN AND ELUCIDATE SOME OF THE DIFFERENCES BETWEEN THESE TWO TYPES OF WIDELY USED FROTHERS. THE RESULTS INDICATE THAT FROTHERS AT THE INTERFACE TEND TO BE LOCATED OUTSIDE THE LIQUID PHASE TOWARDS THE HIGH-DENSITY VAPOR PHASE AND THAT THIS BEHAVIOR IS MORE PRONOUNCED IN POLYGLYCOL-BASED FROTHERS. THE STRUCTURE OF WATER IS MOST AFFECTED BY POLYGLYCOL-TYPE FROTHERS WHOSE POLAR GROUPS INDUCE THE WATER TO ADOPT ORIENTATIONS THAT MAXIMIZE HYDROGEN BONDING. THIS EFFECT INCREASES WITH CONCENTRATION. UNLIKE ALCOHOLS, WHICH PRODUCE THIN AND DRY INTERFACES WITH STABILITY DETERMINED BY THE REPULSION OF THEIR POLAR HEADS, POLYGLYCOL-BASED FROTHERS PRODUCE THICKER INTERFACES WITH STRUCTURED-WATER WHOSE STABILITY IS DETERMINED BY AN EXTENDED NETWORK OF HYDROGEN BONDS THAT PRODUCES WATER LAMELLAE AND PLATEAU BORDERS BETWEEN BUBBLES, PREVENTING COALESCENCE. THE RESULTS SUGGEST THAT HYDROGEN BONDING IN POLYGLYCOLS PREVAILS OVER THE OTHER EXISTING MOLECULAR FORCES IN STABILIZING THE FROTH ZONE.

THE IMPACT OF SALTS ON PARTIALLY HYDROLYZED POLYACRYLAMIDE (HPAM) IS OF GREAT INTEREST IN MINERAL PROCESSING, CONSIDERING THAT THE USE OF SEAWATER SEEMS TO BE THE ONLY SUSTAINABLE SOLUTION IN REGIONS WITH SEVERE ARIDITY. HERE THE CONFORMATION AND TRANSPORT OF AN HPAM CHAIN IN SEVERAL SALINE SOLUTIONS ARE STUDIED BY MEANS OF MOLECULAR DYNAMICS SIMULATIONS. RESULTS INDICATE THAT THE ELECTROSTATIC REPULSION BETWEEN ANIONIC ACRYLATE UNITS CAUSES THE POLYMER TO ADOPT DIVERSE AND COMPLEX EXPANDED TERTIARY CONFORMATIONS, HOWEVER IN THE PRESENCE OF CATIONS THIS REPULSION IS SHIELDED CAUSING THE POLYMER TO FOLD INTO BALLED-UP CONFORMATIONS. THE STRUCTURE ASSUMED BY THE HPAM CHAIN DEPENDS SLIGHTLY ON THE TYPE OF CATION AND MUCH ON INTRAMOLECULAR CROSSLINKING. CATIONS INFLUENCE THE ORDERING OF WATER STRUCTURE AND ORIENTATION OF WATER DIPOLES REDUCING THE MOBILITY OF WATER, IONS, AND HPAM. THESE RESULTS ARE EXPECTED TO CONTRIBUTE TO A BETTER UNDERSTANDING OF PARTICLE FLOCCULATION FOR SUSTAINABLE WATER MANAGEMENT.

POLYMERS HAVE INTERESTING PHYSICOCHEMICAL CHARACTERISTICS SUCH AS CHARGE DENSITY, FUNCTIONALITIES, AND MOLECULAR WEIGHT. SUCH ATTRIBUTES ARE OF GREAT IMPORTANCE FOR USE IN INDUSTRIAL PURPOSES. UNDERSTANDING HOW THESE CHARACTERISTICS ARE AFFECTED IS STILL COMPLEX, BUT WITH THE HELP OF MOLECULAR DYNAMICS (MD) AND QUANTUM CALCULATIONS (QM), IT IS POSSIBLE TO UNDERSTAND THE BEHAVIOR OF POLYMERS AT THE MOLECULAR LEVEL WITH GREAT CONSISTENCY. THIS STUDY WAS APPLIED TO POLYMERS DERIVED FROM POLYACRYLAMIDE (PAM) DUE TO ITS GREAT USE IN VARIOUS INDUSTRIES. THE POLYMERS STUDIED INCLUDE HYDROLYZED POLYACRYLAMIDE (HPAM), POLY (2-ACRYLAMIDO-2-METHYLPROPANESULFONATE) (PAMPS), POLYACRYLIC ACID (PAA), POLYETHYLENE OXIDE POLYMER (PEO), AND GUAR GUM POLYSACCHARIDE (GUAR). EACH ONE HAS DIFFERENT ATTRIBUTES, WHICH HELP IN UNDERSTANDING THE EFFECTS ON THE POLYMER AND THE MEDIUM IN WHICH IT IS APPLIED ALONG A BROAD SPECTRUM. THE RESULTS INCLUDE THE CONFORMATION, DIFFUSION, ION CONDENSATION, THE STRUCTURE OF THE WATER AROUND THE POLYMER, AND INTERATOMIC POLYMER INTERACTIONS. SUCH CHARACTERISTICS ARE IMPORTANT TO SELECTING A POLYMER DEPENDING ON THE ENVIRONMENT IN WHICH IT IS FOUND AND ITS PURPOSE. THE EFFECT CAUSED BY SALINITY IS PARTICULAR TO EACH POLYMER, WHERE POLYMERS WITH AN EXPLICIT CHARGE OR POLYELECTROLYTES ARE MORE SUSCEPTIBLE TO CHANGES DUE TO SALINITY, INCREASING THEIR COILING AND REDUCING THEIR MOBILITY IN SOLUTION. THIS NATURALLY REDUCES ITS ABILITY TO FORM POLYMERIC BRIDGES DUE TO HAVING A POLYMER WITH A SMALLER GYRATION RADIUS. IN CONTRAST, NEUTRAL POLYMERS ARE LESS AFFECTED IN THEIR STRUCTURE, MAKING THEM FAVORABLE IN MEDIA WITH HIGH IONIC CHARGES.

RECENT RESEARCH PROVES THAT PYROLYTIC OILS FROM WASTE TIRES ARE EFFECTIVE IN RESTORING THE CHEMICAL AND RHEOLOGICAL PROPERTIES OF AGED ASPHALT BINDERS. NONETHELESS, THE ROLE OF OIL-BINDER MOLECULAR INTERACTIONS AND BINDE?S AGING DEGREE ON THE DIFFUSIONAL BEHAVIOR OF THE PYRO-OILS IS STILL UNCLEAR. IN THIS STUDY, AUTHORS PROPOSE INTEGRATING OPERANDO FOURIER TRANSFORMED INFRARED SPECTROSCOPY (FTIR) MEASUREMENTS WITH MOLECULAR DYNAMICS (MD) SIMULATIONS AS A NOVEL APPROACH TO UNRAVEL THE DIFFUSION MECHANISMS OF PYRO-OILS IN ASPHALT BINDERS WITH SELF-HEALING PURPOSES. THE PRODUCED PYRO-OILS CONTAINS ALIPHATIC AND SINGLE-RING ALKYL AROMATIC COMPOUNDS AS THE MOST ABUNDANT SPECIES (CA. 80%). THE OPERANDO FTIR MEASUREMENTS WERE CORRELATED BY A FICKIAN MODEL, RESULTING IN DIFFUSION COEFFICIENTS (D0) BETWEEN 10-12 AND 10-11 M2S?1. MOREOVER, MD SIMULATIONS, WITH A MOLECULAR MODEL OF AGED ASPHALT CONTAINING BENZYLIC RINGS, SULFOXIDES, AND HYDROXYL FUNCTIONAL GROUPS, DEMONSTRATED THAT INTERACTIONS OF FUNCTIONAL GROUPS IN THE PYRO-OIL WITH THE BINDER, HINDER THE DIFFUSION BEHAVIOR OF THE PYRO-OIL. THE D0 ESTIMATED FROM THE MD SIMULATIONS AGREED WITH THOSE CALCULATED FROM EXPERIMENTAL DATA AND PREVIOUS REPORTS FOR PETRO- AND BIO-DERIVED REJUVENATORS. THE PREDICTIVE PERFORMANCE OF THE MD SIMULATIONS DEVELOPED IN THIS STUDY CONFIRMS TO DESIGN OF MORE RESILIENT SELF-HEALING ASPHALT BINDERS USING A BOTTOM-UP STRATEGY.

THIS WORK AIMS TO UNDERSTAND HOW RELEVANT PROPERTIES OF POLYMERS LEAD TO DIFFERENT ADSORPTION MODES ON A QUARTZ SURFACE (1 0 1). FOR THIS PURPOSE, SIX POLYMERS WERE CONSIDERED: POLYACRYLAMIDE (PAM), HYDROLYZED POLYACRYLAMIDE (HPAM), POLY(2-ACRYLAMIDO-2-METHYL-1-PROPANESULFONIC ACID) (PAMPS), POLYACRYLIC ACID (PAA), POLYETHYLENE OXIDE (PEO) AND GUAR GUM (GUAR). THE REAGENTS HAVE DIVERSE PHYSICOCHEMICAL PROPERTIES, WITH DIFFERENCES IN CHARGE DENSITY, STRUCTURE, AND FUNCTIONAL GROUPS. CLASSICAL MOLECULAR DYNAMICS (CMD) SIMULATIONS WERE PERFORMED WITH THE GENERALIZED AMBER FORCE FIELD (GAFF). THE RESULTS CLEARLY DISTINGUISH THE DIFFERENT BEHAVIORS OF CHARGED POLYMERS WITH RESPECT TO NEUTRAL POLYMERS AND THEIR RELEVANCE TO THE ADSORPTION MODES AND THE CONFORMATION OF THE POLYMER ON THE SURFACE. THE HIGHEST AFFINITY WAS ACHIEVED IN NEUTRAL POLYMERS, THIS CONSIDERING THAT QUARTZ IS WEAKLY CHARGED AT PH 7. CHARGED POLYMERS ADSORB BUT IN STRETCHED CONFORMATIONS LEAVING THE TAILS OF THE POLYMERS AWAY FROM THE SURFACE, WHICH IS BENEFICIAL TO PRODUCING POLYMER BRIDGES. SALINITY CAN IMPAIR OR BENEFIT THE ADSORPTION OF REAGENTS, DEPENDING MAINLY ON THEIR ELECTRICAL CHARGE. THIS STUDY HELPS TO UNDERSTAND THE CRITICAL FACTORS OF A FLOCCULANT IN THE SEARCH FOR NEW ADDITIVES FOR MINERAL AGGREGATION AND DISPERSION APPLICATIONS, A TOPIC OF SPECIAL RELEVANCE IN SOLID-LIQUID SEPARATION OPERATIONS IN THE MINING INDUSTRY.

EL CRECIMIENTO DEMOGRÁFICO, EL CAMBIO CLIMÁTICO, EL AUMENTO DE LA CONTAMINACIÓN, Y EL CRECIMIENTO ECONÓMICO PRESIONAN CADA VEZ MÁS SOBRE EL RECURSO AGUA PROVOCANDO ESCASEZ Y ESTRÉS HÍDRICO. EN MUCHAS REGIONES EL MUNDO, CHILE EN PARTICULAR, EL FENÓMENO ES VISIBLE. LA ESCASEZ DE AGUA, LA NECESIDAD VITAL DE UNA GESTIÓN QUE GARANTICE LA SEGURIDAD HÍDRICA, EN SU ACEPCIÓN MÁS COMPLETA QUE INCLUYE EL ACCESO AL AGUA PARA UN DESARROLLO ADECUADO QUE FOMENTE EL PROGRESO Y EVITE EL SURGIMIENTO DE CONFLICTOS, Y LEGISLACIONES MODERNAS CADA VEZ MÁS EXIGENTES, HAN IMPULSADO EL USO DE AGUAS TAN SALADAS COMO EL AGUA DE MAR, EN FORMA DIRECTA O PARCIALMENTE DESALADA EN PROCESOS Y FILTRADA PARA LAS PERSONAS. UN PROBLEMA ASOCIADO QUE RECIBE MUCHO MENOR ATENCIÓN ES EL DEPÓSITO DE SALES Y SU INCRUSTACIÓN EN LAS SUPERFICIES DE UNIDADES DE PROCESO, CON CONSECUENCIAS DESASTROSAS COMO PÉRDIDA DE INFRAESTRUCTURA, DISMINUCIÓN DE PRODUCTIVIDAD Y PÉRDIDA DE CALIDAD DE PRODUCTOS. EN ESTA SERIE COMUNICACIONAL SE ABORDA EL PROBLEMA DE LA FORMACIÓN DE DEPÓSITOS E INCRUSTACIONES; LAS BASES QUE PERMITEN COMPRENDER LOS CONCEPTOS DE SOLUBILIDAD, SATURACIÓN Y SOBRESATURACIÓN; LOS MECANISMOS DE FORMACIÓN DE INCRUSTACIONES HOMOGÉNEAS Y HETEROGÉNEAS; LOS TIPOS DE INCRUSTACIONES Y LOS FACTORES QUE PROMUEVEN SU APARICIÓN, ENTRE ELLOS SOBRESATURACIÓN, TEMPERATURA, PH, PRESIÓN, FORTALEZA IÓNICA Y EVAPORACIÓN; EL MANEJO DE LAS INCRUSTACIONES INCLUYENDO SU ESTUDIO, MONITOREO, REPARACIÓN Y PREVENCIÓN; Y, FINALMENTE, LA FORMA DE COMBATIRLOS, QUE INCLUYE ANTI-INCRUSTANTES ?VERDES? DISEÑADOS EN COMPUTADOR MEDIANTE SIMULACIÓN MOLECULAR Y EN LABORATORIO MEDIANTE ROBOTS QUÍMICOS Y COMPUTADORES QUÍMICOS LLAMADOS CHEMPUTERS.

METHYL ISOBUTYL CARBINOL (MIBC) IS A HIGH-PERFORMANCE SURFACTANT WITH UNUSUAL INTERFACIAL PROPERTIES MUCH APPRECIATED IN INDUSTRIAL APPLICATIONS, PARTICULARLY IN MINERAL FLOTATION. IN THIS STUDY, THE STRUCTURE OF AIR?LIQUID INTERFACES OF AQUEOUS SOLUTIONS OF MIBC-NACL IS DETERMINED BY USING MOLECULAR DYNAMICS SIMULATIONS EMPLOYING POLARIZABLE AND NONPOLARIZABLE FORCE FIELDS. DENSITY PROFILES AT THE INTERFACES AND SURFACE TENSION FOR A WIDE RANGE OF MIBC CONCENTRATIONS REVEAL THE KEY ROLE OF POLARIZABILITY IN DETERMINING THE SURFACE SOLVATION OF CL? IONS AND THE EXPULSION OF NON-POLARIZABLE NA+ IONS FROM THE INTERFACE TO THE LIQUID BULK, IN AGREEMENT WITH SPECTROSCOPIC EXPERIMENTS. THE ORIENTATION OF MIBC MOLECULES AT THE WATER LIQUID?VAPOR INTERFACE CHANGES AS THE CONCENTRATION OF MIBC INCREASES, FROM PARALLEL TO THE INTERFACE TO PERPENDICULAR, LEADING TO A WELL-PACKED MONOLAYER. SURFACE TENSION CURVES OF FRESH WATER AND AQUEOUS NACL SOLUTIONS IN THE PRESENCE OF MIBC INTERSECT AT A REPRODUCIBLE SURFACTANT CONCENTRATION FOR A WIDE RANGE OF SALT CONCENTRATIONS. THE SIMULATION RESULTS FOR A 1 M NACL AQUEOUS SOLUTION WITH POLARIZABLE WATER AND IONS CLOSELY CAPTURE THE MIBC CONCENTRATION AT THE INTERCEPT. THE INCREASE IN SURFACE TENSION OF THE AQUEOUS MIBC/NACL MIXTURE BELOW THE CONCENTRATION OF MIBC AT THE INTERSECTION SEEMS TO ORIGINATE IN A DISTURBANCE OF THE INTERFACIAL HYDROGEN BONDING STRUCTURE OF THE SURFACE LIQUID WATER CAUSED BY NA+ IONS ACTING AT A DISTANCE AND NOT BY ITS PRESENCE ON THE INTERFACE.